mod_ssl: Avoid crashes due to stapling callback

2 files changed, 299 insertions, 0 deletions

diff --git a/debian/patches/mod_ssl-oscp_stapling_crash.diff b/debian/patches/mod_ssl-oscp_stapling_crash.diff
new file mode 100644
index 00000000..c2de4eb6
--- /dev/null
+++ b/debian/patches/mod_ssl-oscp_stapling_crash.diff
@@ -0,0 +1,298 @@
+# http://svn.apache.org/viewvc?view=revision&revision=1634529
+#
+# Avoid registering a cleanup function with openssl for the OCSP
+# stapling information. During startup or graceful restart mod_ssl
+# may be reloaded without libssl being reloaded. In this case
+# libssl may still use the cleanup that now points to invalid memory,
+# causing a crash.
+#
+# =================================
+# commit 1046d0c01b67d50af9d4570e975ba418dff3fa96
+# Author: Jim Jagielski <jim@apache.org>
+# Date:   Mon Oct 27 12:50:05 2014 +0000
+# 
+#     Merge r1629372, r1629485, r1629519 from trunk:
+#     
+#     Move OCSP stapling information from a per-certificate store
+#     (ex_data attached to an X509 *) to a per-server hash which is
+#     allocated from the pconf pool. Fixes PR 54357, PR 56919 and
+#     a leak with the certinfo_free cleanup function (missing
+#     OCSP_CERTID_free).
+#     
+#     * modules/ssl/ssl_util_stapling.c: drop certinfo_free, and add
+#       ssl_stapling_certid_free (used with apr_pool_cleanup_register).
+#       Switch to a stapling_certinfo hash which is keyed by the SHA-1
+#       digest of the certificate's DER encoding, rework ssl_stapling_init_cert
+#       to only store info once per certificate (allocated from the pconf
+#       to the extent possible) and extend the logging.
+#     
+#     * modules/ssl/ssl_private.h: adjust prototype for
+#       ssl_stapling_init_cert, replace ssl_stapling_ex_init with
+#       ssl_stapling_certinfo_hash_init
+#     
+#     * modules/ssl/ssl_engine_init.c: adjust ssl_stapling_* calls
+#     
+#     Based on initial work by Alex Bligh <alex alex.org.uk>
+# 
+#     Follow up to r1629372: ensure compatibily with OpenSSL < 1.0 (sk_OPENSSL_STRING_value).
+#     
+#     Follow up to r1629372 and r1629485: ensure compatibily with OpenSSL < 1.0 (sk_OPENSSL_STRING_[num|value|pop] macros).
+#     Submitted by: kbrand, ylavic, ylavic
+#     Reviewed/backported by: jim
+--- apache2.orig/modules/ssl/ssl_util_stapling.c
++++ apache2/modules/ssl/ssl_util_stapling.c
+@@ -43,36 +43,32 @@
+ 
+ #define MAX_STAPLING_DER 10240
+ 
+-/* Cached info stored in certificate ex_info. */
++/* Cached info stored in the global stapling_certinfo hash. */
+ typedef struct {
+-    /* Index in session cache SHA1 hash of certificate */
+-    UCHAR idx[20];
+-    /* Certificate ID for OCSP requests or NULL if ID cannot be determined */
++    /* Index in session cache (SHA-1 digest of DER encoded certificate) */
++    UCHAR idx[SHA_DIGEST_LENGTH];
++    /* Certificate ID for OCSP request */
+     OCSP_CERTID *cid;
+-    /* Responder details */
++    /* URI of the OCSP responder */
+     char *uri;
+ } certinfo;
+ 
+-static void certinfo_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
+-                                        int idx, long argl, void *argp)
++static apr_status_t ssl_stapling_certid_free(void *data)
+ {
+-    certinfo *cinf = ptr;
++    OCSP_CERTID *cid = data;
+ 
+-    if (!cinf)
+-        return;
+-    if (cinf->uri)
+-        OPENSSL_free(cinf->uri);
+-    OPENSSL_free(cinf);
++    if (cid) {
++        OCSP_CERTID_free(cid);
++    }
++
++    return APR_SUCCESS;
+ }
+ 
+-static int stapling_ex_idx = -1;
++static apr_hash_t *stapling_certinfo;
+ 
+-void ssl_stapling_ex_init(void)
++void ssl_stapling_certinfo_hash_init(apr_pool_t *p)
+ {
+-    if (stapling_ex_idx != -1)
+-        return;
+-    stapling_ex_idx = X509_get_ex_new_index(0, "X509 cached OCSP info", 0, 0,
+-                                            certinfo_free);
++    stapling_certinfo = apr_hash_make(p);
+ }
+ 
+ static X509 *stapling_get_issuer(modssl_ctx_t *mctx, X509 *x)
+@@ -106,70 +102,96 @@ static X509 *stapling_get_issuer(modssl_
+ 
+ }
+ 
+-int ssl_stapling_init_cert(server_rec *s, modssl_ctx_t *mctx, X509 *x)
++int ssl_stapling_init_cert(server_rec *s, apr_pool_t *p, apr_pool_t *ptemp,
++                           modssl_ctx_t *mctx, X509 *x)
+ {
+-    certinfo *cinf;
++    UCHAR idx[SHA_DIGEST_LENGTH];
++    certinfo *cinf = NULL;
+     X509 *issuer = NULL;
++    OCSP_CERTID *cid = NULL;
+     STACK_OF(OPENSSL_STRING) *aia = NULL;
+ 
+-    if (x == NULL)
++    if ((x == NULL) || (X509_digest(x, EVP_sha1(), idx, NULL) != 1))
+         return 0;
+-    cinf  = X509_get_ex_data(x, stapling_ex_idx);
++
++    cinf = apr_hash_get(stapling_certinfo, idx, sizeof(idx));
+     if (cinf) {
+-        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02215)
+-                     "ssl_stapling_init_cert: certificate already initialized!");
+-        return 0;
+-    }
+-    cinf = OPENSSL_malloc(sizeof(certinfo));
+-    if (!cinf) {
+-        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02216)
+-                     "ssl_stapling_init_cert: error allocating memory!");
+-        return 0;
++        /* 
++         * We already parsed the certificate, and no OCSP URI was found.
++         * The certificate might be used for multiple vhosts, though,
++         * so we check for a ForceURL for this vhost.
++         */
++        if (!cinf->uri && !mctx->stapling_force_url) {
++            ssl_log_xerror(SSLLOG_MARK, APLOG_ERR, 0, ptemp, s, x,
++                           APLOGNO(02814) "ssl_stapling_init_cert: no OCSP URI "
++                           "in certificate and no SSLStaplingForceURL "
++                           "configured for server %s", mctx->sc->vhost_id);
++            return 0;
++        }
++        return 1;
+     }
+-    cinf->cid = NULL;
+-    cinf->uri = NULL;
+-    X509_set_ex_data(x, stapling_ex_idx, cinf);
+-
+-    issuer = stapling_get_issuer(mctx, x);
+-
+-    if (issuer == NULL) {
+-        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02217)
+-                     "ssl_stapling_init_cert: Can't retrieve issuer certificate!");
++
++    if (!(issuer = stapling_get_issuer(mctx, x))) {
++        ssl_log_xerror(SSLLOG_MARK, APLOG_ERR, 0, ptemp, s, x, APLOGNO(02217)
++                       "ssl_stapling_init_cert: can't retrieve issuer "
++                       "certificate!");
+         return 0;
+     }
+ 
+-    cinf->cid = OCSP_cert_to_id(NULL, x, issuer);
++    cid = OCSP_cert_to_id(NULL, x, issuer);
+     X509_free(issuer);
+-    if (!cinf->cid)
++    if (!cid) {
++        ssl_log_xerror(SSLLOG_MARK, APLOG_ERR, 0, ptemp, s, x, APLOGNO(02815)
++                       "ssl_stapling_init_cert: can't create CertID "
++                       "for OCSP request");
+         return 0;
+-    X509_digest(x, EVP_sha1(), cinf->idx, NULL);
++    }
+ 
+     aia = X509_get1_ocsp(x);
+-    if (aia) {
+-        cinf->uri = sk_OPENSSL_STRING_pop(aia);
+-        X509_email_free(aia);
+-    }
+-    if (!cinf->uri && !mctx->stapling_force_url) {
+-        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02218)
+-                     "ssl_stapling_init_cert: no responder URL");
++    if (!aia && !mctx->stapling_force_url) {
++        OCSP_CERTID_free(cid);
++        ssl_log_xerror(SSLLOG_MARK, APLOG_ERR, 0, ptemp, s, x,
++                       APLOGNO(02218) "ssl_stapling_init_cert: no OCSP URI "
++                       "in certificate and no SSLStaplingForceURL set");
+         return 0;
+     }
++
++    /* At this point, we have determined that there's something to store */
++    cinf = apr_pcalloc(p, sizeof(certinfo));
++    memcpy (cinf->idx, idx, sizeof(idx));
++    cinf->cid = cid;
++    /* make sure cid is also freed at pool cleanup */
++    apr_pool_cleanup_register(p, cid, ssl_stapling_certid_free,
++                              apr_pool_cleanup_null);
++    if (aia) {
++       /* allocate uri from the pconf pool */
++       cinf->uri = apr_pstrdup(p, sk_OPENSSL_STRING_value(aia, 0));
++       X509_email_free(aia);
++    }
++
++    ssl_log_xerror(SSLLOG_MARK, APLOG_TRACE1, 0, ptemp, s, x,
++                   "ssl_stapling_init_cert: storing certinfo for server %s",
++                   mctx->sc->vhost_id);
++
++    apr_hash_set(stapling_certinfo, cinf->idx, sizeof(cinf->idx), cinf);
++
+     return 1;
+ }
+ 
+-static certinfo *stapling_get_cert_info(server_rec *s, modssl_ctx_t *mctx,
++static certinfo *stapling_get_certinfo(server_rec *s, modssl_ctx_t *mctx,
+                                         SSL *ssl)
+ {
+     certinfo *cinf;
+     X509 *x;
++    UCHAR idx[SHA_DIGEST_LENGTH];
+     x = SSL_get_certificate(ssl);
+-    if (x == NULL)
++    if ((x == NULL) || (X509_digest(x, EVP_sha1(), idx, NULL) != 1))
+         return NULL;
+-    cinf = X509_get_ex_data(x, stapling_ex_idx);
++    cinf = apr_hash_get(stapling_certinfo, idx, sizeof(idx));
+     if (cinf && cinf->cid)
+         return cinf;
+     ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(01926)
+-                 "stapling_get_cert_info: stapling not supported for certificate");
++                 "stapling_get_certinfo: stapling not supported for certificate");
+     return NULL;
+ }
+ 
+@@ -585,7 +607,7 @@ static int stapling_cb(SSL *ssl, void *a
+     ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01951)
+                  "stapling_cb: OCSP Stapling callback called");
+ 
+-    cinf = stapling_get_cert_info(s, mctx, ssl);
++    cinf = stapling_get_certinfo(s, mctx, ssl);
+     if (cinf == NULL) {
+         return SSL_TLSEXT_ERR_NOACK;
+     }
+--- apache2.orig/modules/ssl/ssl_private.h
++++ apache2/modules/ssl/ssl_private.h
+@@ -151,6 +151,13 @@
+ /* OCSP stapling */
+ #if !defined(OPENSSL_NO_OCSP) && defined(SSL_CTX_set_tlsext_status_cb)
+ #define HAVE_OCSP_STAPLING
++/* backward compatibility with OpenSSL < 1.0 */
++#ifndef sk_OPENSSL_STRING_num
++#define sk_OPENSSL_STRING_num sk_num
++#endif
++#ifndef sk_OPENSSL_STRING_value
++#define sk_OPENSSL_STRING_value sk_value
++#endif
+ #ifndef sk_OPENSSL_STRING_pop
+ #define sk_OPENSSL_STRING_pop sk_pop
+ #endif
+@@ -812,10 +819,11 @@ const char *ssl_cmd_SSLStaplingErrorCach
+ const char *ssl_cmd_SSLStaplingReturnResponderErrors(cmd_parms *, void *, int);
+ const char *ssl_cmd_SSLStaplingFakeTryLater(cmd_parms *, void *, int);
+ const char *ssl_cmd_SSLStaplingResponderTimeout(cmd_parms *, void *, const char *);
+-const char  *ssl_cmd_SSLStaplingForceURL(cmd_parms *, void *, const char *);
++const char *ssl_cmd_SSLStaplingForceURL(cmd_parms *, void *, const char *);
+ apr_status_t modssl_init_stapling(server_rec *, apr_pool_t *, apr_pool_t *, modssl_ctx_t *);
+-void         ssl_stapling_ex_init(void);
+-int          ssl_stapling_init_cert(server_rec *s, modssl_ctx_t *mctx, X509 *x);
++void         ssl_stapling_certinfo_hash_init(apr_pool_t *);
++int          ssl_stapling_init_cert(server_rec *, apr_pool_t *, apr_pool_t *,
++                                    modssl_ctx_t *, X509 *);
+ #endif
+ #ifdef HAVE_SRP
+ int          ssl_callback_SRPServerParams(SSL *, int *, void *);
+--- apache2.orig/modules/ssl/ssl_engine_init.c
++++ apache2/modules/ssl/ssl_engine_init.c
+@@ -272,7 +272,7 @@ apr_status_t ssl_init_Module(apr_pool_t
+         return HTTP_INTERNAL_SERVER_ERROR;
+     }
+ #ifdef HAVE_OCSP_STAPLING
+-    ssl_stapling_ex_init();
++    ssl_stapling_certinfo_hash_init(p);
+ #endif
+ 
+     /*
+@@ -1067,7 +1067,7 @@ static apr_status_t ssl_init_server_cert
+          * later, we defer to the code in ssl_init_server_ctx.
+          */
+         if ((mctx->stapling_enabled == TRUE) &&
+-            !ssl_stapling_init_cert(s, mctx, cert)) {
++            !ssl_stapling_init_cert(s, p, ptemp, mctx, cert)) {
+             ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02567)
+                          "Unable to configure certificate %s for stapling",
+                          key_id);
+@@ -1425,7 +1425,8 @@ static apr_status_t ssl_init_server_ctx(
+                                            SSL_CERT_SET_FIRST);
+         while (ret) {
+             cert = SSL_CTX_get0_certificate(sc->server->ssl_ctx);
+-            if (!cert || !ssl_stapling_init_cert(s, sc->server, cert)) {
++            if (!cert || !ssl_stapling_init_cert(s, p, ptemp, sc->server,
++                                                 cert)) {
+                 ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(02604)
+                              "Unable to configure certificate %s:%d "
+                              "for stapling", sc->vhost_id, i);
diff --git a/debian/patches/series b/debian/patches/series
index eaab7ca6..3be72f8c 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -9,3 +9,4 @@ pull_upstream_2.4.x_branch.patch
 CVE-2014-3583_mod_proxy_fcgi.diff
 mpm_event_use_after_free.diff
 mod_ssl_memleak.diff
+mod_ssl-oscp_stapling_crash.diff