linux-stable/net/dccp/minisocks.c
Lin, Zhenpeng d9ea761fdd dccp: don't duplicate ccid when cloning dccp sock
Commit 2677d20677 ("dccp: don't free ccid2_hc_tx_sock ...") fixed
a UAF but reintroduced CVE-2017-6074.

When the sock is cloned, two dccps_hc_tx_ccid will reference to the
same ccid. So one can free the ccid object twice from two socks after
cloning.

This issue was found by "Hadar Manor" as well and assigned with
CVE-2020-16119, which was fixed in Ubuntu's kernel. So here I port
the patch from Ubuntu to fix it.

The patch prevents cloned socks from referencing the same ccid.

Fixes: 2677d20677 ("dccp: don't free ccid2_hc_tx_sock ...")
Signed-off-by: Zhenpeng Lin <zplin@psu.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-09-08 11:28:35 +01:00

271 lines
7.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/dccp/minisocks.c
*
* An implementation of the DCCP protocol
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*/
#include <linux/dccp.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/timer.h>
#include <net/sock.h>
#include <net/xfrm.h>
#include <net/inet_timewait_sock.h>
#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"
#include "feat.h"
struct inet_timewait_death_row dccp_death_row = {
.sysctl_max_tw_buckets = NR_FILE * 2,
.hashinfo = &dccp_hashinfo,
};
EXPORT_SYMBOL_GPL(dccp_death_row);
void dccp_time_wait(struct sock *sk, int state, int timeo)
{
struct inet_timewait_sock *tw;
tw = inet_twsk_alloc(sk, &dccp_death_row, state);
if (tw != NULL) {
const struct inet_connection_sock *icsk = inet_csk(sk);
const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
#if IS_ENABLED(CONFIG_IPV6)
if (tw->tw_family == PF_INET6) {
tw->tw_v6_daddr = sk->sk_v6_daddr;
tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
tw->tw_ipv6only = sk->sk_ipv6only;
}
#endif
/* Get the TIME_WAIT timeout firing. */
if (timeo < rto)
timeo = rto;
if (state == DCCP_TIME_WAIT)
timeo = DCCP_TIMEWAIT_LEN;
/* tw_timer is pinned, so we need to make sure BH are disabled
* in following section, otherwise timer handler could run before
* we complete the initialization.
*/
local_bh_disable();
inet_twsk_schedule(tw, timeo);
/* Linkage updates.
* Note that access to tw after this point is illegal.
*/
inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
local_bh_enable();
} else {
/* Sorry, if we're out of memory, just CLOSE this
* socket up. We've got bigger problems than
* non-graceful socket closings.
*/
DCCP_WARN("time wait bucket table overflow\n");
}
dccp_done(sk);
}
struct sock *dccp_create_openreq_child(const struct sock *sk,
const struct request_sock *req,
const struct sk_buff *skb)
{
/*
* Step 3: Process LISTEN state
*
* (* Generate a new socket and switch to that socket *)
* Set S := new socket for this port pair
*/
struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
if (newsk != NULL) {
struct dccp_request_sock *dreq = dccp_rsk(req);
struct inet_connection_sock *newicsk = inet_csk(newsk);
struct dccp_sock *newdp = dccp_sk(newsk);
newdp->dccps_role = DCCP_ROLE_SERVER;
newdp->dccps_hc_rx_ackvec = NULL;
newdp->dccps_service_list = NULL;
newdp->dccps_hc_rx_ccid = NULL;
newdp->dccps_hc_tx_ccid = NULL;
newdp->dccps_service = dreq->dreq_service;
newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
INIT_LIST_HEAD(&newdp->dccps_featneg);
/*
* Step 3: Process LISTEN state
*
* Choose S.ISS (initial seqno) or set from Init Cookies
* Initialize S.GAR := S.ISS
* Set S.ISR, S.GSR from packet (or Init Cookies)
*
* Setting AWL/AWH and SWL/SWH happens as part of the feature
* activation below, as these windows all depend on the local
* and remote Sequence Window feature values (7.5.2).
*/
newdp->dccps_iss = dreq->dreq_iss;
newdp->dccps_gss = dreq->dreq_gss;
newdp->dccps_gar = newdp->dccps_iss;
newdp->dccps_isr = dreq->dreq_isr;
newdp->dccps_gsr = dreq->dreq_gsr;
/*
* Activate features: initialise CCIDs, sequence windows etc.
*/
if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
sk_free_unlock_clone(newsk);
return NULL;
}
dccp_init_xmit_timers(newsk);
__DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
}
return newsk;
}
EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
/*
* Process an incoming packet for RESPOND sockets represented
* as an request_sock.
*/
struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
struct sock *child = NULL;
struct dccp_request_sock *dreq = dccp_rsk(req);
bool own_req;
/* TCP/DCCP listeners became lockless.
* DCCP stores complex state in its request_sock, so we need
* a protection for them, now this code runs without being protected
* by the parent (listener) lock.
*/
spin_lock_bh(&dreq->dreq_lock);
/* Check for retransmitted REQUEST */
if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
dccp_pr_debug("Retransmitted REQUEST\n");
dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
/*
* Send another RESPONSE packet
* To protect against Request floods, increment retrans
* counter (backoff, monitored by dccp_response_timer).
*/
inet_rtx_syn_ack(sk, req);
}
/* Network Duplicate, discard packet */
goto out;
}
DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
goto drop;
/* Invalid ACK */
if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
dreq->dreq_iss, dreq->dreq_gss)) {
dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
"dreq_iss=%llu, dreq_gss=%llu\n",
(unsigned long long)
DCCP_SKB_CB(skb)->dccpd_ack_seq,
(unsigned long long) dreq->dreq_iss,
(unsigned long long) dreq->dreq_gss);
goto drop;
}
if (dccp_parse_options(sk, dreq, skb))
goto drop;
child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
req, &own_req);
if (child) {
child = inet_csk_complete_hashdance(sk, child, req, own_req);
goto out;
}
DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
drop:
if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
req->rsk_ops->send_reset(sk, skb);
inet_csk_reqsk_queue_drop(sk, req);
out:
spin_unlock_bh(&dreq->dreq_lock);
return child;
}
EXPORT_SYMBOL_GPL(dccp_check_req);
/*
* Queue segment on the new socket if the new socket is active,
* otherwise we just shortcircuit this and continue with
* the new socket.
*/
int dccp_child_process(struct sock *parent, struct sock *child,
struct sk_buff *skb)
__releases(child)
{
int ret = 0;
const int state = child->sk_state;
if (!sock_owned_by_user(child)) {
ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
skb->len);
/* Wakeup parent, send SIGIO */
if (state == DCCP_RESPOND && child->sk_state != state)
parent->sk_data_ready(parent);
} else {
/* Alas, it is possible again, because we do lookup
* in main socket hash table and lock on listening
* socket does not protect us more.
*/
__sk_add_backlog(child, skb);
}
bh_unlock_sock(child);
sock_put(child);
return ret;
}
EXPORT_SYMBOL_GPL(dccp_child_process);
void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
struct request_sock *rsk)
{
DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
}
EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
int dccp_reqsk_init(struct request_sock *req,
struct dccp_sock const *dp, struct sk_buff const *skb)
{
struct dccp_request_sock *dreq = dccp_rsk(req);
spin_lock_init(&dreq->dreq_lock);
inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
inet_rsk(req)->acked = 0;
dreq->dreq_timestamp_echo = 0;
/* inherit feature negotiation options from listening socket */
return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
}
EXPORT_SYMBOL_GPL(dccp_reqsk_init);