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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: 郭永刚 <guoyonggang@360.cn>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Hannes Frederic Sowa authored and davem330 committed Dec 14, 2015
1 parent 20b08e1 commit 79462ad02e861803b3840cc782248c7359451cd9
Showing with 16 additions and 0 deletions.
  1. +1 −0 include/net/sock.h
  2. +3 −0 net/ax25/af_ax25.c
  3. +3 −0 net/decnet/af_decnet.c
  4. +3 −0 net/ipv4/af_inet.c
  5. +3 −0 net/ipv6/af_inet6.c
  6. +3 −0 net/irda/af_irda.c
View
@@ -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;
View
@@ -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;
View
@@ -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;
View
@@ -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. */
View
@@ -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;
View
@@ -1086,6 +1086,9 @@ static int irda_create(struct net *net, struct socket *sock, int protocol,
struct sock *sk;
struct irda_sock *self;
if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
return -EINVAL;
if (net != &init_net)
return -EAFNOSUPPORT;

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