commit 2745813367777f406d917b8a42f309f8c4da9953
Author: Oswald Buddenhagen <o...@users.sf.net>
Date: Sat Jul 12 20:35:55 2014 +0200
re-design SSL/TLS configuration
the combinations of the various options made quite a mess. additionally,
'RequireSSL no' is inherently insecure - "use SSL if available" is plain
stupid.
the old options are still accepted, but will elicit a warning.
NEWS | 4 +
src/config.c | 5 +-
src/config.h | 5 ++
src/drv_imap.c | 151 +++++++++++++++++++++++++++++++++---------------
src/mbsync.1 | 58 ++++++-------------
src/socket.c | 10 ++--
src/socket.h | 12 ++++-
7 files changed, 147 insertions(+), 98 deletions(-)
diff --git a/NEWS b/NEWS
index 63f9d78..a4ff5ec 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@
The 'isync' compatibility wrapper is now deprecated.
+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.
+
[1.1.0]
Support for hierarchical mailboxes in Patterns.
diff --git a/src/config.c b/src/config.c
index cf3b165..2ac3e70 100644
--- a/src/config.c
+++ b/src/config.c
@@ -36,10 +36,7 @@
store_conf_t *stores;
-#define ARG_OPTIONAL 0
-#define ARG_REQUIRED 1
-
-static char *
+char *
get_arg( conffile_t *cfile, int required, int *comment )
{
char *ret, *p, *t;
diff --git a/src/config.h b/src/config.h
index b9b4bfe..e3bc72f 100644
--- a/src/config.h
+++ b/src/config.h
@@ -35,6 +35,11 @@ typedef struct conffile {
char *cmd, *val, *rest;
} conffile_t;
+#define ARG_OPTIONAL 0
+#define ARG_REQUIRED 1
+
+char *get_arg( conffile_t *cfile, int required, int *comment );
+
int parse_bool( conffile_t *cfile );
int parse_int( conffile_t *cfile );
int parse_size( conffile_t *cfile );
diff --git a/src/drv_imap.c b/src/drv_imap.c
index 299aa23..8981bb4 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -36,6 +36,10 @@
#include <time.h>
#include <sys/wait.h>
+#ifdef HAVE_LIBSSL
+enum { SSL_None, SSL_STARTTLS, SSL_IMAPS };
+#endif
+
typedef struct imap_server_conf {
struct imap_server_conf *next;
char *name;
@@ -45,9 +49,7 @@ typedef struct imap_server_conf {
char *pass_cmd;
int max_in_progress;
#ifdef HAVE_LIBSSL
- char use_ssl;
- char use_imaps;
- char require_ssl;
+ char ssl_type;
char require_cram;
#endif
} imap_server_conf_t;
@@ -1532,7 +1534,7 @@ imap_open_store_connected( int ok, void *aux )
if (!ok)
imap_open_store_bail( ctx );
#ifdef HAVE_LIBSSL
- else if (srvc->use_imaps)
+ else if (srvc->ssl_type == SSL_IMAPS)
socket_start_tls( &ctx->conn, imap_open_store_tlsstarted1 );
#endif
}
@@ -1582,26 +1584,21 @@ imap_open_store_authenticate( imap_store_t *ctx )
if (ctx->greeting != GreetingPreauth) {
#ifdef HAVE_LIBSSL
- if (!srvc->use_imaps && srvc->use_ssl) {
- /* always try to select SSL support if available */
+ if (srvc->ssl_type == SSL_STARTTLS) {
if (CAP(STARTTLS)) {
imap_exec( ctx, 0,
imap_open_store_authenticate_p2, "STARTTLS" );
return;
} else {
- if (srvc->require_ssl) {
- error( "IMAP error: SSL support not
available\n" );
- imap_open_store_bail( ctx );
- return;
- } else {
- warn( "IMAP warning: SSL support not
available\n" );
- }
+ error( "IMAP error: SSL support not
available\n" );
+ imap_open_store_bail( ctx );
+ return;
}
}
#endif
imap_open_store_authenticate2( ctx );
} else {
#ifdef HAVE_LIBSSL
- if (!srvc->use_imaps && srvc->require_ssl) {
+ if (srvc->ssl_type == SSL_STARTTLS) {
error( "IMAP error: SSL support not available\n" );
imap_open_store_bail( ctx );
return;
@@ -2237,8 +2234,13 @@ imap_parse_store( conffile_t *cfg, store_conf_t **storep
)
{
imap_store_conf_t *store;
imap_server_conf_t *server, *srv, sserver;
- const char *type, *name;
+ const char *type, *name, *arg;
int acc_opt = 0;
+#ifdef HAVE_LIBSSL
+ /* 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;
+#endif
if (!strcasecmp( "IMAPAccount", cfg->cmd )) {
server = nfcalloc( sizeof(*server) );
@@ -2259,32 +2261,30 @@ imap_parse_store( conffile_t *cfg, store_conf_t
**storep )
return 0;
#ifdef HAVE_LIBSSL
- /* this will probably annoy people, but its the best default just in
- * case people forget to turn it on
- */
- server->require_ssl = 1;
- server->sconf.use_tlsv1 = 1;
+ server->ssl_type = -1;
+ server->sconf.ssl_versions = -1;
#endif
server->max_in_progress = INT_MAX;
while (getcline( cfg ) && cfg->cmd) {
if (!strcasecmp( "Host", cfg->cmd )) {
/* The imap[s]: syntax is just a backwards compat hack.
*/
+ arg = cfg->val;
#ifdef HAVE_LIBSSL
- if (starts_with( cfg->val, -1, "imaps:", 6 )) {
- cfg->val += 6;
- server->use_imaps = 1;
- server->sconf.use_sslv2 = 1;
- server->sconf.use_sslv3 = 1;
+ if (starts_with( arg, -1, "imaps:", 6 )) {
+ arg += 6;
+ server->ssl_type = SSL_IMAPS;
+ if (server->sconf.ssl_versions == -1)
+ server->sconf.ssl_versions = SSLv2 |
SSLv3 | TLSv1;
} else
#endif
- {
- if (starts_with( cfg->val, -1, "imap:", 5 ))
- cfg->val += 5;
- }
- if (starts_with( cfg->val, -1, "//", 2 ))
- cfg->val += 2;
- server->sconf.host = nfstrdup( cfg->val );
+ if (starts_with( arg, -1, "imap:", 5 ))
+ arg += 5;
+ if (!memcmp( "//", arg, 2 ))
+ arg += 2;
+ if (arg != cfg->val)
+ warn( "%s:%d: Notice: URL notation is
deprecated; use a plain host name and possibly 'SSLType IMAPS' instead\n",
cfg->file, cfg->line );
+ server->sconf.host = nfstrdup( arg );
}
else if (!strcasecmp( "User", cfg->cmd ))
server->user = nfstrdup( cfg->val );
@@ -2308,20 +2308,51 @@ imap_parse_store( conffile_t *cfg, store_conf_t
**storep )
cfg->file, cfg->line,
server->sconf.cert_file );
cfg->err = 1;
}
+ } else if (!strcasecmp( "SSLType", cfg->cmd )) {
+ if (!strcasecmp( "None", cfg->val )) {
+ server->ssl_type = SSL_None;
+ } else if (!strcasecmp( "STARTTLS", cfg->val )) {
+ server->ssl_type = SSL_STARTTLS;
+ } else if (!strcasecmp( "IMAPS", cfg->val )) {
+ server->ssl_type = SSL_IMAPS;
+ } else {
+ error( "%s:%d: Invalid SSL type\n", cfg->file,
cfg->line );
+ cfg->err = 1;
+ }
+ } else if (!strcasecmp( "SSLVersion", cfg->cmd ) ||
+ !strcasecmp( "SSLVersions", cfg->cmd )) {
+ server->sconf.ssl_versions = 0;
+ arg = cfg->val;
+ do {
+ if (!strcasecmp( "SSLv2", arg )) {
+ server->sconf.ssl_versions |= SSLv2;
+ } else if (!strcasecmp( "SSLv3", arg )) {
+ server->sconf.ssl_versions |= SSLv3;
+ } else if (!strcasecmp( "TLSv1", arg )) {
+ server->sconf.ssl_versions |= TLSv1;
+ } else if (!strcasecmp( "TLSv1.1", arg )) {
+ server->sconf.ssl_versions |= TLSv1_1;
+ } else if (!strcasecmp( "TLSv1.2", arg )) {
+ server->sconf.ssl_versions |= TLSv1_2;
+ } else {
+ error( "%s:%d: Unrecognized SSL
version\n", cfg->file, cfg->line );
+ cfg->err = 1;
+ }
+ } while ((arg = get_arg( cfg, ARG_OPTIONAL, 0 )));
} else if (!strcasecmp( "RequireSSL", cfg->cmd ))
- server->require_ssl = parse_bool( cfg );
+ require_ssl = parse_bool( cfg );
else if (!strcasecmp( "UseIMAPS", cfg->cmd ))
- server->use_imaps = parse_bool( cfg );
+ use_imaps = parse_bool( cfg );
else if (!strcasecmp( "UseSSLv2", cfg->cmd ))
- server->sconf.use_sslv2 = parse_bool( cfg );
+ use_sslv2 = parse_bool( cfg );
else if (!strcasecmp( "UseSSLv3", cfg->cmd ))
- server->sconf.use_sslv3 = parse_bool( cfg );
+ use_sslv3 = parse_bool( cfg );
else if (!strcasecmp( "UseTLSv1", cfg->cmd ))
- server->sconf.use_tlsv1 = parse_bool( cfg );
+ use_tlsv1 = parse_bool( cfg );
else if (!strcasecmp( "UseTLSv1.1", cfg->cmd ))
- server->sconf.use_tlsv11 = parse_bool( cfg );
+ use_tlsv11 = parse_bool( cfg );
else if (!strcasecmp( "UseTLSv1.2", cfg->cmd ))
- server->sconf.use_tlsv12 = parse_bool( cfg );
+ use_tlsv12 = parse_bool( cfg );
else if (!strcasecmp( "RequireCRAM", cfg->cmd ))
server->require_cram = parse_bool( cfg );
#endif
@@ -2369,19 +2400,45 @@ imap_parse_store( conffile_t *cfg, store_conf_t
**storep )
return 1;
}
#ifdef HAVE_LIBSSL
- server->use_ssl =
- server->sconf.use_sslv2 | server->sconf.use_sslv3 |
- server->sconf.use_tlsv1 | server->sconf.use_tlsv11 |
server->sconf.use_tlsv12;
- if (server->require_ssl && !server->use_ssl) {
- error( "%s '%s' requires SSL but no SSL versions
enabled\n", type, name );
- cfg->err = 1;
- return 1;
+ if ((use_sslv2 & use_sslv3 & use_tlsv1 & use_tlsv11 &
use_tlsv12) != -1 || use_imaps >= 0 || require_ssl >= 0) {
+ if (server->ssl_type >= 0 || server->sconf.ssl_versions
>= 0) {
+ error( "%s '%s': The deprecated UseSSL*,
UseTLS*, UseIMAPS, and RequireSSL options are mutually exlusive with SSLType
and SSLVersions.\n", type, name );
+ cfg->err = 1;
+ return 1;
+ }
+ warn( "Notice: %s '%s': UseSSL*, UseTLS*, UseIMAPS, and
RequireSSL are deprecated. Use SSLType and SSLVersions instead.\n", type, name
);
+ server->sconf.ssl_versions =
+ (use_sslv2 != 1 ? 0 : SSLv2) |
+ (use_sslv3 != 1 ? 0 : SSLv3) |
+ (use_tlsv1 == 0 ? 0 : TLSv1) |
+ (use_tlsv11 != 1 ? 0 : TLSv1_1) |
+ (use_tlsv12 != 1 ? 0 : TLSv1_2);
+ if (use_imaps == 1) {
+ server->ssl_type = SSL_IMAPS;
+ } else if (require_ssl) {
+ server->ssl_type = SSL_STARTTLS;
+ } else if (!server->sconf.ssl_versions) {
+ server->ssl_type = SSL_None;
+ } else {
+ warn( "Notice: %s '%s': 'RequireSSL no' is
being ignored\n", type, name );
+ server->ssl_type = SSL_STARTTLS;
+ }
+ if (server->ssl_type != SSL_None &&
!server->sconf.ssl_versions) {
+ error( "%s '%s' requires SSL but no SSL
versions enabled\n", type, name );
+ cfg->err = 1;
+ return 1;
+ }
+ } else {
+ if (server->sconf.ssl_versions < 0)
+ server->sconf.ssl_versions = TLSv1; /* Most
compatible and still reasonably secure. */
+ if (server->ssl_type < 0)
+ server->ssl_type = server->sconf.tunnel ?
SSL_None : SSL_STARTTLS;
}
#endif
if (!server->sconf.port)
server->sconf.port =
#ifdef HAVE_LIBSSL
- server->use_imaps ? 993 :
+ server->ssl_type == SSL_IMAPS ? 993 :
#endif
143;
}
diff --git a/src/mbsync.1 b/src/mbsync.1
index 2af9178..fe24f8a 100644
--- a/src/mbsync.1
+++ b/src/mbsync.1
@@ -271,11 +271,6 @@ optional.
Specify a command to run to establish a connection rather than opening a TCP
socket. This allows you to run an IMAP session over an SSH tunnel, for
example.
-.br
-If \fBUseIMAPS\fR is disabled and the tunnel opens a preauthenticated
-connection, \fBRequireSSL\fR also needs to be disabled.
-If the connection is not preauthenticated, but the tunnel is secure,
-disabling \fBRequireSSL\fR and \fBUseTLSv1\fR is recommended.
..
.TP
\fBRequireCRAM\fR \fIyes\fR|\fIno\fR
@@ -283,18 +278,26 @@ If set to \fIyes\fR, \fBmbsync\fR will abort the
connection if no CRAM-MD5
authentication is possible. (Default: \fIno\fR)
..
.TP
-\fBUseIMAPS\fR \fIyes\fR|\fIno\fR
-If set to \fIyes\fR, the default for \fBPort\fR is changed to 993 and
-\fBmbsync\fR will start SSL negotiation immediately after establishing
-the connection to the server.
+\fBSSLType\fR {\fINone\fR|\fISTARTTLS\fR|\fIIMAPS\fR}
+Select the connection security/encryption method:
+.br
+\fINone\fR - no security.
+This is the default when \fBTunnel\fR is set, as tunnels are usually secure.
+.br
+\fISTARTTLS\fR - security is established via the STARTTLS extension
+after connecting the regular IMAP port 143. Most servers support this,
+so it is the default (unless a tunnel is used).
.br
-Note that modern servers support SSL on the regular IMAP port 143 via the
-STARTTLS extension, which will be used automatically by default.
+\fIIMAPS\fR - security is established by starting SSL/TLS negotiation
+right after connecting the secure IMAP port 993.
..
.TP
-\fBRequireSSL\fR \fIyes\fR|\fIno\fR
-\fBmbsync\fR will abort the connection if a TLS/SSL session cannot be
-established with the IMAP server. (Default: \fIyes\fR)
+\fBSSLVersions\fR [\fISSLv2\fR] [\fISSLv3\fR] [\fITLSv1\fR] [\fITLSv1.1\fR]
[\fITLSv1.2\fR]
+Select the acceptable SSL/TLS versions.
+Use of SSLv2 is strongly discouraged for security reasons, but might be the
+only option on some very old servers.
+Generally, the newest TLS version is recommended, but as this confuses some
+servers, \fBTLSv1\fR is the default.
..
.TP
\fBCertificateFile\fR \fIpath\fR
@@ -306,33 +309,6 @@ Note that the system's default certificate store is always
used and should
not be specified here.
..
.TP
-\fBUseSSLv2\fR \fIyes\fR|\fIno\fR
-Use SSLv2 for communication with the IMAP server over SSL?
-.br
-Note that this option is deprecated for security reasons.
-(Default: \fIno\fR)
-..
-.TP
-\fBUseSSLv3\fR \fIyes\fR|\fIno\fR
-Use SSLv3 for communication with the IMAP server over SSL?
-(Default: \fIno\fR)
-..
-.TP
-\fBUseTLSv1\fR \fIyes\fR|\fIno\fR
-Use TLSv1 for communication with the IMAP server over SSL?
-(Default: \fIyes\fR)
-..
-.TP
-\fBUseTLSv1.1\fR \fIyes\fR|\fIno\fR
-Use TLSv1.1 for communication with the IMAP server over SSL?
-(Default: \fIno\fR)
-..
-.TP
-\fBUseTLSv1.2\fR \fIyes\fR|\fIno\fR
-Use TLSv1.2 for communication with the IMAP server over SSL?
-(Default: \fIno\fR)
-..
-.TP
\fBPipelineDepth\fR \fIdepth\fR
Maximum number of IMAP commands which can be simultaneously in flight.
Setting this to \fI1\fR disables pipelining.
diff --git a/src/socket.c b/src/socket.c
index 4bc2752..c760c0a 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -205,18 +205,18 @@ init_ssl_ctx( const server_conf_t *conf )
mconf->SSLContext = SSL_CTX_new( SSLv23_client_method() );
- if (!conf->use_sslv2)
+ if (!(conf->ssl_versions & SSLv2))
options |= SSL_OP_NO_SSLv2;
- if (!conf->use_sslv3)
+ if (!(conf->ssl_versions & SSLv3))
options |= SSL_OP_NO_SSLv3;
- if (!conf->use_tlsv1)
+ if (!(conf->ssl_versions & TLSv1))
options |= SSL_OP_NO_TLSv1;
#ifdef SSL_OP_NO_TLSv1_1
- if (!conf->use_tlsv11)
+ if (!(conf->ssl_versions & TLSv1_1))
options |= SSL_OP_NO_TLSv1_1;
#endif
#ifdef SSL_OP_NO_TLSv1_2
- if (!conf->use_tlsv12)
+ if (!(conf->ssl_versions & TLSv1_2))
options |= SSL_OP_NO_TLSv1_2;
#endif
diff --git a/src/socket.h b/src/socket.h
index c7fcb78..bfc5ddf 100644
--- a/src/socket.h
+++ b/src/socket.h
@@ -25,16 +25,26 @@
#include "common.h"
+#ifdef HAVE_LIBSSL
typedef struct ssl_st SSL;
typedef struct ssl_ctx_st SSL_CTX;
+enum {
+ SSLv2 = 1,
+ SSLv3 = 2,
+ TLSv1 = 4,
+ TLSv1_1 = 8,
+ TLSv1_2 = 16
+};
+#endif
+
typedef struct server_conf {
char *tunnel;
char *host;
int port;
#ifdef HAVE_LIBSSL
char *cert_file;
- char use_sslv2, use_sslv3, use_tlsv1, use_tlsv11, use_tlsv12;
+ char ssl_versions;
/* these are actually variables and are leaked at the end */
char ssl_ctx_valid;
------------------------------------------------------------------------------
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