commit 1217193fbbbf6dca7c31eab3d418e20dc8c43fd7
Author: Oswald Buddenhagen <[email protected]>
Date: Sat Jul 12 21:02:25 2014 +0200
rework authentication mechanism configuration
RequireCRAM (another fairly stupid "use if available" option) is now
deprecated. instead, the AuthMech option can be used to give a precise
list of acceptable authentication mechanisms (which is currently "a bit"
short). in particular, this allows *not* using CRAM-MD5 even if it's
available.
NEWS | 2 +
src/drv_imap.c | 99 ++++++++++++++++++++++++++++++++++++------------
src/mbsync.1 | 16 ++++++-
3 files changed, 90 insertions(+), 27 deletions(-)
diff --git a/NEWS b/NEWS
index a4ff5ec..7bcc75b 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,8 @@ The SSL/TLS configuration has been re-designed.
SSL is now explicitly enabled or disabled - "use SSL if available" is gone.
Notice: Tunnels are assumed to be secure and thus default to no SSL.
+More flexible configuration of the used authentication mechanism.
+
[1.1.0]
Support for hierarchical mailboxes in Patterns.
diff --git a/src/drv_imap.c b/src/drv_imap.c
index e5e0621..9a1a0d0 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -48,9 +48,9 @@ typedef struct imap_server_conf {
char *pass;
char *pass_cmd;
int max_in_progress;
+ string_list_t *auth_mechs;
#ifdef HAVE_LIBSSL
char ssl_type;
- char require_cram;
#endif
} imap_server_conf_t;
@@ -100,6 +100,7 @@ typedef struct imap_store {
list_t *ns_personal, *ns_other, *ns_shared; /* NAMESPACE info */
message_t **msgapp; /* FETCH results */
unsigned caps; /* CAPABILITY results */
+ string_list_t *auth_mechs;
parse_list_state_t parse_list_sts;
/* command queue */
int nexttag, num_in_progress;
@@ -173,7 +174,6 @@ struct imap_cmd_refcounted {
enum CAPABILITY {
NOLOGIN = 0,
#ifdef HAVE_LIBSSL
- CRAM,
STARTTLS,
#endif
UIDPLUS,
@@ -185,7 +185,6 @@ enum CAPABILITY {
static const char *cap_list[] = {
"LOGINDISABLED",
#ifdef HAVE_LIBSSL
- "AUTH=CRAM-MD5",
"STARTTLS",
#endif
"UIDPLUS",
@@ -983,11 +982,20 @@ parse_capability( imap_store_t *ctx, char *cmd )
char *arg;
unsigned i;
+ free_string_list( ctx->auth_mechs );
+ ctx->auth_mechs = 0;
ctx->caps = 0x80000000;
- while ((arg = next_arg( &cmd )))
- for (i = 0; i < as(cap_list); i++)
- if (!strcmp( cap_list[i], arg ))
- ctx->caps |= 1 << i;
+ while ((arg = next_arg( &cmd ))) {
+ if (!memcmp( "AUTH=", arg, 5 )) {
+ add_string_list( &ctx->auth_mechs, arg + 5 );
+ } else {
+ for (i = 0; i < as(cap_list); i++)
+ if (!strcmp( cap_list[i], arg ))
+ ctx->caps |= 1 << i;
+ }
+ }
+ if (!CAP(NOLOGIN))
+ add_string_list( &ctx->auth_mechs, "LOGIN" );
}
static int
@@ -1354,6 +1362,7 @@ imap_cancel_store( store_t *gctx )
free_list( ctx->ns_personal );
free_list( ctx->ns_other );
free_list( ctx->ns_shared );
+ free_string_list( ctx->auth_mechs );
free( ctx->delimiter );
imap_deref( ctx );
}
@@ -1644,7 +1653,12 @@ imap_open_store_authenticate2( imap_store_t *ctx )
{
imap_store_conf_t *cfg = (imap_store_conf_t *)ctx->gen.conf;
imap_server_conf_t *srvc = cfg->server;
+ string_list_t *mech, *cmech;
char *arg;
+#ifdef HAVE_LIBSSL
+ int auth_cram = 0;
+#endif
+ int auth_login = 0;
info ("Logging in...\n");
if (!srvc->user) {
@@ -1697,31 +1711,47 @@ imap_open_store_authenticate2( imap_store_t *ctx )
*/
srvc->pass = nfstrdup( arg );
}
+ for (mech = srvc->auth_mechs; mech; mech = mech->next) {
+ int any = !strcmp( mech->string, "*" );
+ for (cmech = ctx->auth_mechs; cmech; cmech = cmech->next) {
+ if (any || !strcasecmp( mech->string, cmech->string )) {
+ if (!strcasecmp( cmech->string, "LOGIN" )) {
+#ifdef HAVE_LIBSSL
+ if (ctx->conn.ssl || !any)
+#endif
+ auth_login = 1;
+#ifdef HAVE_LIBSSL
+ } else if (!strcasecmp( cmech->string,
"CRAM-MD5" )) {
+ auth_cram = 1;
+#endif
+ } else {
+ error( "IMAP error: authentication
mechanism %s is not supported\n", cmech->string );
+ goto bail;
+ }
+ }
+ }
+ }
#ifdef HAVE_LIBSSL
- if (CAP(CRAM)) {
+ if (auth_cram) {
struct imap_cmd *cmd = new_imap_cmd( sizeof(*cmd) );
- info( "Authenticating with CRAM-MD5\n" );
+ info( "Authenticating with CRAM-MD5...\n" );
cmd->param.cont = do_cram_auth;
imap_exec( ctx, cmd, imap_open_store_authenticate2_p2,
"AUTHENTICATE CRAM-MD5" );
return;
}
- if (srvc->require_cram) {
- error( "IMAP error: CRAM-MD5 authentication is not supported by
server\n" );
- goto bail;
- }
#endif
- if (CAP(NOLOGIN)) {
- error( "Skipping account %s, server forbids LOGIN\n",
srvc->name );
- goto bail;
- }
+ if (auth_login) {
+ info( "Logging in...\n" );
#ifdef HAVE_LIBSSL
- if (!ctx->conn.ssl)
+ if (!ctx->conn.ssl)
#endif
- warn( "*** IMAP Warning *** Password is being sent in the
clear\n" );
- imap_exec( ctx, 0, imap_open_store_authenticate2_p2,
- "LOGIN \"%\\s\" \"%\\s\"", srvc->user, srvc->pass );
- return;
+ warn( "*** IMAP Warning *** Password is being sent in
the clear\n" );
+ imap_exec( ctx, 0, imap_open_store_authenticate2_p2,
+ "LOGIN \"%\\s\" \"%\\s\"", srvc->user, srvc->pass );
+ return;
+ }
+ error( "IMAP error: server supports no acceptable authentication
mechanism\n" );
bail:
imap_open_store_bail( ctx );
@@ -2240,6 +2270,7 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep )
/* Legacy SSL options */
int require_ssl = -1, use_imaps = -1;
int use_sslv2 = -1, use_sslv3 = -1, use_tlsv1 = -1, use_tlsv11 = -1,
use_tlsv12 = -1;
+ int require_cram = -1;
#endif
if (!strcasecmp( "IMAPAccount", cfg->cmd )) {
@@ -2356,8 +2387,14 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep
)
use_tlsv11 = parse_bool( cfg );
else if (!strcasecmp( "UseTLSv1.2", cfg->cmd ))
use_tlsv12 = parse_bool( cfg );
- else if (!strcasecmp( "RequireCRAM", cfg->cmd ))
- server->require_cram = parse_bool( cfg );
+ else if (!strcasecmp( "AuthMech", cfg->cmd ) ||
+ !strcasecmp( "AuthMechs", cfg->cmd )) {
+ arg = cfg->val;
+ do
+ add_string_list( &server->auth_mechs, arg );
+ while ((arg = get_arg( cfg, ARG_OPTIONAL, 0 )));
+ } else if (!strcasecmp( "RequireCRAM", cfg->cmd ))
+ require_cram = parse_bool( cfg );
#endif
else if (!strcasecmp( "Tunnel", cfg->cmd ))
server->sconf.tunnel = nfstrdup( cfg->val );
@@ -2438,6 +2475,20 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep
)
server->ssl_type = server->sconf.tunnel ?
SSL_None : SSL_STARTTLS;
}
#endif
+#ifdef HAVE_LIBSSL
+ if (require_cram >= 0) {
+ if (server->auth_mechs) {
+ error( "%s '%s': The deprecated RequireCRAM
option is mutually exlusive with AuthMech.\n", type, name );
+ cfg->err = 1;
+ return 1;
+ }
+ warn( "Notice: %s '%s': RequireCRAM is deprecated. Use
AuthMech instead.\n", type, name );
+ if (require_cram)
+ add_string_list(&server->auth_mechs,
"CRAM-MD5");
+ }
+#endif
+ if (!server->auth_mechs)
+ add_string_list( &server->auth_mechs, "*" );
if (!server->sconf.port)
server->sconf.port =
#ifdef HAVE_LIBSSL
diff --git a/src/mbsync.1 b/src/mbsync.1
index 599061e..478fabf 100644
--- a/src/mbsync.1
+++ b/src/mbsync.1
@@ -274,9 +274,16 @@ socket. This allows you to run an IMAP session over an
SSH tunnel, for
example.
..
.TP
-\fBRequireCRAM\fR \fIyes\fR|\fIno\fR
-If set to \fIyes\fR, \fBmbsync\fR will abort the connection if no CRAM-MD5
-authentication is possible. (Default: \fIno\fR)
+\fBAuthMechs\fR \fItype\fR ...
+The list of acceptable authentication mechanisms.
+In addition to the mechanisms listed in the SASL registry (link below),
+the legacy IMAP \fBLOGIN\fR mechanism is known.
+The wildcard \fB*\fR represents all mechanisms that are deemed secure
+enough for the current \fBSSLType\fR setting.
+The actually used mechanism is the most secure choice from the intersection
+of this list, the list supplied by the server, and the mechanisms actually
+supported by \fBmbsync\fR (currently only \fBCRAM-MD5\fR and \fBLOGIN\fR).
+(Default: \fB*\fR)
..
.TP
\fBSSLType\fR {\fINone\fR|\fISTARTTLS\fR|\fIIMAPS\fR}
@@ -594,6 +601,9 @@ Directory containing synchronization state files
mdconvert(1), isync(1), mutt(1), maildir(5)
.P
Up to date information on \fBmbsync\fR can be found at http://isync.sf.net/
+.P
+SASL mechanisms are listed at
+http://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml
..
.SH AUTHORS
Originally written by Michael R. Elkins,
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