From 72671b355f9daaf4b8b9b5f13138b17c67e2959d Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Thu, 29 Oct 2020 21:29:38 -0400 Subject: tipc: add stricter control of reserved service types TIPC reserves 64 service types for current and future internal use. Therefore, the bind() function is meant to block regular user sockets from being bound to these values, while it should let through such bindings from internal users. However, since we at the design moment saw no way to distinguish between regular and internal users the filter function ended up with allowing all bindings of the reserved types which were really in use ([0,1]), and block all the rest ([2,63]). This is risky, since a regular user may bind to the service type representing the topology server (TIPC_TOP_SRV == 1) or the one used for indicating neighboring node status (TIPC_CFG_SRV == 0), and wreak havoc for users of those services, i.e., most users. The reality is however that TIPC_CFG_SRV never is bound through the bind() function, since it doesn't represent a regular socket, and TIPC_TOP_SRV can also be made to bypass the checks in tipc_bind() by introducing a different entry function, tipc_sk_bind(). It should be noted that although this is a change of the API semantics, there is no risk we will break any currently working applications by doing this. Any application trying to bind to the values in question would be badly broken from the outset, so there is no chance we would find any such applications in real-world production systems. v2: Added warning printout when a user is blocked from binding, as suggested by Jakub Kicinski Acked-by: Yung Xue Signed-off-by: Jon Maloy Link: https://lore.kernel.org/r/20201030012938.489557-1-jmaloy@redhat.com Signed-off-by: Jakub Kicinski --- net/tipc/socket.c | 27 ++++++++++++++++++--------- net/tipc/socket.h | 2 +- net/tipc/topsrv.c | 4 ++-- 3 files changed, 21 insertions(+), 12 deletions(-) (limited to 'net/tipc') diff --git a/net/tipc/socket.c b/net/tipc/socket.c index e795a8a2955b..69c4b16e8184 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -658,8 +658,8 @@ static int tipc_release(struct socket *sock) * NOTE: This routine doesn't need to take the socket lock since it doesn't * access any non-constant socket information. */ -static int tipc_bind(struct socket *sock, struct sockaddr *uaddr, - int uaddr_len) + +int tipc_sk_bind(struct socket *sock, struct sockaddr *uaddr, int uaddr_len) { struct sock *sk = sock->sk; struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr; @@ -691,13 +691,6 @@ static int tipc_bind(struct socket *sock, struct sockaddr *uaddr, goto exit; } - if ((addr->addr.nameseq.type < TIPC_RESERVED_TYPES) && - (addr->addr.nameseq.type != TIPC_TOP_SRV) && - (addr->addr.nameseq.type != TIPC_CFG_SRV)) { - res = -EACCES; - goto exit; - } - res = (addr->scope >= 0) ? tipc_sk_publish(tsk, addr->scope, &addr->addr.nameseq) : tipc_sk_withdraw(tsk, -addr->scope, &addr->addr.nameseq); @@ -706,6 +699,22 @@ exit: return res; } +static int tipc_bind(struct socket *sock, struct sockaddr *skaddr, int alen) +{ + struct sockaddr_tipc *addr = (struct sockaddr_tipc *)skaddr; + + if (alen) { + if (alen < sizeof(struct sockaddr_tipc)) + return -EINVAL; + if (addr->addr.nameseq.type < TIPC_RESERVED_TYPES) { + pr_warn_once("Can't bind to reserved service type %u\n", + addr->addr.nameseq.type); + return -EACCES; + } + } + return tipc_sk_bind(sock, skaddr, alen); +} + /** * tipc_getname - get port ID of socket or peer socket * @sock: socket structure diff --git a/net/tipc/socket.h b/net/tipc/socket.h index b11575afc66f..02cdf166807d 100644 --- a/net/tipc/socket.h +++ b/net/tipc/socket.h @@ -74,7 +74,7 @@ int tipc_dump_done(struct netlink_callback *cb); u32 tipc_sock_get_portid(struct sock *sk); bool tipc_sk_overlimit1(struct sock *sk, struct sk_buff *skb); bool tipc_sk_overlimit2(struct sock *sk, struct sk_buff *skb); - +int tipc_sk_bind(struct socket *sock, struct sockaddr *skaddr, int alen); int tsk_set_importance(struct sock *sk, int imp); #endif diff --git a/net/tipc/topsrv.c b/net/tipc/topsrv.c index 5f6f86051c83..cec029349662 100644 --- a/net/tipc/topsrv.c +++ b/net/tipc/topsrv.c @@ -520,12 +520,12 @@ static int tipc_topsrv_create_listener(struct tipc_topsrv *srv) saddr.family = AF_TIPC; saddr.addrtype = TIPC_ADDR_NAMESEQ; - saddr.addr.nameseq.type = TIPC_TOP_SRV; + saddr.addr.nameseq.type = TIPC_TOP_SRV; saddr.addr.nameseq.lower = TIPC_TOP_SRV; saddr.addr.nameseq.upper = TIPC_TOP_SRV; saddr.scope = TIPC_NODE_SCOPE; - rc = kernel_bind(lsock, (struct sockaddr *)&saddr, sizeof(saddr)); + rc = tipc_sk_bind(lsock, (struct sockaddr *)&saddr, sizeof(saddr)); if (rc < 0) goto err; rc = kernel_listen(lsock, 0); -- cgit v1.2.3