diff options
Diffstat (limited to 'kernel/net/dccp/options.c')
| -rw-r--r-- | kernel/net/dccp/options.c | 609 |
1 files changed, 609 insertions, 0 deletions
diff --git a/kernel/net/dccp/options.c b/kernel/net/dccp/options.c new file mode 100644 index 000000000..9bce31886 --- /dev/null +++ b/kernel/net/dccp/options.c @@ -0,0 +1,609 @@ +/* + * 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_BH(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; +} |