X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/63c261606326ad3ca01f57e006312b41e9857d7c..HEAD:/print-macsec.c

diff --git a/print-macsec.c b/print-macsec.c
index 1dc5d051..5fca3922 100644
--- a/print-macsec.c
+++ b/print-macsec.c
@@ -21,22 +21,14 @@
 
 /* \summary: MACsec printer */
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
+#include <config.h>
 
-#include <netdissect-stdinc.h>
-
-#include <string.h>
+#include "netdissect-stdinc.h"
 
 #include "netdissect.h"
 #include "addrtoname.h"
-#include "ether.h"
-#include "ethertype.h"
 #include "extract.h"
 
-static const char tstr[] = "[|MACsec]";
-
 #define MACSEC_DEFAULT_ICV_LEN 16
 
 /* Header format (SecTAG), following an Ethernet header
@@ -78,40 +70,8 @@ struct macsec_sectag {
 #define MACSEC_TCI_CONFID  (MACSEC_TCI_E | MACSEC_TCI_C)
 #define MACSEC_SL_MASK     0x3F /* short length */
 
-#define MACSEC_SECTAG_LEN_NOSCI 6
-#define MACSEC_SECTAG_LEN_SCI 14
-static int
-ieee8021ae_sectag_len(netdissect_options *ndo, const struct macsec_sectag *sectag)
-{
-	return (GET_U_1(sectag->tci_an) & MACSEC_TCI_SC) ?
-	       MACSEC_SECTAG_LEN_SCI :
-	       MACSEC_SECTAG_LEN_NOSCI;
-}
-
-static int macsec_check_length(netdissect_options *ndo, cconst struct macsec_sectag *sectag, u_int length, u_int caplen)
-{
-	u_int len;
-
-	/* we need the full MACsec header in the capture */
-	if (caplen < (MACSEC_SECTAG_LEN_NOSCI + 2))
-		return 0;
-
-	len = ieee8021ae_sectag_len(ndo, sectag);
-	if (caplen < (len + 2))
-		return 0;
-
-	if ((GET_U_1(sectag->short_length) & MACSEC_SL_MASK) != 0) {
-		/* original packet must have exact length */
-		u_int exact = ETHER_HDRLEN + len + 2 + (GET_U_1(sectag->short_length) & MACSEC_SL_MASK);
-		return exact == length;
-	} else {
-		/* original packet must not be short */
-		u_int minlen = ETHER_HDRLEN + len + 2 + 48;
-		return length >= minlen;
-	}
-
-	return 1;
-}
+#define MACSEC_SECTAG_LEN_NOSCI 6  /* length of MACsec header without SCI */
+#define MACSEC_SECTAG_LEN_SCI   14 /* length of MACsec header with SCI */
 
 #define SCI_FMT "%016" PRIx64
 
@@ -124,80 +84,172 @@ static const struct tok macsec_flag_values[] = {
 	{ 0, NULL }
 };
 
+static void
+macsec_print_header(netdissect_options *ndo,
+		    const struct macsec_sectag *sectag,
+		    u_int short_length)
+{
+	ND_PRINT("an %u, pn %u, flags %s",
+		 GET_U_1(sectag->tci_an) & MACSEC_AN_MASK,
+		 GET_BE_U_4(sectag->packet_number),
+		 bittok2str_nosep(macsec_flag_values, "none",
+				  GET_U_1(sectag->tci_an) & MACSEC_TCI_FLAGS));
+
+	if (short_length != 0)
+		ND_PRINT(", sl %u", short_length);
+
+	if (GET_U_1(sectag->tci_an) & MACSEC_TCI_SC)
+		ND_PRINT(", sci " SCI_FMT, GET_BE_U_8(sectag->secure_channel_id));
+
+	ND_PRINT(", ");
+}
+
 /* returns < 0 iff the packet can be decoded completely */
-int macsec_print(netdissect_options *ndo, const u_char **bp,
-		 u_int *lengthp, u_int *caplenp, u_int *hdrlenp,
-		 u_short *length_type)
+int
+macsec_print(netdissect_options *ndo, const u_char **bp,
+	     u_int *lengthp, u_int *caplenp, u_int *hdrlenp,
+	     const struct lladdr_info *src, const struct lladdr_info *dst)
 {
+	const char *save_protocol;
 	const u_char *p = *bp;
 	u_int length = *lengthp;
 	u_int caplen = *caplenp;
 	u_int hdrlen = *hdrlenp;
 	const struct macsec_sectag *sectag = (const struct macsec_sectag *)p;
-	u_int len;
+	u_int sectag_len;
+	u_int short_length;
+
+	save_protocol = ndo->ndo_protocol;
+	ndo->ndo_protocol = "macsec";
 
-	if (!macsec_check_length(sectag, length, caplen)) {
-		ND_PRINT((ndo, tstr));
+	/* we need the full MACsec header in the capture */
+	if (caplen < MACSEC_SECTAG_LEN_NOSCI) {
+		nd_print_trunc(ndo);
+		ndo->ndo_protocol = save_protocol;
 		return hdrlen + caplen;
 	}
-
-	if (sectag->unused || sectag->tci_an & MACSEC_TCI_VERSION) {
-		ND_PRINT((ndo, "%s", istr));
+	if (length < MACSEC_SECTAG_LEN_NOSCI) {
+		nd_print_trunc(ndo);
+		ndo->ndo_protocol = save_protocol;
 		return hdrlen + caplen;
 	}
 
-	if (ndo->ndo_eflag) {
-		char buf[128];
-		int n = snprintf(buf, sizeof(buf), "an %u, pn %u, flags %s",
-				 GET_U_1(sectag->tci_an) & MACSEC_AN_MASK,
-				 GET_BE_U_4(sectag->packet_number),
-				 bittok2str_nosep(macsec_flag_values, "none",
-						  GET_U_1(sectag->tci_an) & MACSEC_TCI_FLAGS));
-		if (n < 0)
+	if (GET_U_1(sectag->tci_an) & MACSEC_TCI_SC) {
+		sectag_len = MACSEC_SECTAG_LEN_SCI;
+		if (caplen < MACSEC_SECTAG_LEN_SCI) {
+			nd_print_trunc(ndo);
+			ndo->ndo_protocol = save_protocol;
 			return hdrlen + caplen;
-
-
-		if (sectag->short_length) {
-			int r = snprintf(buf + n, sizeof(buf) - n, ", sl %u",
-					 GET_U_1(sectag->short_length) & MACSEC_SL_MASK);
-			if (r < 0)
-				return hdrlen + caplen;
-			n += r;
 		}
-
-		if (sectag->tci_an & MACSEC_TCI_SC) {
-			uint64_t sci;
-			int r;
-			sci = GET_BE_U_8(sectag->secure_channel_id);
-			r = snprintf(buf + n, sizeof(buf) - n, ", sci " SCI_FMT, sci);
-			if (r < 0)
-				return hdrlen + caplen;
-			n += r;
+		if (length < MACSEC_SECTAG_LEN_SCI) {
+			nd_print_trunc(ndo);
+			ndo->ndo_protocol = save_protocol;
+			return hdrlen + caplen;
 		}
+	} else
+		sectag_len = MACSEC_SECTAG_LEN_NOSCI;
 
-		ND_PRINT((ndo, "%s, ", buf));
+	if ((GET_U_1(sectag->short_length) & ~MACSEC_SL_MASK) != 0 ||
+	    GET_U_1(sectag->tci_an) & MACSEC_TCI_VERSION) {
+		nd_print_invalid(ndo);
+		ndo->ndo_protocol = save_protocol;
+		return hdrlen + caplen;
 	}
 
-	len = ieee8021ae_sectag_len(ndo, sectag);
-	*length_type = GET_BE_U_2(*bp + len);
-	if (ndo->ndo_eflag && *length_type > ETHERMTU && !(sectag->tci_an & MACSEC_TCI_E))
-		ND_PRINT((ndo, "ethertype %s, ", tok2str(ethertype_values,"0x%04x", *length_type)));
+	short_length = GET_U_1(sectag->short_length) & MACSEC_SL_MASK;
+	if (ndo->ndo_eflag)
+		macsec_print_header(ndo, sectag, short_length);
+
+	/* Skip the MACsec header. */
+	*bp += sectag_len;
+	*hdrlenp += sectag_len;
+
+	/* Remove it from the lengths, as it's been processed. */
+	*lengthp -= sectag_len;
+	*caplenp -= sectag_len;
 
 	if ((GET_U_1(sectag->tci_an) & MACSEC_TCI_CONFID)) {
-		*bp += len;
-		*hdrlenp += len;
+		/*
+		 * The payload is encrypted.  Print link-layer
+		 * information, if it hasn't already been printed.
+		 */
+		if (!ndo->ndo_eflag) {
+			/*
+			 * Nobody printed the link-layer addresses,
+			 * so print them, if we have any.
+			 */
+			if (src != NULL && dst != NULL) {
+				ND_PRINT("%s > %s ",
+					(src->addr_string)(ndo, src->addr),
+					(dst->addr_string)(ndo, dst->addr));
+			}
+
+			ND_PRINT("802.1AE MACsec, ");
+
+			/*
+			 * Print the MACsec header.
+			 */
+			macsec_print_header(ndo, sectag, short_length);
+		}
 
-		*lengthp -= len;
-		*caplenp -= len;
+		/*
+		 * Tell our caller it can't be dissected.
+		 */
+		ndo->ndo_protocol = save_protocol;
 		return 0;
-	} else {
-		len += 2;
-		*bp += len;
-		*hdrlenp += len;
-
-		len += MACSEC_DEFAULT_ICV_LEN;
-		*lengthp -= len;
-		*caplenp -= len;
-		return -1;
 	}
+
+	/*
+	 * The payload isn't encrypted; remove the
+	 * ICV length from the lengths, so our caller
+	 * doesn't treat it as payload.
+	 */
+	if (*lengthp < MACSEC_DEFAULT_ICV_LEN) {
+		nd_print_trunc(ndo);
+		ndo->ndo_protocol = save_protocol;
+		return hdrlen + caplen;
+	}
+	if (*caplenp < MACSEC_DEFAULT_ICV_LEN) {
+		nd_print_trunc(ndo);
+		ndo->ndo_protocol = save_protocol;
+		return hdrlen + caplen;
+	}
+	*lengthp -= MACSEC_DEFAULT_ICV_LEN;
+	*caplenp -= MACSEC_DEFAULT_ICV_LEN;
+	/*
+	 * Update the snapend thus the ICV field is not in the payload for
+	 * the caller.
+	 * The ICV (Integrity Check Value) is at the end of the frame, after
+	 * the secure data.
+	 */
+	ndo->ndo_snapend -= MACSEC_DEFAULT_ICV_LEN;
+
+	/*
+	 * If the SL field is non-zero, then it's the length of the
+	 * Secure Data; otherwise, the Secure Data is what's left
+	 * ver after the MACsec header and ICV are removed.
+	 */
+	if (short_length != 0) {
+		/*
+		 * If the short length is more than we *have*,
+		 * that's an error.
+		 */
+		if (short_length > *lengthp) {
+			nd_print_trunc(ndo);
+			ndo->ndo_protocol = save_protocol;
+			return hdrlen + caplen;
+		}
+		if (short_length > *caplenp) {
+			nd_print_trunc(ndo);
+			ndo->ndo_protocol = save_protocol;
+			return hdrlen + caplen;
+		}
+		if (*lengthp > short_length)
+			*lengthp = short_length;
+		if (*caplenp > short_length)
+			*caplenp = short_length;
+	}
+
+	ndo->ndo_protocol = save_protocol;
+	return -1;
 }