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authorJulian Anastasov <ja@ssi.bg>2016-07-10 21:11:55 +0300
committerDavid S. Miller <davem@davemloft.net>2016-07-11 13:41:09 -0700
commit80610229ef7b26615dbb6cb6e873709a60bacc9f (patch)
treec188416b094b0d14219c39a9b54230140cce5abc /net/ipv4
parent75ff39ccc1bd5d3c455b6822ab09e533c551f758 (diff)
ipv4: reject RTNH_F_DEAD and RTNH_F_LINKDOWN from user space
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: Vegard Nossum <vegard.nossum@oracle.com> Fixes: 0eeb075fad73 ("net: ipv4 sysctl option to ignore routes when nexthop link is down") Signed-off-by: Julian Anastasov <ja@ssi.bg> Cc: Andy Gospodarek <gospo@cumulusnetworks.com> Cc: Dinesh Dutt <ddutt@cumulusnetworks.com> Cc: Scott Feldman <sfeldma@gmail.com> Reviewed-by: Andy Gospodarek <gospo@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/fib_semantics.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d09173bf9500..539fa264e67d 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -479,6 +479,9 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
if (!rtnh_ok(rtnh, remaining))
return -EINVAL;
+ if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
+ return -EINVAL;
+
nexthop_nh->nh_flags =
(cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
@@ -1003,6 +1006,9 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
goto err_inval;
+ if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN))
+ goto err_inval;
+
#ifdef CONFIG_IP_ROUTE_MULTIPATH
if (cfg->fc_mp) {
nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);