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From:   Kees Cook <keescook@chromium.org>
To:     Mimi Zohar <zohar@linux.ibm.com>
Cc:     Kees Cook <keescook@chromium.org>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        Paul Moore <paul@paul-moore.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, Takashi Iwai <tiwai@suse.de>,
        Jonathan McDowell <noodles@fb.com>,
        Casey Schaufler <casey@schaufler-ca.com>,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <mic@digikod.net>,
        KP Singh <kpsingh@kernel.org>,
        John Johansen <john.johansen@canonical.com>,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH 5/9] LSM: Introduce inode_post_setattr hook
Date:   Thu, 13 Oct 2022 15:36:50 -0700
Message-Id: <20221013223654.659758-5-keescook@chromium.org>
In-Reply-To: <20221013222702.never.990-kees@kernel.org>
References: <20221013222702.never.990-kees@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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 <tiwai@suse.de>
Cc: Jonathan McDowell <noodles@fb.com>
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 <keescook@chromium.org>
---
 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