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From Adam Langley: Clean up code for handling keylog files. https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=7329 

svn path=/trunk/; revision=43097
This commit is contained in:
Anders Broman 2012-06-05 05:10:18 +00:00
parent d026ca7ed3
commit 6c85e092cf
1 changed files with 135 additions and 104 deletions
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239
epan/dissectors/packet-ssl-utils.c
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@ -3639,15 +3639,136 @@ from_hex_char(gchar c) {
return 16;
}
/* from_hex converts |hex_len| bytes of hex data from |in| and sets |*out| to
* the result. |out->data| will be allocated using se_alloc. Returns TRUE on
* success. */
static gboolean from_hex(StringInfo* out, const char* in, gsize hex_len) {
gsize i;
if (hex_len & 1)
return FALSE;
out->data_len = (guint)hex_len/2;
out->data = se_alloc(out->data_len);
for (i = 0; i < out->data_len; i++) {
guint8 a = from_hex_char(in[i*2]);
guint8 b = from_hex_char(in[i*2 + 1]);
if (a == 16 || b == 16)
return FALSE;
out->data[i] = a << 4 | b;
}
return TRUE;
}
/* ssl_keylog_parse_session_id parses, from |line|, a string that looks like:
* RSA Session-ID:<hex session id> Master-Key:<hex TLS master secret>.
*
* It returns TRUE iff the session id matches |ssl_session| and the master
* secret is correctly extracted. */
static gboolean
ssl_keylog_parse_session_id(const char* line,
SslDecryptSession* ssl_session)
{
static const unsigned int kRSAMasterSecretLength = 48; /* RFC5246 8.1 */
gsize len = strlen(line);
unsigned int i;
if (ssl_session->session_id.data_len == 0)
return FALSE;
if (len < 14 || memcmp(line, "RSA Session-ID:", 14) != 0)
return FALSE;
line += 14;
len -= 14;
if (len < ssl_session->session_id.data_len*2)
return FALSE;
for (i = 0; i < ssl_session->session_id.data_len; i++) {
if (from_hex_char(line[2*i]) != (ssl_session->session_id.data[i] >> 4) ||
from_hex_char(line[2*i+1]) != (ssl_session->session_id.data[i] & 15)) {
ssl_debug_printf(" line does not match session id\n");
return FALSE;
}
}
line += 2*i;
len -= 2*i;
if (len != 12 + kRSAMasterSecretLength*2 ||
memcmp(line, " Master-Key:", 12) != 0) {
return FALSE;
}
line += 12;
len -= 12;
if (!from_hex(&ssl_session->master_secret, line, len))
return FALSE;
ssl_session->state &= ~(SSL_PRE_MASTER_SECRET|SSL_HAVE_SESSION_KEY);
ssl_session->state |= SSL_MASTER_SECRET;
ssl_debug_printf("found master secret in key log\n");
return TRUE;
}
/* ssl_keylog_parse_session_id parses, from |line|, a string that looks like:
* RSA <hex, 8-bytes of encrypted pre-master secret> <hex pre-master secret>.
*
* It returns TRUE iff the session id matches |ssl_session| and the master
* secret is correctly extracted. */
static gboolean
ssl_keylog_parse_rsa_premaster(const char* line,
SslDecryptSession* ssl_session,
StringInfo* encrypted_pre_master)
{
static const unsigned int kRSAPremasterLength = 48; /* RFC5246 7.4.7.1 */
gsize len = strlen(line);
unsigned int i;
if (encrypted_pre_master == NULL)
return FALSE;
if (encrypted_pre_master->data_len < 8)
return FALSE;
if (len < 4 || memcmp(line, "RSA ", 4) != 0)
return FALSE;
line += 4;
len -= 4;
if (len < 16)
return FALSE;
for (i = 0; i < 8; i++) {
if (from_hex_char(line[2*i]) != (encrypted_pre_master->data[i] >> 4) ||
from_hex_char(line[2*i+1]) != (encrypted_pre_master->data[i] & 15)) {
ssl_debug_printf(" line does not match encrypted pre-master secret");
return FALSE;
}
}
line += 16;
len -= 16;
if (len != 1 + kRSAPremasterLength*2 || line[0] != ' ')
return FALSE;
line++;
len--;
if (!from_hex(&ssl_session->pre_master_secret, line, len))
return FALSE;
ssl_session->state &= ~(SSL_MASTER_SECRET|SSL_HAVE_SESSION_KEY);
ssl_session->state |= SSL_PRE_MASTER_SECRET;
ssl_debug_printf("found pre-master secret in key log\n");
return TRUE;
}
int
ssl_keylog_lookup(SslDecryptSession* ssl_session,
const gchar* ssl_keylog_filename,
StringInfo* encrypted_pre_master) {
static const unsigned int kRSAPremasterLength = 48; /* RFC5246 7.4.7.1 */
FILE* ssl_keylog;
gsize bytes_read;
int ret = -1;
int ret = -1;
ssl_debug_printf("trying to use SSL keylog in %s\n", ssl_keylog_filename);
@ -3663,19 +3784,20 @@ ssl_keylog_lookup(SslDecryptSession* ssl_session,
* Where yyyy is the cleartext pre-master secret (hex-encoded)
* (this is the original format introduced with bug 4349)
*
* - "RSA Sesion-ID:xxxx Master-Key:yyyy"
* - "RSA Session-ID:xxxx Master-Key:yyyy"
* Where xxxx is the SSL session ID (hex-encoded)
* Where yyyy is the cleartext master secret (hex-encoded)
* (added to support openssl s_client Master-Key output)
* This is somewhat is a misnomer because there's nothing RSA specific
* about this.
*/
for (;;) {
char buf[512], *line;
unsigned int i;
unsigned int offset;
gsize bytes_read;
line = fgets(buf, sizeof(buf), ssl_keylog);
if (!line)
break;
break;
bytes_read = strlen(line);
/* fgets includes the \n at the end of the line. */
@ -3686,104 +3808,13 @@ ssl_keylog_lookup(SslDecryptSession* ssl_session,
ssl_debug_printf(" checking keylog line: %s\n", line);
if ( memcmp(line, "RSA ", 4) != 0) {
ssl_debug_printf(" rejecting line due to bad format\n");
continue;
}
offset = 4;
if ( (ssl_session->session_id.data_len > 0) && (memcmp(line+offset,"Session-ID:",11) == 0) ) {
offset += 11;
for (i = 0; i < ssl_session->session_id.data_len; i++) {
if (from_hex_char(line[offset + i*2]) != (ssl_session->session_id.data[i] >> 4) ||
from_hex_char(line[offset + i*2 + 1]) != (ssl_session->session_id.data[i] & 15)) {
line = NULL;
break;
}
}
if (line == NULL) {
ssl_debug_printf(" line does not match SSL-ID\n");
continue;
}
offset += 2*ssl_session->session_id.data_len;
offset++;
} else if( line[offset+16] == ' ' ) {
for (i = 0; i < 8; i++) {
if (from_hex_char(line[offset + i*2]) != (encrypted_pre_master->data[i] >> 4) ||
from_hex_char(line[offset + i*2 + 1]) != (encrypted_pre_master->data[i] & 15)) {
line = NULL;
break;
}
}
if (line == NULL) {
ssl_debug_printf(" line does not match encrypted pre-master secret\n");
continue;
}
offset += 17;
} else {
ssl_debug_printf(" rejecting line due to bad format\n");
continue;
}
/* This record seems to match. */
if (memcmp(line+offset, "Master-Key:", 11) == 0) {
/* Key is a MasterSecret */
offset += 11;
ssl_session->master_secret.data = se_alloc(kRSAPremasterLength);
for (i = 0; i < kRSAPremasterLength; i++) {
guint8 a = from_hex_char(line[offset + i*2]);
guint8 b = from_hex_char(line[offset + i*2 + 1]);
if (a == 16 || b == 16) {
line = NULL;
break;
}
ssl_session->master_secret.data[i] = a << 4 | b;
}
if (line == NULL) {
ssl_debug_printf(" line contains non-hex chars in master secret\n");
continue;
}
ssl_session->master_secret.data_len = kRSAPremasterLength;
ssl_session->state &= ~(SSL_PRE_MASTER_SECRET|SSL_HAVE_SESSION_KEY);
ssl_session->state |= SSL_MASTER_SECRET;
ssl_debug_printf("found master secret in key log\n");
ret = 0;
if (ssl_keylog_parse_session_id(line, ssl_session) ||
ssl_keylog_parse_rsa_premaster(line, ssl_session,
encrypted_pre_master)) {
ret = 1;
break;
} else {
/* Key is a PreMasterSecret */
ssl_session->pre_master_secret.data = se_alloc(kRSAPremasterLength);
for (i = 0; i < kRSAPremasterLength; i++) {
guint8 a = from_hex_char(line[offset + i*2]);
guint8 b = from_hex_char(line[offset + i*2 + 1]);
if (a == 16 || b == 16) {
line = NULL;
break;
}
ssl_session->pre_master_secret.data[i] = a << 4 | b;
}
if (line == NULL) {
ssl_debug_printf(" line contains non-hex chars in pre-master secret\n");
continue;
}
ssl_session->pre_master_secret.data_len = kRSAPremasterLength;
ssl_session->state &= ~(SSL_MASTER_SECRET|SSL_HAVE_SESSION_KEY);
ssl_session->state |= SSL_PRE_MASTER_SECRET;
ssl_debug_printf("found pre-master secret in key log\n");
ret = 0;
break;
ssl_debug_printf(" line does not match\n");
}
}