From 0c96d1f5328e834048480e4696e6867992115c33 Mon Sep 17 00:00:00 2001 From: Vishal Goel Date: Wed, 23 Nov 2016 10:32:54 +0530 Subject: [PATCH] Smack: Fix the issue of wrong SMACK label update in socket bind fail case Fix the issue of wrong SMACK label (SMACK64IPIN) update when a second bind call is made to same IP address & port, but with different SMACK label (SMACK64IPIN) by second instance of server. In this case server returns with "Bind:Address already in use" error but before returning, SMACK label is updated in SMACK port-label mapping list inside smack_socket_bind() hook To fix this issue a new check has been added in smk_ipv6_port_label() function before updating the existing port entry. It checks whether the socket for matching port entry is closed or not. If it is closed then it means port is not bound and it is safe to update the existing port entry else return if port is still getting used. For checking whether socket is closed or not, one more field "smk_can_reuse" has been added in the "smk_port_label" structure. This field will be set to '1' in "smack_sk_free_security()" function which is called to free the socket security blob when the socket is being closed. In this function, port entry is searched in the SMACK port-label mapping list for the closing socket. If entry is found then "smk_can_reuse" field is set to '1'.Initially "smk_can_reuse" field is set to '0' in smk_ipv6_port_label() function after creating a new entry in the list which indicates that socket is in use. Signed-off-by: Vishal Goel Signed-off-by: Himanshu Shukla Signed-off-by: Casey Schaufler --- security/smack/smack.h | 1 + security/smack/smack_lsm.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/security/smack/smack.h b/security/smack/smack.h index 73480ee..2fac3b5 100644 --- a/security/smack/smack.h +++ b/security/smack/smack.h @@ -174,6 +174,7 @@ struct smk_port_label { struct smack_known *smk_in; /* inbound label */ struct smack_known *smk_out; /* outgoing label */ short smk_sock_type; /* Socket type */ + short smk_can_reuse; }; #endif /* SMACK_IPV6_PORT_LABELING */ diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 5e4d2bdb..ed6885bcc 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -2354,6 +2354,20 @@ static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags) */ static void smack_sk_free_security(struct sock *sk) { +#ifdef SMACK_IPV6_PORT_LABELING + struct smk_port_label *spp; + + if (sk->sk_family == PF_INET6) { + rcu_read_lock(); + list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) { + if (spp->smk_sock != sk) + continue; + spp->smk_can_reuse = 1; + break; + } + rcu_read_unlock(); + } +#endif kfree(sk->sk_security); } @@ -2637,10 +2651,15 @@ static void smk_ipv6_port_label(struct socket *sock, struct sockaddr *address) list_for_each_entry_rcu(spp, &smk_ipv6_port_list, list) { if (spp->smk_port != port || spp->smk_sock_type != sock->type) continue; + if (spp->smk_can_reuse != 1) { + rcu_read_unlock(); + return; + } spp->smk_port = port; spp->smk_sock = sk; spp->smk_in = ssp->smk_in; spp->smk_out = ssp->smk_out; + spp->smk_can_reuse = 0; rcu_read_unlock(); return; } @@ -2657,6 +2676,7 @@ static void smk_ipv6_port_label(struct socket *sock, struct sockaddr *address) spp->smk_in = ssp->smk_in; spp->smk_out = ssp->smk_out; spp->smk_sock_type = sock->type; + spp->smk_can_reuse = 0; mutex_lock(&smack_ipv6_lock); list_add_rcu(&spp->list, &smk_ipv6_port_list); -- 2.7.4