commit 802e8004356e6928b0a918f33fc735aa54a01a07
Author: Oswald Buddenhagen <[email protected]>
Date: Sun Sep 26 15:24:22 2010 +0200
add support for ssl server certificate fingerprint checking
based on a patch by Ben Kibbey, sourceforge tracker item 3073733.
src/drv_imap.c | 43 ++++++++++++++++++++++++++++++++++++++++---
src/mbsync.1 | 6 ++++++
2 files changed, 46 insertions(+), 3 deletions(-)
diff --git a/src/drv_imap.c b/src/drv_imap.c
index dbdb1b1..4e23e88 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -59,6 +59,7 @@ typedef struct imap_server_conf {
char *user;
char *pass;
#if HAVE_LIBSSL
+ char *fingerprint;
char *cert_file;
unsigned use_imaps:1;
unsigned require_ssl:1;
@@ -189,8 +190,10 @@ static const char *Flags[] = {
/* this gets called when a certificate is to be verified */
static int
-verify_cert( SSL *ssl )
+verify_cert( imap_store_t *ctx )
{
+ SSL *ssl = ctx->imap->buf.sock.ssl;
+ imap_store_conf_t *conf = (imap_store_conf_t *)ctx->gen.conf;
X509 *cert;
int err;
char buf[256];
@@ -204,8 +207,40 @@ verify_cert( SSL *ssl )
}
err = SSL_get_verify_result( ssl );
- if (err == X509_V_OK)
+ if (err == X509_V_OK) {
+ if (conf->server->fingerprint) {
+ const EVP_MD *digest_tp;
+ unsigned dsz, dp;
+ unsigned char digest[EVP_MAX_MD_SIZE];
+ char text[EVP_MAX_MD_SIZE * 3], *tp;
+
+ if (!(digest_tp = EVP_md5())) {
+ fprintf( stderr, "Error, EVP_md5() failed\n" );
+ return 1;
+ }
+ if (!X509_digest( cert, digest_tp, digest, &dsz )) {
+ fprintf( stderr, "Out of memory\n" );
+ return 1;
+ }
+
+ tp = text;
+ for (dp = 0; dp < dsz; dp++) {
+ if (dp)
+ *tp++ = ':';
+ sprintf(tp, "%02X", digest[dp]);
+ tp += 2;
+ }
+ *tp = 0;
+
+ if (strcasecmp( text, conf->server->fingerprint )) {
+ fprintf( stderr, "Error, certificate
fingerprint mismatch\n" );
+ return 1;
+ } else {
+ info( "Certificate fingerprint ok\n" );
+ }
+ }
return 0;
+ }
fprintf( stderr, "Error, can't verify certificate: %s (%d)\n",
X509_verify_cert_error_string(err), err );
@@ -1103,7 +1138,7 @@ start_tls( imap_store_t *ctx )
}
/* verify the server certificate */
- if (verify_cert( imap->buf.sock.ssl ))
+ if (verify_cert( ctx ))
return 1;
imap->buf.sock.use_ssl = 1;
@@ -1776,6 +1811,8 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep,
int *err )
server->use_tlsv1 = parse_bool( cfg );
else if (!strcasecmp( "RequireCRAM", cfg->cmd ))
server->require_cram = parse_bool( cfg );
+ else if (!strcasecmp( "Fingerprint", cfg->cmd ))
+ server->fingerprint = nfstrdup( cfg->val );
#endif
else if (!strcasecmp( "Tunnel", cfg->cmd ))
server->tunnel = nfstrdup( cfg->val );
diff --git a/src/mbsync.1 b/src/mbsync.1
index 14b5c99..f7902ee 100644
--- a/src/mbsync.1
+++ b/src/mbsync.1
@@ -260,6 +260,12 @@ File containing X.509 CA certificates used to verify
server identities.
This option is \fImandatory\fR if SSL is used. See \fBSSL CERTIFICATES\fR
below.
..
.TP
+\fBFingerprint\fR \fIstring\fR
+A colon separated, hex encoded MD5 fingerprint
+(as printed by \fBopenssl dgst -c\fR \fIfile\fR)
+to check the server certificate against.
+..
+.TP
\fBUseSSLv2\fR \fIyes\fR|\fIno\fR
Use SSLv2 for communication with the IMAP server over SSL?
.br
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