linux-stable.git/net/l2tp, branch v3.16.69

l2tp: copy 4 more bytes to linear part if necessary

2019-05-02T20:41:33+00:00

commit 91c524708de6207f59dd3512518d8a1c7b434ee3 upstream.

The size of L2TPv2 header with all optional fields is 14 bytes.
l2tp_udp_recv_core only moves 10 bytes to the linear part of a
skb. This may lead to l2tp_recv_common read data outside of a skb.

This patch make sure that there is at least 14 bytes in the linear
part of a skb to meet the maximum need of l2tp_udp_recv_core and
l2tp_recv_common. The minimum size of both PPP HDLC-like frame and
Ethernet frame is larger than 14 bytes, so we are safe to do so.

Also remove L2TP_HDR_SIZE_NOSEQ, it is unused now.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Suggested-by: Guillaume Nault 
Signed-off-by: Jacob Wen 
Acked-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: fix a sock refcnt leak in l2tp_tunnel_register

2019-02-11T17:54:04+00:00

commit f8504f4ca0a0e9f84546ef86e00b24d2ea9a0bd2 upstream.

This issue happens when trying to add an existent tunnel. It
doesn't call sock_put() before returning -EEXIST to release
the sock refcnt that was held by calling sock_hold() before
the existence check.

This patch is to fix it by holding the sock after doing the
existence check.

Fixes: f6cd651b056f ("l2tp: fix race in duplicate tunnel detection")
Reported-by: Jianlin Shi 
Signed-off-by: Xin Long 
Reviewed-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: use sk_dst_check() to avoid race on sk->sk_dst_cache

2018-12-16T22:08:45+00:00

commit 6d37fa49da1e8db8fb1995be22ac837ca41ac8a8 upstream.

In l2tp code, if it is a L2TP_UDP_ENCAP tunnel, tunnel->sk points to a
UDP socket. User could call sendmsg() on both this tunnel and the UDP
socket itself concurrently. As l2tp_xmit_skb() holds socket lock and call
__sk_dst_check() to refresh sk->sk_dst_cache, while udpv6_sendmsg() is
lockless and call sk_dst_check() to refresh sk->sk_dst_cache, there
could be a race and cause the dst cache to be freed multiple times.
So we fix l2tp side code to always call sk_dst_check() to garantee
xchg() is called when refreshing sk->sk_dst_cache to avoid race
conditions.

Syzkaller reported stack trace:
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:597 [inline]
BUG: KASAN: use-after-free in dst_hold_safe include/net/dst.h:308 [inline]
BUG: KASAN: use-after-free in ip6_hold_safe+0xe6/0x670 net/ipv6/route.c:1029
Read of size 4 at addr ffff8801aea9a880 by task syz-executor129/4829

CPU: 0 PID: 4829 Comm: syz-executor129 Not tainted 4.18.0-rc7-next-20180802+ #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
 atomic_add_unless include/linux/atomic.h:597 [inline]
 dst_hold_safe include/net/dst.h:308 [inline]
 ip6_hold_safe+0xe6/0x670 net/ipv6/route.c:1029
 rt6_get_pcpu_route net/ipv6/route.c:1249 [inline]
 ip6_pol_route+0x354/0xd20 net/ipv6/route.c:1922
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2098
 fib6_rule_lookup+0x283/0x890 net/ipv6/fib6_rules.c:122
 ip6_route_output_flags+0x2c5/0x350 net/ipv6/route.c:2126
 ip6_dst_lookup_tail+0x1278/0x1da0 net/ipv6/ip6_output.c:978
 ip6_dst_lookup_flow+0xc8/0x270 net/ipv6/ip6_output.c:1079
 ip6_sk_dst_lookup_flow+0x5ed/0xc50 net/ipv6/ip6_output.c:1117
 udpv6_sendmsg+0x2163/0x36b0 net/ipv6/udp.c:1354
 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:632
 ___sys_sendmsg+0x51d/0x930 net/socket.c:2115
 __sys_sendmmsg+0x240/0x6f0 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2236
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446a29
Code: e8 ac b8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4de5532db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000006dcc38 RCX: 0000000000446a29
RDX: 00000000000000b8 RSI: 0000000020001b00 RDI: 0000000000000003
RBP: 00000000006dcc30 R08: 00007f4de5533700 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c
R13: 00007ffe2b830fdf R14: 00007f4de55339c0 R15: 0000000000000001

Fixes: 71b1391a4128 ("l2tp: ensure sk->dst is still valid")
Reported-by: syzbot+05f840f3b04f211bad55@syzkaller.appspotmail.com
Signed-off-by: Wei Wang 
Signed-off-by: Martin KaFai Lau 
Cc: Guillaume Nault 
Cc: David Ahern 
Cc: Cong Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: fix missing refcount drop in pppol2tp_tunnel_ioctl()

2018-11-20T18:05:53+00:00

commit f664e37dcc525768280cb94321424a09beb1c992 upstream.

If 'session' is not NULL and is not a PPP pseudo-wire, then we fail to
drop the reference taken by l2tp_session_get().

Fixes: ecd012e45ab5 ("l2tp: filter out non-PPP sessions in pppol2tp_tunnel_ioctl()")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: Also call session->deref in both cases]
Signed-off-by: Ben Hutchings

l2tp: filter out non-PPP sessions in pppol2tp_tunnel_ioctl()

2018-11-20T18:05:15+00:00

commit ecd012e45ab5fd76ed57546865897ce35920f56b upstream.

pppol2tp_tunnel_ioctl() can act on an L2TPv3 tunnel, in which case
'session' may be an Ethernet pseudo-wire.

However, pppol2tp_session_ioctl() expects a PPP pseudo-wire, as it
assumes l2tp_session_priv() points to a pppol2tp_session structure. For
an Ethernet pseudo-wire l2tp_session_priv() points to an l2tp_eth_sess
structure instead, making pppol2tp_session_ioctl() access invalid
memory.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: reject creation of non-PPP sessions on L2TPv2 tunnels

2018-11-20T18:05:15+00:00

commit de9bada5d389903f4faf33980e6a95a2911c7e6d upstream.

The /proc/net/pppol2tp handlers (pppol2tp_seq_*()) iterate over all
L2TPv2 tunnels, and rightfully expect that only PPP sessions can be
found there. However, l2tp_netlink accepts creating Ethernet sessions
regardless of the underlying tunnel version.

This confuses pppol2tp_seq_session_show(), which expects that
l2tp_session_priv() returns a pppol2tp_session structure. When the
session is an Ethernet pseudo-wire, a struct l2tp_eth_sess is returned
instead. This leads to invalid memory access when
pppol2tp_session_get_sock() later tries to dereference ps->sk.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: clean up stale tunnel or session in pppol2tp_connect's error path

2018-11-20T18:05:15+00:00

commit bda06be2158c7aa7e41b15500c4d3840369c19a6 upstream.

pppol2tp_connect() may create a tunnel or a session. Remove them in
case of error.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: prevent pppol2tp_connect() from creating kernel sockets

2018-11-20T18:05:15+00:00

commit 3e1bc8bf974e2d4e7beb842a4c801c2542eff3bd upstream.

If 'fd' is negative, l2tp_tunnel_create() creates a tunnel socket using
the configuration passed in 'tcfg'. Currently, pppol2tp_connect() sets
the relevant fields to zero, tricking l2tp_tunnel_create() into setting
up an unusable kernel socket.

We can't set 'tcfg' with the required fields because there's no way to
get them from the current connect() parameters. So let's restrict
kernel sockets creation to the netlink API, which is the original use
case.

Fixes: 789a4a2c61d8 ("l2tp: Add support for static unmanaged L2TPv3 tunnels")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: only accept PPP sessions in pppol2tp_connect()

2018-11-20T18:05:14+00:00

commit 7ac6ab1f8a38ba7f8d97f95475bb6a2575db4658 upstream.

l2tp_session_priv() returns a struct pppol2tp_session pointer only for
PPPoL2TP sessions. In particular, if the session is an L2TP_PWTYPE_ETH
pseudo-wire, l2tp_session_priv() returns a pointer to an l2tp_eth_sess
structure, which is much smaller than struct pppol2tp_session. This
leads to invalid memory dereference when trying to lock ps->sk_lock.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

l2tp: fix pseudo-wire type for sessions created by pppol2tp_connect()

2018-11-20T18:05:14+00:00

commit 90904ff5f958a215cc3d26f957a46e80fa178470 upstream.

Define cfg.pw_type so that the new session is created with its .pwtype
field properly set (L2TP_PWTYPE_PPP).

Not setting the pseudo-wire type had several annoying effects:

  * Invalid value returned in the L2TP_ATTR_PW_TYPE attribute when
    dumping sessions with the netlink API.

  * Impossibility to delete the session using the netlink API (because
    l2tp_nl_cmd_session_delete() gets the deletion callback function
    from an array indexed by the session's pseudo-wire type).

Also, there are several cases where we should check a session's
pseudo-wire type. For example, pppol2tp_connect() should refuse to
connect a session that is not PPPoL2TP, but that requires the session's
.pwtype field to be properly set.

Fixes: f7faffa3ff8e ("l2tp: Add L2TPv3 protocol support")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings