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-rw-r--r--net/dccp/options.c609
1 files changed, 609 insertions, 0 deletions
diff --git a/net/dccp/options.c b/net/dccp/options.c
new file mode 100644
index 000000000..d24cad050
--- /dev/null
+++ b/net/dccp/options.c
@@ -0,0 +1,609 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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>
+ */
+#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
+ * @skb: frame to parse
+ */
+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 *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.
+ */
+ fallthrough;
+ 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)
+ * @skb: frame into which to insert option
+ *
+ * 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++;
+ *(u8 *)skb_push(skb, 1) = DCCPO_MANDATORY;
+ return 0;
+}
+
+/**
+ * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
+ * @skb: frame to insert feature negotiation option into
+ * @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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 14:24:13 +0000