linux-hardening - [PATCH 4/9] ima: Move ima_file

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Message-Id: <20221013223654.659758-4-keescook@chromium.org>
Date:   Thu, 13 Oct 2022 15:36:49 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>, Petr Vorel <pvorel@...e.cz>,
        Jonathan McDowell <noodles@...com>,
        Borislav Petkov <bp@...e.de>, Takashi Iwai <tiwai@...e.de>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Mickaël Salaün <mic@...ikod.net>,
        KP Singh <kpsingh@...nel.org>,
        Casey Schaufler <casey@...aufler-ca.com>,
        John Johansen <john.johansen@...onical.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH 4/9] ima: Move ima_file_free() into LSM

The file_free_security hook already exists for managing notification of
released files. Use the LSM hook instead of open-coded stacking.

Cc: Mimi Zohar <zohar@...ux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Cc: Paul Moore <paul@...l-moore.com>
Cc: James Morris <jmorris@...ei.org>
Cc: "Serge E. Hallyn" <serge@...lyn.com>
Cc: Petr Vorel <pvorel@...e.cz>
Cc: Jonathan McDowell <noodles@...com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Takashi Iwai <tiwai@...e.de>
Cc: linux-integrity@...r.kernel.org
Cc: linux-security-module@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/file_table.c                   | 1 -
 include/linux/ima.h               | 6 ------
 security/integrity/ima/ima_main.c | 3 ++-
 3 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index 99c6796c9f28..fa707d221a43 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -311,7 +311,6 @@ static void __fput(struct file *file)
 	eventpoll_release(file);
 	locks_remove_file(file);
 
-	ima_file_free(file);
 	if (unlikely(file->f_flags & FASYNC)) {
 		if (file->f_op->fasync)
 			file->f_op->fasync(-1, file, 0);
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 6dc5143f89f2..9f18df366064 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -19,7 +19,6 @@ extern enum hash_algo ima_get_current_hash_algo(void);
 extern int ima_file_check(struct file *file, int mask);
 extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
 				    struct inode *inode);
-extern void ima_file_free(struct file *file);
 extern void ima_post_path_mknod(struct user_namespace *mnt_userns,
 				struct dentry *dentry);
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
@@ -56,11 +55,6 @@ static inline void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
 {
 }
 
-static inline void ima_file_free(struct file *file)
-{
-	return;
-}
-
 static inline void ima_post_path_mknod(struct user_namespace *mnt_userns,
 				       struct dentry *dentry)
 {
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index b3b79d030a67..94379ba40b58 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -183,7 +183,7 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint,
  *
  * Flag files that changed, based on i_version
  */
-void ima_file_free(struct file *file)
+static void ima_file_free(struct file *file)
 {
 	struct inode *inode = file_inode(file);
 	struct integrity_iint_cache *iint;
@@ -1085,6 +1085,7 @@ static struct security_hook_list ima_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(bprm_check_security, ima_bprm_check),
 	LSM_HOOK_INIT(mmap_file, ima_file_mmap),
 	LSM_HOOK_INIT(file_mprotect, ima_file_mprotect),
+	LSM_HOOK_INIT(file_free_security, ima_file_free),
 	LSM_HOOK_INIT(kernel_read_file, ima_read_file),
 	LSM_HOOK_INIT(kernel_post_read_file, ima_post_read_file),
 	LSM_HOOK_INIT(kernel_load_data, ima_load_data),
-- 
2.34.1