unexport sock_map_fd(), switch to sock_alloc_file()

Both modular callers of sock_map_fd() had been buggy; sctp one leaks
descriptor and file if copy_to_user() fails, 9p one shouldn't be
exposing file in the descriptor table at all.

Switch both to sock_alloc_file(), export it, unexport sock_map_fd() and
make it static.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 20 insertions, 5 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 5e259817a7f..fb5931ca50d 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -70,6 +70,7 @@
 #include <linux/init.h>
 #include <linux/crypto.h>
 #include <linux/slab.h>
+#include <linux/file.h>
 
 #include <net/ip.h>
 #include <net/icmp.h>
@@ -4276,6 +4277,7 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
 {
         sctp_peeloff_arg_t peeloff;
         struct socket *newsock;
+        struct file *newfile;
         int retval = 0;
 
         if (len < sizeof(sctp_peeloff_arg_t))
@@ -4289,22 +4291,35 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
                 goto out;
 
         /* Map the socket to an unused fd that can be returned to the user.  */
-        retval = sock_map_fd(newsock, 0);
+        retval = get_unused_fd();
         if (retval < 0) {
                 sock_release(newsock);
                 goto out;
         }
 
+        newfile = sock_alloc_file(newsock, 0);
+        if (unlikely(IS_ERR(newfile))) {
+                put_unused_fd(retval);
+                sock_release(newsock);
+                return PTR_ERR(newfile);
+        }
+
         SCTP_DEBUG_PRINTK("%s: sk: %p newsk: %p sd: %d\n",
                           __func__, sk, newsock->sk, retval);
 
         /* Return the fd mapped to the new socket.  */
+        if (put_user(len, optlen)) {
+                fput(newfile);
+                put_unused_fd(retval);
+                return -EFAULT;
+        }
         peeloff.sd = retval;
-        if (put_user(len, optlen))
+        if (copy_to_user(optval, &peeloff, len)) {
+                fput(newfile);
+                put_unused_fd(retval);
                 return -EFAULT;
-        if (copy_to_user(optval, &peeloff, len))
-                retval = -EFAULT;
-
+        }
+        fd_install(retval, newfile);
 out:
         return retval;
 }