1. 16 Aug, 2016 3 commits
    • Julian Anastasov's avatar
      ipv4: reject RTNH_F_DEAD and RTNH_F_LINKDOWN from user space · a9c22185
      Julian Anastasov authored
      [ Upstream commit 80610229 ]
      
      Vegard Nossum is reporting for a crash in fib_dump_info
      when nh_dev = NULL and fib_nhs == 1:
      
      Pid: 50, comm: netlink.exe Not tainted 4.7.0-rc5+
      RIP: 0033:[<00000000602b3d18>]
      RSP: 0000000062623890  EFLAGS: 00010202
      RAX: 0000000000000000 RBX: 000000006261b800 RCX: 0000000000000000
      RDX: 0000000000000000 RSI: 0000000000000024 RDI: 000000006245ba00
      RBP: 00000000626238f0 R08: 000000000000029c R09: 0000000000000000
      R10: 0000000062468038 R11: 000000006245ba00 R12: 000000006245ba00
      R13: 00000000625f96c0 R14: 00000000601e16f0 R15: 0000000000000000
      Kernel panic - not syncing: Kernel mode fault at addr 0x2e0, ip 0x602b3d18
      CPU: 0 PID: 50 Comm: netlink.exe Not tainted 4.7.0-rc5+ #581
      Stack:
       626238f0 960226a02 00000400 000000fe
       62623910 600afca7 62623970 62623a48
       62468038 00000018 00000000 00000000
      Call Trace:
       [<602b3e93>] rtmsg_fib+0xd3/0x190
       [<602b6680>] fib_table_insert+0x260/0x500
       [<602b0e5d>] inet_rtm_newroute+0x4d/0x60
       [<60250def>] rtnetlink_rcv_msg+0x8f/0x270
       [<60267079>] netlink_rcv_skb+0xc9/0xe0
       [<60250d4b>] rtnetlink_rcv+0x3b/0x50
       [<60265400>] netlink_unicast+0x1a0/0x2c0
       [<60265e47>] netlink_sendmsg+0x3f7/0x470
       [<6021dc9a>] sock_sendmsg+0x3a/0x90
       [<6021e0d0>] ___sys_sendmsg+0x300/0x360
       [<6021fa64>] __sys_sendmsg+0x54/0xa0
       [<6021fac0>] SyS_sendmsg+0x10/0x20
       [<6001ea68>] handle_syscall+0x88/0x90
       [<600295fd>] userspace+0x3fd/0x500
       [<6001ac55>] fork_handler+0x85/0x90
      
      $ addr2line -e vmlinux -i 0x602b3d18
      include/linux/inetdevice.h:222
      net/ipv4/fib_semantics.c:1264
      
      Problem happens when RTNH_F_LINKDOWN is provided from user space
      when creating routes that do not use the flag, catched with
      netlink fuzzer.
      
      Currently, the kernel allows user space to set both flags
      to nh_flags and fib_flags but this is not intentional, the
      assumption was that they are not set. Fix this by rejecting
      both flags with EINVAL.
      Reported-by: default avatarVegard Nossum <vegard.nossum@oracle.com>
      Fixes: 0eeb075f ("net: ipv4 sysctl option to ignore routes when nexthop link is down")
      Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
      Cc: Andy Gospodarek <gospo@cumulusnetworks.com>
      Cc: Dinesh Dutt <ddutt@cumulusnetworks.com>
      Cc: Scott Feldman <sfeldma@gmail.com>
      Reviewed-by: default avatarAndy Gospodarek <gospo@cumulusnetworks.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a9c22185
    • Jason Baron's avatar
      tcp: enable per-socket rate limiting of all 'challenge acks' · 5413f1a5
      Jason Baron authored
      [ Upstream commit 083ae308 ]
      
      The per-socket rate limit for 'challenge acks' was introduced in the
      context of limiting ack loops:
      
      commit f2b2c582 ("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 <edumazet@google.com>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Neal Cardwell <ncardwell@google.com>
      Cc: Yuchung Cheng <ycheng@google.com>
      Cc: Yue Cao <ycao009@ucr.edu>
      Signed-off-by: default avatarJason Baron <jbaron@akamai.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      5413f1a5
    • Eric Dumazet's avatar
      tcp: make challenge acks less predictable · 72c2d3bc
      Eric Dumazet authored
      [ Upstream commit 75ff39cc ]
      
      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: 282f23c6 ("tcp: implement RFC 5961 3.2")
      Reported-by: default avatarYue Cao <ycao009@ucr.edu>
      Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: Yuchung Cheng <ycheng@google.com>
      Cc: Neal Cardwell <ncardwell@google.com>
      Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
      Acked-by: default avatarYuchung Cheng <ycheng@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      72c2d3bc
  2. 10 Aug, 2016 37 commits