[PATCH 3.4 077/107] net: add validation for the socket syscall protocol argument

[lizf]

From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 79462ad02e861803b3840cc782248c7359451cd9 upstream.

éæå reported that one could simply crash the kernel as root by
using a simple program:

	int socket_fd;
	struct sockaddr_in addr;
	addr.sin_port = 0;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_family = 10;

	socket_fd = socket(10,3,0x40000000);
	connect(socket_fd , &addr,16);

AF_INET, AF_INET6 sockets actually only support 8-bit protocol
identifiers. inet_sock's skc_protocol field thus is sized accordingly,
thus larger protocol identifiers simply cut off the higher bits and
store a zero in the protocol fields.

This could lead to e.g. NULL function pointer because as a result of
the cut off inet_num is zero and we call down to inet_autobind, which
is NULL for raw sockets.

kernel: Call Trace:
kernel:  [<ffffffff816db90e>] ? inet_autobind+0x2e/0x70
kernel:  [<ffffffff816db9a4>] inet_dgram_connect+0x54/0x80
kernel:  [<ffffffff81645069>] SYSC_connect+0xd9/0x110
kernel:  [<ffffffff810ac51b>] ? ptrace_notify+0x5b/0x80
kernel:  [<ffffffff810236d8>] ? syscall_trace_enter_phase2+0x108/0x200
kernel:  [<ffffffff81645e0e>] SyS_connect+0xe/0x10
kernel:  [<ffffffff81779515>] tracesys_phase2+0x84/0x89

I found no particular commit which introduced this problem.

CVE: CVE-2015-8543
Cc: Cong Wang <cwang@xxxxxxxxxxxxxxxx>
Reported-by: éæå <guoyonggang@xxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[lizf: Backported to 3.4: open-code U8_MAX]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 include/net/sock.h     | 1 +
 net/ax25/af_ax25.c     | 3 +++
 net/decnet/af_decnet.c | 3 +++
 net/ipv4/af_inet.c     | 3 +++
 net/ipv6/af_inet6.c    | 3 +++
 net/irda/af_irda.c     | 3 +++
 6 files changed, 16 insertions(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index f673ba5..e2073e0 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -328,6 +328,7 @@ struct sock {
 				sk_no_check  : 2,
 				sk_userlocks : 4,
 				sk_protocol  : 8,
+#define SK_PROTOCOL_MAX ((u8)~0U)
 				sk_type      : 16;
 	kmemcheck_bitfield_end(flags);
 	int			sk_wmem_queued;
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index ca1820c..f59c8af 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -811,6 +811,9 @@ static int ax25_create(struct net *net, struct socket *sock, int protocol,
 	struct sock *sk;
 	ax25_cb *ax25;
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (!net_eq(net, &init_net))
 		return -EAFNOSUPPORT;
 
diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 4136987..4fa941e 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -680,6 +680,9 @@ static int dn_create(struct net *net, struct socket *sock, int protocol,
 {
 	struct sock *sk;
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (!net_eq(net, &init_net))
 		return -EAFNOSUPPORT;
 
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 78ec298..0a828e2 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -284,6 +284,9 @@ static int inet_create(struct net *net, struct socket *sock, int protocol,
 		if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
 			build_ehash_secret();
 
+	if (protocol < 0 || protocol >= IPPROTO_MAX)
+		return -EINVAL;
+
 	sock->state = SS_UNCONNECTED;
 
 	/* Look for the requested type/protocol pair. */
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 8ed1b93..5300ef3 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -113,6 +113,9 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
 	    !inet_ehash_secret)
 		build_ehash_secret();
 
+	if (protocol < 0 || protocol >= IPPROTO_MAX)
+		return -EINVAL;
+
 	/* Look for the requested type/protocol pair. */
 lookup_protocol:
 	err = -ESOCKTNOSUPPORT;
diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c
index 12218f7..3eaf4fe 100644
--- a/net/irda/af_irda.c
+++ b/net/irda/af_irda.c
@@ -1106,6 +1106,9 @@ static int irda_create(struct net *net, struct socket *sock, int protocol,
 
 	IRDA_DEBUG(2, "%s()\n", __func__);
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (net != &init_net)
 		return -EAFNOSUPPORT;
 
-- 
1.9.1