[PATCH 5/9] LSM: Introduce inode_post_setattr hook
From: Kees Cook <hidden>
Date: 2022-10-13 22:37:39
Also in:
linux-hardening, linux-integrity, lkml
Subsystem:
extended verification module (evm), filesystems (vfs and infrastructure), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Mimi Zohar, Roberto Sassu, Alexander Viro, Christian Brauner, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
IMA and EVM need to hook after setattr finishes. Introduce this hook and move IMA and EVM's open-coded stacking to use it. Cc: Mimi Zohar <zohar@linux.ibm.com> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Cc: Paul Moore <paul@paul-moore.com> Cc: James Morris <jmorris@namei.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: Takashi Iwai <redacted> Cc: Jonathan McDowell <redacted> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: linux-integrity@vger.kernel.org Cc: linux-security-module@vger.kernel.org Signed-off-by: Kees Cook <redacted> --- fs/attr.c | 3 +-- include/linux/evm.h | 6 ------ include/linux/ima.h | 9 --------- include/linux/lsm_hook_defs.h | 3 +++ security/integrity/evm/evm_main.c | 10 +++++++++- security/integrity/ima/ima.h | 2 ++ security/integrity/ima/ima_appraise.c | 2 +- security/integrity/ima/ima_main.c | 1 + security/security.c | 8 ++++++++ 9 files changed, 25 insertions(+), 19 deletions(-)
diff --git a/fs/attr.c b/fs/attr.c
index 1552a5f23d6b..e5731057426b 100644
--- a/fs/attr.c
+++ b/fs/attr.c@@ -423,8 +423,7 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry, if (!error) { fsnotify_change(dentry, ia_valid); - ima_inode_post_setattr(mnt_userns, dentry); - evm_inode_post_setattr(dentry, ia_valid); + security_inode_post_setattr(mnt_userns, dentry, ia_valid); } return error;
diff --git a/include/linux/evm.h b/include/linux/evm.h
index aa63e0b3c0a2..53f402bfb9f1 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h@@ -23,7 +23,6 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry, struct integrity_iint_cache *iint); extern int evm_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, struct iattr *attr); -extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid); extern int evm_inode_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name, const void *value, size_t size);
@@ -75,11 +74,6 @@ static inline int evm_inode_setattr(struct user_namespace *mnt_userns, return 0; } -static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid) -{ - return; -} - static inline int evm_inode_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name, const void *value, size_t size)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 9f18df366064..70180b9bd974 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h@@ -127,20 +127,11 @@ static inline void ima_post_key_create_or_update(struct key *keyring, #ifdef CONFIG_IMA_APPRAISE extern bool is_ima_appraise_enabled(void); -extern void ima_inode_post_setattr(struct user_namespace *mnt_userns, - struct dentry *dentry); #else static inline bool is_ima_appraise_enabled(void) { return 0; } - -static inline void ima_inode_post_setattr(struct user_namespace *mnt_userns, - struct dentry *dentry) -{ - return; -} - #endif /* CONFIG_IMA_APPRAISE */ #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 806448173033..0b01473eee8a 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h@@ -135,6 +135,9 @@ LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode, bool rcu) LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask) LSM_HOOK(int, 0, inode_setattr, struct dentry *dentry, struct iattr *attr) +LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, + struct user_namespace *mnt_userns, struct dentry *dentry, + unsigned int ia_valid) LSM_HOOK(int, 0, inode_getattr, const struct path *path) LSM_HOOK(int, 0, inode_setxattr, struct user_namespace *mnt_userns, struct dentry *dentry, const char *name, const void *value,
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 1ef965089417..aca689dc0576 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c@@ -817,7 +817,9 @@ int evm_inode_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, * This function is called from notify_change(), which expects the caller * to lock the inode's i_mutex. */ -void evm_inode_post_setattr(struct dentry *dentry, int ia_valid) +static void evm_inode_post_setattr(struct user_namespace *mnt_userns, + struct dentry *dentry, + unsigned int ia_valid) { if (!evm_revalidate_status(NULL)) return;
@@ -905,6 +907,12 @@ static int __init init_evm(void) late_initcall(init_evm); +static struct security_hook_list evm_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(inode_post_setattr, evm_inode_post_setattr), +}; + void __init integrity_lsm_evm_init(void) { + pr_info("Integrity LSM enabling EVM\n"); + integrity_add_lsm_hooks(evm_hooks, ARRAY_SIZE(evm_hooks)); }
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 15a369df4c00..5c95ea6e6c94 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h@@ -176,6 +176,8 @@ int ima_inode_setxattr(struct user_namespace *mnt_userns, int flags); int ima_inode_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *xattr_name); +void ima_inode_post_setattr(struct user_namespace *mnt_userns, + struct dentry *dentry, unsigned int ia_valid); #endif /*
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ddd9df6b7dac..ccd54b50fe48 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c@@ -631,7 +631,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) * to lock the inode's i_mutex. */ void ima_inode_post_setattr(struct user_namespace *mnt_userns, - struct dentry *dentry) + struct dentry *dentry, unsigned int ia_valid) { struct inode *inode = d_backing_inode(dentry); struct integrity_iint_cache *iint;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 94379ba40b58..ffebd3236f24 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c@@ -1093,6 +1093,7 @@ static struct security_hook_list ima_hooks[] __lsm_ro_after_init = { #ifdef CONFIG_IMA_APPRAISE LSM_HOOK_INIT(inode_setxattr, ima_inode_setxattr), LSM_HOOK_INIT(inode_removexattr, ima_inode_removexattr), + LSM_HOOK_INIT(inode_post_setattr, ima_inode_post_setattr), #endif };
diff --git a/security/security.c b/security/security.c
index ca731132a0e9..af42264ad3e2 100644
--- a/security/security.c
+++ b/security/security.c@@ -1333,6 +1333,14 @@ int security_inode_setattr(struct user_namespace *mnt_userns, } EXPORT_SYMBOL_GPL(security_inode_setattr); +void security_inode_post_setattr(struct user_namespace *mnt_userns, + struct dentry *dentry, unsigned int ia_valid) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(inode_post_setattr, mnt_userns, dentry, ia_valid); +} + int security_inode_getattr(const struct path *path) { if (unlikely(IS_PRIVATE(d_backing_inode(path->dentry))))
--
2.34.1