net/scm: Regularize compat handling of scm_detach_fds()

[mirror_ubuntu-jammy-kernel.git] / net / compat.c

diff --git a/net/compat.c b/net/compat.c
index 2937b816107de2fca7dc4bf66fe1d6ae3e0cb743..27d477fdcaa01442282cf9dd6778948eb1225d38 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -281,40 +281,31 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
        return 0;
 }
 
-void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
+static int scm_max_fds_compat(struct msghdr *msg)
 {
-       struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
-       int fdmax = (kmsg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int);
-       int fdnum = scm->fp->count;
-       struct file **fp = scm->fp->fp;
-       int __user *cmfptr;
-       int err = 0, i;
+       if (msg->msg_controllen <= sizeof(struct compat_cmsghdr))
+               return 0;
+       return (msg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int);
+}
 
-       if (fdnum < fdmax)
-               fdmax = fdnum;
+void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
+{
+       struct compat_cmsghdr __user *cm =
+               (struct compat_cmsghdr __user *)msg->msg_control;
+       unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
+       int fdmax = min_t(int, scm_max_fds_compat(msg), scm->fp->count);
+       int __user *cmsg_data = CMSG_USER_DATA(cm);
+       int err = 0, i;
 
-       for (i = 0, cmfptr = (int __user *) CMSG_COMPAT_DATA(cm); i < fdmax; i++, cmfptr++) {
-               int new_fd;
-               err = security_file_receive(fp[i]);
+       for (i = 0; i < fdmax; i++) {
+               err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
                if (err)
                        break;
-               err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & kmsg->msg_flags
-                                         ? O_CLOEXEC : 0);
-               if (err < 0)
-                       break;
-               new_fd = err;
-               err = put_user(new_fd, cmfptr);
-               if (err) {
-                       put_unused_fd(new_fd);
-                       break;
-               }
-               /* Bump the usage count and install the file. */
-               __receive_sock(fp[i]);
-               fd_install(new_fd, get_file(fp[i]));
        }
 
        if (i > 0) {
                int cmlen = CMSG_COMPAT_LEN(i * sizeof(int));
+
                err = put_user(SOL_SOCKET, &cm->cmsg_level);
                if (!err)
                        err = put_user(SCM_RIGHTS, &cm->cmsg_type);
@@ -322,16 +313,19 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
                        err = put_user(cmlen, &cm->cmsg_len);
                if (!err) {
                        cmlen = CMSG_COMPAT_SPACE(i * sizeof(int));
-                       kmsg->msg_control += cmlen;
-                       kmsg->msg_controllen -= cmlen;
+                       if (msg->msg_controllen < cmlen)
+                               cmlen = msg->msg_controllen;
+                       msg->msg_control += cmlen;
+                       msg->msg_controllen -= cmlen;
                }
        }
-       if (i < fdnum)
-               kmsg->msg_flags |= MSG_CTRUNC;
+
+       if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))
+               msg->msg_flags |= MSG_CTRUNC;
 
        /*
-        * All of the files that fit in the message have had their
-        * usage counts incremented, so we just free the list.
+        * All of the files that fit in the message have had their usage counts
+        * incremented, so we just free the list.
         */
        __scm_destroy(scm);
 }