linux-stable.git/net/ipv4/tcp_input.c, branch linux-4.8.y

tcp: fix a compile error in DBGUNDO()

2016-09-23T12:26:32+00:00

If DBGUNDO() is enabled (FASTRETRANS_DEBUG > 1), a compile
error will happen, since inet6_sk(sk)->daddr became sk->sk_v6_daddr

Fixes: efe4208f47f9 ("ipv6: make lookups simpler and faster")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: properly account Fast Open SYN-ACK retrans

2016-09-22T07:33:01+00:00

Since the TFO socket is accepted right off SYN-data, the socket
owner can call getsockopt(TCP_INFO) to collect ongoing SYN-ACK
retransmission or timeout stats (i.e., tcpi_total_retrans,
tcpi_retransmits). Currently those stats are only updated
upon handshake completes. This patch fixes it.

Signed-off-by: Yuchung Cheng 
Signed-off-by: Eric Dumazet 
Signed-off-by: Neal Cardwell 
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2016-07-30T00:38:46+00:00

Pull security subsystem updates from James Morris:
 "Highlights:

   - TPM core and driver updates/fixes
   - IPv6 security labeling (CALIPSO)
   - Lots of Apparmor fixes
   - Seccomp: remove 2-phase API, close hole where ptrace can change
     syscall #"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (156 commits)
  apparmor: fix SECURITY_APPARMOR_HASH_DEFAULT parameter handling
  tpm: Add TPM 2.0 support to the Nuvoton i2c driver (NPCT6xx family)
  tpm: Factor out common startup code
  tpm: use devm_add_action_or_reset
  tpm2_i2c_nuvoton: add irq validity check
  tpm: read burstcount from TPM_STS in one 32-bit transaction
  tpm: fix byte-order for the value read by tpm2_get_tpm_pt
  tpm_tis_core: convert max timeouts from msec to jiffies
  apparmor: fix arg_size computation for when setprocattr is null terminated
  apparmor: fix oops, validate buffer size in apparmor_setprocattr()
  apparmor: do not expose kernel stack
  apparmor: fix module parameters can be changed after policy is locked
  apparmor: fix oops in profile_unpack() when policy_db is not present
  apparmor: don't check for vmalloc_addr if kvzalloc() failed
  apparmor: add missing id bounds check on dfa verification
  apparmor: allow SYS_CAP_RESOURCE to be sufficient to prlimit another task
  apparmor: use list_next_entry instead of list_entry_next
  apparmor: fix refcount race when finding a child profile
  apparmor: fix ref count leak when profile sha1 hash is read
  apparmor: check that xindex is in trans_table bounds
  ...

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

2016-07-24T04:53:32+00:00

Just several instances of overlapping changes.

Signed-off-by: David S. Miller

tcp: enable per-socket rate limiting of all 'challenge acks'

2016-07-15T21:18:29+00:00

The per-socket rate limit for 'challenge acks' was introduced in the
context of limiting ack loops:

commit f2b2c582e824 ("tcp: mitigate ACK loops for connections as tcp_sock")

And I think it can be extended to rate limit all 'challenge acks' on a
per-socket basis.

Since we have the global tcp_challenge_ack_limit, this patch allows for
tcp_challenge_ack_limit to be set to a large value and effectively rely on
the per-socket limit, or set tcp_challenge_ack_limit to a lower value and
still prevents a single connections from consuming the entire challenge ack
quota.

It further moves in the direction of eliminating the global limit at some
point, as Eric Dumazet has suggested. This a follow-up to:
Subject: tcp: make challenge acks less predictable

Cc: Eric Dumazet 
Cc: David S. Miller 
Cc: Neal Cardwell 
Cc: Yuchung Cheng 
Cc: Yue Cao 
Signed-off-by: Jason Baron 
Signed-off-by: David S. Miller

tcp: make challenge acks less predictable

2016-07-11T20:33:35+00:00

Yue Cao claims that current host rate limiting of challenge ACKS
(RFC 5961) could leak enough information to allow a patient attacker
to hijack TCP sessions. He will soon provide details in an academic
paper.

This patch increases the default limit from 100 to 1000, and adds
some randomization so that the attacker can no longer hijack
sessions without spending a considerable amount of probes.

Based on initial analysis and patch from Linus.

Note that we also have per socket rate limiting, so it is tempting
to remove the host limit in the future.

v2: randomize the count of challenge acks per second, not the period.

Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2")
Reported-by: Yue Cao 
Signed-off-by: Eric Dumazet 
Suggested-by: Linus Torvalds 
Cc: Yuchung Cheng 
Cc: Neal Cardwell 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/selinux into next

2016-07-07T00:15:34+00:00

ipv6: Allow request socks to contain IPv6 options.

2016-06-27T19:05:28+00:00

If set, these will take precedence over the parent's options during
both sending and child creation.  If they're not set, the parent's
options (if any) will be used.

This is to allow the security_inet_conn_request() hook to modify the
IPv6 options in just the same way that it already may do for IPv4.

Signed-off-by: Huw Davies 
Signed-off-by: Paul Moore

tcp: add in_flight to tcp_skb_cb

2016-06-11T06:07:49+00:00

Add in_flight (bytes in flight when packet was sent) field
to tx component of tcp_skb_cb and make it available to
congestion modules' pkts_acked() function through the
ack_sample function argument.

Signed-off-by: Lawrence Brakmo 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: accept RST if SEQ matches right edge of right-most SACK block

2016-06-08T07:36:18+00:00

RFC 5961 advises to only accept RST packets containing a seq number
matching the next expected seq number instead of the whole receive
window in order to avoid spoofing attacks.

However, this situation is not optimal in the case SACK is in use at the
time the RST is sent. I recently run into a scenario in which packet
losses were high while uploading data to a server, and userspace was
willing to frequently terminate connections by sending a RST. In
this case, the ACK sent on the receiver side (rcv_nxt) is frozen waiting
for a lost packet retransmission and SACK blocks are used to let the
client continue uploading data. At some point later on, the client sends
the RST (snd_nxt), which matches the next expected seq number of the
right-most SACK block on the receiver side which is going forward
receiving data.

In this scenario, as RFC 5961 defines, the RST SEQ doesn't match the
frozen main ACK at receiver side and thus gets dropped and a challenge
ACK is sent, which gets usually lost due to network conditions. The main
consequence is that the connection stays alive for a while even if it
made sense to accept the RST. This can get really bad if lots of
connections like this one are created in few seconds, allocating all the
resources of the server easily.

For security reasons, not all SACK blocks are checked (there could be a
big amount of SACK blocks => acceptable SEQ numbers). Furthermore, it
wouldn't make sense to check for RST in blocks other than the right-most
received one because the sender is not expected to be sending new data
after the RST. For simplicity, only up to the 4 most recently updated
SACK blocks (selective_acks[4] field) are compared to find the
right-most block, as usually those are the ones with bigger probability
to contain it.

This patch was tested in a 3.18 kernel and probed to improve the
situation in the scenario described above.

Signed-off-by: Pau Espin Pedrol 
Acked-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Tested-by: Neal Cardwell 
Signed-off-by: David S. Miller