net/smc: tolerate future SMCD versions

CLC proposal messages of future SMCD versions could be larger than SMCD
V1 CLC proposal messages.
To enable toleration in SMC V1 the receival of CLC proposal messages
is adapted:
* accept larger length values in CLC proposal
* check trailing eye catcher for incoming CLC proposal with V1 length only
* receive the whole CLC proposal even in cases it does not fit into the
  V1 buffer

Fixes: e7b7a64 ("smc: support variable CLC proposal messages")
Signed-off-by: Ursula Braun <[email protected]>
Signed-off-by: Karsten Graul <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Ursula Braun

net/smc/smc_clc.c

@@ -27,6 +27,7 @@
 
 #define SMCR_CLC_ACCEPT_CONFIRM_LEN 68
 #define SMCD_CLC_ACCEPT_CONFIRM_LEN 48
+#define SMC_CLC_RECV_BUF_LEN	100
 
 /* eye catcher "SMCR" EBCDIC for CLC messages */
 static const char SMC_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xd9'};
@@ -36,7 +37,7 @@ static const char SMCD_EYECATCHER[4] = {'\xe2', '\xd4', '\xc3', '\xc4'};
 /* check if received message has a correct header length and contains valid
  * heading and trailing eyecatchers
  */
-static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
+static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm, bool check_trl)
 {
 	struct smc_clc_msg_proposal_prefix *pclc_prfx;
 	struct smc_clc_msg_accept_confirm *clc;
@@ -49,12 +50,9 @@ static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
 		return false;
 	switch (clcm->type) {
 	case SMC_CLC_PROPOSAL:
-		if (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
-		    clcm->path != SMC_TYPE_B)
-			return false;
 		pclc = (struct smc_clc_msg_proposal *)clcm;
 		pclc_prfx = smc_clc_proposal_get_prefix(pclc);
-		if (ntohs(pclc->hdr.length) !=
+		if (ntohs(pclc->hdr.length) <
 			sizeof(*pclc) + ntohs(pclc->iparea_offset) +
 			sizeof(*pclc_prfx) +
 			pclc_prfx->ipv6_prefixes_cnt *
@@ -86,7 +84,8 @@ static bool smc_clc_msg_hdr_valid(struct smc_clc_msg_hdr *clcm)
 	default:
 		return false;
 	}
-	if (memcmp(trl->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
+	if (check_trl &&
+	    memcmp(trl->eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER)) &&
 	    memcmp(trl->eyecatcher, SMCD_EYECATCHER, sizeof(SMCD_EYECATCHER)))
 		return false;
 	return true;
@@ -276,7 +275,8 @@ int smc_clc_wait_msg(struct smc_sock *smc, void *buf, int buflen,
 	struct msghdr msg = {NULL, 0};
 	int reason_code = 0;
 	struct kvec vec = {buf, buflen};
-	int len, datlen;
+	int len, datlen, recvlen;
+	bool check_trl = true;
 	int krflags;
 
 	/* peek the first few bytes to determine length of data to receive
@@ -320,27 +320,46 @@ int smc_clc_wait_msg(struct smc_sock *smc, void *buf, int buflen,
 	}
 	datlen = ntohs(clcm->length);
 	if ((len < sizeof(struct smc_clc_msg_hdr)) ||
-	    (datlen > buflen) ||
-	    (clcm->version != SMC_CLC_V1) ||
-	    (clcm->path != SMC_TYPE_R && clcm->path != SMC_TYPE_D &&
-	     clcm->path != SMC_TYPE_B) ||
+	    (clcm->version < SMC_CLC_V1) ||
 	    ((clcm->type != SMC_CLC_DECLINE) &&
 	     (clcm->type != expected_type))) {
 		smc->sk.sk_err = EPROTO;
 		reason_code = -EPROTO;
 		goto out;
 	}
 
+	if (clcm->type == SMC_CLC_PROPOSAL && clcm->path == SMC_TYPE_N)
+		reason_code = SMC_CLC_DECL_VERSMISMAT; /* just V2 offered */
+
 	/* receive the complete CLC message */
 	memset(&msg, 0, sizeof(struct msghdr));
-	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, datlen);
+	if (datlen > buflen) {
+		check_trl = false;
+		recvlen = buflen;
+	} else {
+		recvlen = datlen;
+	}
+	iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
 	krflags = MSG_WAITALL;
 	len = sock_recvmsg(smc->clcsock, &msg, krflags);
-	if (len < datlen || !smc_clc_msg_hdr_valid(clcm)) {
+	if (len < recvlen || !smc_clc_msg_hdr_valid(clcm, check_trl)) {
 		smc->sk.sk_err = EPROTO;
 		reason_code = -EPROTO;
 		goto out;
 	}
+	datlen -= len;
+	while (datlen) {
+		u8 tmp[SMC_CLC_RECV_BUF_LEN];
+
+		vec.iov_base = &tmp;
+		vec.iov_len = SMC_CLC_RECV_BUF_LEN;
+		/* receive remaining proposal message */
+		recvlen = datlen > SMC_CLC_RECV_BUF_LEN ?
+						SMC_CLC_RECV_BUF_LEN : datlen;
+		iov_iter_kvec(&msg.msg_iter, READ, &vec, 1, recvlen);
+		len = sock_recvmsg(smc->clcsock, &msg, krflags);
+		datlen -= len;
+	}
 	if (clcm->type == SMC_CLC_DECLINE) {
 		struct smc_clc_msg_decline *dclc;
 

net/smc/smc_clc.h

@@ -25,6 +25,7 @@
 #define SMC_CLC_V1		0x1		/* SMC version                */
 #define SMC_TYPE_R		0		/* SMC-R only		      */
 #define SMC_TYPE_D		1		/* SMC-D only		      */
+#define SMC_TYPE_N		2		/* neither SMC-R nor SMC-D    */
 #define SMC_TYPE_B		3		/* SMC-R and SMC-D	      */
 #define CLC_WAIT_TIME		(6 * HZ)	/* max. wait time on clcsock  */
 #define CLC_WAIT_TIME_SHORT	HZ		/* short wait time on clcsock */
@@ -46,6 +47,7 @@
 #define SMC_CLC_DECL_ISMVLANERR	0x03090000  /* err to reg vlan id on ism dev  */
 #define SMC_CLC_DECL_NOACTLINK	0x030a0000  /* no active smc-r link in lgr    */
 #define SMC_CLC_DECL_NOSRVLINK	0x030b0000  /* SMC-R link from srv not found  */
+#define SMC_CLC_DECL_VERSMISMAT	0x030c0000  /* SMC version mismatch	      */
 #define SMC_CLC_DECL_SYNCERR	0x04000000  /* synchronization error          */
 #define SMC_CLC_DECL_PEERDECL	0x05000000  /* peer declined during handshake */
 #define SMC_CLC_DECL_INTERR	0x09990000  /* internal error		      */