lsm: constify 'sb' parameter in security_quotactl()

SELinux registers the implementation for the "quotactl" hook. Looking at
the function implementation we observe that the parameter "sb" is not
changing.

Mark the "sb" parameter of LSM hook security_quotactl() as "const" since
it will not be changing in the LSM hook.
Signed-off-by: Khadija Kamran <kamrankhadijadj@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/lsm_hook_defs.h

@@ -43,7 +43,7 @@ LSM_HOOK(int, 0, capset, struct cred *new, const struct cred *old,
 	 const kernel_cap_t *permitted)
 LSM_HOOK(int, 0, capable, const struct cred *cred, struct user_namespace *ns,
 	 int cap, unsigned int opts)
-LSM_HOOK(int, 0, quotactl, int cmds, int type, int id, struct super_block *sb)
+LSM_HOOK(int, 0, quotactl, int cmds, int type, int id, const struct super_block *sb)
 LSM_HOOK(int, 0, quota_on, struct dentry *dentry)
 LSM_HOOK(int, 0, syslog, int type)
 LSM_HOOK(int, 0, settime, const struct timespec64 *ts,

include/linux/security.h

@@ -284,7 +284,7 @@ int security_capable(const struct cred *cred,
 		       struct user_namespace *ns,
 		       int cap,
 		       unsigned int opts);
-int security_quotactl(int cmds, int type, int id, struct super_block *sb);
+int security_quotactl(int cmds, int type, int id, const struct super_block *sb);
 int security_quota_on(struct dentry *dentry);
 int security_syslog(int type);
 int security_settime64(const struct timespec64 *ts, const struct timezone *tz);
@@ -581,7 +581,7 @@ static inline int security_capable(const struct cred *cred,
 }
 
 static inline int security_quotactl(int cmds, int type, int id,
-				     struct super_block *sb)
+				     const struct super_block *sb)
 {
 	return 0;
 }

security/security.c

@@ -957,7 +957,7 @@ int security_capable(const struct cred *cred,
  *
  * Return: Returns 0 if permission is granted.
  */
-int security_quotactl(int cmds, int type, int id, struct super_block *sb)
+int security_quotactl(int cmds, int type, int id, const struct super_block *sb)
 {
 	return call_int_hook(quotactl, 0, cmds, type, id, sb);
 }

security/selinux/hooks.c

@@ -1937,7 +1937,7 @@ static inline int may_rename(struct inode *old_dir,
 
 /* Check whether a task can perform a filesystem operation. */
 static int superblock_has_perm(const struct cred *cred,
-			       struct super_block *sb,
+			       const struct super_block *sb,
 			       u32 perms,
 			       struct common_audit_data *ad)
 {
@@ -2139,7 +2139,7 @@ static int selinux_capable(const struct cred *cred, struct user_namespace *ns,
 	return cred_has_capability(cred, cap, opts, ns == &init_user_ns);
 }
 
-static int selinux_quotactl(int cmds, int type, int id, struct super_block *sb)
+static int selinux_quotactl(int cmds, int type, int id, const struct super_block *sb)
 {
 	const struct cred *cred = current_cred();
 	int rc = 0;