/* * net/dccp/options.c * * An implementation of the DCCP protocol * Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net> * Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/dccp.h> #include <linux/module.h> #include <linux/types.h> #include <asm/unaligned.h> #include <linux/kernel.h> #include <linux/skbuff.h> #include "ackvec.h" #include "ccid.h" #include "dccp.h" #include "feat.h" u64 dccp_decode_value_var(const u8 *bf, const u8 len) { u64 value = 0; if (len >= DCCP_OPTVAL_MAXLEN) value += ((u64)*bf++) << 40; if (len > 4) value += ((u64)*bf++) << 32; if (len > 3) value += ((u64)*bf++) << 24; if (len > 2) value += ((u64)*bf++) << 16; if (len > 1) value += ((u64)*bf++) << 8; if (len > 0) value += *bf; return value; } /** * dccp_parse_options - Parse DCCP options present in @skb * @sk: client|server|listening dccp socket (when @dreq != NULL) * @dreq: request socket to use during connection setup, or NULL */ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); const struct dccp_hdr *dh = dccp_hdr(skb); const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type; unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb); unsigned char *opt_ptr = options; const unsigned char *opt_end = (unsigned char *)dh + (dh->dccph_doff * 4); struct dccp_options_received *opt_recv = &dp->dccps_options_received; unsigned char opt, len; unsigned char *uninitialized_var(value); u32 elapsed_time; __be32 opt_val; int rc; int mandatory = 0; memset(opt_recv, 0, sizeof(*opt_recv)); opt = len = 0; while (opt_ptr != opt_end) { opt = *opt_ptr++; len = 0; value = NULL; /* Check if this isn't a single byte option */ if (opt > DCCPO_MAX_RESERVED) { if (opt_ptr == opt_end) goto out_nonsensical_length; len = *opt_ptr++; if (len < 2) goto out_nonsensical_length; /* * Remove the type and len fields, leaving * just the value size */ len -= 2; value = opt_ptr; opt_ptr += len; if (opt_ptr > opt_end) goto out_nonsensical_length; } /* * CCID-specific options are ignored during connection setup, as * negotiation may still be in progress (see RFC 4340, 10.3). * The same applies to Ack Vectors, as these depend on the CCID. */ if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC || opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1)) goto ignore_option; switch (opt) { case DCCPO_PADDING: break; case DCCPO_MANDATORY: if (mandatory) goto out_invalid_option; if (pkt_type != DCCP_PKT_DATA) mandatory = 1; break; case DCCPO_NDP_COUNT: if (len > 6) goto out_invalid_option; opt_recv->dccpor_ndp = dccp_decode_value_var(value, len); dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk), (unsigned long long)opt_recv->dccpor_ndp); break; case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R: if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */ break; if (len == 0) goto out_invalid_option; rc = dccp_feat_parse_options(sk, dreq, mandatory, opt, *value, value + 1, len - 1); if (rc) goto out_featneg_failed; break; case DCCPO_TIMESTAMP: if (len != 4) goto out_invalid_option; /* * RFC 4340 13.1: "The precise time corresponding to * Timestamp Value zero is not specified". We use * zero to indicate absence of a meaningful timestamp. */ opt_val = get_unaligned((__be32 *)value); if (unlikely(opt_val == 0)) { DCCP_WARN("Timestamp with zero value\n"); break; } if (dreq != NULL) { dreq->dreq_timestamp_echo = ntohl(opt_val); dreq->dreq_timestamp_time = dccp_timestamp(); } else { opt_recv->dccpor_timestamp = dp->dccps_timestamp_echo = ntohl(opt_val); dp->dccps_timestamp_time = dccp_timestamp(); } dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n", dccp_role(sk), ntohl(opt_val), (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq); /* schedule an Ack in case this sender is quiescent */ inet_csk_schedule_ack(sk); break; case DCCPO_TIMESTAMP_ECHO: if (len != 4 && len != 6 && len != 8) goto out_invalid_option; opt_val = get_unaligned((__be32 *)value); opt_recv->dccpor_timestamp_echo = ntohl(opt_val); dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, " "ackno=%llu", dccp_role(sk), opt_recv->dccpor_timestamp_echo, len + 2, (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq); value += 4; if (len == 4) { /* no elapsed time included */ dccp_pr_debug_cat("\n"); break; } if (len == 6) { /* 2-byte elapsed time */ __be16 opt_val2 = get_unaligned((__be16 *)value); elapsed_time = ntohs(opt_val2); } else { /* 4-byte elapsed time */ opt_val = get_unaligned((__be32 *)value); elapsed_time = ntohl(opt_val); } dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time); /* Give precedence to the biggest ELAPSED_TIME */ if (elapsed_time > opt_recv->dccpor_elapsed_time) opt_recv->dccpor_elapsed_time = elapsed_time; break; case DCCPO_ELAPSED_TIME: if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */ break; if (len == 2) { __be16 opt_val2 = get_unaligned((__be16 *)value); elapsed_time = ntohs(opt_val2); } else if (len == 4) { opt_val = get_unaligned((__be32 *)value); elapsed_time = ntohl(opt_val); } else { goto out_invalid_option; } if (elapsed_time > opt_recv->dccpor_elapsed_time) opt_recv->dccpor_elapsed_time = elapsed_time; dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n", dccp_role(sk), elapsed_time); break; case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC: if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk, pkt_type, opt, value, len)) goto out_invalid_option; break; case DCCPO_ACK_VECTOR_0: case DCCPO_ACK_VECTOR_1: if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */ break; /* * Ack vectors are processed by the TX CCID if it is * interested. The RX CCID need not parse Ack Vectors, * since it is only interested in clearing old state. * Fall through. */ case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC: if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk, pkt_type, opt, value, len)) goto out_invalid_option; break; default: DCCP_CRIT("DCCP(%p): option %d(len=%d) not " "implemented, ignoring", sk, opt, len); break; } ignore_option: if (opt != DCCPO_MANDATORY) mandatory = 0; } /* mandatory was the last byte in option list -> reset connection */ if (mandatory) goto out_invalid_option; out_nonsensical_length: /* RFC 4340, 5.8: ignore option and all remaining option space */ return 0; out_invalid_option: DCCP_INC_STATS(DCCP_MIB_INVALIDOPT); rc = DCCP_RESET_CODE_OPTION_ERROR; out_featneg_failed: DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc); DCCP_SKB_CB(skb)->dccpd_reset_code = rc; DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt; DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0; DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0; return -1; } EXPORT_SYMBOL_GPL(dccp_parse_options); void dccp_encode_value_var(const u64 value, u8 *to, const u8 len) { if (len >= DCCP_OPTVAL_MAXLEN) *to++ = (value & 0xFF0000000000ull) >> 40; if (len > 4) *to++ = (value & 0xFF00000000ull) >> 32; if (len > 3) *to++ = (value & 0xFF000000) >> 24; if (len > 2) *to++ = (value & 0xFF0000) >> 16; if (len > 1) *to++ = (value & 0xFF00) >> 8; if (len > 0) *to++ = (value & 0xFF); } static inline u8 dccp_ndp_len(const u64 ndp) { if (likely(ndp <= 0xFF)) return 1; return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6); } int dccp_insert_option(struct sk_buff *skb, const unsigned char option, const void *value, const unsigned char len) { unsigned char *to; if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) return -1; DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2; to = skb_push(skb, len + 2); *to++ = option; *to++ = len + 2; memcpy(to, value, len); return 0; } EXPORT_SYMBOL_GPL(dccp_insert_option); static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); u64 ndp = dp->dccps_ndp_count; if (dccp_non_data_packet(skb)) ++dp->dccps_ndp_count; else dp->dccps_ndp_count = 0; if (ndp > 0) { unsigned char *ptr; const int ndp_len = dccp_ndp_len(ndp); const int len = ndp_len + 2; if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) return -1; DCCP_SKB_CB(skb)->dccpd_opt_len += len; ptr = skb_push(skb, len); *ptr++ = DCCPO_NDP_COUNT; *ptr++ = len; dccp_encode_value_var(ndp, ptr, ndp_len); } return 0; } static inline int dccp_elapsed_time_len(const u32 elapsed_time) { return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4; } static int dccp_insert_option_timestamp(struct sk_buff *skb) { __be32 now = htonl(dccp_timestamp()); /* yes this will overflow but that is the point as we want a * 10 usec 32 bit timer which mean it wraps every 11.9 hours */ return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now)); } static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp, struct dccp_request_sock *dreq, struct sk_buff *skb) { __be32 tstamp_echo; unsigned char *to; u32 elapsed_time, elapsed_time_len, len; if (dreq != NULL) { elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time; tstamp_echo = htonl(dreq->dreq_timestamp_echo); dreq->dreq_timestamp_echo = 0; } else { elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time; tstamp_echo = htonl(dp->dccps_timestamp_echo); dp->dccps_timestamp_echo = 0; } elapsed_time_len = dccp_elapsed_time_len(elapsed_time); len = 6 + elapsed_time_len; if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) return -1; DCCP_SKB_CB(skb)->dccpd_opt_len += len; to = skb_push(skb, len); *to++ = DCCPO_TIMESTAMP_ECHO; *to++ = len; memcpy(to, &tstamp_echo, 4); to += 4; if (elapsed_time_len == 2) { const __be16 var16 = htons((u16)elapsed_time); memcpy(to, &var16, 2); } else if (elapsed_time_len == 4) { const __be32 var32 = htonl(elapsed_time); memcpy(to, &var32, 4); } return 0; } static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); const u16 buflen = dccp_ackvec_buflen(av); /* Figure out how many options do we need to represent the ackvec */ const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN); u16 len = buflen + 2 * nr_opts; u8 i, nonce = 0; const unsigned char *tail, *from; unsigned char *to; if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) { DCCP_WARN("Lacking space for %u bytes on %s packet\n", len, dccp_packet_name(dcb->dccpd_type)); return -1; } /* * Since Ack Vectors are variable-length, we can not always predict * their size. To catch exception cases where the space is running out * on the skb, a separate Sync is scheduled to carry the Ack Vector. */ if (len > DCCPAV_MIN_OPTLEN && len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) { DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), " "MPS=%u ==> reduce payload size?\n", len, skb->len, dcb->dccpd_opt_len, dp->dccps_mss_cache); dp->dccps_sync_scheduled = 1; return 0; } dcb->dccpd_opt_len += len; to = skb_push(skb, len); len = buflen; from = av->av_buf + av->av_buf_head; tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN; for (i = 0; i < nr_opts; ++i) { int copylen = len; if (len > DCCP_SINGLE_OPT_MAXLEN) copylen = DCCP_SINGLE_OPT_MAXLEN; /* * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via * its type; ack_nonce is the sum of all individual buf_nonce's. */ nonce ^= av->av_buf_nonce[i]; *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i]; *to++ = copylen + 2; /* Check if buf_head wraps */ if (from + copylen > tail) { const u16 tailsize = tail - from; memcpy(to, from, tailsize); to += tailsize; len -= tailsize; copylen -= tailsize; from = av->av_buf; } memcpy(to, from, copylen); from += copylen; to += copylen; len -= copylen; } /* * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340. */ if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce)) return -ENOBUFS; return 0; } /** * dccp_insert_option_mandatory - Mandatory option (5.8.2) * Note that since we are using skb_push, this function needs to be called * _after_ inserting the option it is supposed to influence (stack order). */ int dccp_insert_option_mandatory(struct sk_buff *skb) { if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN) return -1; DCCP_SKB_CB(skb)->dccpd_opt_len++; *skb_push(skb, 1) = DCCPO_MANDATORY; return 0; } /** * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R * @feat: one out of %dccp_feature_numbers * @val: NN value or SP array (preferred element first) to copy * @len: true length of @val in bytes (excluding first element repetition) * @repeat_first: whether to copy the first element of @val twice * * The last argument is used to construct Confirm options, where the preferred * value and the preference list appear separately (RFC 4340, 6.3.1). Preference * lists are kept such that the preferred entry is always first, so we only need * to copy twice, and avoid the overhead of cloning into a bigger array. */ int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat, u8 *val, u8 len, bool repeat_first) { u8 tot_len, *to; /* take the `Feature' field and possible repetition into account */ if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) { DCCP_WARN("length %u for feature %u too large\n", len, feat); return -1; } if (unlikely(val == NULL || len == 0)) len = repeat_first = false; tot_len = 3 + repeat_first + len; if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) { DCCP_WARN("packet too small for feature %d option!\n", feat); return -1; } DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len; to = skb_push(skb, tot_len); *to++ = type; *to++ = tot_len; *to++ = feat; if (repeat_first) *to++ = *val; if (len) memcpy(to, val, len); return 0; } /* The length of all options needs to be a multiple of 4 (5.8) */ static void dccp_insert_option_padding(struct sk_buff *skb) { int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4; if (padding != 0) { padding = 4 - padding; memset(skb_push(skb, padding), 0, padding); DCCP_SKB_CB(skb)->dccpd_opt_len += padding; } } int dccp_insert_options(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); DCCP_SKB_CB(skb)->dccpd_opt_len = 0; if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb)) return -1; if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) { /* Feature Negotiation */ if (dccp_feat_insert_opts(dp, NULL, skb)) return -1; if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) { /* * Obtain RTT sample from Request/Response exchange. * This is currently used for TFRC initialisation. */ if (dccp_insert_option_timestamp(skb)) return -1; } else if (dccp_ackvec_pending(sk) && dccp_insert_option_ackvec(sk, skb)) { return -1; } } if (dp->dccps_hc_rx_insert_options) { if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb)) return -1; dp->dccps_hc_rx_insert_options = 0; } if (dp->dccps_timestamp_echo != 0 && dccp_insert_option_timestamp_echo(dp, NULL, skb)) return -1; dccp_insert_option_padding(skb); return 0; } int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb) { DCCP_SKB_CB(skb)->dccpd_opt_len = 0; if (dccp_feat_insert_opts(NULL, dreq, skb)) return -1; /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */ if (dccp_insert_option_timestamp(skb)) return -1; if (dreq->dreq_timestamp_echo != 0 && dccp_insert_option_timestamp_echo(NULL, dreq, skb)) return -1; dccp_insert_option_padding(skb); return 0; }