[3/6] LSM: Manage file security blobs

Message ID	3cb05c5f-a8b1-9bdd-5db6-dd21bdcd4d22@schaufler-ca.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <kernel-hardening-return-8476-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com> Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk To: LSM <linux-security-module@vger.kernel.org>, James Morris <jmorris@namei.org> Cc: John Johansen <john.johansen@canonical.com>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, Paul Moore <paul@paul-moore.com>, Stephen Smalley <sds@tycho.nsa.gov>, Kees Cook <keescook@chromium.org>, "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>, LKLM <linux-kernel@vger.kernel.org> References: <59cec608-608e-6de6-21d9-bdec7b0ded3b@schaufler-ca.com> From: Casey Schaufler <casey@schaufler-ca.com> Message-ID: <3cb05c5f-a8b1-9bdd-5db6-dd21bdcd4d22@schaufler-ca.com> Date: Thu, 8 Jun 2017 13:49:52 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <59cec608-608e-6de6-21d9-bdec7b0ded3b@schaufler-ca.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: [kernel-hardening] [PATCH 3/6] LSM: Manage file security blobs

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 41f01e2..dc012eb 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1894,6 +1894,7 @@ struct security_hook_list { */ struct lsm_blob_sizes { int lbs_cred; + int lbs_file; }; /* diff --git a/security/apparmor/include/context.h b/security/apparmor/include/context.h index f35ad39..3ff3879 100644 --- a/security/apparmor/include/context.h +++ b/security/apparmor/include/context.h @@ -25,6 +25,7 @@ #define cred_ctx(X) apparmor_cred(X) #define current_ctx() cred_ctx(current_cred()) +#define file_ctx(X) apparmor_file(X) /* struct aa_file_ctx - the AppArmor context the file was opened in * @perms: the permission the file was opened with @@ -92,6 +93,11 @@ static inline struct aa_task_ctx *apparmor_cred(const struct cred *cred) return cred->security; } +static inline struct aa_file_ctx *apparmor_file(const struct file *file) +{ + return file->f_security; +} + /** * aa_cred_profile - obtain cred's profiles * @cred: cred to obtain profiles from (NOT NULL) diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index eef5551..12a0265 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -329,7 +329,7 @@ static int apparmor_inode_getattr(const struct path *path) static int apparmor_file_open(struct file *file, const struct cred *cred) { - struct aa_file_ctx *fctx = file->f_security; + struct aa_file_ctx *fctx = file_ctx(file); struct aa_profile *profile; int error = 0; @@ -360,26 +360,9 @@ static int apparmor_file_open(struct file *file, const struct cred *cred) return error; } -static int apparmor_file_alloc_security(struct file *file) -{ - /* freed by apparmor_file_free_security */ - file->f_security = aa_alloc_file_context(GFP_KERNEL); - if (!file->f_security) - return -ENOMEM; - return 0; - -} - -static void apparmor_file_free_security(struct file *file) -{ - struct aa_file_ctx *ctx = file->f_security; - - aa_free_file_context(ctx); -} - static int common_file_perm(const char *op, struct file *file, u32 mask) { - struct aa_file_ctx *fctx = file->f_security; + struct aa_file_ctx *fctx = file_ctx(file); struct aa_profile *profile, *fprofile = aa_cred_profile(file->f_cred); int error = 0; @@ -425,7 +408,7 @@ static int common_mmap(const char *op, struct file *file, unsigned long prot, { int mask = 0; - if (!file || !file->f_security) + if (!file || file_ctx(file) == NULL) return 0; if (prot & PROT_READ) @@ -566,6 +549,7 @@ static int apparmor_task_setrlimit(struct task_struct *task, struct lsm_blob_sizes apparmor_blob_sizes = { .lbs_cred = sizeof(struct aa_task_ctx), + .lbs_file = sizeof(struct aa_file_ctx), }; static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = { @@ -588,8 +572,6 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(file_open, apparmor_file_open), LSM_HOOK_INIT(file_permission, apparmor_file_permission), - LSM_HOOK_INIT(file_alloc_security, apparmor_file_alloc_security), - LSM_HOOK_INIT(file_free_security, apparmor_file_free_security), LSM_HOOK_INIT(mmap_file, apparmor_mmap_file), LSM_HOOK_INIT(file_mprotect, apparmor_file_mprotect), LSM_HOOK_INIT(file_lock, apparmor_file_lock), diff --git a/security/security.c b/security/security.c index 062a9e4..3c22fb1 100644 --- a/security/security.c +++ b/security/security.c @@ -88,6 +88,7 @@ int __init security_init(void) #ifdef CONFIG_SECURITY_LSM_DEBUG pr_info("LSM: cred blob size = %d\n", blob_sizes.lbs_cred); + pr_info("LSM: file blob size = %d\n", blob_sizes.lbs_file); #endif return 0; @@ -246,6 +247,30 @@ static void __init lsm_set_size(int *need, int *lbs) void __init security_add_blobs(struct lsm_blob_sizes *needed) { lsm_set_size(&needed->lbs_cred, &blob_sizes.lbs_cred); + lsm_set_size(&needed->lbs_file, &blob_sizes.lbs_file); +} + +/** + * lsm_file_alloc - allocate a composite file blob + * @file: the file that needs a blob + * + * Allocate the file blob for all the modules + * + * Returns 0, or -ENOMEM if memory can't be allocated. + */ +int lsm_file_alloc(struct file *file) +{ +#ifdef CONFIG_SECURITY_LSM_DEBUG + if (file->f_security) + pr_info("%s: Inbound file blob is not NULL.\n", __func__); +#endif + if (blob_sizes.lbs_file == 0) + return 0; + + file->f_security = kzalloc(blob_sizes.lbs_file, GFP_KERNEL); + if (file->f_security == NULL) + return -ENOMEM; + return 0; } /* @@ -933,12 +958,19 @@ int security_file_permission(struct file *file, int mask) int security_file_alloc(struct file *file) { + int rc = lsm_file_alloc(file); + + if (rc) + return rc; return call_int_hook(file_alloc_security, 0, file); } void security_file_free(struct file *file) { call_void_hook(file_free_security, file); + + kfree(file->f_security); + file->f_security = NULL; } int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 00156c6..223a178 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -127,7 +127,6 @@ int selinux_enabled = 1; #endif static struct kmem_cache *sel_inode_cache; -static struct kmem_cache *file_security_cache; /** * selinux_secmark_enabled - Check to see if SECMARK is currently enabled @@ -347,27 +346,15 @@ static void inode_free_security(struct inode *inode) static int file_alloc_security(struct file *file) { - struct file_security_struct *fsec; + struct file_security_struct *fsec = selinux_file(file); u32 sid = current_sid(); - fsec = kmem_cache_zalloc(file_security_cache, GFP_KERNEL); - if (!fsec) - return -ENOMEM; - fsec->sid = sid; fsec->fown_sid = sid; - file->f_security = fsec; return 0; } -static void file_free_security(struct file *file) -{ - struct file_security_struct *fsec = file->f_security; - file->f_security = NULL; - kmem_cache_free(file_security_cache, fsec); -} - static int superblock_alloc_security(struct super_block *sb) { struct superblock_security_struct *sbsec; @@ -1793,7 +1780,7 @@ static int file_has_perm(const struct cred *cred, struct file *file, u32 av) { - struct file_security_struct *fsec = file->f_security; + struct file_security_struct *fsec = selinux_file(file); struct inode *inode = file_inode(file); struct common_audit_data ad; u32 sid = cred_sid(cred); @@ -2112,7 +2099,7 @@ static int selinux_binder_transfer_file(struct task_struct *from, struct file *file) { u32 sid = task_sid(to); - struct file_security_struct *fsec = file->f_security; + struct file_security_struct *fsec = selinux_file(file); struct dentry *dentry = file->f_path.dentry; struct inode_security_struct *isec; struct common_audit_data ad; @@ -3376,7 +3363,7 @@ static int selinux_revalidate_file_permission(struct file *file, int mask) static int selinux_file_permission(struct file *file, int mask) { struct inode *inode = file_inode(file); - struct file_security_struct *fsec = file->f_security; + struct file_security_struct *fsec = selinux_file(file); struct inode_security_struct *isec; u32 sid = current_sid(); @@ -3398,11 +3385,6 @@ static int selinux_file_alloc_security(struct file *file) return file_alloc_security(file); } -static void selinux_file_free_security(struct file *file) -{ - file_free_security(file); -} - /* * Check whether a task has the ioctl permission and cmd * operation to an inode. @@ -3411,7 +3393,7 @@ static int ioctl_has_perm(const struct cred *cred, struct file *file, u32 requested, u16 cmd) { struct common_audit_data ad; - struct file_security_struct *fsec = file->f_security; + struct file_security_struct *fsec = selinux_file(file); struct inode *inode = file_inode(file); struct inode_security_struct *isec; struct lsm_ioctlop_audit ioctl; @@ -3645,7 +3627,7 @@ static void selinux_file_set_fowner(struct file *file) { struct file_security_struct *fsec; - fsec = file->f_security; + fsec = selinux_file(file); fsec->fown_sid = current_sid(); } @@ -3660,7 +3642,7 @@ static int selinux_file_send_sigiotask(struct task_struct *tsk, /* struct fown_struct is never outside the context of a struct file */ file = container_of(fown, struct file, f_owner); - fsec = file->f_security; + fsec = selinux_file(file); if (!signum) perm = signal_to_av(SIGIO); /* as per send_sigio_to_task */ @@ -3683,7 +3665,7 @@ static int selinux_file_open(struct file *file, const struct cred *cred) struct file_security_struct *fsec; struct inode_security_struct *isec; - fsec = file->f_security; + fsec = selinux_file(file); isec = inode_security(file_inode(file)); /* * Save inode label and policy sequence number @@ -3812,7 +3794,7 @@ static int selinux_kernel_module_from_file(struct file *file) ad.type = LSM_AUDIT_DATA_FILE; ad.u.file = file; - fsec = file->f_security; + fsec = selinux_file(file); if (sid != fsec->sid) { rc = avc_has_perm(sid, fsec->sid, SECCLASS_FD, FD__USE, &ad); if (rc) @@ -6094,6 +6076,7 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer) struct lsm_blob_sizes selinux_blob_sizes = { .lbs_cred = sizeof(struct task_security_struct), + .lbs_file = sizeof(struct file_security_struct), }; static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { @@ -6165,7 +6148,6 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(file_permission, selinux_file_permission), LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security), - LSM_HOOK_INIT(file_free_security, selinux_file_free_security), LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl), LSM_HOOK_INIT(mmap_file, selinux_mmap_file), LSM_HOOK_INIT(mmap_addr, selinux_mmap_addr), @@ -6340,9 +6322,6 @@ static __init int selinux_init(void) sel_inode_cache = kmem_cache_create("selinux_inode_security", sizeof(struct inode_security_struct), 0, SLAB_PANIC, NULL); - file_security_cache = kmem_cache_create("selinux_file_security", - sizeof(struct file_security_struct), - 0, SLAB_PANIC, NULL); avc_init(); security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux"); diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h index 48132cc..6a638da 100644 --- a/security/selinux/include/objsec.h +++ b/security/selinux/include/objsec.h @@ -150,4 +150,9 @@ static inline struct task_security_struct *selinux_cred(const struct cred *cred) return cred->security; } +static inline struct file_security_struct *selinux_file(const struct file *file) +{ + return file->f_security; +} + #endif /* _SELINUX_OBJSEC_H_ */ diff --git a/security/smack/smack.h b/security/smack/smack.h index 17949ec..9e704a6 100644 --- a/security/smack/smack.h +++ b/security/smack/smack.h @@ -361,6 +361,11 @@ static inline struct task_smack *smack_cred(const struct cred *cred) return cred->security; } +static inline struct smack_known **smack_file(const struct file *file) +{ + return file->f_security; +} + /* * Is the directory transmuting? */ diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 3ee5a14..3c95c1f 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -1601,25 +1601,13 @@ static void smack_inode_getsecid(struct inode *inode, u32 *secid) */ static int smack_file_alloc_security(struct file *file) { - struct smack_known *skp = smk_of_current(); + struct smack_known **blob = smack_file(file); - file->f_security = skp; + *blob = smk_of_current(); return 0; } /** - * smack_file_free_security - clear a file security blob - * @file: the object - * - * The security blob for a file is a pointer to the master - * label list, so no memory is freed. - */ -static void smack_file_free_security(struct file *file) -{ - file->f_security = NULL; -} - -/** * smack_file_ioctl - Smack check on ioctls * @file: the object * @cmd: what to do @@ -1843,7 +1831,9 @@ static int smack_mmap_file(struct file *file, */ static void smack_file_set_fowner(struct file *file) { - file->f_security = smk_of_current(); + struct smack_known **blob = smack_file(file); + + *blob = smk_of_current(); } /** @@ -1860,6 +1850,7 @@ static void smack_file_set_fowner(struct file *file) static int smack_file_send_sigiotask(struct task_struct *tsk, struct fown_struct *fown, int signum) { + struct smack_known **blob; struct smack_known *skp; struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred)); struct file *file; @@ -1872,7 +1863,8 @@ static int smack_file_send_sigiotask(struct task_struct *tsk, file = container_of(fown, struct file, f_owner); /* we don't log here as rc can be overriden */ - skp = file->f_security; + blob = smack_file(file); + skp = *blob; rc = smk_access(skp, tkp, MAY_DELIVER, NULL); rc = smk_bu_note("sigiotask", skp, tkp, MAY_DELIVER, rc); if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE)) @@ -4604,6 +4596,7 @@ static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen) struct lsm_blob_sizes smack_blob_sizes = { .lbs_cred = sizeof(struct task_smack), + .lbs_file = sizeof(struct smack_known *), }; static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { @@ -4643,7 +4636,6 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_getsecid, smack_inode_getsecid), LSM_HOOK_INIT(file_alloc_security, smack_file_alloc_security), - LSM_HOOK_INIT(file_free_security, smack_file_free_security), LSM_HOOK_INIT(file_ioctl, smack_file_ioctl), LSM_HOOK_INIT(file_lock, smack_file_lock), LSM_HOOK_INIT(file_fcntl, smack_file_fcntl),

[3/6] LSM: Manage file security blobs

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