net: add validation for the socket syscall protocol argument

[ Upstream commit 79462ad02e861803b3840cc782248c7359451cd9 ]

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>
[bwh: Backported to 3.2: open-code U8_MAX]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/net/sock.h b/include/net/sock.h
index 8f7cb22553fe2081d30d50c3cdfe2ae6e6fb1fb4..ce6f641e40d9aa325bd0c3751d2dc1f5008894c6 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -302,6 +302,7 @@ 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 7b8db0ede163b578a1bb989c66d2260a8e02462d..a314cfd6a642b570edbb17af050f2cd7c269ef8b 100644 (file)
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -806,6 +806,9 @@ 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 16fbf8c28e313b5b52c3f861ae91446b18eadc07..c0486c8877c9ef9fdc471342338afff5493b7e4d 100644 (file)
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -681,6 +681,9 @@ 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 5d228de07b44d1484574422ac7ea404a918058e2..e2ab9681f53a010200a4386105ff28c9011058b7 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -279,6 +279,9 @@ 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;
+
        if (unlikely(!inet_ehash_secret))
                if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
                        build_ehash_secret();

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index b161144aa8d03a6d5446309f4ae1b311f4ac38f9..d57813783830c68c40de59adb7c7694ba1e1948c 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;
+
        if (sock->type != SOCK_RAW &&
            sock->type != SOCK_DGRAM &&
            !inet_ehash_secret)

diff --git a/net/irda/af_irda.c b/net/irda/af_irda.c
index f5d011ad469409f4bcd73cb9ac6c512bbcbce4e8..03c8ea9deaf6122716505281969e27dd58f99956 100644 (file)
--- 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;