| From db57ccf0f2f4624b4c4758379f8165277504fbd7 Mon Sep 17 00:00:00 2001 |
| From: Paolo Abeni <pabeni@redhat.com> |
| Date: Wed, 14 Feb 2018 17:21:19 +0100 |
| Subject: netfilter: nat: cope with negative port range |
| |
| From: Paolo Abeni <pabeni@redhat.com> |
| |
| commit db57ccf0f2f4624b4c4758379f8165277504fbd7 upstream. |
| |
| syzbot reported a division by 0 bug in the netfilter nat code: |
| |
| divide error: 0000 [#1] SMP KASAN |
| Dumping ftrace buffer: |
| (ftrace buffer empty) |
| Modules linked in: |
| CPU: 1 PID: 4168 Comm: syzkaller034710 Not tainted 4.16.0-rc1+ #309 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS |
| Google 01/01/2011 |
| RIP: 0010:nf_nat_l4proto_unique_tuple+0x291/0x530 |
| net/netfilter/nf_nat_proto_common.c:88 |
| RSP: 0018:ffff8801b2466778 EFLAGS: 00010246 |
| RAX: 000000000000f153 RBX: ffff8801b2466dd8 RCX: ffff8801b2466c7c |
| RDX: 0000000000000000 RSI: ffff8801b2466c58 RDI: ffff8801db5293ac |
| RBP: ffff8801b24667d8 R08: ffff8801b8ba6dc0 R09: ffffffff88af5900 |
| R10: ffff8801b24666f0 R11: 0000000000000000 R12: 000000002990f153 |
| R13: 0000000000000001 R14: 0000000000000000 R15: ffff8801b2466c7c |
| FS: 00000000017e3880(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 00000000208fdfe4 CR3: 00000001b5340002 CR4: 00000000001606e0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| Call Trace: |
| dccp_unique_tuple+0x40/0x50 net/netfilter/nf_nat_proto_dccp.c:30 |
| get_unique_tuple+0xc28/0x1c10 net/netfilter/nf_nat_core.c:362 |
| nf_nat_setup_info+0x1c2/0xe00 net/netfilter/nf_nat_core.c:406 |
| nf_nat_redirect_ipv6+0x306/0x730 net/netfilter/nf_nat_redirect.c:124 |
| redirect_tg6+0x7f/0xb0 net/netfilter/xt_REDIRECT.c:34 |
| ip6t_do_table+0xc2a/0x1a30 net/ipv6/netfilter/ip6_tables.c:365 |
| ip6table_nat_do_chain+0x65/0x80 net/ipv6/netfilter/ip6table_nat.c:41 |
| nf_nat_ipv6_fn+0x594/0xa80 net/ipv6/netfilter/nf_nat_l3proto_ipv6.c:302 |
| nf_nat_ipv6_local_fn+0x33/0x5d0 |
| net/ipv6/netfilter/nf_nat_l3proto_ipv6.c:407 |
| ip6table_nat_local_fn+0x2c/0x40 net/ipv6/netfilter/ip6table_nat.c:69 |
| nf_hook_entry_hookfn include/linux/netfilter.h:120 [inline] |
| nf_hook_slow+0xba/0x1a0 net/netfilter/core.c:483 |
| nf_hook include/linux/netfilter.h:243 [inline] |
| NF_HOOK include/linux/netfilter.h:286 [inline] |
| ip6_xmit+0x10ec/0x2260 net/ipv6/ip6_output.c:277 |
| inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139 |
| dccp_transmit_skb+0x9ac/0x10f0 net/dccp/output.c:142 |
| dccp_connect+0x369/0x670 net/dccp/output.c:564 |
| dccp_v6_connect+0xe17/0x1bf0 net/dccp/ipv6.c:946 |
| __inet_stream_connect+0x2d4/0xf00 net/ipv4/af_inet.c:620 |
| inet_stream_connect+0x58/0xa0 net/ipv4/af_inet.c:684 |
| SYSC_connect+0x213/0x4a0 net/socket.c:1639 |
| SyS_connect+0x24/0x30 net/socket.c:1620 |
| do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 |
| entry_SYSCALL_64_after_hwframe+0x26/0x9b |
| RIP: 0033:0x441c69 |
| RSP: 002b:00007ffe50cc0be8 EFLAGS: 00000217 ORIG_RAX: 000000000000002a |
| RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000441c69 |
| RDX: 000000000000001c RSI: 00000000208fdfe4 RDI: 0000000000000003 |
| RBP: 00000000006cc018 R08: 0000000000000000 R09: 0000000000000000 |
| R10: 0000000000000538 R11: 0000000000000217 R12: 0000000000403590 |
| R13: 0000000000403620 R14: 0000000000000000 R15: 0000000000000000 |
| Code: 48 89 f0 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 46 02 00 00 48 8b |
| 45 c8 44 0f b7 20 e8 88 97 04 fd 31 d2 41 0f b7 c4 4c 89 f9 <41> f7 f6 48 |
| c1 e9 03 48 b8 00 00 00 00 00 fc ff df 0f b6 0c 01 |
| RIP: nf_nat_l4proto_unique_tuple+0x291/0x530 |
| net/netfilter/nf_nat_proto_common.c:88 RSP: ffff8801b2466778 |
| |
| The problem is that currently we don't have any check on the |
| configured port range. A port range == -1 triggers the bug, while |
| other negative values may require a very long time to complete the |
| following loop. |
| |
| This commit addresses the issue swapping the two ends on negative |
| ranges. The check is performed in nf_nat_l4proto_unique_tuple() since |
| the nft nat loads the port values from nft registers at runtime. |
| |
| v1 -> v2: use the correct 'Fixes' tag |
| v2 -> v3: update commit message, drop unneeded READ_ONCE() |
| |
| Fixes: 5b1158e909ec ("[NETFILTER]: Add NAT support for nf_conntrack") |
| Reported-by: syzbot+8012e198bd037f4871e5@syzkaller.appspotmail.com |
| Signed-off-by: Paolo Abeni <pabeni@redhat.com> |
| Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| net/netfilter/nf_nat_proto_common.c | 7 +++++-- |
| 1 file changed, 5 insertions(+), 2 deletions(-) |
| |
| --- a/net/netfilter/nf_nat_proto_common.c |
| +++ b/net/netfilter/nf_nat_proto_common.c |
| @@ -41,7 +41,7 @@ void nf_nat_l4proto_unique_tuple(const s |
| const struct nf_conn *ct, |
| u16 *rover) |
| { |
| - unsigned int range_size, min, i; |
| + unsigned int range_size, min, max, i; |
| __be16 *portptr; |
| u_int16_t off; |
| |
| @@ -71,7 +71,10 @@ void nf_nat_l4proto_unique_tuple(const s |
| } |
| } else { |
| min = ntohs(range->min_proto.all); |
| - range_size = ntohs(range->max_proto.all) - min + 1; |
| + max = ntohs(range->max_proto.all); |
| + if (unlikely(max < min)) |
| + swap(max, min); |
| + range_size = max - min + 1; |
| } |
| |
| if (range->flags & NF_NAT_RANGE_PROTO_RANDOM) { |