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Commit d2150b7b authored by Gerrit Renker's avatar Gerrit Renker
Browse files

dccp: Processing Confirm options 



Analogous to the previous patch, this adds code to interpret incoming Confirm
feature-negotiation options. Both functions operate on the feature-negotiation
list of either the request_sock (server) or the dccp_sock (client).

Thanks to Wei Yongjun for pointing out that it is overly restrictive to check
the entire list of confirmed SP values.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: default avatarIan McDonald <ian.mcdonald@jandi.co.nz>
parent 5a146b97

net/dccp/feat.c

+99 −1
Original line number Diff line number Diff line
@@ -99,6 +99,13 @@ static int dccp_feat_default_value(u8 feat_num) 
	return idx < 0 ? : dccp_feat_table[idx].default_value;

}



/* Test for "Req'd" feature (RFC 4340, 6.4) */

static inline int dccp_feat_must_be_understood(u8 feat_num)

{

	return	feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||

		feat_num == DCCPF_SEQUENCE_WINDOW;

}



/* copy constructor, fval must not already contain allocated memory */

static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)

{
@@ -1093,7 +1100,6 @@ int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len) 
}



EXPORT_SYMBOL_GPL(dccp_feat_change_recv);

#endif	/* (later) */



int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,

			   u8 *val, u8 len)
@@ -1148,6 +1154,7 @@ int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature, 
}



EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);

#endif	/* (later) */



void dccp_feat_clean(struct dccp_minisock *dmsk)

{
@@ -1343,6 +1350,93 @@ static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 
			    : DCCP_RESET_CODE_OPTION_ERROR;

}



/**

 * dccp_feat_confirm_recv  -  Process received Confirm options

 * @fn: feature-negotiation list to update

 * @is_mandatory: whether @opt was preceded by a Mandatory option

 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R

 * @feat: one of %dccp_feature_numbers

 * @val: NN value or SP value/preference list

 * @len: length of @val in bytes

 * @server: whether this node is server (1) or client (0)

 */

static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,

				 u8 feat, u8 *val, u8 len, const bool server)

{

	u8 *plist, plen, type = dccp_feat_type(feat);

	const bool local = (opt == DCCPO_CONFIRM_R);

	struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);



	if (entry == NULL) {	/* nothing queued: ignore or handle error */

		if (is_mandatory && type == FEAT_UNKNOWN)

			return DCCP_RESET_CODE_MANDATORY_ERROR;



		if (!local && type == FEAT_NN)		/* 6.3.2 */

			goto confirmation_failed;

		return 0;

	}



	if (entry->state != FEAT_CHANGING)		/* 6.6.2 */

		return 0;



	if (len == 0) {

		if (dccp_feat_must_be_understood(feat))	/* 6.6.7 */

			goto confirmation_failed;

		/*

		 * Empty Confirm during connection setup: this means reverting

		 * to the `old' value, which in this case is the default. Since

		 * we handle default values automatically when no other values

		 * have been set, we revert to the old value by removing this

		 * entry from the list.

		 */

		dccp_feat_list_pop(entry);

		return 0;

	}



	if (type == FEAT_NN) {

		if (len > sizeof(entry->val.nn))

			goto confirmation_failed;



		if (entry->val.nn == dccp_decode_value_var(val, len))

			goto confirmation_succeeded;



		DCCP_WARN("Bogus Confirm for non-existing value\n");

		goto confirmation_failed;

	}



	/*

	 * Parsing SP Confirms: the first element of @val is the preferred

	 * SP value which the peer confirms, the remainder depends on @len.

	 * Note that only the confirmed value need to be a valid SP value.

	 */

	if (!dccp_feat_is_valid_sp_val(feat, *val))

		goto confirmation_failed;



	if (len == 1) {		/* peer didn't supply a preference list */

		plist = val;

		plen  = len;

	} else {		/* preferred value + preference list */

		plist = val + 1;

		plen  = len - 1;

	}



	/* Check whether the peer got the reconciliation right (6.6.8) */

	if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {

		DCCP_WARN("Confirm selected the wrong value %u\n", *val);

		return DCCP_RESET_CODE_OPTION_ERROR;

	}

	entry->val.sp.vec[0] = *val;



confirmation_succeeded:

	entry->state = FEAT_STABLE;

	return 0;



confirmation_failed:

	DCCP_WARN("Confirmation failed\n");

	return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR

			    : DCCP_RESET_CODE_OPTION_ERROR;

}



/**

 * dccp_feat_parse_options  -  Process Feature-Negotiation Options

 * @sk: for general use and used by the client during connection setup
@@ -1373,6 +1467,10 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 
		case DCCPO_CHANGE_R:

			return dccp_feat_change_recv(fn, mandatory, opt, feat,

						     val, len, server);

		case DCCPO_CONFIRM_R:

		case DCCPO_CONFIRM_L:

			return dccp_feat_confirm_recv(fn, mandatory, opt, feat,

						      val, len, server);

		}

	}

	return 0;	/* ignore FN options in all other states */

net/dccp/feat.h

+0 −2
Original line number Diff line number Diff line
@@ -117,8 +117,6 @@ extern int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, 
extern int  dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val);

extern int  dccp_feat_parse_options(struct sock *, struct dccp_request_sock *,

				    u8 mand, u8 opt, u8 feat, u8 *val, u8 len);

extern int  dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,

				   u8 *val, u8 len);

extern void dccp_feat_clean(struct dccp_minisock *dmsk);

extern int  dccp_feat_clone(struct sock *oldsk, struct sock *newsk);

extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);

net/dccp/options.c

+2 −14
Original line number Diff line number Diff line
@@ -134,26 +134,14 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 
			dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),

				      (unsigned long long)opt_recv->dccpor_ndp);

			break;

		case DCCPO_CHANGE_L:

		case DCCPO_CHANGE_R:

			if (pkt_type == DCCP_PKT_DATA)

		case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:

			if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */

				break;

			rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,

						    *value, value + 1, len - 1);

			if (rc)

				goto out_featneg_failed;

			break;

		case DCCPO_CONFIRM_L:

			/* fall through */

		case DCCPO_CONFIRM_R:

			if (pkt_type == DCCP_PKT_DATA)

				break;

			if (len < 2)	/* FIXME this disallows empty confirm */

				goto out_invalid_option;

			if (dccp_feat_confirm_recv(sk, opt, *value,

						   value + 1, len - 1))

				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 */