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Commit 79462ad0 authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller
Browse files

net: add validation for the socket syscall protocol argument 



郭永刚 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@twopensource.com>
Reported-by: default avatar郭永刚 <guoyonggang@360.cn>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 20b08e1a

include/net/sock.h

+1 −0
Original line number Diff line number Diff line
@@ -403,6 +403,7 @@ struct sock { 
				sk_no_check_rx : 1,

				sk_userlocks : 4,

				sk_protocol  : 8,

#define SK_PROTOCOL_MAX U8_MAX

				sk_type      : 16;

	kmemcheck_bitfield_end(flags);

	int			sk_wmem_queued;

net/ax25/af_ax25.c

+3 −0
Original line number Diff line number Diff line
@@ -805,6 +805,9 @@ 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;

net/decnet/af_decnet.c

+3 −0
Original line number Diff line number Diff line
@@ -678,6 +678,9 @@ 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;

net/ipv4/af_inet.c

+3 −0
Original line number Diff line number Diff line
@@ -257,6 +257,9 @@ static int inet_create(struct net *net, struct socket *sock, int protocol, 
	int try_loading_module = 0;

	int err;



	if (protocol < 0 || protocol >= IPPROTO_MAX)

		return -EINVAL;



	sock->state = SS_UNCONNECTED;



	/* Look for the requested type/protocol pair. */

net/ipv6/af_inet6.c

+3 −0
Original line number Diff line number Diff line
@@ -109,6 +109,9 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol, 
	int try_loading_module = 0;

	int err;



	if (protocol < 0 || protocol >= IPPROTO_MAX)

		return -EINVAL;



	/* Look for the requested type/protocol pair. */

lookup_protocol:

	err = -ESOCKTNOSUPPORT;