scm: Convert put_cmsg() to scoped user access

Replace the open coded implementation with the scoped user access guard.

That also corrects the imbalance between masked_user_access_begin() and
user_write_access_end(), which would affect PowerPC when it gains masked
user access support.

No functional change intended.

[ tglx: Amend change log ]

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/793219313f641eda09a892d06768d2837246bf9f.1763396724.git.christophe.leroy@csgroup.eu

diff --git a/net/core/scm.c b/net/core/scm.c
index 66eaee783e8be8ed650a1679a15d0a41309f9f0d..cd87f66671aa00efda4a0c4201d694579110bd76 100644 (file)
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -273,17 +273,13 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
 
                check_object_size(data, cmlen - sizeof(*cm), true);
 
-               if (can_do_masked_user_access())
-                       cm = masked_user_access_begin(cm);
-               else if (!user_write_access_begin(cm, cmlen))
-                       goto efault;
-
-               unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
-               unsafe_put_user(level, &cm->cmsg_level, efault_end);
-               unsafe_put_user(type, &cm->cmsg_type, efault_end);
-               unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
-                                   cmlen - sizeof(*cm), efault_end);
-               user_write_access_end();
+               scoped_user_write_access_size(cm, cmlen, efault) {
+                       unsafe_put_user(cmlen, &cm->cmsg_len, efault);
+                       unsafe_put_user(level, &cm->cmsg_level, efault);
+                       unsafe_put_user(type, &cm->cmsg_type, efault);
+                       unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
+                                           cmlen - sizeof(*cm), efault);
+               }
        } else {
                struct cmsghdr *cm = msg->msg_control;
 
@@ -301,8 +297,6 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
        msg->msg_controllen -= cmlen;
        return 0;
 
-efault_end:
-       user_write_access_end();
 efault:
        return -EFAULT;
 }