Skip to content

Commit

Permalink
ipvs: fix buffer overflow with sync daemon and service
Browse files Browse the repository at this point in the history
syzkaller reports for buffer overflow for interface name
when starting sync daemons [1]

What we do is that we copy user structure into larger stack
buffer but later we search NUL past the stack buffer.
The same happens for sched_name when adding/editing virtual server.

We are restricted by IP_VS_SCHEDNAME_MAXLEN and IP_VS_IFNAME_MAXLEN
being used as size in include/uapi/linux/ip_vs.h, so they
include the space for NUL.

As using strlcpy is wrong for unsafe source, replace it with
strscpy and add checks to return EINVAL if source string is not
NUL-terminated. The incomplete strlcpy fix comes from 2.6.13.

For the netlink interface reduce the len parameter for
IPVS_DAEMON_ATTR_MCAST_IFN and IPVS_SVC_ATTR_SCHED_NAME,
so that we get proper EINVAL.

[1]
kernel BUG at lib/string.c:1052!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 373 Comm: syz-executor936 Not tainted 4.17.0-rc4+ #45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:fortify_panic+0x13/0x20 lib/string.c:1051
RSP: 0018:ffff8801c976f800 EFLAGS: 00010282
RAX: 0000000000000022 RBX: 0000000000000040 RCX: 0000000000000000
RDX: 0000000000000022 RSI: ffffffff8160f6f1 RDI: ffffed00392edef6
RBP: ffff8801c976f800 R08: ffff8801cf4c62c0 R09: ffffed003b5e4fb0
R10: ffffed003b5e4fb0 R11: ffff8801daf27d87 R12: ffff8801c976fa20
R13: ffff8801c976fae4 R14: ffff8801c976fae0 R15: 000000000000048b
FS:  00007fd99f75e700(0000) GS:ffff8801daf00000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200001c0 CR3: 00000001d6843000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  strlen include/linux/string.h:270 [inline]
  strlcpy include/linux/string.h:293 [inline]
  do_ip_vs_set_ctl+0x31c/0x1d00 net/netfilter/ipvs/ip_vs_ctl.c:2388
  nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
  nf_setsockopt+0x7d/0xd0 net/netfilter/nf_sockopt.c:115
  ip_setsockopt+0xd8/0xf0 net/ipv4/ip_sockglue.c:1253
  udp_setsockopt+0x62/0xa0 net/ipv4/udp.c:2487
  ipv6_setsockopt+0x149/0x170 net/ipv6/ipv6_sockglue.c:917
  tcp_setsockopt+0x93/0xe0 net/ipv4/tcp.c:3057
  sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3046
  __sys_setsockopt+0x1bd/0x390 net/socket.c:1903
  __do_sys_setsockopt net/socket.c:1914 [inline]
  __se_sys_setsockopt net/socket.c:1911 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447369
RSP: 002b:00007fd99f75dda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000006e39e4 RCX: 0000000000447369
RDX: 000000000000048b RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000018 R09: 0000000000000000
R10: 00000000200001c0 R11: 0000000000000246 R12: 00000000006e39e0
R13: 75a1ff93f0896195 R14: 6f745f3168746576 R15: 0000000000000001
Code: 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 48 89 df e8 d2 8f 48 fa eb
de 55 48 89 fe 48 c7 c7 60 65 64 88 48 89 e5 e8 91 dd f3 f9 <0f> 0b 90 90
90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56
RIP: fortify_panic+0x13/0x20 lib/string.c:1051 RSP: ffff8801c976f800

Reported-and-tested-by: [email protected]
Fixes: e4ff675 ("ipvs: add sync_maxlen parameter for the sync daemon")
Fixes: 4da62fc ("[IPVS]: Fix for overflows")
Signed-off-by: Julian Anastasov <[email protected]>
Acked-by: Simon Horman <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
  • Loading branch information
Julian Anastasov authored and ummakynes committed May 23, 2018
1 parent 3e0f64b commit 52f9675
Showing 1 changed file with 15 additions and 6 deletions.
21 changes: 15 additions & 6 deletions net/netfilter/ipvs/ip_vs_ctl.c
Original file line number Diff line number Diff line change
Expand Up @@ -2381,8 +2381,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
struct ipvs_sync_daemon_cfg cfg;

memset(&cfg, 0, sizeof(cfg));
strlcpy(cfg.mcast_ifn, dm->mcast_ifn,
sizeof(cfg.mcast_ifn));
ret = -EINVAL;
if (strscpy(cfg.mcast_ifn, dm->mcast_ifn,
sizeof(cfg.mcast_ifn)) <= 0)
goto out_dec;
cfg.syncid = dm->syncid;
ret = start_sync_thread(ipvs, &cfg, dm->state);
} else {
Expand Down Expand Up @@ -2420,12 +2422,19 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
}
}

if ((cmd == IP_VS_SO_SET_ADD || cmd == IP_VS_SO_SET_EDIT) &&
strnlen(usvc.sched_name, IP_VS_SCHEDNAME_MAXLEN) ==
IP_VS_SCHEDNAME_MAXLEN) {
ret = -EINVAL;
goto out_unlock;
}

/* Check for valid protocol: TCP or UDP or SCTP, even for fwmark!=0 */
if (usvc.protocol != IPPROTO_TCP && usvc.protocol != IPPROTO_UDP &&
usvc.protocol != IPPROTO_SCTP) {
pr_err("set_ctl: invalid protocol: %d %pI4:%d %s\n",
pr_err("set_ctl: invalid protocol: %d %pI4:%d\n",
usvc.protocol, &usvc.addr.ip,
ntohs(usvc.port), usvc.sched_name);
ntohs(usvc.port));
ret = -EFAULT;
goto out_unlock;
}
Expand Down Expand Up @@ -2847,7 +2856,7 @@ static const struct nla_policy ip_vs_cmd_policy[IPVS_CMD_ATTR_MAX + 1] = {
static const struct nla_policy ip_vs_daemon_policy[IPVS_DAEMON_ATTR_MAX + 1] = {
[IPVS_DAEMON_ATTR_STATE] = { .type = NLA_U32 },
[IPVS_DAEMON_ATTR_MCAST_IFN] = { .type = NLA_NUL_STRING,
.len = IP_VS_IFNAME_MAXLEN },
.len = IP_VS_IFNAME_MAXLEN - 1 },
[IPVS_DAEMON_ATTR_SYNC_ID] = { .type = NLA_U32 },
[IPVS_DAEMON_ATTR_SYNC_MAXLEN] = { .type = NLA_U16 },
[IPVS_DAEMON_ATTR_MCAST_GROUP] = { .type = NLA_U32 },
Expand All @@ -2865,7 +2874,7 @@ static const struct nla_policy ip_vs_svc_policy[IPVS_SVC_ATTR_MAX + 1] = {
[IPVS_SVC_ATTR_PORT] = { .type = NLA_U16 },
[IPVS_SVC_ATTR_FWMARK] = { .type = NLA_U32 },
[IPVS_SVC_ATTR_SCHED_NAME] = { .type = NLA_NUL_STRING,
.len = IP_VS_SCHEDNAME_MAXLEN },
.len = IP_VS_SCHEDNAME_MAXLEN - 1 },
[IPVS_SVC_ATTR_PE_NAME] = { .type = NLA_NUL_STRING,
.len = IP_VS_PENAME_MAXLEN },
[IPVS_SVC_ATTR_FLAGS] = { .type = NLA_BINARY,
Expand Down

0 comments on commit 52f9675

Please sign in to comment.