lsm: constify the 'target' parameter in security_capget()

Three LSMs register the implementations for the "capget" hook: AppArmor,
SELinux, and the normal capability code. Looking at the function
implementations we may observe that the first parameter "target" is not
changing.

Mark the first argument "target" of LSM hook security_capget() as
"const" since it will not be changing in the LSM hook.

cap_capget() LSM hook declaration exceeds the 80 characters per line
limit. Split the function declaration to multiple lines to decrease the
line length.
Signed-off-by: Khadija Kamran <kamrankhadijadj@gmail.com>
Acked-by: John Johansen <john.johansen@canonical.com>
[PM: align the cap_capget() declaration, spelling fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/lsm_hook_defs.h

@@ -36,7 +36,7 @@ LSM_HOOK(int, 0, binder_transfer_file, const struct cred *from,
 LSM_HOOK(int, 0, ptrace_access_check, struct task_struct *child,
 	 unsigned int mode)
 LSM_HOOK(int, 0, ptrace_traceme, struct task_struct *parent)
-LSM_HOOK(int, 0, capget, struct task_struct *target, kernel_cap_t *effective,
+LSM_HOOK(int, 0, capget, const struct task_struct *target, kernel_cap_t *effective,
 	 kernel_cap_t *inheritable, kernel_cap_t *permitted)
 LSM_HOOK(int, 0, capset, struct cred *new, const struct cred *old,
 	 const kernel_cap_t *effective, const kernel_cap_t *inheritable,

include/linux/security.h

@@ -145,7 +145,8 @@ extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
 extern int cap_settime(const struct timespec64 *ts, const struct timezone *tz);
 extern int cap_ptrace_access_check(struct task_struct *child, unsigned int mode);
 extern int cap_ptrace_traceme(struct task_struct *parent);
-extern int cap_capget(struct task_struct *target, kernel_cap_t *effective, kernel_cap_t *inheritable, kernel_cap_t *permitted);
+extern int cap_capget(const struct task_struct *target, kernel_cap_t *effective,
+		      kernel_cap_t *inheritable, kernel_cap_t *permitted);
 extern int cap_capset(struct cred *new, const struct cred *old,
 		      const kernel_cap_t *effective,
 		      const kernel_cap_t *inheritable,
@@ -271,7 +272,7 @@ int security_binder_transfer_file(const struct cred *from,
 				  const struct cred *to, struct file *file);
 int security_ptrace_access_check(struct task_struct *child, unsigned int mode);
 int security_ptrace_traceme(struct task_struct *parent);
-int security_capget(struct task_struct *target,
+int security_capget(const struct task_struct *target,
 		    kernel_cap_t *effective,
 		    kernel_cap_t *inheritable,
 		    kernel_cap_t *permitted);
@@ -553,7 +554,7 @@ static inline int security_ptrace_traceme(struct task_struct *parent)
 	return cap_ptrace_traceme(parent);
 }
 
-static inline int security_capget(struct task_struct *target,
+static inline int security_capget(const struct task_struct *target,
 				   kernel_cap_t *effective,
 				   kernel_cap_t *inheritable,
 				   kernel_cap_t *permitted)

kernel/capability.c

@@ -112,7 +112,7 @@ static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
 	int ret;
 
 	if (pid && (pid != task_pid_vnr(current))) {
-		struct task_struct *target;
+		const struct task_struct *target;
 
 		rcu_read_lock();
 

security/apparmor/lsm.c

@@ -144,7 +144,7 @@ static int apparmor_ptrace_traceme(struct task_struct *parent)
 }
 
 /* Derived from security/commoncap.c:cap_capget */
-static int apparmor_capget(struct task_struct *target, kernel_cap_t *effective,
+static int apparmor_capget(const struct task_struct *target, kernel_cap_t *effective,
 			   kernel_cap_t *inheritable, kernel_cap_t *permitted)
 {
 	struct aa_label *label;

security/commoncap.c

@@ -197,7 +197,7 @@ int cap_ptrace_traceme(struct task_struct *parent)
  * This function retrieves the capabilities of the nominated task and returns
  * them to the caller.
  */
-int cap_capget(struct task_struct *target, kernel_cap_t *effective,
+int cap_capget(const struct task_struct *target, kernel_cap_t *effective,
 	       kernel_cap_t *inheritable, kernel_cap_t *permitted)
 {
 	const struct cred *cred;

security/security.c

@@ -894,7 +894,7 @@ int security_ptrace_traceme(struct task_struct *parent)
  *
  * Return: Returns 0 if the capability sets were successfully obtained.
  */
-int security_capget(struct task_struct *target,
+int security_capget(const struct task_struct *target,
 		    kernel_cap_t *effective,
 		    kernel_cap_t *inheritable,
 		    kernel_cap_t *permitted)

security/selinux/hooks.c

@@ -2082,7 +2082,7 @@ static int selinux_ptrace_traceme(struct task_struct *parent)
 			    SECCLASS_PROCESS, PROCESS__PTRACE, NULL);
 }
 
-static int selinux_capget(struct task_struct *target, kernel_cap_t *effective,
+static int selinux_capget(const struct task_struct *target, kernel_cap_t *effective,
 			  kernel_cap_t *inheritable, kernel_cap_t *permitted)
 {
 	return avc_has_perm(current_sid(), task_sid_obj(target),