rlimits: switch more rlimit syscalls to do_prlimit

After we added more generic do_prlimit, switch sys_getrlimit to that.
Also switch compat handling, so we can get rid of ugly __user casts
and avoid setting process' address limit to kernel data and back.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

kernel/compat.c

@@ -279,11 +279,6 @@ asmlinkage long compat_sys_setrlimit(unsigned int resource,
 		struct compat_rlimit __user *rlim)
 {
 	struct rlimit r;
-	int ret;
-	mm_segment_t old_fs = get_fs ();
-
-	if (resource >= RLIM_NLIMITS)
-		return -EINVAL;
 
 	if (!access_ok(VERIFY_READ, rlim, sizeof(*rlim)) ||
 	    __get_user(r.rlim_cur, &rlim->rlim_cur) ||
@@ -294,10 +289,7 @@ asmlinkage long compat_sys_setrlimit(unsigned int resource,
 		r.rlim_cur = RLIM_INFINITY;
 	if (r.rlim_max == COMPAT_RLIM_INFINITY)
 		r.rlim_max = RLIM_INFINITY;
-	set_fs(KERNEL_DS);
-	ret = sys_setrlimit(resource, (struct rlimit __user *) &r);
-	set_fs(old_fs);
-	return ret;
+	return do_prlimit(current, resource, &r, NULL);
 }
 
 #ifdef COMPAT_RLIM_OLD_INFINITY
@@ -329,16 +321,13 @@ asmlinkage long compat_sys_old_getrlimit(unsigned int resource,
 
 #endif
 
-asmlinkage long compat_sys_getrlimit (unsigned int resource,
+asmlinkage long compat_sys_getrlimit(unsigned int resource,
 		struct compat_rlimit __user *rlim)
 {
 	struct rlimit r;
 	int ret;
-	mm_segment_t old_fs = get_fs();
 
-	set_fs(KERNEL_DS);
-	ret = sys_getrlimit(resource, (struct rlimit __user *) &r);
-	set_fs(old_fs);
+	ret = do_prlimit(current, resource, NULL, &r);
 	if (!ret) {
 		if (r.rlim_cur > COMPAT_RLIM_INFINITY)
 			r.rlim_cur = COMPAT_RLIM_INFINITY;

kernel/sys.c

@@ -1236,15 +1236,14 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
 
 SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
 {
-	if (resource >= RLIM_NLIMITS)
-		return -EINVAL;
-	else {
-		struct rlimit value;
-		task_lock(current->group_leader);
-		value = current->signal->rlim[resource];
-		task_unlock(current->group_leader);
-		return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
-	}
+	struct rlimit value;
+	int ret;
+
+	ret = do_prlimit(current, resource, NULL, &value);
+	if (!ret)
+		ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
+
+	return ret;
 }
 
 #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT