From cf9ddf73b9ba21a5cd6d3fcb0a45cfa9ec452033 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Thu, 4 Sep 2008 07:30:19 +0200 Subject: [PATCH] dccp: Header option insertion routine for feature-negotiation The patch extends existing code: * Confirm options divide into the confirmed value plus an optional preference list for SP values. Previously only the preference list was echoed for SP values, now the confirmed value is added as per RFC 4340, 6.1; * length and sanity checks are added to avoid illegal memory (or NULL) access. Signed-off-by: Gerrit Renker Acked-by: Ian McDonald --- net/dccp/feat.h | 2 + net/dccp/options.c | 91 ++++++++++++++++------------------------------ 2 files changed, 33 insertions(+), 60 deletions(-) diff --git a/net/dccp/feat.h b/net/dccp/feat.h index 602e0a7294ba..8e863839ed91 100644 --- a/net/dccp/feat.h +++ b/net/dccp/feat.h @@ -140,4 +140,6 @@ extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len); extern u64 dccp_decode_value_var(const u8 *bf, const u8 len); extern int dccp_insert_option_mandatory(struct sk_buff *skb); +extern int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat, + u8 *val, u8 len, bool repeat_first); #endif /* _DCCP_FEAT_H */ diff --git a/net/dccp/options.c b/net/dccp/options.c index 676d53065de9..bfa1cb8f3ef1 100644 --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -482,23 +482,46 @@ int dccp_insert_option_mandatory(struct sk_buff *skb) return 0; } -static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat, - u8 *val, u8 len) +/** + * 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 *to; + u8 tot_len, *to; - if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) { - DCCP_WARN("packet too small for feature %d option!\n", feat); + /* 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; } - DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3; + if (unlikely(val == NULL || len == 0)) + len = repeat_first = 0; + tot_len = 3 + repeat_first + len; - to = skb_push(skb, len + 3); + 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++ = len + 3; + *to++ = tot_len; *to++ = feat; + if (repeat_first) + *to++ = *val; if (len) memcpy(to, val, len); @@ -508,51 +531,6 @@ static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat, return 0; } -static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb) -{ - struct dccp_minisock *dmsk = dccp_msk(sk); - struct dccp_opt_pend *opt, *next; - int change = 0; - - /* confirm any options [NN opts] */ - list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) { - dccp_insert_feat_opt(skb, opt->dccpop_type, - opt->dccpop_feat, opt->dccpop_val, - opt->dccpop_len); - /* fear empty confirms */ - if (opt->dccpop_val) - kfree(opt->dccpop_val); - kfree(opt); - } - INIT_LIST_HEAD(&dmsk->dccpms_conf); - - /* see which features we need to send */ - list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) { - /* see if we need to send any confirm */ - if (opt->dccpop_sc) { - dccp_insert_feat_opt(skb, opt->dccpop_type + 1, - opt->dccpop_feat, - opt->dccpop_sc->dccpoc_val, - opt->dccpop_sc->dccpoc_len); - - BUG_ON(!opt->dccpop_sc->dccpoc_val); - kfree(opt->dccpop_sc->dccpoc_val); - kfree(opt->dccpop_sc); - opt->dccpop_sc = NULL; - } - - /* any option not confirmed, re-send it */ - if (!opt->dccpop_conf) { - dccp_insert_feat_opt(skb, opt->dccpop_type, - opt->dccpop_feat, opt->dccpop_val, - opt->dccpop_len); - change++; - } - } - - 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) { @@ -589,13 +567,6 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb) dp->dccps_hc_rx_insert_options = 0; } - /* Feature negotiation */ - /* Data packets can't do feat negotiation */ - if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA && - DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK && - dccp_insert_options_feat(sk, skb)) - return -1; - /* * Obtain RTT sample from Request/Response exchange. * This is currently used in CCID 3 initialisation.