diff mbox series

lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()

Message ID 163294304032.208242.9097581875096098591.stgit@olly (mailing list archive)
State Accepted
Delegated to: Paul Moore
Headers show
Series lsm: security_task_getsecid_subj() -> security_current_getsecid_subj() | expand

Commit Message

Paul Moore Sept. 29, 2021, 7:17 p.m. UTC 
The security_task_getsecid_subj() LSM hook invites misuse by allowing
callers to specify a task even though the hook is only safe when the
current task is referenced.  Fix this by removing the task_struct
argument to the hook, requiring LSM implementations to use the
current task.  While we are changing the hook declaration we also
rename the function to security_current_getsecid_subj() in an effort
to reinforce that the hook captures the subjective credentials of the
current task and not an arbitrary task on the system.

Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 include/linux/lsm_hook_defs.h         |    3 +--
 include/linux/lsm_hooks.h             |    8 +++-----
 include/linux/security.h              |    4 ++--
 kernel/audit.c                        |    4 ++--
 kernel/auditfilter.c                  |    3 +--
 kernel/auditsc.c                      |   10 +++++++++-
 net/netlabel/netlabel_unlabeled.c     |    2 +-
 net/netlabel/netlabel_user.h          |    2 +-
 security/apparmor/lsm.c               |   13 ++++++++++---
 security/integrity/ima/ima_appraise.c |    2 +-
 security/integrity/ima/ima_main.c     |   14 +++++++-------
 security/security.c                   |    6 +++---
 security/selinux/hooks.c              |   19 +++----------------
 security/smack/smack.h                |   16 ----------------
 security/smack/smack_lsm.c            |    9 ++++-----
 15 files changed, 48 insertions(+), 67 deletions(-)

Comments

Paul Moore Sept. 29, 2021, 7:19 p.m. UTC | #1 
On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>
> The security_task_getsecid_subj() LSM hook invites misuse by allowing
> callers to specify a task even though the hook is only safe when the
> current task is referenced.  Fix this by removing the task_struct
> argument to the hook, requiring LSM implementations to use the
> current task.  While we are changing the hook declaration we also
> rename the function to security_current_getsecid_subj() in an effort
> to reinforce that the hook captures the subjective credentials of the
> current task and not an arbitrary task on the system.
>
> Signed-off-by: Paul Moore <paul@paul-moore.com>
> ---
>  include/linux/lsm_hook_defs.h         |    3 +--
>  include/linux/lsm_hooks.h             |    8 +++-----
>  include/linux/security.h              |    4 ++--
>  kernel/audit.c                        |    4 ++--
>  kernel/auditfilter.c                  |    3 +--
>  kernel/auditsc.c                      |   10 +++++++++-
>  net/netlabel/netlabel_unlabeled.c     |    2 +-
>  net/netlabel/netlabel_user.h          |    2 +-
>  security/apparmor/lsm.c               |   13 ++++++++++---
>  security/integrity/ima/ima_appraise.c |    2 +-
>  security/integrity/ima/ima_main.c     |   14 +++++++-------
>  security/security.c                   |    6 +++---
>  security/selinux/hooks.c              |   19 +++----------------
>  security/smack/smack.h                |   16 ----------------
>  security/smack/smack_lsm.c            |    9 ++++-----
>  15 files changed, 48 insertions(+), 67 deletions(-)

FYI, this patch is based on v5.15-rc3 as it needs the LSM subj/obj
credential fix present in the v5.15-rcX releases.  Applying it on top
of previous releases will result in compilation errors.
Paul Moore Nov. 19, 2021, 10:52 p.m. UTC | #2 
On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>
> The security_task_getsecid_subj() LSM hook invites misuse by allowing
> callers to specify a task even though the hook is only safe when the
> current task is referenced.  Fix this by removing the task_struct
> argument to the hook, requiring LSM implementations to use the
> current task.  While we are changing the hook declaration we also
> rename the function to security_current_getsecid_subj() in an effort
> to reinforce that the hook captures the subjective credentials of the
> current task and not an arbitrary task on the system.
>
> Signed-off-by: Paul Moore <paul@paul-moore.com>
> ---
>  include/linux/lsm_hook_defs.h         |    3 +--
>  include/linux/lsm_hooks.h             |    8 +++-----
>  include/linux/security.h              |    4 ++--
>  kernel/audit.c                        |    4 ++--
>  kernel/auditfilter.c                  |    3 +--
>  kernel/auditsc.c                      |   10 +++++++++-
>  net/netlabel/netlabel_unlabeled.c     |    2 +-
>  net/netlabel/netlabel_user.h          |    2 +-
>  security/apparmor/lsm.c               |   13 ++++++++++---
>  security/integrity/ima/ima_appraise.c |    2 +-
>  security/integrity/ima/ima_main.c     |   14 +++++++-------
>  security/security.c                   |    6 +++---
>  security/selinux/hooks.c              |   19 +++----------------
>  security/smack/smack.h                |   16 ----------------
>  security/smack/smack_lsm.c            |    9 ++++-----
>  15 files changed, 48 insertions(+), 67 deletions(-)

I never saw any comments, positive or negative, on this patch so I'll
plan on merging it early next week.  If you've got objections, now is
the time to speak up.

> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index 2adeea44c0d5..8d04b18155a3 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -205,8 +205,7 @@ LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
>  LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
>  LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
>  LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
> -LSM_HOOK(void, LSM_RET_VOID, task_getsecid_subj,
> -        struct task_struct *p, u32 *secid)
> +LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
>  LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
>          struct task_struct *p, u32 *secid)
>  LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 5c4c5c0602cb..9f5b93011ecb 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -716,11 +716,9 @@
>   *     @p.
>   *     @p contains the task_struct for the process.
>   *     Return 0 if permission is granted.
> - * @task_getsecid_subj:
> - *     Retrieve the subjective security identifier of the task_struct in @p
> - *     and return it in @secid.  Special care must be taken to ensure that @p
> - *     is the either the "current" task, or the caller has exclusive access
> - *     to @p.
> + * @current_getsecid_subj:
> + *     Retrieve the subjective security identifier of the current task and
> + *     return it in @secid.
>   *     In case of failure, @secid will be set to zero.
>   * @task_getsecid_obj:
>   *     Retrieve the objective security identifier of the task_struct in @p
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 5b7288521300..24190cf61858 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -417,7 +417,7 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old,
>  int security_task_setpgid(struct task_struct *p, pid_t pgid);
>  int security_task_getpgid(struct task_struct *p);
>  int security_task_getsid(struct task_struct *p);
> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid);
> +void security_current_getsecid_subj(u32 *secid);
>  void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
>  int security_task_setnice(struct task_struct *p, int nice);
>  int security_task_setioprio(struct task_struct *p, int ioprio);
> @@ -1112,7 +1112,7 @@ static inline int security_task_getsid(struct task_struct *p)
>         return 0;
>  }
>
> -static inline void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
> +static inline void security_current_getsecid_subj(u32 *secid)
>  {
>         *secid = 0;
>  }
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 121d37e700a6..d4084751cfe6 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2132,7 +2132,7 @@ int audit_log_task_context(struct audit_buffer *ab)
>         int error;
>         u32 sid;
>
> -       security_task_getsecid_subj(current, &sid);
> +       security_current_getsecid_subj(&sid);
>         if (!sid)
>                 return 0;
>
> @@ -2353,7 +2353,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>                         audit_sig_uid = auid;
>                 else
>                         audit_sig_uid = uid;
> -               security_task_getsecid_subj(current, &audit_sig_sid);
> +               security_current_getsecid_subj(&audit_sig_sid);
>         }
>
>         return audit_signal_info_syscall(t);
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index db2c6b59dfc3..f4ebd2f1cfca 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -1359,8 +1359,7 @@ int audit_filter(int msgtype, unsigned int listtype)
>                         case AUDIT_SUBJ_SEN:
>                         case AUDIT_SUBJ_CLR:
>                                 if (f->lsm_rule) {
> -                                       security_task_getsecid_subj(current,
> -                                                                   &sid);
> +                                       security_current_getsecid_subj(&sid);
>                                         result = security_audit_rule_match(sid,
>                                                    f->type, f->op, f->lsm_rule);
>                                 }
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 8dd73a64f921..e0987ee71b8f 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -673,7 +673,15 @@ static int audit_filter_rules(struct task_struct *tsk,
>                            logged upon error */
>                         if (f->lsm_rule) {
>                                 if (need_sid) {
> -                                       security_task_getsecid_subj(tsk, &sid);
> +                                       /* @tsk should always be equal to
> +                                        * @current with the exception of
> +                                        * fork()/copy_process() in which case
> +                                        * the new @tsk creds are still a dup
> +                                        * of @current's creds so we can still
> +                                        * use security_current_getsecid_subj()
> +                                        * here even though it always refs
> +                                        * @current's creds */
> +                                       security_current_getsecid_subj(&sid);
>                                         need_sid = 0;
>                                 }
>                                 result = security_audit_rule_match(sid, f->type,
> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
> index 566ba4397ee4..8490e46359ae 100644
> --- a/net/netlabel/netlabel_unlabeled.c
> +++ b/net/netlabel/netlabel_unlabeled.c
> @@ -1537,7 +1537,7 @@ int __init netlbl_unlabel_defconf(void)
>         /* Only the kernel is allowed to call this function and the only time
>          * it is called is at bootup before the audit subsystem is reporting
>          * messages so don't worry to much about these values. */
> -       security_task_getsecid_subj(current, &audit_info.secid);
> +       security_current_getsecid_subj(&audit_info.secid);
>         audit_info.loginuid = GLOBAL_ROOT_UID;
>         audit_info.sessionid = 0;
>
> diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
> index 6190cbf94bf0..d6c5b31eb4eb 100644
> --- a/net/netlabel/netlabel_user.h
> +++ b/net/netlabel/netlabel_user.h
> @@ -32,7 +32,7 @@
>   */
>  static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
>  {
> -       security_task_getsecid_subj(current, &audit_info->secid);
> +       security_current_getsecid_subj(&audit_info->secid);
>         audit_info->loginuid = audit_get_loginuid(current);
>         audit_info->sessionid = audit_get_sessionid(current);
>  }
> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> index f72406fe1bf2..fc21190c4f4f 100644
> --- a/security/apparmor/lsm.c
> +++ b/security/apparmor/lsm.c
> @@ -728,7 +728,14 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
>         return;
>  }
>
> -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
> +static void apparmor_current_getsecid_subj(u32 *secid)
> +{
> +       struct aa_label *label = aa_get_task_label(current);
> +       *secid = label->secid;
> +       aa_put_label(label);
> +}
> +
> +static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid)
>  {
>         struct aa_label *label = aa_get_task_label(p);
>         *secid = label->secid;
> @@ -1252,8 +1259,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
>
>         LSM_HOOK_INIT(task_free, apparmor_task_free),
>         LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
> -       LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
> -       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
> +       LSM_HOOK_INIT(current_getsecid_subj, apparmor_current_getsecid_subj),
> +       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj),
>         LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
>         LSM_HOOK_INIT(task_kill, apparmor_task_kill),
>
> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> index dbba51583e7c..17232bbfb9f9 100644
> --- a/security/integrity/ima/ima_appraise.c
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -76,7 +76,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
>         if (!ima_appraise)
>                 return 0;
>
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         return ima_match_policy(mnt_userns, inode, current_cred(), secid,
>                                 func, mask, IMA_APPRAISE | IMA_HASH, NULL,
>                                 NULL, NULL, NULL);
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 465865412100..8c6e4514d494 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -408,7 +408,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
>         u32 secid;
>
>         if (file && (prot & PROT_EXEC)) {
> -               security_task_getsecid_subj(current, &secid);
> +               security_current_getsecid_subj(&secid);
>                 return process_measurement(file, current_cred(), secid, NULL,
>                                            0, MAY_EXEC, MMAP_CHECK);
>         }
> @@ -446,7 +446,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
>             !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
>                 return 0;
>
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         inode = file_inode(vma->vm_file);
>         action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
>                                 current_cred(), secid, MAY_EXEC, MMAP_CHECK,
> @@ -487,7 +487,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
>         int ret;
>         u32 secid;
>
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
>                                   MAY_EXEC, BPRM_CHECK);
>         if (ret)
> @@ -512,7 +512,7 @@ int ima_file_check(struct file *file, int mask)
>  {
>         u32 secid;
>
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         return process_measurement(file, current_cred(), secid, NULL, 0,
>                                    mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
>                                            MAY_APPEND), FILE_CHECK);
> @@ -709,7 +709,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
>
>         /* Read entire file for all partial reads. */
>         func = read_idmap[read_id] ?: FILE_CHECK;
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         return process_measurement(file, current_cred(), secid, NULL,
>                                    0, MAY_READ, func);
>  }
> @@ -752,7 +752,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
>         }
>
>         func = read_idmap[read_id] ?: FILE_CHECK;
> -       security_task_getsecid_subj(current, &secid);
> +       security_current_getsecid_subj(&secid);
>         return process_measurement(file, current_cred(), secid, buf, size,
>                                    MAY_READ, func);
>  }
> @@ -905,7 +905,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
>          * buffer measurements.
>          */
>         if (func) {
> -               security_task_getsecid_subj(current, &secid);
> +               security_current_getsecid_subj(&secid);
>                 action = ima_get_action(mnt_userns, inode, current_cred(),
>                                         secid, 0, func, &pcr, &template,
>                                         func_data, NULL);
> diff --git a/security/security.c b/security/security.c
> index 9ffa9e9c5c55..827bd161f8b0 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1807,12 +1807,12 @@ int security_task_getsid(struct task_struct *p)
>         return call_int_hook(task_getsid, 0, p);
>  }
>
> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
> +void security_current_getsecid_subj(u32 *secid)
>  {
>         *secid = 0;
> -       call_void_hook(task_getsecid_subj, p, secid);
> +       call_void_hook(current_getsecid_subj, secid);
>  }
> -EXPORT_SYMBOL(security_task_getsecid_subj);
> +EXPORT_SYMBOL(security_current_getsecid_subj);
>
>  void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
>  {
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index e7ebd45ca345..5c766b901f66 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -229,19 +229,6 @@ static inline u32 cred_sid(const struct cred *cred)
>         return tsec->sid;
>  }
>
> -/*
> - * get the subjective security ID of a task
> - */
> -static inline u32 task_sid_subj(const struct task_struct *task)
> -{
> -       u32 sid;
> -
> -       rcu_read_lock();
> -       sid = cred_sid(rcu_dereference(task->cred));
> -       rcu_read_unlock();
> -       return sid;
> -}
> -
>  /*
>   * get the objective security ID of a task
>   */
> @@ -4222,9 +4209,9 @@ static int selinux_task_getsid(struct task_struct *p)
>                             PROCESS__GETSESSION, NULL);
>  }
>
> -static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
> +static void selinux_current_getsecid_subj(u32 *secid)
>  {
> -       *secid = task_sid_subj(p);
> +       *secid = current_sid();
>  }
>
>  static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
> @@ -7221,7 +7208,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>         LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
>         LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
>         LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
> -       LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
> +       LSM_HOOK_INIT(current_getsecid_subj, selinux_current_getsecid_subj),
>         LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
>         LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
>         LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 99c3422596ab..fc837dcebf96 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -389,22 +389,6 @@ static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
>         return tsp->smk_task;
>  }
>
> -static inline struct smack_known *smk_of_task_struct_subj(
> -                                               const struct task_struct *t)
> -{
> -       struct smack_known *skp;
> -       const struct cred *cred;
> -
> -       rcu_read_lock();
> -
> -       cred = rcu_dereference(t->cred);
> -       skp = smk_of_task(smack_cred(cred));
> -
> -       rcu_read_unlock();
> -
> -       return skp;
> -}
> -
>  static inline struct smack_known *smk_of_task_struct_obj(
>                                                 const struct task_struct *t)
>  {
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 21a0e7c3b8de..40e1d764e616 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -2061,15 +2061,14 @@ static int smack_task_getsid(struct task_struct *p)
>  }
>
>  /**
> - * smack_task_getsecid_subj - get the subjective secid of the task
> - * @p: the task
> + * smack_current_getsecid_subj - get the subjective secid of the current task
>   * @secid: where to put the result
>   *
>   * Sets the secid to contain a u32 version of the task's subjective smack label.
>   */
> -static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
> +static void smack_current_getsecid_subj(u32 *secid)
>  {
> -       struct smack_known *skp = smk_of_task_struct_subj(p);
> +       struct smack_known *skp = smk_of_current();
>
>         *secid = skp->smk_secid;
>  }
> @@ -4756,7 +4755,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>         LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
>         LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
>         LSM_HOOK_INIT(task_getsid, smack_task_getsid),
> -       LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
> +       LSM_HOOK_INIT(current_getsecid_subj, smack_current_getsecid_subj),
>         LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
>         LSM_HOOK_INIT(task_setnice, smack_task_setnice),
>         LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
>
Serge E. Hallyn Nov. 19, 2021, 11:23 p.m. UTC | #3 
On Fri, Nov 19, 2021 at 05:52:33PM -0500, Paul Moore wrote:
> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> >
> > The security_task_getsecid_subj() LSM hook invites misuse by allowing
> > callers to specify a task even though the hook is only safe when the
> > current task is referenced.  Fix this by removing the task_struct
> > argument to the hook, requiring LSM implementations to use the
> > current task.  While we are changing the hook declaration we also
> > rename the function to security_current_getsecid_subj() in an effort
> > to reinforce that the hook captures the subjective credentials of the
> > current task and not an arbitrary task on the system.
> >
> > Signed-off-by: Paul Moore <paul@paul-moore.com>

Makes perfect sense given the motivation of 4ebd7651b  :)

Reviewed-by: Serge Hallyn <serge@hallyn.com>

Oh, actually, one question below (cc:ing John explicitly)

> > ---
> >  include/linux/lsm_hook_defs.h         |    3 +--
> >  include/linux/lsm_hooks.h             |    8 +++-----
> >  include/linux/security.h              |    4 ++--
> >  kernel/audit.c                        |    4 ++--
> >  kernel/auditfilter.c                  |    3 +--
> >  kernel/auditsc.c                      |   10 +++++++++-
> >  net/netlabel/netlabel_unlabeled.c     |    2 +-
> >  net/netlabel/netlabel_user.h          |    2 +-
> >  security/apparmor/lsm.c               |   13 ++++++++++---
> >  security/integrity/ima/ima_appraise.c |    2 +-
> >  security/integrity/ima/ima_main.c     |   14 +++++++-------
> >  security/security.c                   |    6 +++---
> >  security/selinux/hooks.c              |   19 +++----------------
> >  security/smack/smack.h                |   16 ----------------
> >  security/smack/smack_lsm.c            |    9 ++++-----
> >  15 files changed, 48 insertions(+), 67 deletions(-)
> 
> I never saw any comments, positive or negative, on this patch so I'll
> plan on merging it early next week.  If you've got objections, now is
> the time to speak up.
> 
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index 2adeea44c0d5..8d04b18155a3 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -205,8 +205,7 @@ LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
> >  LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
> >  LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
> >  LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
> > -LSM_HOOK(void, LSM_RET_VOID, task_getsecid_subj,
> > -        struct task_struct *p, u32 *secid)
> > +LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
> >  LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
> >          struct task_struct *p, u32 *secid)
> >  LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
> > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> > index 5c4c5c0602cb..9f5b93011ecb 100644
> > --- a/include/linux/lsm_hooks.h
> > +++ b/include/linux/lsm_hooks.h
> > @@ -716,11 +716,9 @@
> >   *     @p.
> >   *     @p contains the task_struct for the process.
> >   *     Return 0 if permission is granted.
> > - * @task_getsecid_subj:
> > - *     Retrieve the subjective security identifier of the task_struct in @p
> > - *     and return it in @secid.  Special care must be taken to ensure that @p
> > - *     is the either the "current" task, or the caller has exclusive access
> > - *     to @p.
> > + * @current_getsecid_subj:
> > + *     Retrieve the subjective security identifier of the current task and
> > + *     return it in @secid.
> >   *     In case of failure, @secid will be set to zero.
> >   * @task_getsecid_obj:
> >   *     Retrieve the objective security identifier of the task_struct in @p
> > diff --git a/include/linux/security.h b/include/linux/security.h
> > index 5b7288521300..24190cf61858 100644
> > --- a/include/linux/security.h
> > +++ b/include/linux/security.h
> > @@ -417,7 +417,7 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old,
> >  int security_task_setpgid(struct task_struct *p, pid_t pgid);
> >  int security_task_getpgid(struct task_struct *p);
> >  int security_task_getsid(struct task_struct *p);
> > -void security_task_getsecid_subj(struct task_struct *p, u32 *secid);
> > +void security_current_getsecid_subj(u32 *secid);
> >  void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
> >  int security_task_setnice(struct task_struct *p, int nice);
> >  int security_task_setioprio(struct task_struct *p, int ioprio);
> > @@ -1112,7 +1112,7 @@ static inline int security_task_getsid(struct task_struct *p)
> >         return 0;
> >  }
> >
> > -static inline void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
> > +static inline void security_current_getsecid_subj(u32 *secid)
> >  {
> >         *secid = 0;
> >  }
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index 121d37e700a6..d4084751cfe6 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -2132,7 +2132,7 @@ int audit_log_task_context(struct audit_buffer *ab)
> >         int error;
> >         u32 sid;
> >
> > -       security_task_getsecid_subj(current, &sid);
> > +       security_current_getsecid_subj(&sid);
> >         if (!sid)
> >                 return 0;
> >
> > @@ -2353,7 +2353,7 @@ int audit_signal_info(int sig, struct task_struct *t)
> >                         audit_sig_uid = auid;
> >                 else
> >                         audit_sig_uid = uid;
> > -               security_task_getsecid_subj(current, &audit_sig_sid);
> > +               security_current_getsecid_subj(&audit_sig_sid);
> >         }
> >
> >         return audit_signal_info_syscall(t);
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index db2c6b59dfc3..f4ebd2f1cfca 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -1359,8 +1359,7 @@ int audit_filter(int msgtype, unsigned int listtype)
> >                         case AUDIT_SUBJ_SEN:
> >                         case AUDIT_SUBJ_CLR:
> >                                 if (f->lsm_rule) {
> > -                                       security_task_getsecid_subj(current,
> > -                                                                   &sid);
> > +                                       security_current_getsecid_subj(&sid);
> >                                         result = security_audit_rule_match(sid,
> >                                                    f->type, f->op, f->lsm_rule);
> >                                 }
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index 8dd73a64f921..e0987ee71b8f 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -673,7 +673,15 @@ static int audit_filter_rules(struct task_struct *tsk,
> >                            logged upon error */
> >                         if (f->lsm_rule) {
> >                                 if (need_sid) {
> > -                                       security_task_getsecid_subj(tsk, &sid);
> > +                                       /* @tsk should always be equal to
> > +                                        * @current with the exception of
> > +                                        * fork()/copy_process() in which case
> > +                                        * the new @tsk creds are still a dup
> > +                                        * of @current's creds so we can still
> > +                                        * use security_current_getsecid_subj()
> > +                                        * here even though it always refs
> > +                                        * @current's creds */
> > +                                       security_current_getsecid_subj(&sid);
> >                                         need_sid = 0;
> >                                 }
> >                                 result = security_audit_rule_match(sid, f->type,
> > diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
> > index 566ba4397ee4..8490e46359ae 100644
> > --- a/net/netlabel/netlabel_unlabeled.c
> > +++ b/net/netlabel/netlabel_unlabeled.c
> > @@ -1537,7 +1537,7 @@ int __init netlbl_unlabel_defconf(void)
> >         /* Only the kernel is allowed to call this function and the only time
> >          * it is called is at bootup before the audit subsystem is reporting
> >          * messages so don't worry to much about these values. */
> > -       security_task_getsecid_subj(current, &audit_info.secid);
> > +       security_current_getsecid_subj(&audit_info.secid);
> >         audit_info.loginuid = GLOBAL_ROOT_UID;
> >         audit_info.sessionid = 0;
> >
> > diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
> > index 6190cbf94bf0..d6c5b31eb4eb 100644
> > --- a/net/netlabel/netlabel_user.h
> > +++ b/net/netlabel/netlabel_user.h
> > @@ -32,7 +32,7 @@
> >   */
> >  static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
> >  {
> > -       security_task_getsecid_subj(current, &audit_info->secid);
> > +       security_current_getsecid_subj(&audit_info->secid);
> >         audit_info->loginuid = audit_get_loginuid(current);
> >         audit_info->sessionid = audit_get_sessionid(current);
> >  }
> > diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> > index f72406fe1bf2..fc21190c4f4f 100644
> > --- a/security/apparmor/lsm.c
> > +++ b/security/apparmor/lsm.c
> > @@ -728,7 +728,14 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
> >         return;
> >  }
> >
> > -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
> > +static void apparmor_current_getsecid_subj(u32 *secid)
> > +{
> > +       struct aa_label *label = aa_get_task_label(current);

Should you use aa_get_current_label() here instead?

> > +       *secid = label->secid;
> > +       aa_put_label(label);
> > +}
> > +
> > +static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid)
> >  {
> >         struct aa_label *label = aa_get_task_label(p);
> >         *secid = label->secid;
> > @@ -1252,8 +1259,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
> >
> >         LSM_HOOK_INIT(task_free, apparmor_task_free),
> >         LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
> > -       LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
> > -       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
> > +       LSM_HOOK_INIT(current_getsecid_subj, apparmor_current_getsecid_subj),
> > +       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj),
> >         LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
> >         LSM_HOOK_INIT(task_kill, apparmor_task_kill),
> >
> > diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> > index dbba51583e7c..17232bbfb9f9 100644
> > --- a/security/integrity/ima/ima_appraise.c
> > +++ b/security/integrity/ima/ima_appraise.c
> > @@ -76,7 +76,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
> >         if (!ima_appraise)
> >                 return 0;
> >
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         return ima_match_policy(mnt_userns, inode, current_cred(), secid,
> >                                 func, mask, IMA_APPRAISE | IMA_HASH, NULL,
> >                                 NULL, NULL, NULL);
> > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> > index 465865412100..8c6e4514d494 100644
> > --- a/security/integrity/ima/ima_main.c
> > +++ b/security/integrity/ima/ima_main.c
> > @@ -408,7 +408,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
> >         u32 secid;
> >
> >         if (file && (prot & PROT_EXEC)) {
> > -               security_task_getsecid_subj(current, &secid);
> > +               security_current_getsecid_subj(&secid);
> >                 return process_measurement(file, current_cred(), secid, NULL,
> >                                            0, MAY_EXEC, MMAP_CHECK);
> >         }
> > @@ -446,7 +446,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
> >             !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
> >                 return 0;
> >
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         inode = file_inode(vma->vm_file);
> >         action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
> >                                 current_cred(), secid, MAY_EXEC, MMAP_CHECK,
> > @@ -487,7 +487,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
> >         int ret;
> >         u32 secid;
> >
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
> >                                   MAY_EXEC, BPRM_CHECK);
> >         if (ret)
> > @@ -512,7 +512,7 @@ int ima_file_check(struct file *file, int mask)
> >  {
> >         u32 secid;
> >
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         return process_measurement(file, current_cred(), secid, NULL, 0,
> >                                    mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
> >                                            MAY_APPEND), FILE_CHECK);
> > @@ -709,7 +709,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
> >
> >         /* Read entire file for all partial reads. */
> >         func = read_idmap[read_id] ?: FILE_CHECK;
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         return process_measurement(file, current_cred(), secid, NULL,
> >                                    0, MAY_READ, func);
> >  }
> > @@ -752,7 +752,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
> >         }
> >
> >         func = read_idmap[read_id] ?: FILE_CHECK;
> > -       security_task_getsecid_subj(current, &secid);
> > +       security_current_getsecid_subj(&secid);
> >         return process_measurement(file, current_cred(), secid, buf, size,
> >                                    MAY_READ, func);
> >  }
> > @@ -905,7 +905,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
> >          * buffer measurements.
> >          */
> >         if (func) {
> > -               security_task_getsecid_subj(current, &secid);
> > +               security_current_getsecid_subj(&secid);
> >                 action = ima_get_action(mnt_userns, inode, current_cred(),
> >                                         secid, 0, func, &pcr, &template,
> >                                         func_data, NULL);
> > diff --git a/security/security.c b/security/security.c
> > index 9ffa9e9c5c55..827bd161f8b0 100644
> > --- a/security/security.c
> > +++ b/security/security.c
> > @@ -1807,12 +1807,12 @@ int security_task_getsid(struct task_struct *p)
> >         return call_int_hook(task_getsid, 0, p);
> >  }
> >
> > -void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
> > +void security_current_getsecid_subj(u32 *secid)
> >  {
> >         *secid = 0;
> > -       call_void_hook(task_getsecid_subj, p, secid);
> > +       call_void_hook(current_getsecid_subj, secid);
> >  }
> > -EXPORT_SYMBOL(security_task_getsecid_subj);
> > +EXPORT_SYMBOL(security_current_getsecid_subj);
> >
> >  void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
> >  {
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index e7ebd45ca345..5c766b901f66 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -229,19 +229,6 @@ static inline u32 cred_sid(const struct cred *cred)
> >         return tsec->sid;
> >  }
> >
> > -/*
> > - * get the subjective security ID of a task
> > - */
> > -static inline u32 task_sid_subj(const struct task_struct *task)
> > -{
> > -       u32 sid;
> > -
> > -       rcu_read_lock();
> > -       sid = cred_sid(rcu_dereference(task->cred));
> > -       rcu_read_unlock();
> > -       return sid;
> > -}
> > -
> >  /*
> >   * get the objective security ID of a task
> >   */
> > @@ -4222,9 +4209,9 @@ static int selinux_task_getsid(struct task_struct *p)
> >                             PROCESS__GETSESSION, NULL);
> >  }
> >
> > -static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
> > +static void selinux_current_getsecid_subj(u32 *secid)
> >  {
> > -       *secid = task_sid_subj(p);
> > +       *secid = current_sid();
> >  }
> >
> >  static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
> > @@ -7221,7 +7208,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
> >         LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
> >         LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
> >         LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
> > -       LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
> > +       LSM_HOOK_INIT(current_getsecid_subj, selinux_current_getsecid_subj),
> >         LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
> >         LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
> >         LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
> > diff --git a/security/smack/smack.h b/security/smack/smack.h
> > index 99c3422596ab..fc837dcebf96 100644
> > --- a/security/smack/smack.h
> > +++ b/security/smack/smack.h
> > @@ -389,22 +389,6 @@ static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
> >         return tsp->smk_task;
> >  }
> >
> > -static inline struct smack_known *smk_of_task_struct_subj(
> > -                                               const struct task_struct *t)
> > -{
> > -       struct smack_known *skp;
> > -       const struct cred *cred;
> > -
> > -       rcu_read_lock();
> > -
> > -       cred = rcu_dereference(t->cred);
> > -       skp = smk_of_task(smack_cred(cred));
> > -
> > -       rcu_read_unlock();
> > -
> > -       return skp;
> > -}
> > -
> >  static inline struct smack_known *smk_of_task_struct_obj(
> >                                                 const struct task_struct *t)
> >  {
> > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> > index 21a0e7c3b8de..40e1d764e616 100644
> > --- a/security/smack/smack_lsm.c
> > +++ b/security/smack/smack_lsm.c
> > @@ -2061,15 +2061,14 @@ static int smack_task_getsid(struct task_struct *p)
> >  }
> >
> >  /**
> > - * smack_task_getsecid_subj - get the subjective secid of the task
> > - * @p: the task
> > + * smack_current_getsecid_subj - get the subjective secid of the current task
> >   * @secid: where to put the result
> >   *
> >   * Sets the secid to contain a u32 version of the task's subjective smack label.
> >   */
> > -static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
> > +static void smack_current_getsecid_subj(u32 *secid)
> >  {
> > -       struct smack_known *skp = smk_of_task_struct_subj(p);
> > +       struct smack_known *skp = smk_of_current();
> >
> >         *secid = skp->smk_secid;
> >  }
> > @@ -4756,7 +4755,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
> >         LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
> >         LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
> >         LSM_HOOK_INIT(task_getsid, smack_task_getsid),
> > -       LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
> > +       LSM_HOOK_INIT(current_getsecid_subj, smack_current_getsecid_subj),
> >         LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
> >         LSM_HOOK_INIT(task_setnice, smack_task_setnice),
> >         LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
> >
> 
> 
> -- 
> paul moore
> www.paul-moore.com
John Johansen Nov. 19, 2021, 11:59 p.m. UTC | #4 
On 11/19/21 3:23 PM, Serge E. Hallyn wrote:
> On Fri, Nov 19, 2021 at 05:52:33PM -0500, Paul Moore wrote:
>> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>>>
>>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
>>> callers to specify a task even though the hook is only safe when the
>>> current task is referenced.  Fix this by removing the task_struct
>>> argument to the hook, requiring LSM implementations to use the
>>> current task.  While we are changing the hook declaration we also
>>> rename the function to security_current_getsecid_subj() in an effort
>>> to reinforce that the hook captures the subjective credentials of the
>>> current task and not an arbitrary task on the system.
>>>
>>> Signed-off-by: Paul Moore <paul@paul-moore.com>
> 
> Makes perfect sense given the motivation of 4ebd7651b  :)
> 
> Reviewed-by: Serge Hallyn <serge@hallyn.com>
> 
> Oh, actually, one question below (cc:ing John explicitly)
> 

<< snip >>

>>> -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
>>> +static void apparmor_current_getsecid_subj(u32 *secid)
>>> +{
>>> +       struct aa_label *label = aa_get_task_label(current);
> 
> Should you use aa_get_current_label() here instead?
> 

yes, that would be better
Casey Schaufler Nov. 20, 2021, 12:42 a.m. UTC | #5 
On 11/19/2021 2:52 PM, Paul Moore wrote:
> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
>> callers to specify a task even though the hook is only safe when the
>> current task is referenced.  Fix this by removing the task_struct
>> argument to the hook, requiring LSM implementations to use the
>> current task.  While we are changing the hook declaration we also
>> rename the function to security_current_getsecid_subj() in an effort
>> to reinforce that the hook captures the subjective credentials of the
>> current task and not an arbitrary task on the system.
>>
>> Signed-off-by: Paul Moore <paul@paul-moore.com>
>> ---
>>   include/linux/lsm_hook_defs.h         |    3 +--
>>   include/linux/lsm_hooks.h             |    8 +++-----
>>   include/linux/security.h              |    4 ++--
>>   kernel/audit.c                        |    4 ++--
>>   kernel/auditfilter.c                  |    3 +--
>>   kernel/auditsc.c                      |   10 +++++++++-
>>   net/netlabel/netlabel_unlabeled.c     |    2 +-
>>   net/netlabel/netlabel_user.h          |    2 +-
>>   security/apparmor/lsm.c               |   13 ++++++++++---
>>   security/integrity/ima/ima_appraise.c |    2 +-
>>   security/integrity/ima/ima_main.c     |   14 +++++++-------
>>   security/security.c                   |    6 +++---
>>   security/selinux/hooks.c              |   19 +++----------------
>>   security/smack/smack.h                |   16 ----------------
>>   security/smack/smack_lsm.c            |    9 ++++-----
>>   15 files changed, 48 insertions(+), 67 deletions(-)
> I never saw any comments, positive or negative, on this patch so I'll
> plan on merging it early next week.  If you've got objections, now is
> the time to speak up.

It's OK by me.

Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>

>
>> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
>> index 2adeea44c0d5..8d04b18155a3 100644
>> --- a/include/linux/lsm_hook_defs.h
>> +++ b/include/linux/lsm_hook_defs.h
>> @@ -205,8 +205,7 @@ LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
>>   LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
>>   LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
>>   LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
>> -LSM_HOOK(void, LSM_RET_VOID, task_getsecid_subj,
>> -        struct task_struct *p, u32 *secid)
>> +LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
>>   LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
>>           struct task_struct *p, u32 *secid)
>>   LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index 5c4c5c0602cb..9f5b93011ecb 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -716,11 +716,9 @@
>>    *     @p.
>>    *     @p contains the task_struct for the process.
>>    *     Return 0 if permission is granted.
>> - * @task_getsecid_subj:
>> - *     Retrieve the subjective security identifier of the task_struct in @p
>> - *     and return it in @secid.  Special care must be taken to ensure that @p
>> - *     is the either the "current" task, or the caller has exclusive access
>> - *     to @p.
>> + * @current_getsecid_subj:
>> + *     Retrieve the subjective security identifier of the current task and
>> + *     return it in @secid.
>>    *     In case of failure, @secid will be set to zero.
>>    * @task_getsecid_obj:
>>    *     Retrieve the objective security identifier of the task_struct in @p
>> diff --git a/include/linux/security.h b/include/linux/security.h
>> index 5b7288521300..24190cf61858 100644
>> --- a/include/linux/security.h
>> +++ b/include/linux/security.h
>> @@ -417,7 +417,7 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old,
>>   int security_task_setpgid(struct task_struct *p, pid_t pgid);
>>   int security_task_getpgid(struct task_struct *p);
>>   int security_task_getsid(struct task_struct *p);
>> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid);
>> +void security_current_getsecid_subj(u32 *secid);
>>   void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
>>   int security_task_setnice(struct task_struct *p, int nice);
>>   int security_task_setioprio(struct task_struct *p, int ioprio);
>> @@ -1112,7 +1112,7 @@ static inline int security_task_getsid(struct task_struct *p)
>>          return 0;
>>   }
>>
>> -static inline void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static inline void security_current_getsecid_subj(u32 *secid)
>>   {
>>          *secid = 0;
>>   }
>> diff --git a/kernel/audit.c b/kernel/audit.c
>> index 121d37e700a6..d4084751cfe6 100644
>> --- a/kernel/audit.c
>> +++ b/kernel/audit.c
>> @@ -2132,7 +2132,7 @@ int audit_log_task_context(struct audit_buffer *ab)
>>          int error;
>>          u32 sid;
>>
>> -       security_task_getsecid_subj(current, &sid);
>> +       security_current_getsecid_subj(&sid);
>>          if (!sid)
>>                  return 0;
>>
>> @@ -2353,7 +2353,7 @@ int audit_signal_info(int sig, struct task_struct *t)
>>                          audit_sig_uid = auid;
>>                  else
>>                          audit_sig_uid = uid;
>> -               security_task_getsecid_subj(current, &audit_sig_sid);
>> +               security_current_getsecid_subj(&audit_sig_sid);
>>          }
>>
>>          return audit_signal_info_syscall(t);
>> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
>> index db2c6b59dfc3..f4ebd2f1cfca 100644
>> --- a/kernel/auditfilter.c
>> +++ b/kernel/auditfilter.c
>> @@ -1359,8 +1359,7 @@ int audit_filter(int msgtype, unsigned int listtype)
>>                          case AUDIT_SUBJ_SEN:
>>                          case AUDIT_SUBJ_CLR:
>>                                  if (f->lsm_rule) {
>> -                                       security_task_getsecid_subj(current,
>> -                                                                   &sid);
>> +                                       security_current_getsecid_subj(&sid);
>>                                          result = security_audit_rule_match(sid,
>>                                                     f->type, f->op, f->lsm_rule);
>>                                  }
>> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
>> index 8dd73a64f921..e0987ee71b8f 100644
>> --- a/kernel/auditsc.c
>> +++ b/kernel/auditsc.c
>> @@ -673,7 +673,15 @@ static int audit_filter_rules(struct task_struct *tsk,
>>                             logged upon error */
>>                          if (f->lsm_rule) {
>>                                  if (need_sid) {
>> -                                       security_task_getsecid_subj(tsk, &sid);
>> +                                       /* @tsk should always be equal to
>> +                                        * @current with the exception of
>> +                                        * fork()/copy_process() in which case
>> +                                        * the new @tsk creds are still a dup
>> +                                        * of @current's creds so we can still
>> +                                        * use security_current_getsecid_subj()
>> +                                        * here even though it always refs
>> +                                        * @current's creds */
>> +                                       security_current_getsecid_subj(&sid);
>>                                          need_sid = 0;
>>                                  }
>>                                  result = security_audit_rule_match(sid, f->type,
>> diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
>> index 566ba4397ee4..8490e46359ae 100644
>> --- a/net/netlabel/netlabel_unlabeled.c
>> +++ b/net/netlabel/netlabel_unlabeled.c
>> @@ -1537,7 +1537,7 @@ int __init netlbl_unlabel_defconf(void)
>>          /* Only the kernel is allowed to call this function and the only time
>>           * it is called is at bootup before the audit subsystem is reporting
>>           * messages so don't worry to much about these values. */
>> -       security_task_getsecid_subj(current, &audit_info.secid);
>> +       security_current_getsecid_subj(&audit_info.secid);
>>          audit_info.loginuid = GLOBAL_ROOT_UID;
>>          audit_info.sessionid = 0;
>>
>> diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
>> index 6190cbf94bf0..d6c5b31eb4eb 100644
>> --- a/net/netlabel/netlabel_user.h
>> +++ b/net/netlabel/netlabel_user.h
>> @@ -32,7 +32,7 @@
>>    */
>>   static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
>>   {
>> -       security_task_getsecid_subj(current, &audit_info->secid);
>> +       security_current_getsecid_subj(&audit_info->secid);
>>          audit_info->loginuid = audit_get_loginuid(current);
>>          audit_info->sessionid = audit_get_sessionid(current);
>>   }
>> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
>> index f72406fe1bf2..fc21190c4f4f 100644
>> --- a/security/apparmor/lsm.c
>> +++ b/security/apparmor/lsm.c
>> @@ -728,7 +728,14 @@ static void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
>>          return;
>>   }
>>
>> -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
>> +static void apparmor_current_getsecid_subj(u32 *secid)
>> +{
>> +       struct aa_label *label = aa_get_task_label(current);
>> +       *secid = label->secid;
>> +       aa_put_label(label);
>> +}
>> +
>> +static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid)
>>   {
>>          struct aa_label *label = aa_get_task_label(p);
>>          *secid = label->secid;
>> @@ -1252,8 +1259,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
>>
>>          LSM_HOOK_INIT(task_free, apparmor_task_free),
>>          LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
>> -       LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
>> -       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
>> +       LSM_HOOK_INIT(current_getsecid_subj, apparmor_current_getsecid_subj),
>> +       LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj),
>>          LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
>>          LSM_HOOK_INIT(task_kill, apparmor_task_kill),
>>
>> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
>> index dbba51583e7c..17232bbfb9f9 100644
>> --- a/security/integrity/ima/ima_appraise.c
>> +++ b/security/integrity/ima/ima_appraise.c
>> @@ -76,7 +76,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
>>          if (!ima_appraise)
>>                  return 0;
>>
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          return ima_match_policy(mnt_userns, inode, current_cred(), secid,
>>                                  func, mask, IMA_APPRAISE | IMA_HASH, NULL,
>>                                  NULL, NULL, NULL);
>> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>> index 465865412100..8c6e4514d494 100644
>> --- a/security/integrity/ima/ima_main.c
>> +++ b/security/integrity/ima/ima_main.c
>> @@ -408,7 +408,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
>>          u32 secid;
>>
>>          if (file && (prot & PROT_EXEC)) {
>> -               security_task_getsecid_subj(current, &secid);
>> +               security_current_getsecid_subj(&secid);
>>                  return process_measurement(file, current_cred(), secid, NULL,
>>                                             0, MAY_EXEC, MMAP_CHECK);
>>          }
>> @@ -446,7 +446,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
>>              !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
>>                  return 0;
>>
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          inode = file_inode(vma->vm_file);
>>          action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
>>                                  current_cred(), secid, MAY_EXEC, MMAP_CHECK,
>> @@ -487,7 +487,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
>>          int ret;
>>          u32 secid;
>>
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
>>                                    MAY_EXEC, BPRM_CHECK);
>>          if (ret)
>> @@ -512,7 +512,7 @@ int ima_file_check(struct file *file, int mask)
>>   {
>>          u32 secid;
>>
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          return process_measurement(file, current_cred(), secid, NULL, 0,
>>                                     mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
>>                                             MAY_APPEND), FILE_CHECK);
>> @@ -709,7 +709,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
>>
>>          /* Read entire file for all partial reads. */
>>          func = read_idmap[read_id] ?: FILE_CHECK;
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          return process_measurement(file, current_cred(), secid, NULL,
>>                                     0, MAY_READ, func);
>>   }
>> @@ -752,7 +752,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
>>          }
>>
>>          func = read_idmap[read_id] ?: FILE_CHECK;
>> -       security_task_getsecid_subj(current, &secid);
>> +       security_current_getsecid_subj(&secid);
>>          return process_measurement(file, current_cred(), secid, buf, size,
>>                                     MAY_READ, func);
>>   }
>> @@ -905,7 +905,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
>>           * buffer measurements.
>>           */
>>          if (func) {
>> -               security_task_getsecid_subj(current, &secid);
>> +               security_current_getsecid_subj(&secid);
>>                  action = ima_get_action(mnt_userns, inode, current_cred(),
>>                                          secid, 0, func, &pcr, &template,
>>                                          func_data, NULL);
>> diff --git a/security/security.c b/security/security.c
>> index 9ffa9e9c5c55..827bd161f8b0 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -1807,12 +1807,12 @@ int security_task_getsid(struct task_struct *p)
>>          return call_int_hook(task_getsid, 0, p);
>>   }
>>
>> -void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +void security_current_getsecid_subj(u32 *secid)
>>   {
>>          *secid = 0;
>> -       call_void_hook(task_getsecid_subj, p, secid);
>> +       call_void_hook(current_getsecid_subj, secid);
>>   }
>> -EXPORT_SYMBOL(security_task_getsecid_subj);
>> +EXPORT_SYMBOL(security_current_getsecid_subj);
>>
>>   void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
>>   {
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index e7ebd45ca345..5c766b901f66 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -229,19 +229,6 @@ static inline u32 cred_sid(const struct cred *cred)
>>          return tsec->sid;
>>   }
>>
>> -/*
>> - * get the subjective security ID of a task
>> - */
>> -static inline u32 task_sid_subj(const struct task_struct *task)
>> -{
>> -       u32 sid;
>> -
>> -       rcu_read_lock();
>> -       sid = cred_sid(rcu_dereference(task->cred));
>> -       rcu_read_unlock();
>> -       return sid;
>> -}
>> -
>>   /*
>>    * get the objective security ID of a task
>>    */
>> @@ -4222,9 +4209,9 @@ static int selinux_task_getsid(struct task_struct *p)
>>                              PROCESS__GETSESSION, NULL);
>>   }
>>
>> -static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static void selinux_current_getsecid_subj(u32 *secid)
>>   {
>> -       *secid = task_sid_subj(p);
>> +       *secid = current_sid();
>>   }
>>
>>   static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
>> @@ -7221,7 +7208,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>>          LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
>>          LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
>>          LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
>> -       LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
>> +       LSM_HOOK_INIT(current_getsecid_subj, selinux_current_getsecid_subj),
>>          LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
>>          LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
>>          LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
>> diff --git a/security/smack/smack.h b/security/smack/smack.h
>> index 99c3422596ab..fc837dcebf96 100644
>> --- a/security/smack/smack.h
>> +++ b/security/smack/smack.h
>> @@ -389,22 +389,6 @@ static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
>>          return tsp->smk_task;
>>   }
>>
>> -static inline struct smack_known *smk_of_task_struct_subj(
>> -                                               const struct task_struct *t)
>> -{
>> -       struct smack_known *skp;
>> -       const struct cred *cred;
>> -
>> -       rcu_read_lock();
>> -
>> -       cred = rcu_dereference(t->cred);
>> -       skp = smk_of_task(smack_cred(cred));
>> -
>> -       rcu_read_unlock();
>> -
>> -       return skp;
>> -}
>> -
>>   static inline struct smack_known *smk_of_task_struct_obj(
>>                                                  const struct task_struct *t)
>>   {
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 21a0e7c3b8de..40e1d764e616 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -2061,15 +2061,14 @@ static int smack_task_getsid(struct task_struct *p)
>>   }
>>
>>   /**
>> - * smack_task_getsecid_subj - get the subjective secid of the task
>> - * @p: the task
>> + * smack_current_getsecid_subj - get the subjective secid of the current task
>>    * @secid: where to put the result
>>    *
>>    * Sets the secid to contain a u32 version of the task's subjective smack label.
>>    */
>> -static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
>> +static void smack_current_getsecid_subj(u32 *secid)
>>   {
>> -       struct smack_known *skp = smk_of_task_struct_subj(p);
>> +       struct smack_known *skp = smk_of_current();
>>
>>          *secid = skp->smk_secid;
>>   }
>> @@ -4756,7 +4755,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>>          LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
>>          LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
>>          LSM_HOOK_INIT(task_getsid, smack_task_getsid),
>> -       LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
>> +       LSM_HOOK_INIT(current_getsecid_subj, smack_current_getsecid_subj),
>>          LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
>>          LSM_HOOK_INIT(task_setnice, smack_task_setnice),
>>          LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
>>
>
Paul Moore Nov. 20, 2021, 3:04 p.m. UTC | #6 
On Fri, Nov 19, 2021 at 6:59 PM John Johansen
<john.johansen@canonical.com> wrote:
> On 11/19/21 3:23 PM, Serge E. Hallyn wrote:
> > On Fri, Nov 19, 2021 at 05:52:33PM -0500, Paul Moore wrote:
> >> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> >>>
> >>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
> >>> callers to specify a task even though the hook is only safe when the
> >>> current task is referenced.  Fix this by removing the task_struct
> >>> argument to the hook, requiring LSM implementations to use the
> >>> current task.  While we are changing the hook declaration we also
> >>> rename the function to security_current_getsecid_subj() in an effort
> >>> to reinforce that the hook captures the subjective credentials of the
> >>> current task and not an arbitrary task on the system.
> >>>
> >>> Signed-off-by: Paul Moore <paul@paul-moore.com>
> >
> > Makes perfect sense given the motivation of 4ebd7651b  :)
> >
> > Reviewed-by: Serge Hallyn <serge@hallyn.com>
> >
> > Oh, actually, one question below (cc:ing John explicitly)
> >
>
> << snip >>
>
> >>> -static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
> >>> +static void apparmor_current_getsecid_subj(u32 *secid)
> >>> +{
> >>> +       struct aa_label *label = aa_get_task_label(current);
> >
> > Should you use aa_get_current_label() here instead?
> >
>
> yes, that would be better

Will do, thanks guys.
Paul Moore Nov. 20, 2021, 3:06 p.m. UTC | #7 
On Fri, Nov 19, 2021 at 7:42 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>
> On 11/19/2021 2:52 PM, Paul Moore wrote:
> > On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> >> The security_task_getsecid_subj() LSM hook invites misuse by allowing
> >> callers to specify a task even though the hook is only safe when the
> >> current task is referenced.  Fix this by removing the task_struct
> >> argument to the hook, requiring LSM implementations to use the
> >> current task.  While we are changing the hook declaration we also
> >> rename the function to security_current_getsecid_subj() in an effort
> >> to reinforce that the hook captures the subjective credentials of the
> >> current task and not an arbitrary task on the system.
> >>
> >> Signed-off-by: Paul Moore <paul@paul-moore.com>
> >> ---
> >>   include/linux/lsm_hook_defs.h         |    3 +--
> >>   include/linux/lsm_hooks.h             |    8 +++-----
> >>   include/linux/security.h              |    4 ++--
> >>   kernel/audit.c                        |    4 ++--
> >>   kernel/auditfilter.c                  |    3 +--
> >>   kernel/auditsc.c                      |   10 +++++++++-
> >>   net/netlabel/netlabel_unlabeled.c     |    2 +-
> >>   net/netlabel/netlabel_user.h          |    2 +-
> >>   security/apparmor/lsm.c               |   13 ++++++++++---
> >>   security/integrity/ima/ima_appraise.c |    2 +-
> >>   security/integrity/ima/ima_main.c     |   14 +++++++-------
> >>   security/security.c                   |    6 +++---
> >>   security/selinux/hooks.c              |   19 +++----------------
> >>   security/smack/smack.h                |   16 ----------------
> >>   security/smack/smack_lsm.c            |    9 ++++-----
> >>   15 files changed, 48 insertions(+), 67 deletions(-)
> > I never saw any comments, positive or negative, on this patch so I'll
> > plan on merging it early next week.  If you've got objections, now is
> > the time to speak up.
>
> It's OK by me.
>
> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>

Thanks Casey.  Are you okay with the AppArmor tweak mentioned by Serge and John?
Casey Schaufler Nov. 20, 2021, 5:54 p.m. UTC | #8 
On 11/20/2021 7:06 AM, Paul Moore wrote:
> On Fri, Nov 19, 2021 at 7:42 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>> On 11/19/2021 2:52 PM, Paul Moore wrote:
>>> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>>>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
>>>> callers to specify a task even though the hook is only safe when the
>>>> current task is referenced.  Fix this by removing the task_struct
>>>> argument to the hook, requiring LSM implementations to use the
>>>> current task.  While we are changing the hook declaration we also
>>>> rename the function to security_current_getsecid_subj() in an effort
>>>> to reinforce that the hook captures the subjective credentials of the
>>>> current task and not an arbitrary task on the system.
>>>>
>>>> Signed-off-by: Paul Moore <paul@paul-moore.com>
>>>> ---
>>>>    include/linux/lsm_hook_defs.h         |    3 +--
>>>>    include/linux/lsm_hooks.h             |    8 +++-----
>>>>    include/linux/security.h              |    4 ++--
>>>>    kernel/audit.c                        |    4 ++--
>>>>    kernel/auditfilter.c                  |    3 +--
>>>>    kernel/auditsc.c                      |   10 +++++++++-
>>>>    net/netlabel/netlabel_unlabeled.c     |    2 +-
>>>>    net/netlabel/netlabel_user.h          |    2 +-
>>>>    security/apparmor/lsm.c               |   13 ++++++++++---
>>>>    security/integrity/ima/ima_appraise.c |    2 +-
>>>>    security/integrity/ima/ima_main.c     |   14 +++++++-------
>>>>    security/security.c                   |    6 +++---
>>>>    security/selinux/hooks.c              |   19 +++----------------
>>>>    security/smack/smack.h                |   16 ----------------
>>>>    security/smack/smack_lsm.c            |    9 ++++-----
>>>>    15 files changed, 48 insertions(+), 67 deletions(-)
>>> I never saw any comments, positive or negative, on this patch so I'll
>>> plan on merging it early next week.  If you've got objections, now is
>>> the time to speak up.
>> It's OK by me.
>>
>> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
> Thanks Casey.  Are you okay with the AppArmor tweak mentioned by Serge and John?

Yes.
Paul Moore Nov. 22, 2021, 11:12 p.m. UTC | #9 
On Fri, Nov 19, 2021 at 5:52 PM Paul Moore <paul@paul-moore.com> wrote:
> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> >
> > The security_task_getsecid_subj() LSM hook invites misuse by allowing
> > callers to specify a task even though the hook is only safe when the
> > current task is referenced.  Fix this by removing the task_struct
> > argument to the hook, requiring LSM implementations to use the
> > current task.  While we are changing the hook declaration we also
> > rename the function to security_current_getsecid_subj() in an effort
> > to reinforce that the hook captures the subjective credentials of the
> > current task and not an arbitrary task on the system.
> >
> > Signed-off-by: Paul Moore <paul@paul-moore.com>
> > ---
> >  include/linux/lsm_hook_defs.h         |    3 +--
> >  include/linux/lsm_hooks.h             |    8 +++-----
> >  include/linux/security.h              |    4 ++--
> >  kernel/audit.c                        |    4 ++--
> >  kernel/auditfilter.c                  |    3 +--
> >  kernel/auditsc.c                      |   10 +++++++++-
> >  net/netlabel/netlabel_unlabeled.c     |    2 +-
> >  net/netlabel/netlabel_user.h          |    2 +-
> >  security/apparmor/lsm.c               |   13 ++++++++++---
> >  security/integrity/ima/ima_appraise.c |    2 +-
> >  security/integrity/ima/ima_main.c     |   14 +++++++-------
> >  security/security.c                   |    6 +++---
> >  security/selinux/hooks.c              |   19 +++----------------
> >  security/smack/smack.h                |   16 ----------------
> >  security/smack/smack_lsm.c            |    9 ++++-----
> >  15 files changed, 48 insertions(+), 67 deletions(-)
>
> I never saw any comments, positive or negative, on this patch so I'll
> plan on merging it early next week.  If you've got objections, now is
> the time to speak up.

I just merged this patch, with the AppArmor tweak suggested by Serge,
into selinux/next.  Thanks everyone.
Serge E. Hallyn Nov. 22, 2021, 11:25 p.m. UTC | #10 
On Mon, Nov 22, 2021 at 06:12:19PM -0500, Paul Moore wrote:
> On Fri, Nov 19, 2021 at 5:52 PM Paul Moore <paul@paul-moore.com> wrote:
> > On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> > >
> > > The security_task_getsecid_subj() LSM hook invites misuse by allowing
> > > callers to specify a task even though the hook is only safe when the
> > > current task is referenced.  Fix this by removing the task_struct
> > > argument to the hook, requiring LSM implementations to use the
> > > current task.  While we are changing the hook declaration we also
> > > rename the function to security_current_getsecid_subj() in an effort
> > > to reinforce that the hook captures the subjective credentials of the
> > > current task and not an arbitrary task on the system.
> > >
> > > Signed-off-by: Paul Moore <paul@paul-moore.com>
> > > ---
> > >  include/linux/lsm_hook_defs.h         |    3 +--
> > >  include/linux/lsm_hooks.h             |    8 +++-----
> > >  include/linux/security.h              |    4 ++--
> > >  kernel/audit.c                        |    4 ++--
> > >  kernel/auditfilter.c                  |    3 +--
> > >  kernel/auditsc.c                      |   10 +++++++++-
> > >  net/netlabel/netlabel_unlabeled.c     |    2 +-
> > >  net/netlabel/netlabel_user.h          |    2 +-
> > >  security/apparmor/lsm.c               |   13 ++++++++++---
> > >  security/integrity/ima/ima_appraise.c |    2 +-
> > >  security/integrity/ima/ima_main.c     |   14 +++++++-------
> > >  security/security.c                   |    6 +++---
> > >  security/selinux/hooks.c              |   19 +++----------------
> > >  security/smack/smack.h                |   16 ----------------
> > >  security/smack/smack_lsm.c            |    9 ++++-----
> > >  15 files changed, 48 insertions(+), 67 deletions(-)
> >
> > I never saw any comments, positive or negative, on this patch so I'll
> > plan on merging it early next week.  If you've got objections, now is
> > the time to speak up.
> 
> I just merged this patch, with the AppArmor tweak suggested by Serge,
> into selinux/next.  Thanks everyone.

Thanks, Paul.

-serge
Casey Schaufler Nov. 23, 2021, 12:40 a.m. UTC | #11 
On 11/22/2021 3:12 PM, Paul Moore wrote:
> On Fri, Nov 19, 2021 at 5:52 PM Paul Moore <paul@paul-moore.com> wrote:
>> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
>>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
>>> callers to specify a task even though the hook is only safe when the
>>> current task is referenced.  Fix this by removing the task_struct
>>> argument to the hook, requiring LSM implementations to use the
>>> current task.  While we are changing the hook declaration we also
>>> rename the function to security_current_getsecid_subj() in an effort
>>> to reinforce that the hook captures the subjective credentials of the
>>> current task and not an arbitrary task on the system.
>>>
>>> Signed-off-by: Paul Moore <paul@paul-moore.com>
>>> ---
>>>   include/linux/lsm_hook_defs.h         |    3 +--
>>>   include/linux/lsm_hooks.h             |    8 +++-----
>>>   include/linux/security.h              |    4 ++--
>>>   kernel/audit.c                        |    4 ++--
>>>   kernel/auditfilter.c                  |    3 +--
>>>   kernel/auditsc.c                      |   10 +++++++++-
>>>   net/netlabel/netlabel_unlabeled.c     |    2 +-
>>>   net/netlabel/netlabel_user.h          |    2 +-
>>>   security/apparmor/lsm.c               |   13 ++++++++++---
>>>   security/integrity/ima/ima_appraise.c |    2 +-
>>>   security/integrity/ima/ima_main.c     |   14 +++++++-------
>>>   security/security.c                   |    6 +++---
>>>   security/selinux/hooks.c              |   19 +++----------------
>>>   security/smack/smack.h                |   16 ----------------
>>>   security/smack/smack_lsm.c            |    9 ++++-----
>>>   15 files changed, 48 insertions(+), 67 deletions(-)
>> I never saw any comments, positive or negative, on this patch so I'll
>> plan on merging it early next week.  If you've got objections, now is
>> the time to speak up.
> I just merged this patch, with the AppArmor tweak suggested by Serge,
> into selinux/next.  Thanks everyone.

Has the security tree been abandoned as a path for general LSM
changes? Except for the initial Landlock pull and a couple touch-ups
to capabilities nothing has gone in via security this year. This
change should have gone in through security, not selinux. I'm glad
that this change is going in, don't get me wrong on that. I am
somewhat concerned about the LSM infrastructure work I'm doing,
and how it's going to get upstream. The diffstats from that look
a lot like the one here. I seriously doubt that taking the full
set of changes for stacking through the Smack tree is going to fly. ;)
Paul Moore Nov. 23, 2021, 3:14 a.m. UTC | #12 
On Mon, Nov 22, 2021 at 7:40 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 11/22/2021 3:12 PM, Paul Moore wrote:
> > On Fri, Nov 19, 2021 at 5:52 PM Paul Moore <paul@paul-moore.com> wrote:
> >> On Wed, Sep 29, 2021 at 3:17 PM Paul Moore <paul@paul-moore.com> wrote:
> >>> The security_task_getsecid_subj() LSM hook invites misuse by allowing
> >>> callers to specify a task even though the hook is only safe when the
> >>> current task is referenced.  Fix this by removing the task_struct
> >>> argument to the hook, requiring LSM implementations to use the
> >>> current task.  While we are changing the hook declaration we also
> >>> rename the function to security_current_getsecid_subj() in an effort
> >>> to reinforce that the hook captures the subjective credentials of the
> >>> current task and not an arbitrary task on the system.
> >>>
> >>> Signed-off-by: Paul Moore <paul@paul-moore.com>
> >>> ---
> >>>   include/linux/lsm_hook_defs.h         |    3 +--
> >>>   include/linux/lsm_hooks.h             |    8 +++-----
> >>>   include/linux/security.h              |    4 ++--
> >>>   kernel/audit.c                        |    4 ++--
> >>>   kernel/auditfilter.c                  |    3 +--
> >>>   kernel/auditsc.c                      |   10 +++++++++-
> >>>   net/netlabel/netlabel_unlabeled.c     |    2 +-
> >>>   net/netlabel/netlabel_user.h          |    2 +-
> >>>   security/apparmor/lsm.c               |   13 ++++++++++---
> >>>   security/integrity/ima/ima_appraise.c |    2 +-
> >>>   security/integrity/ima/ima_main.c     |   14 +++++++-------
> >>>   security/security.c                   |    6 +++---
> >>>   security/selinux/hooks.c              |   19 +++----------------
> >>>   security/smack/smack.h                |   16 ----------------
> >>>   security/smack/smack_lsm.c            |    9 ++++-----
> >>>   15 files changed, 48 insertions(+), 67 deletions(-)
> >> I never saw any comments, positive or negative, on this patch so I'll
> >> plan on merging it early next week.  If you've got objections, now is
> >> the time to speak up.
> >
> > I just merged this patch, with the AppArmor tweak suggested by Serge,
> > into selinux/next.  Thanks everyone.
>
> Has the security tree been abandoned as a path for general LSM
> changes? Except for the initial Landlock pull and a couple touch-ups
> to capabilities nothing has gone in via security this year. This
> change should have gone in through security, not selinux. I'm glad
> that this change is going in, don't get me wrong on that. I am
> somewhat concerned about the LSM infrastructure work I'm doing,
> and how it's going to get upstream. The diffstats from that look
> a lot like the one here. I seriously doubt that taking the full
> set of changes for stacking through the Smack tree is going to fly. ;)

I don't think there is ever a clear answer when you have a patch(set)
that crosses subsystem boundaries, there is always going to be a bit
of awkwardness and merge-fun for those affected.  If something touches
SELinux, and this patch qualifies as far as I'm concerned, I tend to
offer to take it via the SELinux tree (mostly for selfish reasons as
it helps with merge conflicts) unless James wants to pull it via the
LSM tree; in almost all of those cases James has deferred the changes
to the SELinux tree.  In this particular case I guess I didn't
explicitly ask about the LSM tree vs the SELinux tree, but the patch
has been on-list for weeks and it wasn't snatched up so I felt like
pulling it into the SELinux tree was justified.  If nothing else,
between the SELinux, audit, and netlabel changes I guess I can claim
some level of merge authority ;)

However, regardless of this particular patchset, I agree that the LSM
stacking patches should almost surely go in via the LSM tree.
diff mbox series

Patch

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 2adeea44c0d5..8d04b18155a3 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -205,8 +205,7 @@  LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old,
 LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid)
 LSM_HOOK(int, 0, task_getpgid, struct task_struct *p)
 LSM_HOOK(int, 0, task_getsid, struct task_struct *p)
-LSM_HOOK(void, LSM_RET_VOID, task_getsecid_subj,
-	 struct task_struct *p, u32 *secid)
+LSM_HOOK(void, LSM_RET_VOID, current_getsecid_subj, u32 *secid)
 LSM_HOOK(void, LSM_RET_VOID, task_getsecid_obj,
 	 struct task_struct *p, u32 *secid)
 LSM_HOOK(int, 0, task_setnice, struct task_struct *p, int nice)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 5c4c5c0602cb..9f5b93011ecb 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -716,11 +716,9 @@ 
  *	@p.
  *	@p contains the task_struct for the process.
  *	Return 0 if permission is granted.
- * @task_getsecid_subj:
- *	Retrieve the subjective security identifier of the task_struct in @p
- *	and return it in @secid.  Special care must be taken to ensure that @p
- *	is the either the "current" task, or the caller has exclusive access
- *	to @p.
+ * @current_getsecid_subj:
+ *	Retrieve the subjective security identifier of the current task and
+ *	return it in @secid.
  *	In case of failure, @secid will be set to zero.
  * @task_getsecid_obj:
  *	Retrieve the objective security identifier of the task_struct in @p
diff --git a/include/linux/security.h b/include/linux/security.h
index 5b7288521300..24190cf61858 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -417,7 +417,7 @@  int security_task_fix_setgid(struct cred *new, const struct cred *old,
 int security_task_setpgid(struct task_struct *p, pid_t pgid);
 int security_task_getpgid(struct task_struct *p);
 int security_task_getsid(struct task_struct *p);
-void security_task_getsecid_subj(struct task_struct *p, u32 *secid);
+void security_current_getsecid_subj(u32 *secid);
 void security_task_getsecid_obj(struct task_struct *p, u32 *secid);
 int security_task_setnice(struct task_struct *p, int nice);
 int security_task_setioprio(struct task_struct *p, int ioprio);
@@ -1112,7 +1112,7 @@  static inline int security_task_getsid(struct task_struct *p)
 	return 0;
 }
 
-static inline void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
+static inline void security_current_getsecid_subj(u32 *secid)
 {
 	*secid = 0;
 }
diff --git a/kernel/audit.c b/kernel/audit.c
index 121d37e700a6..d4084751cfe6 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2132,7 +2132,7 @@  int audit_log_task_context(struct audit_buffer *ab)
 	int error;
 	u32 sid;
 
-	security_task_getsecid_subj(current, &sid);
+	security_current_getsecid_subj(&sid);
 	if (!sid)
 		return 0;
 
@@ -2353,7 +2353,7 @@  int audit_signal_info(int sig, struct task_struct *t)
 			audit_sig_uid = auid;
 		else
 			audit_sig_uid = uid;
-		security_task_getsecid_subj(current, &audit_sig_sid);
+		security_current_getsecid_subj(&audit_sig_sid);
 	}
 
 	return audit_signal_info_syscall(t);
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index db2c6b59dfc3..f4ebd2f1cfca 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1359,8 +1359,7 @@  int audit_filter(int msgtype, unsigned int listtype)
 			case AUDIT_SUBJ_SEN:
 			case AUDIT_SUBJ_CLR:
 				if (f->lsm_rule) {
-					security_task_getsecid_subj(current,
-								    &sid);
+					security_current_getsecid_subj(&sid);
 					result = security_audit_rule_match(sid,
 						   f->type, f->op, f->lsm_rule);
 				}
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8dd73a64f921..e0987ee71b8f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -673,7 +673,15 @@  static int audit_filter_rules(struct task_struct *tsk,
 			   logged upon error */
 			if (f->lsm_rule) {
 				if (need_sid) {
-					security_task_getsecid_subj(tsk, &sid);
+					/* @tsk should always be equal to
+					 * @current with the exception of
+					 * fork()/copy_process() in which case
+					 * the new @tsk creds are still a dup
+					 * of @current's creds so we can still
+					 * use security_current_getsecid_subj()
+					 * here even though it always refs
+					 * @current's creds */
+					security_current_getsecid_subj(&sid);
 					need_sid = 0;
 				}
 				result = security_audit_rule_match(sid, f->type,
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index 566ba4397ee4..8490e46359ae 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -1537,7 +1537,7 @@  int __init netlbl_unlabel_defconf(void)
 	/* Only the kernel is allowed to call this function and the only time
 	 * it is called is at bootup before the audit subsystem is reporting
 	 * messages so don't worry to much about these values. */
-	security_task_getsecid_subj(current, &audit_info.secid);
+	security_current_getsecid_subj(&audit_info.secid);
 	audit_info.loginuid = GLOBAL_ROOT_UID;
 	audit_info.sessionid = 0;
 
diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
index 6190cbf94bf0..d6c5b31eb4eb 100644
--- a/net/netlabel/netlabel_user.h
+++ b/net/netlabel/netlabel_user.h
@@ -32,7 +32,7 @@ 
  */
 static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
 {
-	security_task_getsecid_subj(current, &audit_info->secid);
+	security_current_getsecid_subj(&audit_info->secid);
 	audit_info->loginuid = audit_get_loginuid(current);
 	audit_info->sessionid = audit_get_sessionid(current);
 }
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index f72406fe1bf2..fc21190c4f4f 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -728,7 +728,14 @@  static void apparmor_bprm_committed_creds(struct linux_binprm *bprm)
 	return;
 }
 
-static void apparmor_task_getsecid(struct task_struct *p, u32 *secid)
+static void apparmor_current_getsecid_subj(u32 *secid)
+{
+	struct aa_label *label = aa_get_task_label(current);
+	*secid = label->secid;
+	aa_put_label(label);
+}
+
+static void apparmor_task_getsecid_obj(struct task_struct *p, u32 *secid)
 {
 	struct aa_label *label = aa_get_task_label(p);
 	*secid = label->secid;
@@ -1252,8 +1259,8 @@  static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
 
 	LSM_HOOK_INIT(task_free, apparmor_task_free),
 	LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
-	LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
-	LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
+	LSM_HOOK_INIT(current_getsecid_subj, apparmor_current_getsecid_subj),
+	LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid_obj),
 	LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
 	LSM_HOOK_INIT(task_kill, apparmor_task_kill),
 
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index dbba51583e7c..17232bbfb9f9 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -76,7 +76,7 @@  int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
 	if (!ima_appraise)
 		return 0;
 
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	return ima_match_policy(mnt_userns, inode, current_cred(), secid,
 				func, mask, IMA_APPRAISE | IMA_HASH, NULL,
 				NULL, NULL, NULL);
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 465865412100..8c6e4514d494 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -408,7 +408,7 @@  int ima_file_mmap(struct file *file, unsigned long prot)
 	u32 secid;
 
 	if (file && (prot & PROT_EXEC)) {
-		security_task_getsecid_subj(current, &secid);
+		security_current_getsecid_subj(&secid);
 		return process_measurement(file, current_cred(), secid, NULL,
 					   0, MAY_EXEC, MMAP_CHECK);
 	}
@@ -446,7 +446,7 @@  int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
 	    !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
 		return 0;
 
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	inode = file_inode(vma->vm_file);
 	action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
 				current_cred(), secid, MAY_EXEC, MMAP_CHECK,
@@ -487,7 +487,7 @@  int ima_bprm_check(struct linux_binprm *bprm)
 	int ret;
 	u32 secid;
 
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
 				  MAY_EXEC, BPRM_CHECK);
 	if (ret)
@@ -512,7 +512,7 @@  int ima_file_check(struct file *file, int mask)
 {
 	u32 secid;
 
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	return process_measurement(file, current_cred(), secid, NULL, 0,
 				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
 					   MAY_APPEND), FILE_CHECK);
@@ -709,7 +709,7 @@  int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
 
 	/* Read entire file for all partial reads. */
 	func = read_idmap[read_id] ?: FILE_CHECK;
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	return process_measurement(file, current_cred(), secid, NULL,
 				   0, MAY_READ, func);
 }
@@ -752,7 +752,7 @@  int ima_post_read_file(struct file *file, void *buf, loff_t size,
 	}
 
 	func = read_idmap[read_id] ?: FILE_CHECK;
-	security_task_getsecid_subj(current, &secid);
+	security_current_getsecid_subj(&secid);
 	return process_measurement(file, current_cred(), secid, buf, size,
 				   MAY_READ, func);
 }
@@ -905,7 +905,7 @@  int process_buffer_measurement(struct user_namespace *mnt_userns,
 	 * buffer measurements.
 	 */
 	if (func) {
-		security_task_getsecid_subj(current, &secid);
+		security_current_getsecid_subj(&secid);
 		action = ima_get_action(mnt_userns, inode, current_cred(),
 					secid, 0, func, &pcr, &template,
 					func_data, NULL);
diff --git a/security/security.c b/security/security.c
index 9ffa9e9c5c55..827bd161f8b0 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1807,12 +1807,12 @@  int security_task_getsid(struct task_struct *p)
 	return call_int_hook(task_getsid, 0, p);
 }
 
-void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
+void security_current_getsecid_subj(u32 *secid)
 {
 	*secid = 0;
-	call_void_hook(task_getsecid_subj, p, secid);
+	call_void_hook(current_getsecid_subj, secid);
 }
-EXPORT_SYMBOL(security_task_getsecid_subj);
+EXPORT_SYMBOL(security_current_getsecid_subj);
 
 void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
 {
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e7ebd45ca345..5c766b901f66 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -229,19 +229,6 @@  static inline u32 cred_sid(const struct cred *cred)
 	return tsec->sid;
 }
 
-/*
- * get the subjective security ID of a task
- */
-static inline u32 task_sid_subj(const struct task_struct *task)
-{
-	u32 sid;
-
-	rcu_read_lock();
-	sid = cred_sid(rcu_dereference(task->cred));
-	rcu_read_unlock();
-	return sid;
-}
-
 /*
  * get the objective security ID of a task
  */
@@ -4222,9 +4209,9 @@  static int selinux_task_getsid(struct task_struct *p)
 			    PROCESS__GETSESSION, NULL);
 }
 
-static void selinux_task_getsecid_subj(struct task_struct *p, u32 *secid)
+static void selinux_current_getsecid_subj(u32 *secid)
 {
-	*secid = task_sid_subj(p);
+	*secid = current_sid();
 }
 
 static void selinux_task_getsecid_obj(struct task_struct *p, u32 *secid)
@@ -7221,7 +7208,7 @@  static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
 	LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
-	LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid_subj),
+	LSM_HOOK_INIT(current_getsecid_subj, selinux_current_getsecid_subj),
 	LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid_obj),
 	LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
diff --git a/security/smack/smack.h b/security/smack/smack.h
index 99c3422596ab..fc837dcebf96 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -389,22 +389,6 @@  static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
 	return tsp->smk_task;
 }
 
-static inline struct smack_known *smk_of_task_struct_subj(
-						const struct task_struct *t)
-{
-	struct smack_known *skp;
-	const struct cred *cred;
-
-	rcu_read_lock();
-
-	cred = rcu_dereference(t->cred);
-	skp = smk_of_task(smack_cred(cred));
-
-	rcu_read_unlock();
-
-	return skp;
-}
-
 static inline struct smack_known *smk_of_task_struct_obj(
 						const struct task_struct *t)
 {
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 21a0e7c3b8de..40e1d764e616 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2061,15 +2061,14 @@  static int smack_task_getsid(struct task_struct *p)
 }
 
 /**
- * smack_task_getsecid_subj - get the subjective secid of the task
- * @p: the task
+ * smack_current_getsecid_subj - get the subjective secid of the current task
  * @secid: where to put the result
  *
  * Sets the secid to contain a u32 version of the task's subjective smack label.
  */
-static void smack_task_getsecid_subj(struct task_struct *p, u32 *secid)
+static void smack_current_getsecid_subj(u32 *secid)
 {
-	struct smack_known *skp = smk_of_task_struct_subj(p);
+	struct smack_known *skp = smk_of_current();
 
 	*secid = skp->smk_secid;
 }
@@ -4756,7 +4755,7 @@  static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
 	LSM_HOOK_INIT(task_getsid, smack_task_getsid),
-	LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid_subj),
+	LSM_HOOK_INIT(current_getsecid_subj, smack_current_getsecid_subj),
 	LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid_obj),
 	LSM_HOOK_INIT(task_setnice, smack_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),