linux.git/net/ipv4/ip_gre.c, branch v5.19

erspan: do not assume transport header is always set

2022-06-20T09:00:55+00:00

Rewrite tests in ip6erspan_tunnel_xmit() and
erspan_fb_xmit() to not assume transport header is set.

syzbot reported:

WARNING: CPU: 0 PID: 1350 at include/linux/skbuff.h:2911 skb_transport_header include/linux/skbuff.h:2911 [inline]
WARNING: CPU: 0 PID: 1350 at include/linux/skbuff.h:2911 ip6erspan_tunnel_xmit+0x15af/0x2eb0 net/ipv6/ip6_gre.c:963
Modules linked in:
CPU: 0 PID: 1350 Comm: aoe_tx0 Not tainted 5.19.0-rc2-syzkaller-00160-g274295c6e53f #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:skb_transport_header include/linux/skbuff.h:2911 [inline]
RIP: 0010:ip6erspan_tunnel_xmit+0x15af/0x2eb0 net/ipv6/ip6_gre.c:963
Code: 0f 47 f0 40 88 b5 7f fe ff ff e8 8c 16 4b f9 89 de bf ff ff ff ff e8 a0 12 4b f9 66 83 fb ff 0f 85 1d f1 ff ff e8 71 16 4b f9 <0f> 0b e9 43 f0 ff ff e8 65 16 4b f9 48 8d 85 30 ff ff ff ba 60 00
RSP: 0018:ffffc90005daf910 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 000000000000ffff RCX: 0000000000000000
RDX: ffff88801f032100 RSI: ffffffff882e8d3f RDI: 0000000000000003
RBP: ffffc90005dafab8 R08: 0000000000000003 R09: 000000000000ffff
R10: 000000000000ffff R11: 0000000000000000 R12: ffff888024f21d40
R13: 000000000000a288 R14: 00000000000000b0 R15: ffff888025a2e000
FS: 0000000000000000(0000) GS:ffff88802c800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e425000 CR3: 000000006d099000 CR4: 0000000000152ef0
Call Trace:

__netdev_start_xmit include/linux/netdevice.h:4805 [inline]
netdev_start_xmit include/linux/netdevice.h:4819 [inline]
xmit_one net/core/dev.c:3588 [inline]
dev_hard_start_xmit+0x188/0x880 net/core/dev.c:3604
sch_direct_xmit+0x19f/0xbe0 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3815 [inline]
__dev_queue_xmit+0x14a1/0x3900 net/core/dev.c:4219
dev_queue_xmit include/linux/netdevice.h:2994 [inline]
tx+0x6a/0xc0 drivers/block/aoe/aoenet.c:63
kthread+0x1e7/0x3b0 drivers/block/aoe/aoecmd.c:1229
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302


Fixes: d5db21a3e697 ("erspan: auto detect truncated ipv6 packets.")
Reported-by: syzbot 
Signed-off-by: Eric Dumazet 
Cc: William Tu 
Signed-off-by: David S. Miller

ip_gre: test csum_start instead of transport header

2022-06-09T03:34:43+00:00

GRE with TUNNEL_CSUM will apply local checksum offload on
CHECKSUM_PARTIAL packets.

ipgre_xmit must validate csum_start after an optional skb_pull,
else lco_csum may trigger an overflow. The original check was

	if (csum && skb_checksum_start(skb) < skb->data)
		return -EINVAL;

This had false positives when skb_checksum_start is undefined:
when ip_summed is not CHECKSUM_PARTIAL. A discussed refinement
was straightforward

	if (csum && skb->ip_summed == CHECKSUM_PARTIAL &&
	    skb_checksum_start(skb) < skb->data)
		return -EINVAL;

But was eventually revised more thoroughly:
- restrict the check to the only branch where needed, in an
  uncommon GRE path that uses header_ops and calls skb_pull.
- test skb_transport_header, which is set along with csum_start
  in skb_partial_csum_set in the normal header_ops datapath.

Turns out skbs can arrive in this branch without the transport
header set, e.g., through BPF redirection.

Revise the check back to check csum_start directly, and only if
CHECKSUM_PARTIAL. Do leave the check in the updated location.
Check field regardless of whether TUNNEL_CSUM is configured.

Link: https://lore.kernel.org/netdev/YS+h%2FtqCJJiQei+W@shredder/
Link: https://lore.kernel.org/all/20210902193447.94039-2-willemdebruijn.kernel@gmail.com/T/#u
Fixes: 8a0ed250f911 ("ip_gre: validate csum_start only on pull")
Reported-by: syzbot 
Signed-off-by: Willem de Bruijn 
Reviewed-by: Eric Dumazet 
Reviewed-by: Alexander Duyck 
Link: https://lore.kernel.org/r/20220606132107.3582565-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski

ip_gre: Make GRE and GRETAP devices always NETIF_F_LLTX

2022-05-02T08:30:33+00:00

Recently we made o_seqno atomic_t.  Stop special-casing TUNNEL_SEQ, and
always mark GRE[TAP] devices as NETIF_F_LLTX, since we no longer need
the TX lock (&txq->_xmit_lock).

Signed-off-by: Peilin Ye 
Signed-off-by: Paolo Abeni

ip_gre, ip6_gre: Fix race condition on o_seqno in collect_md mode

2022-04-25T10:40:45+00:00

As pointed out by Jakub Kicinski, currently using TUNNEL_SEQ in
collect_md mode is racy for [IP6]GRE[TAP] devices.  Consider the
following sequence of events:

1. An [IP6]GRE[TAP] device is created in collect_md mode using "ip link
   add ... external".  "ip" ignores "[o]seq" if "external" is specified,
   so TUNNEL_SEQ is off, and the device is marked as NETIF_F_LLTX (i.e.
   it uses lockless TX);
2. Someone sets TUNNEL_SEQ on outgoing skb's, using e.g.
   bpf_skb_set_tunnel_key() in an eBPF program attached to this device;
3. gre_fb_xmit() or __gre6_xmit() processes these skb's:

	gre_build_header(skb, tun_hlen,
			 flags, protocol,
			 tunnel_id_to_key32(tun_info->key.tun_id),
			 (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++)
					      : 0);   ^^^^^^^^^^^^^^^^^

Since we are not using the TX lock (&txq->_xmit_lock), multiple CPUs may
try to do this tunnel->o_seqno++ in parallel, which is racy.  Fix it by
making o_seqno atomic_t.

As mentioned by Eric Dumazet in commit b790e01aee74 ("ip_gre: lockless
xmit"), making o_seqno atomic_t increases "chance for packets being out
of order at receiver" when NETIF_F_LLTX is on.

Maybe a better fix would be:

1. Do not ignore "oseq" in external mode.  Users MUST specify "oseq" if
   they want the kernel to allow sequencing of outgoing packets;
2. Reject all outgoing TUNNEL_SEQ packets if the device was not created
   with "oseq".

Unfortunately, that would break userspace.

We could now make [IP6]GRE[TAP] devices always NETIF_F_LLTX, but let us
do it in separate patches to keep this fix minimal.

Suggested-by: Jakub Kicinski 
Fixes: 77a5196a804e ("gre: add sequence number for collect md mode.")
Signed-off-by: Peilin Ye 
Acked-by: William Tu 
Signed-off-by: David S. Miller

ip_gre: Make o_seqno start from 0 in native mode

2022-04-25T10:40:45+00:00

For GRE and GRETAP devices, currently o_seqno starts from 1 in native
mode.  According to RFC 2890 2.2., "The first datagram is sent with a
sequence number of 0."  Fix it.

It is worth mentioning that o_seqno already starts from 0 in collect_md
mode, see gre_fb_xmit(), where tunnel->o_seqno is passed to
gre_build_header() before getting incremented.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Peilin Ye 
Acked-by: William Tu 
Signed-off-by: David S. Miller

net: Handle l3mdev in ip_tunnel_init_flow

2022-04-15T21:27:30+00:00

Ido reported that the commit referenced in the Fixes tag broke
a gre use case with dummy devices. Add a check to ip_tunnel_init_flow
to see if the oif is an l3mdev port and if so set the oif to 0 to
avoid the oif comparison in fib_lookup_good_nhc.

Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices")
Reported-by: Ido Schimmel 
Signed-off-by: David Ahern 
Signed-off-by: Jakub Kicinski

gre: Don't accidentally set RTO_ONLINK in gre_fill_metadata_dst()

2022-01-12T04:36:08+00:00

Mask the ECN bits before initialising ->flowi4_tos. The tunnel key may
have the last ECN bit set, which will interfere with the route lookup
process as ip_route_output_key_hash() interpretes this bit specially
(to restrict the route scope).

Found by code inspection, compile tested only.

Fixes: 962924fa2b7a ("ip_gre: Refactor collect metatdata mode tunnel xmit to ip_md_tunnel_xmit")
Signed-off-by: Guillaume Nault 
Signed-off-by: Jakub Kicinski

ip: use dev_addr_set() in tunnels

2021-10-13T16:41:37+00:00

Use dev_addr_set() instead of writing to netdev->dev_addr
directly in ip tunnels drivers.

Signed-off-by: Jakub Kicinski

ip_gre: validate csum_start only on pull

2021-09-05T17:59:32+00:00

The GRE tunnel device can pull existing outer headers in ipge_xmit.
This is a rare path, apparently unique to this device. The below
commit ensured that pulling does not move skb->data beyond csum_start.

But it has a false positive if ip_summed is not CHECKSUM_PARTIAL and
thus csum_start is irrelevant.

Refine to exclude this. At the same time simplify and strengthen the
test.

Simplify, by moving the check next to the offending pull, making it
more self documenting and removing an unnecessary branch from other
code paths.

Strengthen, by also ensuring that the transport header is correct and
therefore the inner headers will be after skb_reset_inner_headers.
The transport header is set to csum_start in skb_partial_csum_set.

Link: https://lore.kernel.org/netdev/YS+h%2FtqCJJiQei+W@shredder/
Fixes: 1d011c4803c7 ("ip_gre: add validation for csum_start")
Reported-by: Ido Schimmel 
Suggested-by: Alexander Duyck 
Signed-off-by: Willem de Bruijn 
Reviewed-by: Alexander Duyck 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2021-08-27T00:57:57+00:00

drivers/net/wwan/mhi_wwan_mbim.c - drop the extra arg.

Signed-off-by: Jakub Kicinski