From MAILER-DAEMON Wed Oct 14 16:34:37 2020 From: Kleber Sacilotto de Souza To: netdev@vger.kernel.org Cc: Gerrit Renker , "David S. Miller" , Jakub Kicinski , Thadeu Lima de Souza Cascardo , "Gustavo A. R. Silva" , "Alexander A. Klimov" , Kees Cook , Eric Dumazet , Alexey Kodanev , dccp@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] dccp: ccid: move timers to struct dccp_sock Date: Tue, 13 Oct 2020 19:18:48 +0200 Message-Id: <20201013171849.236025-2-kleber.souza@canonical.com> In-Reply-To: <20201013171849.236025-1-kleber.souza@canonical.com> References: <20201013171849.236025-1-kleber.souza@canonical.com> List-ID: X-Mailing-List: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit From: Thadeu Lima de Souza Cascardo When dccps_hc_tx_ccid is freed, ccid timers may still trigger. The reason del_timer_sync can't be used is because this relies on keeping a reference to struct sock. But as we keep a pointer to dccps_hc_tx_ccid and free that during disconnect, the timer should really belong to struct dccp_sock. This addresses CVE-2020-16119. Fixes: 839a6094140a (net: dccp: Convert timers to use timer_setup()) Signed-off-by: Kleber Sacilotto de Souza Signed-off-by: Thadeu Lima de Souza Cascardo Acked-bd: Richard Sailer --- include/linux/dccp.h | 2 ++ net/dccp/ccids/ccid2.c | 32 +++++++++++++++++++------------- net/dccp/ccids/ccid3.c | 30 ++++++++++++++++++++---------- 3 files changed, 41 insertions(+), 23 deletions(-) diff --git a/include/linux/dccp.h b/include/linux/dccp.h index 07e547c02fd8..504afa1a4be6 100644 --- a/include/linux/dccp.h +++ b/include/linux/dccp.h @@ -259,6 +259,7 @@ struct dccp_ackvec; * @dccps_sync_scheduled - flag which signals "send out-of-band message soon" * @dccps_xmitlet - tasklet scheduled by the TX CCID to dequeue data packets * @dccps_xmit_timer - used by the TX CCID to delay sending (rate-based pacing) + * @dccps_ccid_timer - used by the CCIDs * @dccps_syn_rtt - RTT sample from Request/Response exchange (in usecs) */ struct dccp_sock { @@ -303,6 +304,7 @@ struct dccp_sock { __u8 dccps_sync_scheduled:1; struct tasklet_struct dccps_xmitlet; struct timer_list dccps_xmit_timer; + struct timer_list dccps_ccid_timer; }; static inline struct dccp_sock *dccp_sk(const struct sock *sk) diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c index 3da1f77bd039..dbca1f1e2449 100644 --- a/net/dccp/ccids/ccid2.c +++ b/net/dccp/ccids/ccid2.c @@ -126,21 +126,26 @@ static void dccp_tasklet_schedule(struct sock *sk) static void ccid2_hc_tx_rto_expire(struct timer_list *t) { - struct ccid2_hc_tx_sock *hc = from_timer(hc, t, tx_rtotimer); - struct sock *sk = hc->sk; - const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); + struct dccp_sock *dp = from_timer(dp, t, dccps_ccid_timer); + struct sock *sk = (struct sock *)dp; + struct ccid2_hc_tx_sock *hc; + bool sender_was_blocked; bh_lock_sock(sk); + + if (inet_sk_state_load(sk) == DCCP_CLOSED) + goto out; + + hc = ccid_priv(dp->dccps_hc_tx_ccid); + sender_was_blocked = ccid2_cwnd_network_limited(hc); + if (sock_owned_by_user(sk)) { - sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + HZ / 5); + sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + HZ / 5); goto out; } ccid2_pr_debug("RTO_EXPIRE\n"); - if (sk->sk_state == DCCP_CLOSED) - goto out; - /* back-off timer */ hc->tx_rto <<= 1; if (hc->tx_rto > DCCP_RTO_MAX) @@ -166,7 +171,7 @@ static void ccid2_hc_tx_rto_expire(struct timer_list *t) if (sender_was_blocked) dccp_tasklet_schedule(sk); /* restart backed-off timer */ - sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); + sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); out: bh_unlock_sock(sk); sock_put(sk); @@ -330,7 +335,7 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) } #endif - sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); + sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); #ifdef CONFIG_IP_DCCP_CCID2_DEBUG do { @@ -700,9 +705,9 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) /* restart RTO timer if not all outstanding data has been acked */ if (hc->tx_pipe == 0) - sk_stop_timer(sk, &hc->tx_rtotimer); + sk_stop_timer(sk, &dp->dccps_ccid_timer); else - sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); + sk_reset_timer(sk, &dp->dccps_ccid_timer, jiffies + hc->tx_rto); done: /* check if incoming Acks allow pending packets to be sent */ if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) @@ -737,17 +742,18 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) hc->tx_last_cong = hc->tx_lsndtime = hc->tx_cwnd_stamp = ccid2_jiffies32; hc->tx_cwnd_used = 0; hc->sk = sk; - timer_setup(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, 0); + timer_setup(&dp->dccps_ccid_timer, ccid2_hc_tx_rto_expire, 0); INIT_LIST_HEAD(&hc->tx_av_chunks); return 0; } static void ccid2_hc_tx_exit(struct sock *sk) { + struct dccp_sock *dp = dccp_sk(sk); struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); int i; - sk_stop_timer(sk, &hc->tx_rtotimer); + sk_stop_timer(sk, &dp->dccps_ccid_timer); for (i = 0; i < hc->tx_seqbufc; i++) kfree(hc->tx_seqbuf[i]); diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index b9ee1a4a8955..685f4d046c0d 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -184,17 +184,24 @@ static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc, static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) { - struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer); - struct sock *sk = hc->sk; + struct dccp_sock *dp = from_timer(dp, t, dccps_ccid_timer); + struct ccid3_hc_tx_sock *hc; + struct sock *sk = (struct sock *)dp; unsigned long t_nfb = USEC_PER_SEC / 5; bh_lock_sock(sk); + + if (inet_sk_state_load(sk) == DCCP_CLOSED) + goto out; + if (sock_owned_by_user(sk)) { /* Try again later. */ /* XXX: set some sensible MIB */ goto restart_timer; } + hc = ccid_priv(dp->dccps_hc_tx_ccid); + ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk, ccid3_tx_state_name(hc->tx_state)); @@ -250,8 +257,8 @@ static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t) t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); restart_timer: - sk_reset_timer(sk, &hc->tx_no_feedback_timer, - jiffies + usecs_to_jiffies(t_nfb)); + sk_reset_timer(sk, &dp->dccps_ccid_timer, + jiffies + usecs_to_jiffies(t_nfb)); out: bh_unlock_sock(sk); sock_put(sk); @@ -280,7 +287,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb) return -EBADMSG; if (hc->tx_state == TFRC_SSTATE_NO_SENT) { - sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + + sk_reset_timer(sk, &dp->dccps_ccid_timer, (jiffies + usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); hc->tx_last_win_count = 0; hc->tx_t_last_win_count = now; @@ -354,6 +361,7 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len) static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) { struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); + struct dccp_sock *dp = dccp_sk(sk); struct tfrc_tx_hist_entry *acked; ktime_t now; unsigned long t_nfb; @@ -420,7 +428,7 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) (unsigned int)(hc->tx_x >> 6)); /* unschedule no feedback timer */ - sk_stop_timer(sk, &hc->tx_no_feedback_timer); + sk_stop_timer(sk, &dp->dccps_ccid_timer); /* * As we have calculated new ipi, delta, t_nom it is possible @@ -445,8 +453,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) "expire in %lu jiffies (%luus)\n", dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); - sk_reset_timer(sk, &hc->tx_no_feedback_timer, - jiffies + usecs_to_jiffies(t_nfb)); + sk_reset_timer(sk, &dp->dccps_ccid_timer, + jiffies + usecs_to_jiffies(t_nfb)); } static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, @@ -488,21 +496,23 @@ static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk) { + struct dccp_sock *dp = dccp_sk(sk); struct ccid3_hc_tx_sock *hc = ccid_priv(ccid); hc->tx_state = TFRC_SSTATE_NO_SENT; hc->tx_hist = NULL; hc->sk = sk; - timer_setup(&hc->tx_no_feedback_timer, + timer_setup(&dp->dccps_ccid_timer, ccid3_hc_tx_no_feedback_timer, 0); return 0; } static void ccid3_hc_tx_exit(struct sock *sk) { + struct dccp_sock *dp = dccp_sk(sk); struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); - sk_stop_timer(sk, &hc->tx_no_feedback_timer); + sk_stop_timer(sk, &dp->dccps_ccid_timer); tfrc_tx_hist_purge(&hc->tx_hist); } -- 2.25.1 From MAILER-DAEMON Wed Oct 14 16:34:37 2020 From: Kleber Sacilotto de Souza To: netdev@vger.kernel.org Cc: Gerrit Renker , "David S. Miller" , Jakub Kicinski , Thadeu Lima de Souza Cascardo , "Gustavo A. R. Silva" , "Alexander A. Klimov" , Kees Cook , Eric Dumazet , Alexey Kodanev , dccp@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] Revert "dccp: don't free ccid2_hc_tx_sock struct in dccp_disconnect()" Date: Tue, 13 Oct 2020 19:18:49 +0200 Message-Id: <20201013171849.236025-3-kleber.souza@canonical.com> In-Reply-To: <20201013171849.236025-1-kleber.souza@canonical.com> References: <20201013171849.236025-1-kleber.souza@canonical.com> List-ID: X-Mailing-List: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit From: Thadeu Lima de Souza Cascardo This reverts commit 2677d20677314101293e6da0094ede7b5526d2b1. This fixes an issue that after disconnect, dccps_hc_tx_ccid will still be kept, allowing the socket to be reused as a listener socket, and the cloned socket will free its dccps_hc_tx_ccid, leading to a later use after free, when the listener socket is closed. This addresses CVE-2020-16119. Fixes: 2677d2067731 (dccp: don't free ccid2_hc_tx_sock struct in dccp_disconnect()) Reported-by: Hadar Manor Signed-off-by: Kleber Sacilotto de Souza Signed-off-by: Thadeu Lima de Souza Cascardo Acked-by: Richard Sailer --- net/dccp/proto.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/dccp/proto.c b/net/dccp/proto.c index 6d705d90c614..359e848dba6c 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -279,7 +279,9 @@ int dccp_disconnect(struct sock *sk, int flags) dccp_clear_xmit_timers(sk); ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); + ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); dp->dccps_hc_rx_ccid = NULL; + dp->dccps_hc_tx_ccid = NULL; __skb_queue_purge(&sk->sk_receive_queue); __skb_queue_purge(&sk->sk_write_queue); -- 2.25.1