X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/695ce83d0ad8eeaec1e1dec218279ac2d2168189..HEAD:/print-ntp.c?ds=sidebyside diff --git a/print-ntp.c b/print-ntp.c index f4ea80f6..5f791feb 100644 --- a/print-ntp.c +++ b/print-ntp.c @@ -32,11 +32,10 @@ * RFC 5905 - NTPv4 */ -#ifdef HAVE_CONFIG_H #include -#endif #include "netdissect-stdinc.h" +#include "netdissect-ctype.h" #define ND_LONGJMP_FROM_TCHECK #include "netdissect.h" @@ -50,7 +49,7 @@ * This file is based on Version 2 of the NTP spec (RFC1119). */ -/* rfc2030 +/* RFC 5905 updated by RFC 7822 * 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -67,7 +66,7 @@ * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | - * | Originate Timestamp (64) | + * | Origin Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | @@ -78,12 +77,10 @@ * | Transmit Timestamp (64) | * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - * | Key Identifier (optional) (32) | - * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - * | | - * | | - * | Message Digest (optional) (128) | * | | + * . . + * . Optional Extensions (variable) . + * . . * | | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ @@ -106,9 +103,15 @@ struct ntp_time_data { struct l_fixedpt org_timestamp; struct l_fixedpt rec_timestamp; struct l_fixedpt xmt_timestamp; - nd_uint32_t key_id; - nd_uint8_t message_digest[20]; + /* extension fields and/or MAC follow */ }; + +struct ntp_extension_field { + nd_uint16_t type; + nd_uint16_t length; + /* body follows */ +}; + /* * Leap Second Codes (high order two bits) */ @@ -154,6 +157,7 @@ struct ntp_time_data { static void p_sfix(netdissect_options *ndo, const struct s_fixedpt *); static void p_ntp_delta(netdissect_options *, const struct l_fixedpt *, const struct l_fixedpt *); static void p_poll(netdissect_options *, const int); +static u_int p_ext_fields(netdissect_options *, const u_char *, u_int length); static const struct tok ntp_mode_values[] = { { MODE_UNSPEC, "unspecified" }, @@ -177,7 +181,16 @@ static const struct tok ntp_leapind_values[] = { static const struct tok ntp_stratum_values[] = { { UNSPECIFIED, "unspecified" }, - { PRIM_REF, "primary reference" }, + { PRIM_REF, "primary reference" }, + { 0, NULL } +}; + +static const struct tok ntp_ef_types[] = { + { 0x0104, "Unique Identifier" }, + { 0x0204, "NTS Cookie" }, + { 0x0304, "NTS Cookie Placeholder" }, + { 0x0404, "NTS Authenticator and Encrypted Extension Fields" }, + { 0x2005, "Checksum Complement" }, { 0, NULL } }; @@ -226,9 +239,11 @@ struct ntp_control_data { */ static void ntp_time_print(netdissect_options *ndo, - const struct ntp_time_data *bp, u_int length) + const struct ntp_time_data *bp, u_int length, u_int version) { + const u_char *mac; uint8_t stratum; + u_int efs_len; if (length < NTP_TIMEMSG_MINLEN) goto invalid; @@ -254,8 +269,20 @@ ntp_time_print(netdissect_options *ndo, switch (stratum) { case UNSPECIFIED: - ND_PRINT("(unspec)"); - ND_TCHECK_4(bp->refid); + /* NTPv4 (RFC 5905, section 7.4) formalizes that refid _may_ + * contain a printable, four-character, left justified, zero + * filled ASCII string ("kiss code") for status reporting + * and debugging. Some kiss codes are defined in the RFC as + * initial set for a new IANA registry, but the list may be + * modified or extended in the future, and unregistered kiss + * codes are possible (and are being seen in the field). + */ + if (!ND_ASCII_ISPRINT(GET_U_1(bp->refid))) { + ND_PRINT("(unspec)"); + ND_TCHECK_4(bp->refid); + } else { + nd_printjn(ndo, (const u_char *)&(bp->refid), 4); + } break; case PRIM_REF: @@ -282,7 +309,7 @@ ntp_time_print(netdissect_options *ndo, ND_PRINT("\n\t Reference Timestamp: "); p_ntp_time(ndo, &(bp->ref_timestamp)); - ND_PRINT("\n\t Originator Timestamp: "); + ND_PRINT("\n\t Origin Timestamp: "); p_ntp_time(ndo, &(bp->org_timestamp)); ND_PRINT("\n\t Receive Timestamp: "); @@ -297,26 +324,33 @@ ntp_time_print(netdissect_options *ndo, ND_PRINT("\n\t Originator - Transmit Timestamp: "); p_ntp_delta(ndo, &(bp->org_timestamp), &(bp->xmt_timestamp)); - /* FIXME: this code is not aware of any extension fields */ - if (length == NTP_TIMEMSG_MINLEN + 4) { /* Optional: key-id (crypto-NAK) */ - ND_PRINT("\n\tKey id: %u", GET_BE_U_4(bp->key_id)); - } else if (length == NTP_TIMEMSG_MINLEN + 4 + 16) { /* Optional: key-id + 128-bit digest */ - ND_PRINT("\n\tKey id: %u", GET_BE_U_4(bp->key_id)); + if (version == 4) + efs_len = p_ext_fields(ndo, (const u_char *)bp + NTP_TIMEMSG_MINLEN, length - NTP_TIMEMSG_MINLEN); + else + efs_len = 0; + + mac = (const u_char *)bp + NTP_TIMEMSG_MINLEN + efs_len; + + if (length == NTP_TIMEMSG_MINLEN + efs_len + 4) { /* Optional: key-id (crypto-NAK) */ + ND_PRINT("\n\tKey id: %u", GET_BE_U_4(mac)); + } else if (length == NTP_TIMEMSG_MINLEN + efs_len + 4 + 16) { /* Optional: key-id + 128-bit digest */ + ND_PRINT("\n\tKey id: %u", GET_BE_U_4(mac)); ND_PRINT("\n\tAuthentication: %08x%08x%08x%08x", - GET_BE_U_4(bp->message_digest), - GET_BE_U_4(bp->message_digest + 4), - GET_BE_U_4(bp->message_digest + 8), - GET_BE_U_4(bp->message_digest + 12)); - } else if (length == NTP_TIMEMSG_MINLEN + 4 + 20) { /* Optional: key-id + 160-bit digest */ - ND_PRINT("\n\tKey id: %u", GET_BE_U_4(bp->key_id)); + GET_BE_U_4(mac + 4), + GET_BE_U_4(mac + 8), + GET_BE_U_4(mac + 12), + GET_BE_U_4(mac + 16)); + } else if (length == NTP_TIMEMSG_MINLEN + efs_len + 4 + 20) { /* Optional: key-id + 160-bit digest */ + ND_PRINT("\n\tKey id: %u", GET_BE_U_4(mac)); ND_PRINT("\n\tAuthentication: %08x%08x%08x%08x%08x", - GET_BE_U_4(bp->message_digest), - GET_BE_U_4(bp->message_digest + 4), - GET_BE_U_4(bp->message_digest + 8), - GET_BE_U_4(bp->message_digest + 12), - GET_BE_U_4(bp->message_digest + 16)); - } else if (length > NTP_TIMEMSG_MINLEN) { - ND_PRINT("\n\t(%u more bytes after the header)", length - NTP_TIMEMSG_MINLEN); + GET_BE_U_4(mac + 4), + GET_BE_U_4(mac + 8), + GET_BE_U_4(mac + 12), + GET_BE_U_4(mac + 16), + GET_BE_U_4(mac + 20)); + } else if (length > NTP_TIMEMSG_MINLEN + efs_len) { + ND_PRINT("\n\t(%u more bytes after the header and extension fields)", + length - NTP_TIMEMSG_MINLEN - efs_len); } return; @@ -422,7 +456,7 @@ ntp_print(netdissect_options *ndo, case MODE_CLIENT: case MODE_SERVER: case MODE_BROADCAST: - ntp_time_print(ndo, &bp->td, length); + ntp_time_print(ndo, &bp->td, length, version); break; case MODE_CONTROL: @@ -516,3 +550,67 @@ p_poll(netdissect_options *ndo, ND_PRINT(" (1/%us)", 1U << -poll_interval); } +/* Prints an NTPv4 extension field */ +static void +p_ntp_ef(netdissect_options *ndo, u_int type, u_int length, const u_char *ef_body) +{ + ND_PRINT("\n\t %s", tok2str(ntp_ef_types, "Unknown type", type)); + ND_PRINT(" (0x%04x), length %u", type, length); + + if (ndo->ndo_vflag > 2) + hex_print(ndo, "\n\t ", ef_body, length - 4); + else { + /* + * If we're not going to print it, at least make sure + * it's present in the packet, so if ef_len is too long, + * we stop. + */ + ND_TCHECK_LEN(ef_body, length - 4); + } +} + +/* Prints list of extension fields per RFC 7822 */ +static u_int +p_ext_fields(netdissect_options *ndo, const u_char *cp, u_int length) +{ + const struct ntp_extension_field *ef; + u_int ef_type, ef_len, efs_len; + int first_ef; + + first_ef = 1; + efs_len = 0; + + /* RFC 7822 requires the last EF in the packet to have at least + 28 octets to avoid ambiguity with MACs */ + while (length - efs_len >= 28) { + ef = (const struct ntp_extension_field *)(cp + efs_len); + ef_type = GET_BE_U_2(ef->type); + ef_len = GET_BE_U_2(ef->length); + + if (efs_len + ef_len > length || ef_len < 4 || ef_len % 4 != 0) { + nd_print_invalid(ndo); + break; + } + + if (first_ef) { + ND_PRINT("\n\tExtension fields:"); + first_ef = 0; + } + + p_ntp_ef(ndo, ef_type, ef_len, (const u_char *)(ef + 1)); + + /* + * The entire extension field is guaranteed to be in the + * captured data, as p_ntp_ef() will longjmp out if it + * isn't. + * + * As the total length of the captured data fits in a + * u_int, this means that the total length of all the + * extension fields will fit in a u_int, so this will + * never overflow. + */ + efs_len += ef_len; + } + + return efs_len; +}