kernel/include/net/sctp/sctp.h, branch linux-4.1.y

sctp: fix the check for _sctp_walk_params and _sctp_walk_errors

2017-09-10T20:36:03Z

[ Upstream commit 6b84202c946cd3da3a8daa92c682510e9ed80321 ] Commit b1f5bfc27a19 ("sctp: don't dereference ptr before leaving _sctp_walk_{params, errors}()") tried to fix the issue that it may overstep the chunk end for _sctp_walk_{params, errors} with 'chunk_end > offset(length) + sizeof(length)'. But it introduced a side effect: When processing INIT, it verifies the chunks with 'param.v == chunk_end' after iterating all params by sctp_walk_params(). With the check 'chunk_end > offset(length) + sizeof(length)', it would return when the last param is not yet accessed. Because the last param usually is fwdtsn supported param whose size is 4 and 'chunk_end == offset(length) + sizeof(length)' This is a badly issue even causing sctp couldn't process 4-shakes. Client would always get abort when connecting to server, due to the failure of INIT chunk verification on server. The patch is to use 'chunk_end <= offset(length) + sizeof(length)' instead of 'chunk_end < offset(length) + sizeof(length)' for both _sctp_walk_params and _sctp_walk_errors. Fixes: b1f5bfc27a19 ("sctp: don't dereference ptr before leaving _sctp_walk_{params, errors}()") Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

sctp: don't dereference ptr before leaving _sctp_walk_{params, errors}()

2017-09-10T20:36:03Z

[ Upstream commit b1f5bfc27a19f214006b9b4db7b9126df2dfdf5a ] If the length field of the iterator (|pos.p| or |err|) is past the end of the chunk, we shouldn't access it. This bug has been detected by KMSAN. For the following pair of system calls: socket(PF_INET6, SOCK_STREAM, 0x84 /* IPPROTO_??? */) = 3 sendto(3, "A", 1, MSG_OOB, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 1 the tool has reported a use of uninitialized memory: ================================================================== BUG: KMSAN: use of uninitialized memory in sctp_rcv+0x17b8/0x43b0 CPU: 1 PID: 2940 Comm: probe Not tainted 4.11.0-rc5+ #2926 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x172/0x1c0 lib/dump_stack.c:52 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:927 __msan_warning_32+0x61/0xb0 mm/kmsan/kmsan_instr.c:469 __sctp_rcv_init_lookup net/sctp/input.c:1074 __sctp_rcv_lookup_harder net/sctp/input.c:1233 __sctp_rcv_lookup net/sctp/input.c:1255 sctp_rcv+0x17b8/0x43b0 net/sctp/input.c:170 sctp6_rcv+0x32/0x70 net/sctp/ipv6.c:984 ip6_input_finish+0x82f/0x1ee0 net/ipv6/ip6_input.c:279 NF_HOOK ./include/linux/netfilter.h:257 ip6_input+0x239/0x290 net/ipv6/ip6_input.c:322 dst_input ./include/net/dst.h:492 ip6_rcv_finish net/ipv6/ip6_input.c:69 NF_HOOK ./include/linux/netfilter.h:257 ipv6_rcv+0x1dbd/0x22e0 net/ipv6/ip6_input.c:203 __netif_receive_skb_core+0x2f6f/0x3a20 net/core/dev.c:4208 __netif_receive_skb net/core/dev.c:4246 process_backlog+0x667/0xba0 net/core/dev.c:4866 napi_poll net/core/dev.c:5268 net_rx_action+0xc95/0x1590 net/core/dev.c:5333 __do_softirq+0x485/0x942 kernel/softirq.c:284 do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902 do_softirq kernel/softirq.c:328 __local_bh_enable_ip+0x25b/0x290 kernel/softirq.c:181 local_bh_enable+0x37/0x40 ./include/linux/bottom_half.h:31 rcu_read_unlock_bh ./include/linux/rcupdate.h:931 ip6_finish_output2+0x19b2/0x1cf0 net/ipv6/ip6_output.c:124 ip6_finish_output+0x764/0x970 net/ipv6/ip6_output.c:149 NF_HOOK_COND ./include/linux/netfilter.h:246 ip6_output+0x456/0x520 net/ipv6/ip6_output.c:163 dst_output ./include/net/dst.h:486 NF_HOOK ./include/linux/netfilter.h:257 ip6_xmit+0x1841/0x1c00 net/ipv6/ip6_output.c:261 sctp_v6_xmit+0x3b7/0x470 net/sctp/ipv6.c:225 sctp_packet_transmit+0x38cb/0x3a20 net/sctp/output.c:632 sctp_outq_flush+0xeb3/0x46e0 net/sctp/outqueue.c:885 sctp_outq_uncork+0xb2/0xd0 net/sctp/outqueue.c:750 sctp_side_effects net/sctp/sm_sideeffect.c:1773 sctp_do_sm+0x6962/0x6ec0 net/sctp/sm_sideeffect.c:1147 sctp_primitive_ASSOCIATE+0x12c/0x160 net/sctp/primitive.c:88 sctp_sendmsg+0x43e5/0x4f90 net/sctp/socket.c:1954 inet_sendmsg+0x498/0x670 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:633 sock_sendmsg net/socket.c:643 SYSC_sendto+0x608/0x710 net/socket.c:1696 SyS_sendto+0x8a/0xb0 net/socket.c:1664 do_syscall_64+0xe6/0x130 arch/x86/entry/common.c:285 entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:246 RIP: 0033:0x401133 RSP: 002b:00007fff6d99cd38 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000401133 RDX: 0000000000000001 RSI: 0000000000494088 RDI: 0000000000000003 RBP: 00007fff6d99cd90 R08: 00007fff6d99cd50 R09: 000000000000001c R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000004063d0 R14: 0000000000406460 R15: 0000000000000000 origin: save_stack_trace+0x37/0x40 arch/x86/kernel/stacktrace.c:59 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:302 kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:198 kmsan_poison_shadow+0x6d/0xc0 mm/kmsan/kmsan.c:211 slab_alloc_node mm/slub.c:2743 __kmalloc_node_track_caller+0x200/0x360 mm/slub.c:4351 __kmalloc_reserve net/core/skbuff.c:138 __alloc_skb+0x26b/0x840 net/core/skbuff.c:231 alloc_skb ./include/linux/skbuff.h:933 sctp_packet_transmit+0x31e/0x3a20 net/sctp/output.c:570 sctp_outq_flush+0xeb3/0x46e0 net/sctp/outqueue.c:885 sctp_outq_uncork+0xb2/0xd0 net/sctp/outqueue.c:750 sctp_side_effects net/sctp/sm_sideeffect.c:1773 sctp_do_sm+0x6962/0x6ec0 net/sctp/sm_sideeffect.c:1147 sctp_primitive_ASSOCIATE+0x12c/0x160 net/sctp/primitive.c:88 sctp_sendmsg+0x43e5/0x4f90 net/sctp/socket.c:1954 inet_sendmsg+0x498/0x670 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:633 sock_sendmsg net/socket.c:643 SYSC_sendto+0x608/0x710 net/socket.c:1696 SyS_sendto+0x8a/0xb0 net/socket.c:1664 do_syscall_64+0xe6/0x130 arch/x86/entry/common.c:285 return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:246 ================================================================== Signed-off-by: Alexander Potapenko Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

sctp: Fix mangled IPv4 addresses on a IPv6 listening socket

2015-05-27T18:15:26Z

sctp_v4_map_v6 was subtly writing and reading from members of a union in a way the clobbered data it needed to read before it read it. Zeroing the v6 flowinfo overwrites the v4 sin_addr with 0, meaning that every place that calls sctp_v4_map_v6 gets ::ffff:0.0.0.0 as the result. Reorder things to guarantee correct behaviour no matter what the union layout is. This impacts user space clients that open an IPv6 SCTP socket and receive IPv4 connections. Prior to 299ee user space would see a sockaddr with AF_INET and a correct address, after 299ee the sockaddr is AF_INET6, but the address is wrong. Fixes: 299ee123e198 (sctp: Fixup v4mapped behaviour to comply with Sock API) Signed-off-by: Jason Gunthorpe Acked-by: Daniel Borkmann Acked-by: Neil Horman Signed-off-by: David S. Miller

sctp: avoid to repeatedly declare external variables

2015-03-25T15:40:16Z

Move the declaration for external variables to sctp.h file avoiding to repeatedly declare them with extern keyword. Signed-off-by: Ying Xue Signed-off-by: David S. Miller

net: sctp: fix panic on duplicate ASCONF chunks

2014-10-14T16:46:22Z

When receiving a e.g. semi-good formed connection scan in the form of ... -------------- INIT[ASCONF; ASCONF_ACK] -------------> <----------- INIT-ACK[ASCONF; ASCONF_ACK] ------------ -------------------- COOKIE-ECHO --------------------> <-------------------- COOKIE-ACK --------------------- ---------------- ASCONF_a; ASCONF_b -----------------> ... where ASCONF_a equals ASCONF_b chunk (at least both serials need to be equal), we panic an SCTP server! The problem is that good-formed ASCONF chunks that we reply with ASCONF_ACK chunks are cached per serial. Thus, when we receive a same ASCONF chunk twice (e.g. through a lost ASCONF_ACK), we do not need to process them again on the server side (that was the idea, also proposed in the RFC). Instead, we know it was cached and we just resend the cached chunk instead. So far, so good. Where things get nasty is in SCTP's side effect interpreter, that is, sctp_cmd_interpreter(): While incoming ASCONF_a (chunk = event_arg) is being marked !end_of_packet and !singleton, and we have an association context, we do not flush the outqueue the first time after processing the ASCONF_ACK singleton chunk via SCTP_CMD_REPLY. Instead, we keep it queued up, although we set local_cork to 1. Commit 2e3216cd54b1 changed the precedence, so that as long as we get bundled, incoming chunks we try possible bundling on outgoing queue as well. Before this commit, we would just flush the output queue. Now, while ASCONF_a's ASCONF_ACK sits in the corked outq, we continue to process the same ASCONF_b chunk from the packet. As we have cached the previous ASCONF_ACK, we find it, grab it and do another SCTP_CMD_REPLY command on it. So, effectively, we rip the chunk->list pointers and requeue the same ASCONF_ACK chunk another time. Since we process ASCONF_b, it's correctly marked with end_of_packet and we enforce an uncork, and thus flush, thus crashing the kernel. Fix it by testing if the ASCONF_ACK is currently pending and if that is the case, do not requeue it. When flushing the output queue we may relink the chunk for preparing an outgoing packet, but eventually unlink it when it's copied into the skb right before transmission. Joint work with Vlad Yasevich. Fixes: 2e3216cd54b1 ("sctp: Follow security requirement of responding with 1 packet") Signed-off-by: Daniel Borkmann Signed-off-by: Vlad Yasevich Signed-off-by: David S. Miller

net: sctp: fix ABI mismatch through sctp_assoc_to_state helper

2014-08-30T03:31:08Z

Since SCTP day 1, that is, 19b55a2af145 ("Initial commit") from lksctp tree, the official header carries a copy of enum sctp_sstat_state that looks like (compared to the current in-kernel enumeration): User definition: Kernel definition: enum sctp_sstat_state { typedef enum { SCTP_EMPTY = 0, SCTP_CLOSED = 1, SCTP_STATE_CLOSED = 0, SCTP_COOKIE_WAIT = 2, SCTP_STATE_COOKIE_WAIT = 1, SCTP_COOKIE_ECHOED = 3, SCTP_STATE_COOKIE_ECHOED = 2, SCTP_ESTABLISHED = 4, SCTP_STATE_ESTABLISHED = 3, SCTP_SHUTDOWN_PENDING = 5, SCTP_STATE_SHUTDOWN_PENDING = 4, SCTP_SHUTDOWN_SENT = 6, SCTP_STATE_SHUTDOWN_SENT = 5, SCTP_SHUTDOWN_RECEIVED = 7, SCTP_STATE_SHUTDOWN_RECEIVED = 6, SCTP_SHUTDOWN_ACK_SENT = 8, SCTP_STATE_SHUTDOWN_ACK_SENT = 7, }; } sctp_state_t; This header was later on also placed into the uapi, so that user space programs can compile without having , but the shipped with instead. While RFC6458 under 8.2.1.Association Status (SCTP_STATUS) says that sstat_state can range from SCTP_CLOSED to SCTP_SHUTDOWN_ACK_SENT, we nevertheless have a what it appears to be dummy SCTP_EMPTY state from the very early days. While it seems to do just nothing, commit 0b8f9e25b0aa ("sctp: remove completely unsed EMPTY state") did the right thing and removed this dead code. That however, causes an off-by-one when the user asks the SCTP stack via SCTP_STATUS API and checks for the current socket state thus yielding possibly undefined behaviour in applications as they expect the kernel to tell the right thing. The enumeration had to be changed however as based on the current socket state, we access a function pointer lookup-table through this. Therefore, I think the best way to deal with this is just to add a helper function sctp_assoc_to_state() to encapsulate the off-by-one quirk. Reported-by: Tristan Su Fixes: 0b8f9e25b0aa ("sctp: remove completely unsed EMPTY state") Signed-off-by: Daniel Borkmann Acked-by: Vlad Yasevich Signed-off-by: David S. Miller

sctp: Fixup v4mapped behaviour to comply with Sock API

2014-08-01T04:49:06Z

The SCTP socket extensions API document describes the v4mapping option as follows: 8.1.15. Set/Clear IPv4 Mapped Addresses (SCTP_I_WANT_MAPPED_V4_ADDR) This socket option is a Boolean flag which turns on or off the mapping of IPv4 addresses. If this option is turned on, then IPv4 addresses will be mapped to V6 representation. If this option is turned off, then no mapping will be done of V4 addresses and a user will receive both PF_INET6 and PF_INET type addresses on the socket. See [RFC3542] for more details on mapped V6 addresses. This description isn't really in line with what the code does though. Introduce addr_to_user (renamed addr_v4map), which should be called before any sockaddr is passed back to user space. The new function places the sockaddr into the correct format depending on the SCTP_I_WANT_MAPPED_V4_ADDR option. Audit all places that touched v4mapped and either sanely construct a v4 or v6 address then call addr_to_user, or drop the unnecessary v4mapped check entirely. Audit all places that call addr_to_user and verify they are on a sycall return path. Add a custom getname that formats the address properly. Several bugs are addressed: - SCTP_I_WANT_MAPPED_V4_ADDR=0 often returned garbage for addresses to user space - The addr_len returned from recvmsg was not correct when returning AF_INET on a v6 socket - flowlabel and scope_id were not zerod when promoting a v4 to v6 - Some syscalls like bind and connect behaved differently depending on v4mapped Tested bind, getpeername, getsockname, connect, and recvmsg for proper behaviour in v4mapped = 1 and 0 cases. Signed-off-by: Neil Horman Tested-by: Jason Gunthorpe Signed-off-by: Jason Gunthorpe Signed-off-by: David S. Miller

net: sctp: implement rfc6458, 5.3.6. SCTP_NXTINFO cmsg support

2014-07-16T21:40:03Z

This patch implements section 5.3.6. of RFC6458, that is, support for 'SCTP Next Receive Information Structure' (SCTP_NXTINFO) which is placed into ancillary data cmsghdr structure for each recvmsg() call, if this information is already available when delivering the current message. This option can be enabled/disabled via setsockopt(2) on SOL_SCTP level by setting an int value with 1/0 for SCTP_RECVNXTINFO in user space applications as per RFC6458, section 8.1.30. The sctp_nxtinfo structure is defined as per RFC as below ... struct sctp_nxtinfo { uint16_t nxt_sid; uint16_t nxt_flags; uint32_t nxt_ppid; uint32_t nxt_length; sctp_assoc_t nxt_assoc_id; }; ... and provided under cmsg_level IPPROTO_SCTP, cmsg_type SCTP_NXTINFO, while cmsg_data[] contains struct sctp_nxtinfo. Joint work with Daniel Borkmann. Signed-off-by: Geir Ola Vaagland Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: sctp: improve timer slack calculation for transport HBs

2014-07-03T01:44:07Z

RFC4960, section 8.3 says: On an idle destination address that is allowed to heartbeat, it is recommended that a HEARTBEAT chunk is sent once per RTO of that destination address plus the protocol parameter 'HB.interval', with jittering of +/- 50% of the RTO value, and exponential backoff of the RTO if the previous HEARTBEAT is unanswered. Currently, we calculate jitter via sctp_jitter() function first, and then add its result to the current RTO for the new timeout: TMO = RTO + (RAND() % RTO) - (RTO / 2) `------------------------^-=> sctp_jitter() Instead, we can just simplify all this by directly calculating: TMO = (RTO / 2) + (RAND() % RTO) With the help of prandom_u32_max(), we don't need to open code our own global PRNG, but can instead just make use of the per CPU implementation of prandom with better quality numbers. Also, we can now spare us the conditional for divide by zero check since no div or mod operation needs to be used. Note that prandom_u32_max() won't emit the same result as a mod operation, but we really don't care here as we only want to have a random number scaled into RTO interval. Note, exponential RTO backoff is handeled elsewhere, namely in sctp_do_8_2_transport_strike(). Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: Fix use after free by removing length arg from sk_data_ready callbacks.

2014-04-11T20:15:36Z

Several spots in the kernel perform a sequence like: skb_queue_tail(&sk->s_receive_queue, skb); sk->sk_data_ready(sk, skb->len); But at the moment we place the SKB onto the socket receive queue it can be consumed and freed up. So this skb->len access is potentially to freed up memory. Furthermore, the skb->len can be modified by the consumer so it is possible that the value isn't accurate. And finally, no actual implementation of this callback actually uses the length argument. And since nobody actually cared about it's value, lots of call sites pass arbitrary values in such as '0' and even '1'. So just remove the length argument from the callback, that way there is no confusion whatsoever and all of these use-after-free cases get fixed as a side effect. Based upon a patch by Eric Dumazet and his suggestion to audit this issue tree-wide. Signed-off-by: David S. Miller