kernel.git/net/core/flow_dissector.c, branch linux-4.4.y

flow_dissector: Check for IP fragmentation even if not using IPv4 address

2020-05-10T08:26:15Z

commit 918c023f29ab2dd8c63cfcc6a1239ee15933871a upstream. This patch corrects the logic for the IPv4 parsing so that it is consistent with how we handle IPv6. Specifically if we do not have the flow key indicating we want the addresses we still may need to take a look at the IP fragmentation bits and to see if we should stop after we have recognized the L3 header. Fixes: 807e165dc44f ("flow_dissector: Add control/reporting of fragmentation") Signed-off-by: Alexander Duyck Acked-by: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net/flow_dissector: switch to siphash

2019-11-10T10:21:14Z

commit 55667441c84fa5e0911a0aac44fb059c15ba6da2 upstream. UDP IPv6 packets auto flowlabels are using a 32bit secret (static u32 hashrnd in net/core/flow_dissector.c) and apply jhash() over fields known by the receivers. Attackers can easily infer the 32bit secret and use this information to identify a device and/or user, since this 32bit secret is only set at boot time. Really, using jhash() to generate cookies sent on the wire is a serious security concern. Trying to change the rol32(hash, 16) in ip6_make_flowlabel() would be a dead end. Trying to periodically change the secret (like in sch_sfq.c) could change paths taken in the network for long lived flows. Let's switch to siphash, as we did in commit df453700e8d8 ("inet: switch IP ID generator to siphash") Using a cryptographically strong pseudo random function will solve this privacy issue and more generally remove other weak points in the stack. Packet schedulers using skb_get_hash_perturb() benefit from this change. Fixes: b56774163f99 ("ipv6: Enable auto flow labels by default") Fixes: 42240901f7c4 ("ipv6: Implement different admin modes for automatic flow labels") Fixes: 67800f9b1f4e ("ipv6: Call skb_get_hash_flowi6 to get skb->hash in ip6_make_flowlabel") Fixes: cb1ce2ef387b ("ipv6: Implement automatic flow label generation on transmit") Signed-off-by: Eric Dumazet Reported-by: Jonathan Berger Reported-by: Amit Klein Reported-by: Benny Pinkas Cc: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Mahesh Bandewar Signed-off-by: Greg Kroah-Hartman

flow_dissector: do not dissect l4 ports for fragments

2018-11-27T15:07:56Z

[ Upstream commit 62230715fd2453b3ba948c9d83cfb3ada9169169 ] Only first fragment has the sport/dport information, not the following ones. If we want consistent hash for all fragments, we need to ignore ports even for first fragment. This bug is visible for IPv6 traffic, if incoming fragments do not have a flow label, since skb_get_hash() will give different results for first fragment and following ones. It is also visible if any routing rule wants dissection and sport or dport. See commit 5e5d6fed3741 ("ipv6: route: dissect flow in input path if fib rules need it") for details. [edumazet] rewrote the changelog completely. Fixes: 06635a35d13d ("flow_dissect: use programable dissector in skb_flow_dissect and friends") Signed-off-by: 배석진 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

flow_dissector: properly cap thoff field

2018-01-31T11:06:14Z

[ Upstream commit d0c081b49137cd3200f2023c0875723be66e7ce5 ] syzbot reported yet another crash [1] that is caused by insufficient validation of DODGY packets. Two bugs are happening here to trigger the crash. 1) Flow dissection leaves with incorrect thoff field. 2) skb_probe_transport_header() sets transport header to this invalid thoff, even if pointing after skb valid data. 3) qdisc_pkt_len_init() reads out-of-bound data because it trusts tcp_hdrlen(skb) Possible fixes : - Full flow dissector validation before injecting bad DODGY packets in the stack. This approach was attempted here : https://patchwork.ozlabs.org/patch/ 861874/ - Have more robust functions in the core. This might be needed anyway for stable versions. This patch fixes the flow dissection issue. [1] CPU: 1 PID: 3144 Comm: syzkaller271204 Not tainted 4.15.0-rc4-mm1+ #49 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:355 [inline] kasan_report+0x23b/0x360 mm/kasan/report.c:413 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:432 __tcp_hdrlen include/linux/tcp.h:35 [inline] tcp_hdrlen include/linux/tcp.h:40 [inline] qdisc_pkt_len_init net/core/dev.c:3160 [inline] __dev_queue_xmit+0x20d3/0x2200 net/core/dev.c:3465 dev_queue_xmit+0x17/0x20 net/core/dev.c:3554 packet_snd net/packet/af_packet.c:2943 [inline] packet_sendmsg+0x3ad5/0x60a0 net/packet/af_packet.c:2968 sock_sendmsg_nosec net/socket.c:628 [inline] sock_sendmsg+0xca/0x110 net/socket.c:638 sock_write_iter+0x31a/0x5d0 net/socket.c:907 call_write_iter include/linux/fs.h:1776 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x684/0x970 fs/read_write.c:482 vfs_write+0x189/0x510 fs/read_write.c:544 SYSC_write fs/read_write.c:589 [inline] SyS_write+0xef/0x220 fs/read_write.c:581 entry_SYSCALL_64_fastpath+0x1f/0x96 Fixes: 34fad54c2537 ("net: __skb_flow_dissect() must cap its return value") Fixes: a6e544b0a88b ("flow_dissector: Jump to exit code in __skb_flow_dissect") Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Reported-by: syzbot Acked-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

flow_dissect: call init_default_flow_dissectors() earlier

2016-12-02T08:09:02Z

commit c9b8af1330198ae241cd545e1f040019010d44d9 upstream. Andre Noll reported panics after my recent fix (commit 34fad54c2537 "net: __skb_flow_dissect() must cap its return value") After some more headaches, Alexander root caused the problem to init_default_flow_dissectors() being called too late, in case a network driver like IGB is not a module and receives DHCP message very early. Fix is to call init_default_flow_dissectors() much earlier, as it is a core infrastructure and does not depend on another kernel service. Fixes: 06635a35d13d4 ("flow_dissect: use programable dissector in skb_flow_dissect and friends") Signed-off-by: Eric Dumazet Reported-by: Andre Noll Diagnosed-by: Alexander Duyck Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: __skb_flow_dissect() must cap its return value

2016-11-21T09:06:40Z

[ Upstream commit 34fad54c2537f7c99d07375e50cb30aa3c23bd83 ] After Tom patch, thoff field could point past the end of the buffer, this could fool some callers. If an skb was provided, skb->len should be the upper limit. If not, hlen is supposed to be the upper limit. Fixes: a6e544b0a88b ("flow_dissector: Jump to exit code in __skb_flow_dissect") Signed-off-by: Eric Dumazet Reported-by: Yibin Yang Acked-by: Willem de Bruijn Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

packet: Use symmetric hash for PACKET_FANOUT_HASH.

2016-07-27T16:47:31Z

[ Upstream commit eb70db8756717b90c01ccc765fdefc4dd969fc74 ] People who use PACKET_FANOUT_HASH want a symmetric hash, meaning that they want packets going in both directions on a flow to hash to the same bucket. The core kernel SKB hash became non-symmetric when the ipv6 flow label and other entities were incorporated into the standard flow hash order to increase entropy. But there are no users of PACKET_FANOUT_HASH who want an assymetric hash, they all want a symmetric one. Therefore, use the flow dissector to compute a flat symmetric hash over only the protocol, addresses and ports. This hash does not get installed into and override the normal skb hash, so this change has no effect whatsoever on the rest of the stack. Reported-by: Eric Leblond Tested-by: Eric Leblond Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen

2016-03-03T23:07:06Z

[ Upstream commit 461547f3158978c180d74484d58e82be9b8e7357 ] This patch fixes an issue with unaligned accesses when using eth_get_headlen on a page that was DMA aligned instead of being IP aligned. The fact is when trying to check the length we don't need to be looking at the flow label so we can reorder the checks to first check if we are supposed to gather the flow label and then make the call to actually get it. v2: Updated path so that either STOP_AT_FLOW_LABEL or KEY_FLOW_LABEL can cause us to check for the flow label. Reported-by: Sowmini Varadhan Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: Copy inner L3 and L4 headers as unaligned on GRE TEB

2016-03-03T23:07:06Z

[ Upstream commit 78565208d73ca9b654fb9a6b142214d52eeedfd1 ] This patch corrects the unaligned accesses seen on GRE TEB tunnels when generating hash keys. Specifically what this patch does is make it so that we force the use of skb_copy_bits when the GRE inner headers will be unaligned due to NET_IP_ALIGNED being a non-zero value. Signed-off-by: Alexander Duyck Acked-by: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

flow_dissector: Use 'const' where possible.

2015-09-02T04:19:17Z

Signed-off-by: David S. Miller