linux-stable.git/net/sctp/socket.c, branch linux-4.0.y

sctp: fix ASCONF list handling

2015-07-10T16:45:33+00:00

[ Upstream commit 2d45a02d0166caf2627fe91897c6ffc3b19514c4 ]

->auto_asconf_splist is per namespace and mangled by functions like
sctp_setsockopt_auto_asconf() which doesn't guarantee any serialization.

Also, the call to inet_sk_copy_descendant() was backuping
->auto_asconf_list through the copy but was not honoring
->do_auto_asconf, which could lead to list corruption if it was
different between both sockets.

This commit thus fixes the list handling by using ->addr_wq_lock
spinlock to protect the list. A special handling is done upon socket
creation and destruction for that. Error handlig on sctp_init_sock()
will never return an error after having initialized asconf, so
sctp_destroy_sock() can be called without addrq_wq_lock. The lock now
will be take on sctp_close_sock(), before locking the socket, so we
don't do it in inverse order compared to sctp_addr_wq_timeout_handler().

Instead of taking the lock on sctp_sock_migrate() for copying and
restoring the list values, it's preferred to avoid rewritting it by
implementing sctp_copy_descendant().

Issue was found with a test application that kept flipping sysctl
default_auto_asconf on and off, but one could trigger it by issuing
simultaneous setsockopt() calls on multiple sockets or by
creating/destroying sockets fast enough. This is only triggerable
locally.

Fixes: 9f7d653b67ae ("sctp: Add Auto-ASCONF support (core).")
Reported-by: Ji Jianwen 
Suggested-by: Neil Horman 
Suggested-by: Hannes Frederic Sowa 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: sctp: fix race for one-to-many sockets in sendmsg's auto associate

2015-01-18T04:52:20+00:00

I.e. one-to-many sockets in SCTP are not required to explicitly
call into connect(2) or sctp_connectx(2) prior to data exchange.
Instead, they can directly invoke sendmsg(2) and the SCTP stack
will automatically trigger connection establishment through 4WHS
via sctp_primitive_ASSOCIATE(). However, this in its current
implementation is racy: INIT is being sent out immediately (as
it cannot be bundled anyway) and the rest of the DATA chunks are
queued up for later xmit when connection is established, meaning
sendmsg(2) will return successfully. This behaviour can result
in an undesired side-effect that the kernel made the application
think the data has already been transmitted, although none of it
has actually left the machine, worst case even after close(2)'ing
the socket.

Instead, when the association from client side has been shut down
e.g. first gracefully through SCTP_EOF and then close(2), the
client could afterwards still receive the server's INIT_ACK due
to a connection with higher latency. This INIT_ACK is then considered
out of the blue and hence responded with ABORT as there was no
alive assoc found anymore. This can be easily reproduced f.e.
with sctp_test application from lksctp. One way to fix this race
is to wait for the handshake to actually complete.

The fix defers waiting after sctp_primitive_ASSOCIATE() and
sctp_primitive_SEND() succeeded, so that DATA chunks cooked up
from sctp_sendmsg() have already been placed into the output
queue through the side-effect interpreter, and therefore can then
be bundeled together with COOKIE_ECHO control chunks.

strace from example application (shortened):

socket(PF_INET, SOCK_SEQPACKET, IPPROTO_SCTP) = 3
sendmsg(3, {msg_name(28)={sa_family=AF_INET, sin_port=htons(8888), sin_addr=inet_addr("192.168.1.115")},
           msg_iov(1)=[{"hello", 5}], msg_controllen=0, msg_flags=0}, 0) = 5
sendmsg(3, {msg_name(28)={sa_family=AF_INET, sin_port=htons(8888), sin_addr=inet_addr("192.168.1.115")},
           msg_iov(1)=[{"hello", 5}], msg_controllen=0, msg_flags=0}, 0) = 5
sendmsg(3, {msg_name(28)={sa_family=AF_INET, sin_port=htons(8888), sin_addr=inet_addr("192.168.1.115")},
           msg_iov(1)=[{"hello", 5}], msg_controllen=0, msg_flags=0}, 0) = 5
sendmsg(3, {msg_name(28)={sa_family=AF_INET, sin_port=htons(8888), sin_addr=inet_addr("192.168.1.115")},
           msg_iov(1)=[{"hello", 5}], msg_controllen=0, msg_flags=0}, 0) = 5
sendmsg(3, {msg_name(28)={sa_family=AF_INET, sin_port=htons(8888), sin_addr=inet_addr("192.168.1.115")},
           msg_iov(0)=[], msg_controllen=48, {cmsg_len=48, cmsg_level=0x84 /* SOL_??? */, cmsg_type=, ...},
           msg_flags=0}, 0) = 0 // graceful shutdown for SOCK_SEQPACKET via SCTP_EOF
close(3) = 0

tcpdump before patch (fooling the application):

22:33:36.306142 IP 192.168.1.114.41462 > 192.168.1.115.8888: sctp (1) [INIT] [init tag: 3879023686] [rwnd: 106496] [OS: 10] [MIS: 65535] [init TSN: 3139201684]
22:33:36.316619 IP 192.168.1.115.8888 > 192.168.1.114.41462: sctp (1) [INIT ACK] [init tag: 3345394793] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 3380109591]
22:33:36.317600 IP 192.168.1.114.41462 > 192.168.1.115.8888: sctp (1) [ABORT]

tcpdump after patch:

14:28:58.884116 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [INIT] [init tag: 438593213] [rwnd: 106496] [OS: 10] [MIS: 65535] [init TSN: 3092969729]
14:28:58.888414 IP 192.168.1.115.8888 > 192.168.1.114.35846: sctp (1) [INIT ACK] [init tag: 381429855] [rwnd: 106496] [OS: 10] [MIS: 10] [init TSN: 2141904492]
14:28:58.888638 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [COOKIE ECHO] , (2) [DATA] (B)(E) [TSN: 3092969729] [...]
14:28:58.893278 IP 192.168.1.115.8888 > 192.168.1.114.35846: sctp (1) [COOKIE ACK] , (2) [SACK] [cum ack 3092969729] [a_rwnd 106491] [#gap acks 0] [#dup tsns 0]
14:28:58.893591 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [DATA] (B)(E) [TSN: 3092969730] [...]
14:28:59.096963 IP 192.168.1.115.8888 > 192.168.1.114.35846: sctp (1) [SACK] [cum ack 3092969730] [a_rwnd 106496] [#gap acks 0] [#dup tsns 0]
14:28:59.097086 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [DATA] (B)(E) [TSN: 3092969731] [...] , (2) [DATA] (B)(E) [TSN: 3092969732] [...]
14:28:59.103218 IP 192.168.1.115.8888 > 192.168.1.114.35846: sctp (1) [SACK] [cum ack 3092969732] [a_rwnd 106486] [#gap acks 0] [#dup tsns 0]
14:28:59.103330 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [SHUTDOWN]
14:28:59.107793 IP 192.168.1.115.8888 > 192.168.1.114.35846: sctp (1) [SHUTDOWN ACK]
14:28:59.107890 IP 192.168.1.114.35846 > 192.168.1.115.8888: sctp (1) [SHUTDOWN COMPLETE]

Looks like this bug is from the pre-git history museum. ;)

Fixes: 08707d5482df ("lksctp-2_5_31-0_5_1.patch")
Signed-off-by: Daniel Borkmann 
Acked-by: Vlad Yasevich 
Signed-off-by: David S. Miller

net: introduce helper macro for_each_cmsghdr

2014-12-11T03:41:55+00:00

Introduce helper macro for_each_cmsghdr as a wrapper of the enumerating
cmsghdr from msghdr, just cleanup.

Signed-off-by: Gu Zheng 
Signed-off-by: David S. Miller

put iov_iter into msghdr

2014-12-09T21:29:03+00:00

Note that the code _using_ ->msg_iter at that point will be very
unhappy with anything other than unshifted iovec-backed iov_iter.
We still need to convert users to proper primitives.

Signed-off-by: Al Viro

switch sctp_user_addto_chunk() and sctp_datamsg_from_user() to passing iov_iter

2014-11-24T10:16:40+00:00

Signed-off-by: Al Viro

net: sctp: keep owned chunk in destructor_arg instead of skb->cb

2014-11-21T19:46:12+00:00

It's just silly to hold the skb destructor argument around inside
skb->cb[] as we currently do in SCTP.

Nowadays, we're sort of cheating on data accounting in the sense
that due to commit 4c3a5bdae293 ("sctp: Don't charge for data in
sndbuf again when transmitting packet"), we orphan the skb already
in the SCTP output path, i.e. giving back charged data memory, and
use a different destructor only to make sure the sk doesn't vanish
on skb destruction time. Thus, cb[] is still valid here as we
operate within the SCTP layer. (It's generally actually a big
candidate for future rework, imho.)

However, storing the destructor in the cb[] can easily cause issues
should an non sctp_packet_set_owner_w()'ed skb ever escape the SCTP
layer, since cb[] may get overwritten by lower layers and thus can
corrupt the chunk pointer. There are no such issues at present,
but lets keep the chunk in destructor_arg, as this is the actual
purpose for it.

Signed-off-by: Daniel Borkmann 
Acked-by: Vlad Yasevich 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller

net: Add and use skb_copy_datagram_msg() helper.

2014-11-05T21:46:40+00:00

This encapsulates all of the skb_copy_datagram_iovec() callers
with call argument signature "skb, offset, msghdr->msg_iov, length".

When we move to iov_iters in the networking, the iov_iter object will
sit in the msghdr.

Having a helper like this means there will be less places to touch
during that transformation.

Based upon descriptions and patch from Al Viro.

Signed-off-by: David S. Miller

net: sctp: fix ABI mismatch through sctp_assoc_to_state helper

2014-08-30T03:31:08+00:00

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

2014-08-01T04:49:06+00:00

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: deprecate rfc6458, 5.3.2. SCTP_SNDRCV support

2014-07-16T21:40:04+00:00

With support of SCTP_SNDINFO/SCTP_RCVINFO as described in RFC6458,
5.3.4/5.3.5, we can now deprecate SCTP_SNDRCV. The RFC already
declares it as deprecated:

  This structure mixes the send and receive path. SCTP_SNDINFO
  (described in Section 5.3.4) and SCTP_RCVINFO (described in
  Section 5.3.5) split this information. These structures should
  be used, when possible, since SCTP_SNDRCV is deprecated.

So whenever a user tries to subscribe to sctp_data_io_event via
setsockopt(2) which triggers inclusion of SCTP_SNDRCV cmsg_type,
issue a warning in the log.

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller