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Date: Thu, 8 Oct 2015 11:56:32 -0400
From: Paul Moore <paul@...l-moore.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: David Miller <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>,
Stephen Smalley <sds@...ho.nsa.gov>,
Eric Paris <eparis@...isplace.org>
Subject: Re: [PATCH net-next] net: synack packets can be attached to request sockets
On Thu, Oct 8, 2015 at 8:01 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> selinux needs few changes to accommodate fact that SYNACK messages
> can be attached to a request socket, lacking sk_security pointer
>
> (Only syncookies are still attached to a TCP_LISTEN socket)
>
> Adds a new sk_listener() helper, and use it in selinux and sch_fq
>
> Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported by: kernel test robot <ying.huang@...ux.intel.com>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: Stephen Smalley <sds@...ho.nsa.gov>
> Cc: Eric Paris <eparis@...isplace.org>
> ---
> include/net/sock.h | 8 ++++++++
> net/sched/sch_fq.c | 3 ++-
> security/selinux/hooks.c | 12 ++++++++----
> 3 files changed, 18 insertions(+), 5 deletions(-)
Acked-by: Paul Moore <paul@...l-moore.com>
> diff --git a/include/net/sock.h b/include/net/sock.h
> index dfe2eb8e1132..771ca1996442 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -2201,6 +2201,14 @@ static inline bool sk_fullsock(const struct sock *sk)
> return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
> }
>
> +/* This helper checks if a socket is a LISTEN or NEW_SYN_RECV
> + * SYNACK messages can be attached to either ones (depending on SYNCOOKIE)
> + */
> +static inline bool sk_listener(const struct sock *sk)
> +{
> + return (1 << sk->sk_state) & (TCPF_LISTEN | TCPF_NEW_SYN_RECV);
> +}
> +
> void sock_enable_timestamp(struct sock *sk, int flag);
> int sock_get_timestamp(struct sock *, struct timeval __user *);
> int sock_get_timestampns(struct sock *, struct timespec __user *);
> diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
> index 3386cce4751e..109b2322778f 100644
> --- a/net/sched/sch_fq.c
> +++ b/net/sched/sch_fq.c
> @@ -225,6 +225,7 @@ static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
> return &q->internal;
>
> /* SYNACK messages are attached to a TCP_NEW_SYN_RECV request socket
> + * or a listener (SYNCOOKIE mode)
> * 1) request sockets are not full blown,
> * they do not contain sk_pacing_rate
> * 2) They are not part of a 'flow' yet
> @@ -232,7 +233,7 @@ static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
> * especially if the listener set SO_MAX_PACING_RATE
> * 4) We pretend they are orphaned
> */
> - if (!sk || sk->sk_state == TCP_NEW_SYN_RECV) {
> + if (!sk || sk_listener(sk)) {
> unsigned long hash = skb_get_hash(skb) & q->orphan_mask;
>
> /* By forcing low order bit to 1, we make sure to not
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 64340160f4ac..6e50841ef1f6 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4898,7 +4898,7 @@ static unsigned int selinux_ip_output(struct sk_buff *skb,
> if (sk) {
> struct sk_security_struct *sksec;
>
> - if (sk->sk_state == TCP_LISTEN)
> + if (sk_listener(sk))
> /* if the socket is the listening state then this
> * packet is a SYN-ACK packet which means it needs to
> * be labeled based on the connection/request_sock and
> @@ -5005,7 +5005,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb,
> * unfortunately, this means more work, but it is only once per
> * connection. */
> if (skb_dst(skb) != NULL && skb_dst(skb)->xfrm != NULL &&
> - !(sk != NULL && sk->sk_state == TCP_LISTEN))
> + !(sk && sk_listener(sk)))
> return NF_ACCEPT;
> #endif
>
> @@ -5022,7 +5022,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb,
> secmark_perm = PACKET__SEND;
> peer_sid = SECINITSID_KERNEL;
> }
> - } else if (sk->sk_state == TCP_LISTEN) {
> + } else if (sk_listener(sk)) {
> /* Locally generated packet but the associated socket is in the
> * listening state which means this is a SYN-ACK packet. In
> * this particular case the correct security label is assigned
> @@ -5033,7 +5033,11 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb,
> * selinux_inet_conn_request(). See also selinux_ip_output()
> * for similar problems. */
> u32 skb_sid;
> - struct sk_security_struct *sksec = sk->sk_security;
> + struct sk_security_struct *sksec;
> +
> + if (sk->sk_state == TCP_NEW_SYN_RECV)
> + sk = inet_reqsk(sk)->rsk_listener;
> + sksec = sk->sk_security;
> if (selinux_skb_peerlbl_sid(skb, family, &skb_sid))
> return NF_DROP;
> /* At this point, if the returned skb peerlbl is SECSID_NULL
>
>
--
paul moore
www.paul-moore.com
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