linux-kernel - [PATCH 4.9 179/212] net/compat: Add missing sock updates for SCM

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Date:   Thu, 20 Aug 2020 11:22:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Sargun Dhillon <sargun@...gun.me>,
        Jakub Kicinski <kuba@...nel.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH 4.9 179/212] net/compat: Add missing sock updates for SCM_RIGHTS

From: Kees Cook <keescook@...omium.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@....de>
Cc: Sargun Dhillon <sargun@...gun.me>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: stable@...r.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@...ntu.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -784,6 +784,8 @@ static inline int sk_memalloc_socks(void
 {
 	return static_key_false(&memalloc_socks);
 }
+
+void __receive_sock(struct file *file);
 #else
 
 static inline int sk_memalloc_socks(void)
@@ -791,6 +793,8 @@ 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
@@ -284,6 +284,7 @@ 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
@@ -2323,6 +2323,27 @@ 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;