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mptcp: only admit explicitly supported sockopt
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Unrolling mcast state at msk dismantel time is bug prone, as
syzkaller reported:

======================================================
WARNING: possible circular locking dependency detected
5.11.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor905/8822 is trying to acquire lock:
ffffffff8d678fe8 (rtnl_mutex){+.+.}-{3:3}, at: ipv6_sock_mc_close+0xd7/0x110 net/ipv6/mcast.c:323

but task is already holding lock:
ffff888024390120 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1600 [inline]
ffff888024390120 (sk_lock-AF_INET6){+.+.}-{0:0}, at: mptcp6_release+0x57/0x130 net/mptcp/protocol.c:3507

which lock already depends on the new lock.

Instead we can simply forbid any mcast-related setsockopt.
Let's do the same with all other non supported sockopts.

Fixes: 717e79c ("mptcp: Add setsockopt()/getsockopt() socket operations")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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@matttbe
Paolo Abeni authored and matttbe committed Mar 9, 2021
1 parent 7973a7b commit ce35fc3
Showing 1 changed file with 214 additions and 0 deletions.
214 changes: 214 additions & 0 deletions net/mptcp/sockopt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,217 @@ static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
return ret;
}

static bool mptcp_supported_sockopt(int level, int optname)
{
if (level == SOL_SOCKET) {
switch (optname) {
case SO_DEBUG:
case SO_REUSEPORT:
case SO_REUSEADDR:

/* the following ones need a better implementation,
* but are quite common we want to preserve them
*/
case SO_BINDTODEVICE:
case SO_SNDBUF:
case SO_SNDBUFFORCE:
case SO_RCVBUF:
case SO_RCVBUFFORCE:
case SO_KEEPALIVE:
case SO_PRIORITY:
case SO_LINGER:
case SO_TIMESTAMP_OLD:
case SO_TIMESTAMP_NEW:
case SO_TIMESTAMPNS_OLD:
case SO_TIMESTAMPNS_NEW:
case SO_TIMESTAMPING_OLD:
case SO_TIMESTAMPING_NEW:
case SO_RCVLOWAT:
case SO_RCVTIMEO_OLD:
case SO_RCVTIMEO_NEW:
case SO_MARK:
case SO_INCOMING_CPU:
case SO_BINDTOIFINDEX:
case SO_BUSY_POLL:
case SO_PREFER_BUSY_POLL:
case SO_BUSY_POLL_BUDGET:

/* next ones are no-op for plain TCP */
case SO_NO_CHECK:
case SO_DONTROUTE:
case SO_BROADCAST:
case SO_BSDCOMPAT:
case SO_PASSCRED:
case SO_PASSSEC:
case SO_RXQ_OVFL:
case SO_WIFI_STATUS:
case SO_NOFCS:
case SO_SELECT_ERR_QUEUE:
return true;
}

/* SO_OOBINLINE is not supported, let's avoid the related mess */
/* SO_ATTACH_FILTER, SO_ATTACH_BPF, SO_ATTACH_REUSEPORT_CBPF,
* SO_DETACH_REUSEPORT_BPF, SO_DETACH_FILTER, SO_LOCK_FILTER,
* we must be careful with subflows
*/
/* SO_ATTACH_REUSEPORT_EBPF is not supported, at it checks
* explicitly the sk_protocol field
*/
/* SO_PEEK_OFF is unsupported, as it is for plain TCP */
/* SO_MAX_PACING_RATE is unsupported, we must be careful with subflows */
/* SO_CNX_ADVICE is currently unsupported, could possibly be relevant,
* but likely needs careful design
*/
/* SO_ZEROCOPY is currently unsupported, TODO in sndmsg */
/* SO_TXTIME is currently unsupported */
return false;
}
if (level == SOL_IP) {
switch (optname) {
/* should work fine */
case IP_FREEBIND:
case IP_TRANSPARENT:

/* the following are control cmsg related */
case IP_PKTINFO:
case IP_RECVTTL:
case IP_RECVTOS:
case IP_RECVOPTS:
case IP_RETOPTS:
case IP_PASSSEC:
case IP_RECVORIGDSTADDR:
case IP_CHECKSUM:
case IP_RECVFRAGSIZE:

/* common stuff that need some love */
case IP_TOS:
case IP_TTL:
case IP_BIND_ADDRESS_NO_PORT:
case IP_MTU_DISCOVER:
case IP_RECVERR:

/* possibly less common may deserve some love */
case IP_MINTTL:

/* the following is apparently a no-op for plain TCP */
case IP_RECVERR_RFC4884:
return true;
}

/* IP_OPTIONS is not supported, needs subflow care */
/* IP_HDRINCL, IP_NODEFRAG are not supported, RAW specific */
/* IP_MULTICAST_TTL, IP_MULTICAST_LOOP, IP_UNICAST_IF,
* IP_ADD_MEMBERSHIP, IP_ADD_SOURCE_MEMBERSHIP, IP_DROP_MEMBERSHIP,
* IP_DROP_SOURCE_MEMBERSHIP, IP_BLOCK_SOURCE, IP_UNBLOCK_SOURCE,
* MCAST_JOIN_GROUP, MCAST_LEAVE_GROUP MCAST_JOIN_SOURCE_GROUP,
* MCAST_LEAVE_SOURCE_GROUP, MCAST_BLOCK_SOURCE, MCAST_UNBLOCK_SOURCE,
* MCAST_MSFILTER, IP_MULTICAST_ALL are not supported, better not deal
* with mcast stuff
*/
/* IP_IPSEC_POLICY, IP_XFRM_POLICY are nut supported, unrelated here */
return false;
}
if (level == SOL_IPV6) {
switch (optname) {
case IPV6_V6ONLY:

/* the following are control cmsg related */
case IPV6_RECVPKTINFO:
case IPV6_2292PKTINFO:
case IPV6_RECVHOPLIMIT:
case IPV6_2292HOPLIMIT:
case IPV6_RECVRTHDR:
case IPV6_2292RTHDR:
case IPV6_RECVHOPOPTS:
case IPV6_2292HOPOPTS:
case IPV6_RECVDSTOPTS:
case IPV6_2292DSTOPTS:
case IPV6_RECVTCLASS:
case IPV6_FLOWINFO:
case IPV6_RECVPATHMTU:
case IPV6_RECVORIGDSTADDR:
case IPV6_RECVFRAGSIZE:

/* the following ones need some love but are quite common */
case IPV6_TCLASS:
case IPV6_TRANSPARENT:
case IPV6_FREEBIND:
case IPV6_PKTINFO:
case IPV6_2292PKTOPTIONS:
case IPV6_UNICAST_HOPS:
case IPV6_MTU_DISCOVER:
case IPV6_MTU:
case IPV6_RECVERR:
case IPV6_FLOWINFO_SEND:
case IPV6_FLOWLABEL_MGR:
case IPV6_MINHOPCOUNT:
case IPV6_DONTFRAG:
case IPV6_AUTOFLOWLABEL:

/* the following one is a no-op for plain TCP */
case IPV6_RECVERR_RFC4884:
return true;
}

/* IPV6_HOPOPTS, IPV6_RTHDRDSTOPTS, IPV6_RTHDR, IPV6_DSTOPTS are
* not supported
*/
/* IPV6_MULTICAST_HOPS, IPV6_MULTICAST_LOOP, IPV6_UNICAST_IF,
* IPV6_MULTICAST_IF, IPV6_ADDRFORM,
* IPV6_ADD_MEMBERSHIP, IPV6_DROP_MEMBERSHIP, IPV6_JOIN_ANYCAST,
* IPV6_LEAVE_ANYCAST, IPV6_MULTICAST_ALL, MCAST_JOIN_GROUP, MCAST_LEAVE_GROUP,
* MCAST_JOIN_SOURCE_GROUP, MCAST_LEAVE_SOURCE_GROUP,
* MCAST_BLOCK_SOURCE, MCAST_UNBLOCK_SOURCE, MCAST_MSFILTER
* are not supported better not deal with mcast
*/
/* IPV6_ROUTER_ALERT, IPV6_ROUTER_ALERT_ISOLATE are not supported, since are evil */

/* IPV6_IPSEC_POLICY, IPV6_XFRM_POLICY are not supported */
/* IPV6_ADDR_PREFERENCES is not supported, we must be careful with subflows */
return false;
}
if (level == SOL_TCP) {
switch (optname) {
/* the following are no-op or should work just fine */
case TCP_THIN_DUPACK:
case TCP_DEFER_ACCEPT:

/* the following need some love */
case TCP_MAXSEG:
case TCP_NODELAY:
case TCP_THIN_LINEAR_TIMEOUTS:
case TCP_CONGESTION:
case TCP_ULP:
case TCP_CORK:
case TCP_KEEPIDLE:
case TCP_KEEPINTVL:
case TCP_KEEPCNT:
case TCP_SYNCNT:
case TCP_SAVE_SYN:
case TCP_LINGER2:
case TCP_WINDOW_CLAMP:
case TCP_QUICKACK:
case TCP_USER_TIMEOUT:
case TCP_TIMESTAMP:
case TCP_NOTSENT_LOWAT:
case TCP_TX_DELAY:
return true;
}

/* TCP_MD5SIG, TCP_MD5SIG_EXT are not supported, MD5 is not compatible with MPTCP */

/* TCP_REPAIR, TCP_REPAIR_QUEUE, TCP_QUEUE_SEQ, TCP_REPAIR_OPTIONS,
* TCP_REPAIR_WINDOW are not supported, better avoid this mess
*/
/* TCP_FASTOPEN_KEY, TCP_FASTOPEN TCP_FASTOPEN_CONNECT, TCP_FASTOPEN_NO_COOKIE,
* are not supported fastopen is currently unsupported
*/
/* TCP_INQ is currently unsupported, needs some recvmsg work */
}
return false;
}

int mptcp_setsockopt(struct sock *sk, int level, int optname,
sockptr_t optval, unsigned int optlen)
{
Expand All @@ -90,6 +301,9 @@ int mptcp_setsockopt(struct sock *sk, int level, int optname,

pr_debug("msk=%p", msk);

if (!mptcp_supported_sockopt(level, optname))
return -ENOPROTOOPT;

if (level == SOL_SOCKET)
return mptcp_setsockopt_sol_socket(msk, optname, optval, optlen);

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