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>

diff --git a/include/net/sock.h b/include/net/sock.h
index eaef41433d7a3d1137ac5a54af45b4bdddc4ef7c..c4205e0a3a2d28066c207221eeacb75c6c99eedc 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -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;

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index ae3a47f9d1d5298406ca33900624fe49c9c85719..fbd0acf80b13236bd8c768bc8bf5d69d6a7e7125 100644 (file)
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -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;
 

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index eebf5ac8ce18abdb7ac094a1e6de081fcbfa79aa..13d6b1a6e0fc2b0730827d93d154d6464a3e58ec 100644 (file)
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -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;
 

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 11c4ca13ec3b0434090b3d5cbdd7a0aae784952f..5c5db6636704daa0c49fc13e84b2c5b282a44ed3 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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. */

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 8ec0df75f1c4f81bea71cb466c4da802c39099d8..9f5137cd604e51316c6c3a85ca5423b30ed7ce30 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -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;

diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c
index e6aa48b5395c67e2600eed9482c97b9a626d01bd..923abd6b3064074f39f84644b2d3d1f068403f51 100644 (file)
--- a/net/irda/af_irda.c
+++ b/net/irda/af_irda.c
@@ -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;