[RFC,2/3] security: two more call_int_hook_ignore_default use-cases

Commit Message

Paolo Abeni Aug. 3, 2023, 5:12 p.m. UTC

Quite similar to the previous commit, the hooks:

inode_setxattr
inode_removexattr

don't allow the LSM to tell the core to ignore it's return code.
The main difference it that the above mentioned hooks explicitly check
for a non zero return value from the hook to perform the default action.

Changing the LSM_RET_DEFAULT to 1 and using call_int_hook_ignore_default
allows LSM returning the LSM_RET_DEFAULT value will become no-op for the
mentioned hooks.

All the exiting LSM except BPF never use 1 as return value, so no
functional change is expected.

Signed-off-by: Paolo Abeni <[e-mail]>
---
 include/linux/lsm_hook_defs.h | 4 ++--
 security/security.c           | 7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

Patch

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index c9032e20d0b3..49f1f9bed958 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -136,14 +136,14 @@  LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode,
 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(int, 0, inode_getattr, const struct path *path)
-LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap,
+LSM_HOOK(int, 1, inode_setxattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name, const void *value,
 	 size_t size, int flags)
 LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry,
 	 const char *name, const void *value, size_t size, int flags)
 LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
-LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
+LSM_HOOK(int, 1, inode_removexattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
diff --git a/security/security.c b/security/security.c
index b9a7b15e269e..0528cbef0624 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2158,8 +2158,8 @@  int security_inode_setxattr(struct mnt_idmap *idmap,
 	 * SELinux and Smack integrate the cap call,
 	 * so assume that all LSMs supplying this call do so.
 	 */
-	ret = call_int_hook(inode_setxattr, 1, idmap, dentry, name, value,
-			    size, flags);
+	ret = call_int_hook_ignore_default(inode_setxattr, 1, idmap, dentry, name,
+					   value, size, flags);
 
 	if (ret == 1)
 		ret = cap_inode_setxattr(dentry, name, value, size, flags);
@@ -2321,7 +2321,8 @@  int security_inode_removexattr(struct mnt_idmap *idmap,
 	 * SELinux and Smack integrate the cap call,
 	 * so assume that all LSMs supplying this call do so.
 	 */
-	ret = call_int_hook(inode_removexattr, 1, idmap, dentry, name);
+	ret = call_int_hook_ignore_default(inode_removexattr, 1, idmap, dentry,
+					   name);
 	if (ret == 1)
 		ret = cap_inode_removexattr(idmap, dentry, name);
 	if (ret)