diff options
Diffstat (limited to 'net/sctp/sm_statefuns.c')
| -rw-r--r-- | net/sctp/sm_statefuns.c | 340 |
1 files changed, 282 insertions, 58 deletions
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index a583d67cab63..f01b408508ff 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -138,6 +138,11 @@ static sctp_disposition_t sctp_sf_violation_chunk( void *arg, sctp_cmd_seq_t *commands); +static sctp_ierror_t sctp_sf_authenticate(const struct sctp_endpoint *ep, + const struct sctp_association *asoc, + const sctp_subtype_t type, + struct sctp_chunk *chunk); + /* Small helper function that checks if the chunk length * is of the appropriate length. The 'required_length' argument * is set to be the size of a specific chunk we are testing. @@ -495,8 +500,6 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep, (sctp_init_chunk_t *)chunk->chunk_hdr, chunk, &err_chunk)) { - SCTP_INC_STATS(SCTP_MIB_ABORTEDS); - /* This chunk contains fatal error. It is to be discarded. * Send an ABORT, with causes if there is any. */ @@ -521,6 +524,22 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep, sctp_sf_tabort_8_4_8(ep, asoc, type, arg, commands); error = SCTP_ERROR_INV_PARAM; } + + /* SCTP-AUTH, Section 6.3: + * It should be noted that if the receiver wants to tear + * down an association in an authenticated way only, the + * handling of malformed packets should not result in + * tearing down the association. + * + * This means that if we only want to abort associations + * in an authenticated way (i.e AUTH+ABORT), then we + * can't destory this association just becuase the packet + * was malformed. + */ + if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc)) + return sctp_sf_pdiscard(ep, asoc, type, arg, commands); + + SCTP_INC_STATS(SCTP_MIB_ABORTEDS); return sctp_stop_t1_and_abort(commands, error, ECONNREFUSED, asoc, chunk->transport); } @@ -549,6 +568,11 @@ sctp_disposition_t sctp_sf_do_5_1C_ack(const struct sctp_endpoint *ep, sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_COOKIE_ECHOED)); + /* SCTP-AUTH: genereate the assocition shared keys so that + * we can potentially signe the COOKIE-ECHO. + */ + sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_SHKEY, SCTP_NULL()); + /* 5.1 C) "A" shall then send the State Cookie received in the * INIT ACK chunk in a COOKIE ECHO chunk, ... */ @@ -686,6 +710,44 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(const struct sctp_endpoint *ep, peer_init, GFP_ATOMIC)) goto nomem_init; + /* SCTP-AUTH: Now that we've populate required fields in + * sctp_process_init, set up the assocaition shared keys as + * necessary so that we can potentially authenticate the ACK + */ + error = sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC); + if (error) + goto nomem_init; + + /* SCTP-AUTH: auth_chunk pointer is only set when the cookie-echo + * is supposed to be authenticated and we have to do delayed + * authentication. We've just recreated the association using + * the information in the cookie and now it's much easier to + * do the authentication. + */ + if (chunk->auth_chunk) { + struct sctp_chunk auth; + sctp_ierror_t ret; + + /* set-up our fake chunk so that we can process it */ + auth.skb = chunk->auth_chunk; + auth.asoc = chunk->asoc; + auth.sctp_hdr = chunk->sctp_hdr; + auth.chunk_hdr = (sctp_chunkhdr_t *)skb_push(chunk->auth_chunk, + sizeof(sctp_chunkhdr_t)); + skb_pull(chunk->auth_chunk, sizeof(sctp_chunkhdr_t)); + auth.transport = chunk->transport; + + ret = sctp_sf_authenticate(ep, new_asoc, type, &auth); + + /* We can now safely free the auth_chunk clone */ + kfree_skb(chunk->auth_chunk); + + if (ret != SCTP_IERROR_NO_ERROR) { + sctp_association_free(new_asoc); + return sctp_sf_pdiscard(ep, asoc, type, arg, commands); + } + } + repl = sctp_make_cookie_ack(new_asoc, chunk); if (!repl) goto nomem_init; @@ -1247,6 +1309,26 @@ static void sctp_tietags_populate(struct sctp_association *new_asoc, new_asoc->c.initial_tsn = asoc->c.initial_tsn; } +static void sctp_auth_params_populate(struct sctp_association *new_asoc, + const struct sctp_association *asoc) +{ + /* Only perform this if AUTH extension is enabled */ + if (!sctp_auth_enable) + return; + + /* We need to provide the same parameter information as + * was in the original INIT. This means that we need to copy + * the HMACS, CHUNKS, and RANDOM parameter from the original + * assocaition. + */ + memcpy(new_asoc->c.auth_random, asoc->c.auth_random, + sizeof(asoc->c.auth_random)); + memcpy(new_asoc->c.auth_hmacs, asoc->c.auth_hmacs, + sizeof(asoc->c.auth_hmacs)); + memcpy(new_asoc->c.auth_chunks, asoc->c.auth_chunks, + sizeof(asoc->c.auth_chunks)); +} + /* * Compare vtag/tietag values to determine unexpected COOKIE-ECHO * handling action. @@ -1404,6 +1486,8 @@ static sctp_disposition_t sctp_sf_do_unexpected_init( sctp_tietags_populate(new_asoc, asoc); + sctp_auth_params_populate(new_asoc, asoc); + /* B) "Z" shall respond immediately with an INIT ACK chunk. */ /* If there are errors need to be reported for unknown parameters, @@ -3618,6 +3702,169 @@ gen_shutdown: } /* + * SCTP-AUTH Section 6.3 Receving authenticated chukns + * + * The receiver MUST use the HMAC algorithm indicated in the HMAC + * Identifier field. If this algorithm was not specified by the + * receiver in the HMAC-ALGO parameter in the INIT or INIT-ACK chunk + * during association setup, the AUTH chunk and all chunks after it MUST + * be discarded and an ERROR chunk SHOULD be sent with the error cause + * defined in Section 4.1. + * + * If an endpoint with no shared key receives a Shared Key Identifier + * other than 0, it MUST silently discard all authenticated chunks. If + * the endpoint has at least one endpoint pair shared key for the peer, + * it MUST use the key specified by the Shared Key Identifier if a + * key has been configured for that Shared Key Identifier. If no + * endpoint pair shared key has been configured for that Shared Key + * Identifier, all authenticated chunks MUST be silently discarded. + * + * Verification Tag: 8.5 Verification Tag [Normal verification] + * + * The return value is the disposition of the chunk. + */ +static sctp_ierror_t sctp_sf_authenticate(const struct sctp_endpoint *ep, + const struct sctp_association *asoc, + const sctp_subtype_t type, + struct sctp_chunk *chunk) +{ + struct sctp_authhdr *auth_hdr; + struct sctp_hmac *hmac; + unsigned int sig_len; + __u16 key_id; + __u8 *save_digest; + __u8 *digest; + + /* Pull in the auth header, so we can do some more verification */ + auth_hdr = (struct sctp_authhdr *)chunk->skb->data; + chunk->subh.auth_hdr = auth_hdr; + skb_pull(chunk->skb, sizeof(struct sctp_authhdr)); + + /* Make sure that we suport the HMAC algorithm from the auth + * chunk. + */ + if (!sctp_auth_asoc_verify_hmac_id(asoc, auth_hdr->hmac_id)) + return SCTP_IERROR_AUTH_BAD_HMAC; + + /* Make sure that the provided shared key identifier has been + * configured + */ + key_id = ntohs(auth_hdr->shkey_id); + if (key_id != asoc->active_key_id && !sctp_auth_get_shkey(asoc, key_id)) + return SCTP_IERROR_AUTH_BAD_KEYID; + + + /* Make sure that the length of the signature matches what + * we expect. + */ + sig_len = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_auth_chunk_t); + hmac = sctp_auth_get_hmac(ntohs(auth_hdr->hmac_id)); + if (sig_len != hmac->hmac_len) + return SCTP_IERROR_PROTO_VIOLATION; + + /* Now that we've done validation checks, we can compute and + * verify the hmac. The steps involved are: + * 1. Save the digest from the chunk. + * 2. Zero out the digest in the chunk. + * 3. Compute the new digest + * 4. Compare saved and new digests. + */ + digest = auth_hdr->hmac; + skb_pull(chunk->skb, sig_len); + + save_digest = kmemdup(digest, sig_len, GFP_ATOMIC); + if (!save_digest) + goto nomem; + + memset(digest, 0, sig_len); + + sctp_auth_calculate_hmac(asoc, chunk->skb, + (struct sctp_auth_chunk *)chunk->chunk_hdr, + GFP_ATOMIC); + + /* Discard the packet if the digests do not match */ + if (memcmp(save_digest, digest, sig_len)) { + kfree(save_digest); + return SCTP_IERROR_BAD_SIG; + } + + kfree(save_digest); + chunk->auth = 1; + + return SCTP_IERROR_NO_ERROR; +nomem: + return SCTP_IERROR_NOMEM; +} + +sctp_disposition_t sctp_sf_eat_auth(const struct sctp_endpoint *ep, + const struct sctp_association *asoc, + const sctp_subtype_t type, + void *arg, + sctp_cmd_seq_t *commands) +{ + struct sctp_authhdr *auth_hdr; + struct sctp_chunk *chunk = arg; + struct sctp_chunk *err_chunk; + sctp_ierror_t error; + + if (!sctp_vtag_verify(chunk, asoc)) { + sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, + SCTP_NULL()); + return sctp_sf_pdiscard(ep, asoc, type, arg, commands); + } + + /* Make sure that the AUTH chunk has valid length. */ + if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_auth_chunk))) + return sctp_sf_violation_chunklen(ep, asoc, type, arg, + commands); + + auth_hdr = (struct sctp_authhdr *)chunk->skb->data; + error = sctp_sf_authenticate(ep, asoc, type, chunk); + switch (error) { + case SCTP_IERROR_AUTH_BAD_HMAC: + /* Generate the ERROR chunk and discard the rest + * of the packet + */ + err_chunk = sctp_make_op_error(asoc, chunk, + SCTP_ERROR_UNSUP_HMAC, + &auth_hdr->hmac_id, + sizeof(__u16)); + if (err_chunk) { + sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, + SCTP_CHUNK(err_chunk)); + } + /* Fall Through */ + case SCTP_IERROR_AUTH_BAD_KEYID: + case SCTP_IERROR_BAD_SIG: + return sctp_sf_pdiscard(ep, asoc, type, arg, commands); + break; + case SCTP_IERROR_PROTO_VIOLATION: + return sctp_sf_violation_chunklen(ep, asoc, type, arg, + commands); + break; + case SCTP_IERROR_NOMEM: + return SCTP_DISPOSITION_NOMEM; + default: + break; + } + + if (asoc->active_key_id != ntohs(auth_hdr->shkey_id)) { + struct sctp_ulpevent *ev; + + ev = sctp_ulpevent_make_authkey(asoc, ntohs(auth_hdr->shkey_id), + SCTP_AUTH_NEWKEY, GFP_ATOMIC); + + if (!ev) + return -ENOMEM; + + sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, + SCTP_ULPEVENT(ev)); + } + + return SCTP_DISPOSITION_CONSUME; +} + +/* * Process an unknown chunk. * * Section: 3.2. Also, 2.1 in the implementor's guide. @@ -3822,6 +4069,20 @@ static sctp_disposition_t sctp_sf_abort_violation( if (!abort) goto nomem; + /* SCTP-AUTH, Section 6.3: + * It should be noted that if the receiver wants to tear + * down an association in an authenticated way only, the + * handling of malformed packets should not result in + * tearing down the association. + * + * This means that if we only want to abort associations + * in an authenticated way (i.e AUTH+ABORT), then we + * can't destory this association just becuase the packet + * was malformed. + */ + if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc)) + goto discard; + if (asoc) { sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS); @@ -3859,6 +4120,7 @@ static sctp_disposition_t sctp_sf_abort_violation( SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS); } +discard: sctp_sf_pdiscard(ep, asoc, SCTP_ST_CHUNK(0), arg, commands); SCTP_INC_STATS(SCTP_MIB_ABORTEDS); @@ -5428,10 +5690,8 @@ static int sctp_eat_data(const struct sctp_association *asoc, sctp_verb_t deliver; int tmp; __u32 tsn; - int account_value; struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map; struct sock *sk = asoc->base.sk; - int rcvbuf_over = 0; data_hdr = chunk->subh.data_hdr = (sctp_datahdr_t *)chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_datahdr_t)); @@ -5441,48 +5701,6 @@ static int sctp_eat_data(const struct sctp_association *asoc, /* ASSERT: Now skb->data is really the user data. */ - /* - * If we are established, and we have used up our receive buffer - * memory, think about droping the frame. - * Note that we have an opportunity to improve performance here. - * If we accept one chunk from an skbuff, we have to keep all the - * memory of that skbuff around until the chunk is read into user - * space. Therefore, once we accept 1 chunk we may as well accept all - * remaining chunks in the skbuff. The data_accepted flag helps us do - * that. - */ - if ((asoc->state == SCTP_STATE_ESTABLISHED) && (!chunk->data_accepted)) { - /* - * If the receive buffer policy is 1, then each - * association can allocate up to sk_rcvbuf bytes - * otherwise, all the associations in aggregate - * may allocate up to sk_rcvbuf bytes - */ - if (asoc->ep->rcvbuf_policy) - account_value = atomic_read(&asoc->rmem_alloc); - else - account_value = atomic_read(&sk->sk_rmem_alloc); - if (account_value > sk->sk_rcvbuf) { - /* - * We need to make forward progress, even when we are - * under memory pressure, so we always allow the - * next tsn after the ctsn ack point to be accepted. - * This lets us avoid deadlocks in which we have to - * drop frames that would otherwise let us drain the - * receive queue. - */ - if ((sctp_tsnmap_get_ctsn(map) + 1) != tsn) - return SCTP_IERROR_IGNORE_TSN; - - /* - * We're going to accept the frame but we should renege - * to make space for it. This will send us down that - * path later in this function. - */ - rcvbuf_over = 1; - } - } - /* Process ECN based congestion. * * Since the chunk structure is reused for all chunks within @@ -5542,18 +5760,9 @@ static int sctp_eat_data(const struct sctp_association *asoc, * seems a bit troublesome in that frag_point varies based on * PMTU. In cases, such as loopback, this might be a rather * large spill over. - * NOTE: If we have a full receive buffer here, we only renege if - * our receiver can still make progress without the tsn being - * received. We do this because in the event that the associations - * receive queue is empty we are filling a leading gap, and since - * reneging moves the gap to the end of the tsn stream, we are likely - * to stall again very shortly. Avoiding the renege when we fill a - * leading gap is a good heuristic for avoiding such steady state - * stalls. - */ - if (!asoc->rwnd || asoc->rwnd_over || - (datalen > asoc->rwnd + asoc->frag_point) || - (rcvbuf_over && (!skb_queue_len(&sk->sk_receive_queue)))) { + */ + if ((!chunk->data_accepted) && (!asoc->rwnd || asoc->rwnd_over || + (datalen > asoc->rwnd + asoc->frag_point))) { /* If this is the next TSN, consider reneging to make * room. Note: Playing nice with a confused sender. A @@ -5574,6 +5783,21 @@ static int sctp_eat_data(const struct sctp_association *asoc, } /* + * Also try to renege to limit our memory usage in the event that + * we are under memory pressure + * If we can't renege, don't worry about it, the sk_stream_rmem_schedule + * in sctp_ulpevent_make_rcvmsg will drop the frame if we grow our + * memory usage too much + */ + if (*sk->sk_prot_creator->memory_pressure) { + if (sctp_tsnmap_has_gap(map) && + (sctp_tsnmap_get_ctsn(map) + 1) == tsn) { + SCTP_DEBUG_PRINTK("Under Pressure! Reneging for tsn:%u\n", tsn); + deliver = SCTP_CMD_RENEGE; + } + } + + /* * Section 3.3.10.9 No User Data (9) * * Cause of error |