diff mbox series

[02/10] Smack: Abstract use of cred security blob

Message ID 18c20c50-3ec5-0c85-93ef-58a3dbf3498c@schaufler-ca.com (mailing list archive)
State Superseded
Headers show
Series LSM: Module stacking in support of S.A.R.A and Landlock | expand

Commit Message

Casey Schaufler Sept. 11, 2018, 4:41 p.m. UTC 
Don't use the cred->security pointer directly.
Provide a helper function that provides the security blob pointer.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 security/smack/smack.h        | 14 +++++++--
 security/smack/smack_access.c |  4 +--
 security/smack/smack_lsm.c    | 57 +++++++++++++++++------------------
 security/smack/smackfs.c      | 18 +++++------
 4 files changed, 50 insertions(+), 43 deletions(-)

Comments

Kees Cook Sept. 12, 2018, 11:04 p.m. UTC | #1 
On Tue, Sep 11, 2018 at 9:41 AM, Casey Schaufler <casey@schaufler-ca.com> wrote:
> Don't use the cred->security pointer directly.
> Provide a helper function that provides the security blob pointer.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>  security/smack/smack.h        | 14 +++++++--
>  security/smack/smack_access.c |  4 +--
>  security/smack/smack_lsm.c    | 57 +++++++++++++++++------------------
>  security/smack/smackfs.c      | 18 +++++------
>  4 files changed, 50 insertions(+), 43 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index f7db791fb566..0b55d6a55b26 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -356,6 +356,11 @@ extern struct list_head smack_onlycap_list;
>  #define SMACK_HASH_SLOTS 16
>  extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
>
> +static inline struct task_smack *smack_cred(const struct cred *cred)
> +{
> +       return cred->security;
> +}
> +
>  /*
>   * Is the directory transmuting?
>   */
> @@ -382,13 +387,16 @@ 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(const struct task_struct *t)
> +static inline struct smack_known *smk_of_task_struct(
> +                                               const struct task_struct *t)
>  {
>         struct smack_known *skp;
> +       const struct cred *cred;
>
>         rcu_read_lock();
> -       skp = smk_of_task(__task_cred(t)->security);
> +       cred = __task_cred(t);
>         rcu_read_unlock();
> +       skp = smk_of_task(smack_cred(cred));

Hm, why is this safe? (i.e. what is pinning the cred?) I would expect
get_cred()/put_cred() since this is not for "current"? And then what
controls the skp lifetime?

Everything else looks to be mechanical replacement, so that's fine.
Did you use some tooling to do the mechanical replacement or was it
done by hand?

-Kees
diff mbox series

Patch

diff --git a/security/smack/smack.h b/security/smack/smack.h
index f7db791fb566..0b55d6a55b26 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -356,6 +356,11 @@  extern struct list_head smack_onlycap_list;
 #define SMACK_HASH_SLOTS 16
 extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
 
+static inline struct task_smack *smack_cred(const struct cred *cred)
+{
+	return cred->security;
+}
+
 /*
  * Is the directory transmuting?
  */
@@ -382,13 +387,16 @@  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(const struct task_struct *t)
+static inline struct smack_known *smk_of_task_struct(
+						const struct task_struct *t)
 {
 	struct smack_known *skp;
+	const struct cred *cred;
 
 	rcu_read_lock();
-	skp = smk_of_task(__task_cred(t)->security);
+	cred = __task_cred(t);
 	rcu_read_unlock();
+	skp = smk_of_task(smack_cred(cred));
 	return skp;
 }
 
@@ -405,7 +413,7 @@  static inline struct smack_known *smk_of_forked(const struct task_smack *tsp)
  */
 static inline struct smack_known *smk_of_current(void)
 {
-	return smk_of_task(current_security());
+	return smk_of_task(smack_cred(current_cred()));
 }
 
 /*
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 9a4c0ad46518..489d49a20b47 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -275,7 +275,7 @@  int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
 int smk_curacc(struct smack_known *obj_known,
 	       u32 mode, struct smk_audit_info *a)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_tskacc(tsp, obj_known, mode, a);
 }
@@ -635,7 +635,7 @@  DEFINE_MUTEX(smack_onlycap_lock);
  */
 bool smack_privileged_cred(int cap, const struct cred *cred)
 {
-	struct task_smack *tsp = cred->security;
+	struct task_smack *tsp = smack_cred(cred);
 	struct smack_known *skp = tsp->smk_task;
 	struct smack_known_list_elem *sklep;
 	int rc;
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 340fc30ad85d..68ee3ae8f25c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -122,7 +122,7 @@  static int smk_bu_note(char *note, struct smack_known *sskp,
 static int smk_bu_current(char *note, struct smack_known *oskp,
 			  int mode, int rc)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
 	if (rc <= 0)
@@ -143,7 +143,7 @@  static int smk_bu_current(char *note, struct smack_known *oskp,
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 static int smk_bu_task(struct task_struct *otp, int mode, int rc)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	struct smack_known *smk_task = smk_of_task_struct(otp);
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
@@ -165,7 +165,7 @@  static int smk_bu_task(struct task_struct *otp, int mode, int rc)
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 static int smk_bu_inode(struct inode *inode, int mode, int rc)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	struct inode_smack *isp = inode->i_security;
 	char acc[SMK_NUM_ACCESS_TYPE + 1];
 
@@ -195,7 +195,7 @@  static int smk_bu_inode(struct inode *inode, int mode, int rc)
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 static int smk_bu_file(struct file *file, int mode, int rc)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	struct smack_known *sskp = tsp->smk_task;
 	struct inode *inode = file_inode(file);
 	struct inode_smack *isp = inode->i_security;
@@ -225,7 +225,7 @@  static int smk_bu_file(struct file *file, int mode, int rc)
 static int smk_bu_credfile(const struct cred *cred, struct file *file,
 				int mode, int rc)
 {
-	struct task_smack *tsp = cred->security;
+	struct task_smack *tsp = smack_cred(cred);
 	struct smack_known *sskp = tsp->smk_task;
 	struct inode *inode = file_inode(file);
 	struct inode_smack *isp = inode->i_security;
@@ -429,7 +429,7 @@  static int smk_ptrace_rule_check(struct task_struct *tracer,
 	}
 
 	rcu_read_lock();
-	tsp = __task_cred(tracer)->security;
+	tsp = smack_cred(__task_cred(tracer));
 	tracer_known = smk_of_task(tsp);
 
 	if ((mode & PTRACE_MODE_ATTACH) &&
@@ -496,7 +496,7 @@  static int smack_ptrace_traceme(struct task_struct *ptp)
 	int rc;
 	struct smack_known *skp;
 
-	skp = smk_of_task(current_security());
+	skp = smk_of_task(smack_cred(current_cred()));
 
 	rc = smk_ptrace_rule_check(ptp, skp, PTRACE_MODE_ATTACH, __func__);
 	return rc;
@@ -913,7 +913,7 @@  static int smack_sb_statfs(struct dentry *dentry)
 static int smack_bprm_set_creds(struct linux_binprm *bprm)
 {
 	struct inode *inode = file_inode(bprm->file);
-	struct task_smack *bsp = bprm->cred->security;
+	struct task_smack *bsp = smack_cred(bprm->cred);
 	struct inode_smack *isp;
 	struct superblock_smack *sbsp;
 	int rc;
@@ -1744,7 +1744,7 @@  static int smack_mmap_file(struct file *file,
 		return -EACCES;
 	mkp = isp->smk_mmap;
 
-	tsp = current_security();
+	tsp = smack_cred(current_cred());
 	skp = smk_of_current();
 	rc = 0;
 
@@ -1840,7 +1840,7 @@  static int smack_file_send_sigiotask(struct task_struct *tsk,
 				     struct fown_struct *fown, int signum)
 {
 	struct smack_known *skp;
-	struct smack_known *tkp = smk_of_task(tsk->cred->security);
+	struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred));
 	struct file *file;
 	int rc;
 	struct smk_audit_info ad;
@@ -1888,7 +1888,7 @@  static int smack_file_receive(struct file *file)
 	if (inode->i_sb->s_magic == SOCKFS_MAGIC) {
 		sock = SOCKET_I(inode);
 		ssp = sock->sk->sk_security;
-		tsp = current_security();
+		tsp = smack_cred(current_cred());
 		/*
 		 * If the receiving process can't write to the
 		 * passed socket or if the passed socket can't
@@ -1930,7 +1930,7 @@  static int smack_file_receive(struct file *file)
  */
 static int smack_file_open(struct file *file)
 {
-	struct task_smack *tsp = file->f_cred->security;
+	struct task_smack *tsp = smack_cred(file->f_cred);
 	struct inode *inode = file_inode(file);
 	struct smk_audit_info ad;
 	int rc;
@@ -1977,7 +1977,7 @@  static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
  */
 static void smack_cred_free(struct cred *cred)
 {
-	struct task_smack *tsp = cred->security;
+	struct task_smack *tsp = smack_cred(cred);
 	struct smack_rule *rp;
 	struct list_head *l;
 	struct list_head *n;
@@ -2007,7 +2007,7 @@  static void smack_cred_free(struct cred *cred)
 static int smack_cred_prepare(struct cred *new, const struct cred *old,
 			      gfp_t gfp)
 {
-	struct task_smack *old_tsp = old->security;
+	struct task_smack *old_tsp = smack_cred(old);
 	struct task_smack *new_tsp;
 	int rc;
 
@@ -2038,15 +2038,14 @@  static int smack_cred_prepare(struct cred *new, const struct cred *old,
  */
 static void smack_cred_transfer(struct cred *new, const struct cred *old)
 {
-	struct task_smack *old_tsp = old->security;
-	struct task_smack *new_tsp = new->security;
+	struct task_smack *old_tsp = smack_cred(old);
+	struct task_smack *new_tsp = smack_cred(new);
 
 	new_tsp->smk_task = old_tsp->smk_task;
 	new_tsp->smk_forked = old_tsp->smk_task;
 	mutex_init(&new_tsp->smk_rules_lock);
 	INIT_LIST_HEAD(&new_tsp->smk_rules);
 
-
 	/* cbs copy rule list */
 }
 
@@ -2057,12 +2056,12 @@  static void smack_cred_transfer(struct cred *new, const struct cred *old)
  *
  * Sets the secid to contain a u32 version of the smack label.
  */
-static void smack_cred_getsecid(const struct cred *c, u32 *secid)
+static void smack_cred_getsecid(const struct cred *cred, u32 *secid)
 {
 	struct smack_known *skp;
 
 	rcu_read_lock();
-	skp = smk_of_task(c->security);
+	skp = smk_of_task(smack_cred(cred));
 	*secid = skp->smk_secid;
 	rcu_read_unlock();
 }
@@ -2076,7 +2075,7 @@  static void smack_cred_getsecid(const struct cred *c, u32 *secid)
  */
 static int smack_kernel_act_as(struct cred *new, u32 secid)
 {
-	struct task_smack *new_tsp = new->security;
+	struct task_smack *new_tsp = smack_cred(new);
 
 	new_tsp->smk_task = smack_from_secid(secid);
 	return 0;
@@ -2094,7 +2093,7 @@  static int smack_kernel_create_files_as(struct cred *new,
 					struct inode *inode)
 {
 	struct inode_smack *isp = inode->i_security;
-	struct task_smack *tsp = new->security;
+	struct task_smack *tsp = smack_cred(new);
 
 	tsp->smk_forked = isp->smk_inode;
 	tsp->smk_task = tsp->smk_forked;
@@ -2278,7 +2277,7 @@  static int smack_task_kill(struct task_struct *p, struct siginfo *info,
 	 * specific behavior. This is not clean. For one thing
 	 * we can't take privilege into account.
 	 */
-	skp = smk_of_task(cred->security);
+	skp = smk_of_task(smack_cred(cred));
 	rc = smk_access(skp, tkp, MAY_DELIVER, &ad);
 	rc = smk_bu_note("USB signal", skp, tkp, MAY_DELIVER, rc);
 	return rc;
@@ -3605,7 +3604,7 @@  static int smack_getprocattr(struct task_struct *p, char *name, char **value)
  */
 static int smack_setprocattr(const char *name, void *value, size_t size)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	struct cred *new;
 	struct smack_known *skp;
 	struct smack_known_list_elem *sklep;
@@ -3646,7 +3645,7 @@  static int smack_setprocattr(const char *name, void *value, size_t size)
 	if (new == NULL)
 		return -ENOMEM;
 
-	tsp = new->security;
+	tsp = smack_cred(new);
 	tsp->smk_task = skp;
 	/*
 	 * process can change its label only once
@@ -4291,7 +4290,7 @@  static void smack_inet_csk_clone(struct sock *sk,
 static int smack_key_alloc(struct key *key, const struct cred *cred,
 			   unsigned long flags)
 {
-	struct smack_known *skp = smk_of_task(cred->security);
+	struct smack_known *skp = smk_of_task(smack_cred(cred));
 
 	key->security = skp;
 	return 0;
@@ -4322,7 +4321,7 @@  static int smack_key_permission(key_ref_t key_ref,
 {
 	struct key *keyp;
 	struct smk_audit_info ad;
-	struct smack_known *tkp = smk_of_task(cred->security);
+	struct smack_known *tkp = smk_of_task(smack_cred(cred));
 	int request = 0;
 	int rc;
 
@@ -4591,7 +4590,7 @@  static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
 			return -ENOMEM;
 	}
 
-	tsp = new_creds->security;
+	tsp = smack_cred(new_creds);
 
 	/*
 	 * Get label from overlay inode and set it in create_sid
@@ -4619,8 +4618,8 @@  static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
 					const struct cred *old,
 					struct cred *new)
 {
-	struct task_smack *otsp = old->security;
-	struct task_smack *ntsp = new->security;
+	struct task_smack *otsp = smack_cred(old);
+	struct task_smack *ntsp = smack_cred(new);
 	struct inode_smack *isp;
 	int may;
 
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index f6482e53d55a..9d2dde608298 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -2208,14 +2208,14 @@  static const struct file_operations smk_logging_ops = {
 
 static void *load_self_seq_start(struct seq_file *s, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_start(s, pos, &tsp->smk_rules);
 }
 
 static void *load_self_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_next(s, v, pos, &tsp->smk_rules);
 }
@@ -2262,7 +2262,7 @@  static int smk_open_load_self(struct inode *inode, struct file *file)
 static ssize_t smk_write_load_self(struct file *file, const char __user *buf,
 			      size_t count, loff_t *ppos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_write_rules_list(file, buf, count, ppos, &tsp->smk_rules,
 				    &tsp->smk_rules_lock, SMK_FIXED24_FMT);
@@ -2414,14 +2414,14 @@  static const struct file_operations smk_load2_ops = {
 
 static void *load_self2_seq_start(struct seq_file *s, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_start(s, pos, &tsp->smk_rules);
 }
 
 static void *load_self2_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_next(s, v, pos, &tsp->smk_rules);
 }
@@ -2467,7 +2467,7 @@  static int smk_open_load_self2(struct inode *inode, struct file *file)
 static ssize_t smk_write_load_self2(struct file *file, const char __user *buf,
 			      size_t count, loff_t *ppos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_write_rules_list(file, buf, count, ppos, &tsp->smk_rules,
 				    &tsp->smk_rules_lock, SMK_LONG_FMT);
@@ -2681,14 +2681,14 @@  static const struct file_operations smk_syslog_ops = {
 
 static void *relabel_self_seq_start(struct seq_file *s, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_start(s, pos, &tsp->smk_relabel);
 }
 
 static void *relabel_self_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 
 	return smk_seq_next(s, v, pos, &tsp->smk_relabel);
 }
@@ -2736,7 +2736,7 @@  static int smk_open_relabel_self(struct inode *inode, struct file *file)
 static ssize_t smk_write_relabel_self(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	struct task_smack *tsp = current_security();
+	struct task_smack *tsp = smack_cred(current_cred());
 	char *data;
 	int rc;
 	LIST_HEAD(list_tmp);