[PATCH 4.19 27/92] net/compat: Add missing sock updates for SCM_RIGHTS

[Greg Kroah-Hartman]

From: Kees Cook <keesc...@chromium.org>

commit d9539752d23283db4692384a634034f451261e29 upstream.

Add missed sock updates to compat path via a new helper, which will be
used more in coming patches. (The net/core/scm.c code is left as-is here
to assist with -stable backports for the compat path.)

Cc: Christoph Hellwig <h...@lst.de>
Cc: Sargun Dhillon <sar...@sargun.me>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: sta...@vger.kernel.org
Fixes: 48a87cc26c13 ("net: netprio: fd passed in SCM_RIGHTS datagram not set 
correctly")
Fixes: d84295067fc7 ("net: net_cls: fd passed in SCM_RIGHTS datagram not set 
correctly")
Acked-by: Christian Brauner <christian.brau...@ubuntu.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 include/net/sock.h |    4 ++++
 net/compat.c       |    1 +
 net/core/sock.c    |   21 +++++++++++++++++++++
 3 files changed, 26 insertions(+)

--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -845,6 +845,8 @@ static inline int sk_memalloc_socks(void
 {
        return static_branch_unlikely(&memalloc_socks_key);
 }
+
+void __receive_sock(struct file *file);
 #else
 
 static inline int sk_memalloc_socks(void)
@@ -852,6 +854,8 @@ static inline int sk_memalloc_socks(void
        return 0;
 }
 
+static inline void __receive_sock(struct file *file)
+{ }
 #endif
 
 static inline gfp_t sk_gfp_mask(const struct sock *sk, gfp_t gfp_mask)
--- a/net/compat.c
+++ b/net/compat.c
@@ -289,6 +289,7 @@ void scm_detach_fds_compat(struct msghdr
                        break;
                }
                /* Bump the usage count and install the file. */
+               __receive_sock(fp[i]);
                fd_install(new_fd, get_file(fp[i]));
        }
 
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2636,6 +2636,27 @@ int sock_no_mmap(struct file *file, stru
 }
 EXPORT_SYMBOL(sock_no_mmap);
 
+/*
+ * When a file is received (via SCM_RIGHTS, etc), we must bump the
+ * various sock-based usage counts.
+ */
+void __receive_sock(struct file *file)
+{
+       struct socket *sock;
+       int error;
+
+       /*
+        * The resulting value of "error" is ignored here since we only
+        * need to take action when the file is a socket and testing
+        * "sock" for NULL is sufficient.
+        */
+       sock = sock_from_file(file, &error);
+       if (sock) {
+               sock_update_netprioidx(&sock->sk->sk_cgrp_data);
+               sock_update_classid(&sock->sk->sk_cgrp_data);
+       }
+}
+
 ssize_t sock_no_sendpage(struct socket *sock, struct page *page, int offset, 
size_t size, int flags)
 {
        ssize_t res;