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[SCTP] Implement Sec 2.41 of SCTP Implementers guide.
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- Fixed sctp_vtag_verify_either() to comply with impguide 2.41 B) and C).
- Make sure vtag is reflected when T-bit is set in SHUTDOWN-COMPLETE sent
  due to an OOTB SHUTDOWN-ACK and in ABORT sent due to an OOTB packet.
- Do not set T-Bit in ABORT chunk in response to INIT.
- Fixed some comments to reflect the new meaning of the T-Bit.

Signed-off-by: Jerome Forissier <jerome.forissier@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jerome Forissier authored and David S. Miller committed Apr 28, 2005
1 parent 1733721 commit 047a242
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Showing 3 changed files with 86 additions and 52 deletions.
42 changes: 24 additions & 18 deletions include/net/sctp/sm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -407,32 +407,38 @@ sctp_vtag_verify(const struct sctp_chunk *chunk,
return 0;
}

/* Check VTAG of the packet matches the sender's own tag OR its peer's
* tag and the T bit is set in the Chunk Flags.
/* Check VTAG of the packet matches the sender's own tag and the T bit is
* not set, OR its peer's tag and the T bit is set in the Chunk Flags.
*/
static inline int
sctp_vtag_verify_either(const struct sctp_chunk *chunk,
const struct sctp_association *asoc)
{
/* RFC 2960 Section 8.5.1, sctpimpguide-06 Section 2.13.2
/* RFC 2960 Section 8.5.1, sctpimpguide Section 2.41
*
* B) The receiver of a ABORT shall accept the packet if the
* Verification Tag field of the packet matches its own tag OR it
* is set to its peer's tag and the T bit is set in the Chunk
* Flags. Otherwise, the receiver MUST silently discard the packet
* and take no further action.
*
* (C) The receiver of a SHUTDOWN COMPLETE shall accept the
* packet if the Verification Tag field of the packet
* matches its own tag OR it is set to its peer's tag and
* the T bit is set in the Chunk Flags. Otherwise, the
* receiver MUST silently discard the packet and take no
* further action....
* B) The receiver of a ABORT MUST accept the packet
* if the Verification Tag field of the packet matches its own tag
* and the T bit is not set
* OR
* it is set to its peer's tag and the T bit is set in the Chunk
* Flags.
* Otherwise, the receiver MUST silently discard the packet
* and take no further action.
*
* C) The receiver of a SHUTDOWN COMPLETE shall accept the packet
* if the Verification Tag field of the packet matches its own tag
* and the T bit is not set
* OR
* it is set to its peer's tag and the T bit is set in the Chunk
* Flags.
* Otherwise, the receiver MUST silently discard the packet
* and take no further action. An endpoint MUST ignore the
* SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
*/
if ((ntohl(chunk->sctp_hdr->vtag) == asoc->c.my_vtag) ||
(sctp_test_T_bit(chunk) && (ntohl(chunk->sctp_hdr->vtag)
== asoc->c.peer_vtag))) {
if ((!sctp_test_T_bit(chunk) &&
(ntohl(chunk->sctp_hdr->vtag) == asoc->c.my_vtag)) ||
(sctp_test_T_bit(chunk) &&
(ntohl(chunk->sctp_hdr->vtag) == asoc->c.peer_vtag))) {
return 1;
}

Expand Down
19 changes: 14 additions & 5 deletions net/sctp/sm_make_chunk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -710,7 +710,9 @@ struct sctp_chunk *sctp_make_shutdown_complete(
struct sctp_chunk *retval;
__u8 flags = 0;

/* Maybe set the T-bit if we have no association. */
/* Set the T-bit if we have no association (vtag will be
* reflected)
*/
flags |= asoc ? 0 : SCTP_CHUNK_FLAG_T;

retval = sctp_make_chunk(asoc, SCTP_CID_SHUTDOWN_COMPLETE, flags, 0);
Expand All @@ -732,7 +734,7 @@ struct sctp_chunk *sctp_make_shutdown_complete(
}

/* Create an ABORT. Note that we set the T bit if we have no
* association.
* association, except when responding to an INIT (sctpimpguide 2.41).
*/
struct sctp_chunk *sctp_make_abort(const struct sctp_association *asoc,
const struct sctp_chunk *chunk,
Expand All @@ -741,8 +743,16 @@ struct sctp_chunk *sctp_make_abort(const struct sctp_association *asoc,
struct sctp_chunk *retval;
__u8 flags = 0;

/* Maybe set the T-bit if we have no association. */
flags |= asoc ? 0 : SCTP_CHUNK_FLAG_T;
/* Set the T-bit if we have no association and 'chunk' is not
* an INIT (vtag will be reflected).
*/
if (!asoc) {
if (chunk && chunk->chunk_hdr &&
chunk->chunk_hdr->type == SCTP_CID_INIT)
flags = 0;
else
flags = SCTP_CHUNK_FLAG_T;
}

retval = sctp_make_chunk(asoc, SCTP_CID_ABORT, flags, hint);

Expand Down Expand Up @@ -2744,7 +2754,6 @@ struct sctp_chunk *sctp_make_fwdtsn(const struct sctp_association *asoc,

hint = (nstreams + 1) * sizeof(__u32);

/* Maybe set the T-bit if we have no association. */
retval = sctp_make_chunk(asoc, SCTP_CID_FWD_TSN, 0, hint);

if (!retval)
Expand Down
77 changes: 48 additions & 29 deletions net/sctp/sm_statefuns.c
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Original file line number Diff line number Diff line change
Expand Up @@ -126,15 +126,18 @@ sctp_chunk_length_valid(struct sctp_chunk *chunk,
* should stop the T2-shutdown timer and remove all knowledge of the
* association (and thus the association enters the CLOSED state).
*
* Verification Tag: 8.5.1(C)
* Verification Tag: 8.5.1(C), sctpimpguide 2.41.
* C) Rules for packet carrying SHUTDOWN COMPLETE:
* ...
* - The receiver of a SHUTDOWN COMPLETE shall accept the packet if the
* Verification Tag field of the packet matches its own tag OR it is
* set to its peer's tag and the T bit is set in the Chunk Flags.
* Otherwise, the receiver MUST silently discard the packet and take
* no further action. An endpoint MUST ignore the SHUTDOWN COMPLETE if
* it is not in the SHUTDOWN-ACK-SENT state.
* - The receiver of a SHUTDOWN COMPLETE shall accept the packet
* if the Verification Tag field of the packet matches its own tag and
* the T bit is not set
* OR
* it is set to its peer's tag and the T bit is set in the Chunk
* Flags.
* Otherwise, the receiver MUST silently discard the packet
* and take no further action. An endpoint MUST ignore the
* SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
*
* Inputs
* (endpoint, asoc, chunk)
Expand Down Expand Up @@ -2858,16 +2861,16 @@ sctp_disposition_t sctp_sf_eat_sack_6_2(const struct sctp_endpoint *ep,
/*
* Generate an ABORT in response to a packet.
*
* Section: 8.4 Handle "Out of the blue" Packets
* Section: 8.4 Handle "Out of the blue" Packets, sctpimpguide 2.41
*
* 8) The receiver should respond to the sender of the OOTB packet
* with an ABORT. When sending the ABORT, the receiver of the
* OOTB packet MUST fill in the Verification Tag field of the
* outbound packet with the value found in the Verification Tag
* field of the OOTB packet and set the T-bit in the Chunk Flags
* to indicate that no TCB was found. After sending this ABORT,
* the receiver of the OOTB packet shall discard the OOTB packet
* and take no further action.
* 8) The receiver should respond to the sender of the OOTB packet with
* an ABORT. When sending the ABORT, the receiver of the OOTB packet
* MUST fill in the Verification Tag field of the outbound packet
* with the value found in the Verification Tag field of the OOTB
* packet and set the T-bit in the Chunk Flags to indicate that the
* Verification Tag is reflected. After sending this ABORT, the
* receiver of the OOTB packet shall discard the OOTB packet and take
* no further action.
*
* Verification Tag:
*
Expand Down Expand Up @@ -2895,6 +2898,10 @@ sctp_disposition_t sctp_sf_tabort_8_4_8(const struct sctp_endpoint *ep,
return SCTP_DISPOSITION_NOMEM;
}

/* Reflect vtag if T-Bit is set */
if (sctp_test_T_bit(abort))
packet->vtag = ntohl(chunk->sctp_hdr->vtag);

/* Set the skb to the belonging sock for accounting. */
abort->skb->sk = ep->base.sk;

Expand Down Expand Up @@ -3026,22 +3033,24 @@ sctp_disposition_t sctp_sf_do_9_2_final(const struct sctp_endpoint *ep,
}

/*
* RFC 2960, 8.4 - Handle "Out of the blue" Packets
* RFC 2960, 8.4 - Handle "Out of the blue" Packets, sctpimpguide 2.41.
*
* 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
* respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
* When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
* packet must fill in the Verification Tag field of the outbound
* packet with the Verification Tag received in the SHUTDOWN ACK and
* set the T-bit in the Chunk Flags to indicate that no TCB was
* found. Otherwise,
* set the T-bit in the Chunk Flags to indicate that the Verification
* Tag is reflected.
*
* 8) The receiver should respond to the sender of the OOTB packet with
* an ABORT. When sending the ABORT, the receiver of the OOTB packet
* MUST fill in the Verification Tag field of the outbound packet
* with the value found in the Verification Tag field of the OOTB
* packet and set the T-bit in the Chunk Flags to indicate that no
* TCB was found. After sending this ABORT, the receiver of the OOTB
* packet shall discard the OOTB packet and take no further action.
* packet and set the T-bit in the Chunk Flags to indicate that the
* Verification Tag is reflected. After sending this ABORT, the
* receiver of the OOTB packet shall discard the OOTB packet and take
* no further action.
*/
sctp_disposition_t sctp_sf_ootb(const struct sctp_endpoint *ep,
const struct sctp_association *asoc,
Expand Down Expand Up @@ -3090,13 +3099,15 @@ sctp_disposition_t sctp_sf_ootb(const struct sctp_endpoint *ep,
/*
* Handle an "Out of the blue" SHUTDOWN ACK.
*
* Section: 8.4 5)
* Section: 8.4 5, sctpimpguide 2.41.
*
* 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
* respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
* When sending the SHUTDOWN COMPLETE, the receiver of the OOTB packet
* must fill in the Verification Tag field of the outbound packet with
* the Verification Tag received in the SHUTDOWN ACK and set the
* T-bit in the Chunk Flags to indicate that no TCB was found.
* respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
* When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
* packet must fill in the Verification Tag field of the outbound
* packet with the Verification Tag received in the SHUTDOWN ACK and
* set the T-bit in the Chunk Flags to indicate that the Verification
* Tag is reflected.
*
* Inputs
* (endpoint, asoc, type, arg, commands)
Expand Down Expand Up @@ -3128,6 +3139,10 @@ static sctp_disposition_t sctp_sf_shut_8_4_5(const struct sctp_endpoint *ep,
return SCTP_DISPOSITION_NOMEM;
}

/* Reflect vtag if T-Bit is set */
if (sctp_test_T_bit(shut))
packet->vtag = ntohl(chunk->sctp_hdr->vtag);

/* Set the skb to the belonging sock for accounting. */
shut->skb->sk = ep->base.sk;

Expand Down Expand Up @@ -3591,7 +3606,6 @@ sctp_disposition_t sctp_sf_discard_chunk(const struct sctp_endpoint *ep,
*
* 2) If the OOTB packet contains an ABORT chunk, the receiver MUST
* silently discard the OOTB packet and take no further action.
* Otherwise,
*
* Verification Tag: No verification necessary
*
Expand Down Expand Up @@ -4961,6 +4975,11 @@ static struct sctp_packet *sctp_abort_pkt_new(const struct sctp_endpoint *ep,
sctp_ootb_pkt_free(packet);
return NULL;
}

/* Reflect vtag if T-Bit is set */
if (sctp_test_T_bit(abort))
packet->vtag = ntohl(chunk->sctp_hdr->vtag);

/* Add specified error causes, i.e., payload, to the
* end of the chunk.
*/
Expand Down

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