| From: Julian Anastasov <ja@ssi.bg> |
| Date: Sat, 19 May 2018 18:22:35 +0300 |
| Subject: ipvs: fix buffer overflow with sync daemon and service |
| |
| commit 52f96757905bbf0edef47f3ee6c7c784e7f8ff8a upstream. |
| |
| 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: syzbot+aac887f77319868646df@syzkaller.appspotmail.com |
| Fixes: e4ff67513096 ("ipvs: add sync_maxlen parameter for the sync daemon") |
| Fixes: 4da62fc70d7c ("[IPVS]: Fix for overflows") |
| Signed-off-by: Julian Anastasov <ja@ssi.bg> |
| Acked-by: Simon Horman <horms+renesas@verge.net.au> |
| Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> |
| [bwh: Backported to 3.16: Interface name is copied in start_sync_thread(), |
| not do_ip_vs_set_ctl()] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| --- a/net/netfilter/ipvs/ip_vs_ctl.c |
| +++ b/net/netfilter/ipvs/ip_vs_ctl.c |
| @@ -2417,12 +2417,19 @@ do_ip_vs_set_ctl(struct sock *sk, int cm |
| } |
| } |
| |
| + 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; |
| } |
| @@ -2845,7 +2852,7 @@ static const struct nla_policy ip_vs_cmd |
| 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 }, |
| }; |
| |
| @@ -2858,7 +2865,7 @@ static const struct nla_policy ip_vs_svc |
| [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, |
| --- a/net/netfilter/ipvs/ip_vs_sync.c |
| +++ b/net/netfilter/ipvs/ip_vs_sync.c |
| @@ -1738,8 +1738,9 @@ int start_sync_thread(struct net *net, i |
| if (ipvs->ms) |
| return -EEXIST; |
| |
| - strlcpy(ipvs->master_mcast_ifn, mcast_ifn, |
| - sizeof(ipvs->master_mcast_ifn)); |
| + if (strscpy(ipvs->master_mcast_ifn, mcast_ifn, |
| + sizeof(ipvs->master_mcast_ifn)) <= 0) |
| + return -EINVAL; |
| ipvs->master_syncid = syncid; |
| name = "ipvs-m:%d:%d"; |
| threadfn = sync_thread_master; |
| @@ -1747,8 +1748,9 @@ int start_sync_thread(struct net *net, i |
| if (ipvs->backup_threads) |
| return -EEXIST; |
| |
| - strlcpy(ipvs->backup_mcast_ifn, mcast_ifn, |
| - sizeof(ipvs->backup_mcast_ifn)); |
| + if (strscpy(ipvs->backup_mcast_ifn, mcast_ifn, |
| + sizeof(ipvs->backup_mcast_ifn)) <= 0) |
| + return -EINVAL; |
| ipvs->backup_syncid = syncid; |
| name = "ipvs-b:%d:%d"; |
| threadfn = sync_thread_backup; |