.option tls_verify_certificates main string&!! unset
.cindex "TLS" "client certificate verification"
.cindex "certificate" "verification of client"
-The value of this option is expanded, and must then be the absolute path to
-a file containing permitted certificates for clients that
-match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&. Alternatively, if you
-are using either GnuTLS version 3.3.6 (or later) or OpenSSL,
-you can set &%tls_verify_certificates%& to the name of a
-directory containing certificate files.
-For earlier versions of GnuTLS
-the option must be set to the name of a single file.
+The value of this option is expanded, and must then be either the
+word "system"
+or the absolute path to
+a file or directory containing permitted certificates for clients that
+match &%tls_verify_hosts%& or &%tls_try_verify_hosts%&.
+
+The "system" value for the option will use a
+system default location compiled into the SSL library.
+This is not available for GnuTLS versions preceding 3.0.20 and an explicit location
+must be specified.
+
+The use of a directory for the option value is not avilable for GnuTLS versions
+preceding 3.3.6 and a single file must be used.
+
+With OpenSSL the certificates specified
+explicitly
+either by file or directory
+are added to those given by the system default location.
With OpenSSL the certificates specified
explicitly
.cindex "certificate" "verification of server"
.vindex "&$host$&"
.vindex "&$host_address$&"
-The value of this option must be the absolute path to a file containing
-permitted server certificates, for use when setting up an encrypted connection.
-Alternatively,
-if you are using either GnuTLS version 3.3.6 (or later) or OpenSSL,
-you can set
-&%tls_verify_certificates%& to the name of a directory containing certificate
-files.
-For earlier versions of GnuTLS the option must be set to the name of a
-single file.
+The value of this option must be either the
+word "system"
+or the absolute path to
+a file or directory containing permitted certificates for servers,
+for use when setting up an encrypted connection.
+
+The "system" value for the option will use a location compiled into the SSL library.
+This is not available for GnuTLS versions preceding 3.0.20 and an explicit location
+must be specified.
+
+The use of a directory for the option value is not avilable for GnuTLS versions
+preceding 3.3.6 and a single file must be used.
With OpenSSL the certificates specified
explicitly
There are some differences in usage when using GnuTLS instead of OpenSSL:
.ilist
-The &%tls_verify_certificates%& option must contain the name of a file, not the
-name of a directory for GnuTLS versions before 3.3.6
+The &%tls_verify_certificates%& option
+cannot be the path of a directory
+for GnuTLS versions before 3.3.6
(for later versions, or OpenSSL, it can be either).
.next
The default value for &%tls_dhparam%& differs for historical reasons.
apply to all TLS connections. For any host that matches one of these options,
Exim requests a certificate as part of the setup of the TLS session. The
contents of the certificate are verified by comparing it with a list of
-expected certificates. These must be available in a file or,
-for OpenSSL only (not GnuTLS), a directory, identified by
+expected certificates.
+These may be the system default set (depending on library version),
+an explicit file or,
+depending on library version, a directory, identified by
&%tls_verify_certificates%&.
A file can contain multiple certificates, concatenated end to end. If a
&%tls_verify_hosts%& or &%tls_try_verify_hosts%& matches the client.
If the &%tls_verify_certificates%& option is set on the &(smtp)& transport, it
+specified a collection of expected server certificates.
+These may be the system default set (depeding on library version),
+a file or,
+depnding on liibrary version, a directory,
must name a file or,
-for OpenSSL only (not GnuTLS), a directory, that contains a collection of
-expected server certificates. The client verifies the server's certificate
+for OpenSSL only (not GnuTLS), a directory.
+The client verifies the server's certificate
against this collection, taking into account any revoked certificates that are
in the list defined by &%tls_crl%&.
Failure to verify fails the TLS connection unless either of the
can be used to disable this per-host. The build option
EXPERIMENTAL_CERTNAMES is withdrawn.
+JH/05 The value of the tls_verify_certificates smtp transport and main options
+ can now be the word "system" to access the system default CA bundle.
+ For GnuTLS, only version 3.0.20 or later.
+
Exim version 4.85
-----------------
#else
# undef SUPPORT_CA_DIR
#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030314
+# define SUPPORT_SYSDEFAULT_CABUNDLE
+#endif
#ifndef DISABLE_OCSP
# include <gnutls/ocsp.h>
return OK;
}
-if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
+#ifdef SUPPORT_SYSDEFAULT_CABUNDLE
+if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
+ cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
+else
+#endif
{
- log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
- "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
- strerror(errno));
- return DEFER;
- }
+ if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
+ "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
+ strerror(errno));
+ return DEFER;
+ }
#ifndef SUPPORT_CA_DIR
-/* The test suite passes in /dev/null; we could check for that path explicitly,
-but who knows if someone has some weird FIFO which always dumps some certs, or
-other weirdness. The thing we really want to check is that it's not a
-directory, since while OpenSSL supports that, GnuTLS does not.
-So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */
-if (S_ISDIR(statbuf.st_mode))
- {
- DEBUG(D_tls)
- debug_printf("verify certificates path is a dir: \"%s\"\n",
- state->exp_tls_verify_certificates);
- log_write(0, LOG_MAIN|LOG_PANIC,
- "tls_verify_certificates \"%s\" is a directory",
- state->exp_tls_verify_certificates);
- return DEFER;
- }
+ /* The test suite passes in /dev/null; we could check for that path explicitly,
+ but who knows if someone has some weird FIFO which always dumps some certs, or
+ other weirdness. The thing we really want to check is that it's not a
+ directory, since while OpenSSL supports that, GnuTLS does not.
+ So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */
+ if (S_ISDIR(statbuf.st_mode))
+ {
+ DEBUG(D_tls)
+ debug_printf("verify certificates path is a dir: \"%s\"\n",
+ state->exp_tls_verify_certificates);
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "tls_verify_certificates \"%s\" is a directory",
+ state->exp_tls_verify_certificates);
+ return DEFER;
+ }
#endif
-DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
- state->exp_tls_verify_certificates, statbuf.st_size);
+ DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
+ state->exp_tls_verify_certificates, statbuf.st_size);
-if (statbuf.st_size == 0)
- {
- DEBUG(D_tls)
- debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
- return OK;
- }
+ if (statbuf.st_size == 0)
+ {
+ DEBUG(D_tls)
+ debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
+ return OK;
+ }
-cert_count =
+ cert_count =
#ifdef SUPPORT_CA_DIR
- (statbuf.st_mode & S_IFMT) == S_IFDIR
- ?
- gnutls_certificate_set_x509_trust_dir(state->x509_cred,
- CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
- :
+ (statbuf.st_mode & S_IFMT) == S_IFDIR
+ ?
+ gnutls_certificate_set_x509_trust_dir(state->x509_cred,
+ CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
+ :
#endif
- gnutls_certificate_set_x509_trust_file(state->x509_cred,
- CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
+ gnutls_certificate_set_x509_trust_file(state->x509_cred,
+ CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
+ }
if (cert_count < 0)
{
rc = cert_count;
- exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file");
+ exim_gnutls_err_check(US"setting certificate trust");
}
DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count);
if (expcerts != NULL && *expcerts != '\0')
{
- struct stat statbuf;
- if (!SSL_CTX_set_default_verify_paths(sctx))
- return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
-
- if (Ustat(expcerts, &statbuf) < 0)
+ if (Ustrcmp(expcerts, "system") == 0)
{
- log_write(0, LOG_MAIN|LOG_PANIC,
- "failed to stat %s for certificates", expcerts);
- return DEFER;
+ /* Tell the library to use its compiled-in location for the system default
+ CA bundle, only */
+
+ if (!SSL_CTX_set_default_verify_paths(sctx))
+ return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
}
else
{
- uschar *file, *dir;
- if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
- { file = NULL; dir = expcerts; }
+ struct stat statbuf;
+
+ /* Tell the library to use its compiled-in location for the system default
+ CA bundle. Those given by the exim config are additional to these */
+
+ if (!SSL_CTX_set_default_verify_paths(sctx))
+ return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
+
+ if (Ustat(expcerts, &statbuf) < 0)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "failed to stat %s for certificates", expcerts);
+ return DEFER;
+ }
else
- { file = expcerts; dir = NULL; }
-
- /* If a certificate file is empty, the next function fails with an
- unhelpful error message. If we skip it, we get the correct behaviour (no
- certificates are recognized, but the error message is still misleading (it
- says no certificate was supplied.) But this is better. */
-
- if ((file == NULL || statbuf.st_size > 0) &&
- !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
- return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
-
- /* Load the list of CAs for which we will accept certs, for sending
- to the client. This is only for the one-file tls_verify_certificates
- variant.
- If a list isn't loaded into the server, but
- some verify locations are set, the server end appears to make
- a wildcard reqest for client certs.
- Meanwhile, the client library as deafult behaviour *ignores* the list
- we send over the wire - see man SSL_CTX_set_client_cert_cb.
- Because of this, and that the dir variant is likely only used for
- the public-CA bundle (not for a private CA), not worth fixing.
- */
- if (file != NULL)
{
- STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
-DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
- sk_X509_NAME_num(names));
- SSL_CTX_set_client_CA_list(sctx, names);
+ uschar *file, *dir;
+ if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
+ { file = NULL; dir = expcerts; }
+ else
+ { file = expcerts; dir = NULL; }
+
+ /* If a certificate file is empty, the next function fails with an
+ unhelpful error message. If we skip it, we get the correct behaviour (no
+ certificates are recognized, but the error message is still misleading (it
+ says no certificate was supplied.) But this is better. */
+
+ if ((file == NULL || statbuf.st_size > 0) &&
+ !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
+ return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
+
+ /* Load the list of CAs for which we will accept certs, for sending
+ to the client. This is only for the one-file tls_verify_certificates
+ variant.
+ If a list isn't loaded into the server, but
+ some verify locations are set, the server end appears to make
+ a wildcard reqest for client certs.
+ Meanwhile, the client library as deafult behaviour *ignores* the list
+ we send over the wire - see man SSL_CTX_set_client_cert_cb.
+ Because of this, and that the dir variant is likely only used for
+ the public-CA bundle (not for a private CA), not worth fixing.
+ */
+ if (file != NULL)
+ {
+ STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
+ DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
+ sk_X509_NAME_num(names));
+ SSL_CTX_set_client_CA_list(sctx, names);
+ }
}
}
projects / exim.git / commitdiff