From 79462ad02e861803b3840cc782248c7359451cd9 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 14 Dec 2015 22:03:39 +0100 Subject: net: add validation for the socket syscall protocol argument MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: [] ? inet_autobind+0x2e/0x70 kernel: [] inet_dgram_connect+0x54/0x80 kernel: [] SYSC_connect+0xd9/0x110 kernel: [] ? ptrace_notify+0x5b/0x80 kernel: [] ? syscall_trace_enter_phase2+0x108/0x200 kernel: [] SyS_connect+0xe/0x10 kernel: [] tracesys_phase2+0x84/0x89 I found no particular commit which introduced this problem. CVE: CVE-2015-8543 Cc: Cong Wang Reported-by: 郭永刚 Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- 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 eaef414..c4205e0 100644 --- 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 ae3a47f..fbd0acf 100644 --- 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 eebf5ac..13d6b1a 100644 --- 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 11c4ca1..5c5db66 100644 --- 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 8ec0df7..9f5137c 100644 --- 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 e6aa48b..923abd6 100644 --- 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; -- cgit v1.1