[PATCH 5.7 056/204] net/compat: Add missing sock updates for SCM_RIGHTS

Greg Kroah-Hartman
2020-08-20T09:37:54Z

From: Kees Cook <keescook@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 <hch@lst.de>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: stable@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.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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
@@ -890,6 +890,8 @@ 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)
@@ -897,6 +899,8 @@ 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
@@ -307,6 +307,7 @@ 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
@@ -2753,6 +2753,27 @@ 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;