[openssl-commits] [openssl] master update
Viktor Dukhovni
viktor at openssl.org
Sun Jan 3 22:22:20 UTC 2016
The branch master has been updated
via 0e7abc903799a32d9d4eb34316cb72f1f4b28a52 (commit)
via d9b8b89bec4480de3a10bdaf9425db371c19145b (commit)
from 63c6aa6b9311d2834cbfea2b6311d44be9075dd0 (commit)
- Log -----------------------------------------------------------------
commit 0e7abc903799a32d9d4eb34316cb72f1f4b28a52
Author: Viktor Dukhovni <openssl-users at dukhovni.org>
Date: Tue Dec 29 13:16:47 2015 -0500
Drop incorrect id == -1 case from X509_check_trust
Reviewed-by: Richard Levitte <levitte at openssl.org>
commit d9b8b89bec4480de3a10bdaf9425db371c19145b
Author: Viktor Dukhovni <openssl-users at dukhovni.org>
Date: Tue Dec 29 12:42:57 2015 -0500
X509_verify_cert() cleanup
Reviewed-by: Richard Levitte <levitte at openssl.org>
-----------------------------------------------------------------------
Summary of changes:
crypto/x509/x509_err.c | 1 +
crypto/x509/x509_trs.c | 3 +-
crypto/x509/x509_vfy.c | 739 ++++++++++++++++++++++++---------------------
include/openssl/x509.h | 1 +
include/openssl/x509_vfy.h | 4 +-
5 files changed, 401 insertions(+), 347 deletions(-)
diff --git a/crypto/x509/x509_err.c b/crypto/x509/x509_err.c
index 25f90ea..668af28 100644
--- a/crypto/x509/x509_err.c
+++ b/crypto/x509/x509_err.c
@@ -71,6 +71,7 @@
static ERR_STRING_DATA X509_str_functs[] = {
{ERR_FUNC(X509_F_ADD_CERT_DIR), "add_cert_dir"},
+ {ERR_FUNC(X509_F_BUILD_CHAIN), "build_chain"},
{ERR_FUNC(X509_F_BY_FILE_CTRL), "by_file_ctrl"},
{ERR_FUNC(X509_F_CHECK_POLICY), "check_policy"},
{ERR_FUNC(X509_F_DIR_CTRL), "dir_ctrl"},
diff --git a/crypto/x509/x509_trs.c b/crypto/x509/x509_trs.c
index 27ee475..8f2ff83 100644
--- a/crypto/x509/x509_trs.c
+++ b/crypto/x509/x509_trs.c
@@ -116,8 +116,7 @@ int X509_check_trust(X509 *x, int id, int flags)
{
X509_TRUST *pt;
int idx;
- if (id == -1)
- return 1;
+
/* We get this as a default value */
if (id == 0) {
int rv;
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c
index 3acb374..9b88031 100644
--- a/crypto/x509/x509_vfy.c
+++ b/crypto/x509/x509_vfy.c
@@ -59,6 +59,7 @@
#include <stdio.h>
#include <time.h>
#include <errno.h>
+#include <limits.h>
#include "internal/cryptlib.h"
#include <openssl/crypto.h>
@@ -69,7 +70,7 @@
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/objects.h>
-#include "internal/x509_int.h"
+#include <internal/x509_int.h>
#include "x509_lcl.h"
/* CRL score values */
@@ -110,13 +111,15 @@
#define CRL_SCORE_TIME_DELTA 0x002
+static int build_chain(X509_STORE_CTX *ctx);
+static int verify_chain(X509_STORE_CTX *ctx);
static int null_callback(int ok, X509_STORE_CTX *e);
static int check_issued(X509_STORE_CTX *ctx, X509 *x, X509 *issuer);
static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x);
static int check_chain_extensions(X509_STORE_CTX *ctx);
static int check_name_constraints(X509_STORE_CTX *ctx);
static int check_id(X509_STORE_CTX *ctx);
-static int check_trust(X509_STORE_CTX *ctx);
+static int check_trust(X509_STORE_CTX *ctx, int num_untrusted);
static int check_revocation(X509_STORE_CTX *ctx);
static int check_cert(X509_STORE_CTX *ctx);
static int check_policy(X509_STORE_CTX *ctx);
@@ -148,6 +151,11 @@ static int null_callback(int ok, X509_STORE_CTX *e)
/* Return 1 is a certificate is self signed */
static int cert_self_signed(X509 *x)
{
+ /*
+ * FIXME: x509v3_cache_extensions() needs to detect more failures and not
+ * set EXFLAG_SET when that happens. Especially, if the failures are
+ * parse errors, rather than memory pressure!
+ */
X509_check_purpose(x, -1, 0);
if (x->ex_flags & EXFLAG_SS)
return 1;
@@ -180,19 +188,60 @@ static X509 *lookup_cert_match(X509_STORE_CTX *ctx, X509 *x)
return xtmp;
}
+static int verify_chain(X509_STORE_CTX *ctx)
+{
+ int (*cb) (int xok, X509_STORE_CTX *xctx) = ctx->verify_cb;
+ int err;
+ int ok;
+
+ /*
+ * Before either returning with an error, or continuing with CRL checks,
+ * instantiate chain public key parameters.
+ */
+ if ((ok = build_chain(ctx)) == 0 ||
+ (ok = check_chain_extensions(ctx)) == 0 ||
+ (ok = check_name_constraints(ctx)) == 0 ||
+ (ok = check_id(ctx)) == 0 || 1)
+ X509_get_pubkey_parameters(NULL, ctx->chain);
+ if (ok == 0 || (ok = ctx->check_revocation(ctx)) == 0)
+ return ok;
+
+ err = X509_chain_check_suiteb(&ctx->error_depth, NULL, ctx->chain,
+ ctx->param->flags);
+ if (err != X509_V_OK) {
+ ctx->error = err;
+ ctx->current_cert = sk_X509_value(ctx->chain, ctx->error_depth);
+ if ((ok = cb(0, ctx)) == 0)
+ return ok;
+ }
+
+ /* Verify chain signatures and expiration times */
+ ok = (ctx->verify != NULL) ? ctx->verify(ctx) : internal_verify(ctx);
+ if (!ok)
+ return ok;
+
+#ifndef OPENSSL_NO_RFC3779
+ /* RFC 3779 path validation, now that CRL check has been done */
+ if ((ok = v3_asid_validate_path(ctx)) == 0)
+ return ok;
+ if ((ok = v3_addr_validate_path(ctx)) == 0)
+ return ok;
+#endif
+
+ /* If we get this far evaluate policies */
+ if (ctx->param->flags & X509_V_FLAG_POLICY_CHECK)
+ ok = ctx->check_policy(ctx);
+ return ok;
+}
+
int X509_verify_cert(X509_STORE_CTX *ctx)
{
- X509 *x, *xtmp, *xtmp2, *chain_ss = NULL;
- int bad_chain = 0;
- X509_VERIFY_PARAM *param = ctx->param;
- int depth, i, ok = 0;
- int num, j, retry;
- int (*cb) (int xok, X509_STORE_CTX *xctx);
- STACK_OF(X509) *sktmp = NULL;
+
if (ctx->cert == NULL) {
X509err(X509_F_X509_VERIFY_CERT, X509_R_NO_CERT_SET_FOR_US_TO_VERIFY);
return -1;
}
+
if (ctx->chain != NULL) {
/*
* This X509_STORE_CTX has already been used to verify a cert. We
@@ -202,8 +251,6 @@ int X509_verify_cert(X509_STORE_CTX *ctx)
return -1;
}
- cb = ctx->verify_cb;
-
/*
* first we make sure the chain we are going to build is present and that
* the first entry is in place
@@ -211,302 +258,12 @@ int X509_verify_cert(X509_STORE_CTX *ctx)
if (((ctx->chain = sk_X509_new_null()) == NULL) ||
(!sk_X509_push(ctx->chain, ctx->cert))) {
X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
- goto end;
+ return -1;
}
X509_up_ref(ctx->cert);
- ctx->last_untrusted = 1;
-
- /* We use a temporary STACK so we can chop and hack at it */
- if (ctx->untrusted != NULL
- && (sktmp = sk_X509_dup(ctx->untrusted)) == NULL) {
- X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
- goto end;
- }
-
- num = sk_X509_num(ctx->chain);
- x = sk_X509_value(ctx->chain, num - 1);
- depth = param->depth;
-
- for (;;) {
- /* If we have enough, we break */
- if (depth < num)
- break; /* FIXME: If this happens, we should take
- * note of it and, if appropriate, use the
- * X509_V_ERR_CERT_CHAIN_TOO_LONG error code
- * later. */
-
- /* If we are self signed, we break */
- if (cert_self_signed(x))
- break;
- /*
- * If asked see if we can find issuer in trusted store first
- */
- if (ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST) {
- ok = ctx->get_issuer(&xtmp, ctx, x);
- if (ok < 0)
- goto end;
- /*
- * If successful for now free up cert so it will be picked up
- * again later.
- */
- if (ok > 0) {
- X509_free(xtmp);
- break;
- }
- }
-
- /* If we were passed a cert chain, use it first */
- if (ctx->untrusted != NULL) {
- xtmp = find_issuer(ctx, sktmp, x);
- if (xtmp != NULL) {
- if (!sk_X509_push(ctx->chain, xtmp)) {
- X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
- goto end;
- }
- X509_up_ref(xtmp);
- (void)sk_X509_delete_ptr(sktmp, xtmp);
- ctx->last_untrusted++;
- x = xtmp;
- num++;
- /*
- * reparse the full chain for the next one
- */
- continue;
- }
- }
- break;
- }
-
- /* Remember how many untrusted certs we have */
- j = num;
- /*
- * at this point, chain should contain a list of untrusted certificates.
- * We now need to add at least one trusted one, if possible, otherwise we
- * complain.
- */
-
- do {
- /*
- * Examine last certificate in chain and see if it is self signed.
- */
- i = sk_X509_num(ctx->chain);
- x = sk_X509_value(ctx->chain, i - 1);
- if (cert_self_signed(x)) {
- /* we have a self signed certificate */
- if (sk_X509_num(ctx->chain) == 1) {
- /*
- * We have a single self signed certificate: see if we can
- * find it in the store. We must have an exact match to avoid
- * possible impersonation.
- */
- ok = ctx->get_issuer(&xtmp, ctx, x);
- if ((ok <= 0) || X509_cmp(x, xtmp)) {
- ctx->error = X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT;
- ctx->current_cert = x;
- ctx->error_depth = i - 1;
- if (ok == 1)
- X509_free(xtmp);
- bad_chain = 1;
- ok = cb(0, ctx);
- if (!ok)
- goto end;
- } else {
- /*
- * We have a match: replace certificate with store
- * version so we get any trust settings.
- */
- X509_free(x);
- x = xtmp;
- (void)sk_X509_set(ctx->chain, i - 1, x);
- ctx->last_untrusted = 0;
- }
- } else {
- /*
- * extract and save self signed certificate for later use
- */
- chain_ss = sk_X509_pop(ctx->chain);
- ctx->last_untrusted--;
- num--;
- j--;
- x = sk_X509_value(ctx->chain, num - 1);
- }
- }
- /* We now lookup certs from the certificate store */
- for (;;) {
- /* If we have enough, we break */
- if (depth < num)
- break;
- /* If we are self signed, we break */
- if (cert_self_signed(x))
- break;
- ok = ctx->get_issuer(&xtmp, ctx, x);
-
- if (ok < 0)
- goto end;
- if (ok == 0)
- break;
- x = xtmp;
- if (!sk_X509_push(ctx->chain, x)) {
- X509_free(xtmp);
- X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE);
- ok = 0;
- goto done;
- }
- num++;
- }
-
- /* we now have our chain, lets check it... */
- i = check_trust(ctx);
-
- /* If explicitly rejected error */
- if (i == X509_TRUST_REJECTED)
- goto end;
- /*
- * If it's not explicitly trusted then check if there is an alternative
- * chain that could be used. We only do this if we haven't already
- * checked via TRUSTED_FIRST and the user hasn't switched off alternate
- * chain checking
- */
- retry = 0;
- if (i != X509_TRUST_TRUSTED
- && !(ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST)
- && !(ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS)) {
- while (j-- > 1) {
- STACK_OF(X509) *chtmp = ctx->chain;
- xtmp2 = sk_X509_value(ctx->chain, j - 1);
- /*
- * Temporarily set chain to NULL so we don't discount
- * duplicates: the same certificate could be an untrusted
- * CA found in the trusted store.
- */
- ctx->chain = NULL;
- ok = ctx->get_issuer(&xtmp, ctx, xtmp2);
- ctx->chain = chtmp;
- if (ok < 0)
- goto end;
- /* Check if we found an alternate chain */
- if (ok > 0) {
- /*
- * Free up the found cert we'll add it again later
- */
- X509_free(xtmp);
-
- /*
- * Dump all the certs above this point - we've found an
- * alternate chain
- */
- while (num > j) {
- xtmp = sk_X509_pop(ctx->chain);
- X509_free(xtmp);
- num--;
- }
- ctx->last_untrusted = sk_X509_num(ctx->chain);
- retry = 1;
- break;
- }
- }
- }
- } while (retry);
-
- /*
- * If not explicitly trusted then indicate error unless it's a single
- * self signed certificate in which case we've indicated an error already
- * and set bad_chain == 1
- */
- if (i != X509_TRUST_TRUSTED && !bad_chain) {
- if ((chain_ss == NULL) || !ctx->check_issued(ctx, x, chain_ss)) {
- if (ctx->last_untrusted >= num)
- ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY;
- else
- ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT;
- ctx->current_cert = x;
- } else {
-
- sk_X509_push(ctx->chain, chain_ss);
- num++;
- ctx->last_untrusted = num;
- ctx->current_cert = chain_ss;
- ctx->error = X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN;
- chain_ss = NULL;
- }
-
- ctx->error_depth = num - 1;
- bad_chain = 1;
- ok = cb(0, ctx);
- if (!ok)
- goto end;
- }
-
- /* We have the chain complete: now we need to check its purpose */
- ok = check_chain_extensions(ctx);
-
- if (!ok)
- goto end;
-
- /* Check name constraints */
-
- ok = check_name_constraints(ctx);
-
- if (!ok)
- goto end;
-
- ok = check_id(ctx);
-
- if (!ok)
- goto end;
-
- /* We may as well copy down any DSA parameters that are required */
- X509_get_pubkey_parameters(NULL, ctx->chain);
-
- /*
- * Check revocation status: we do this after copying parameters because
- * they may be needed for CRL signature verification.
- */
-
- ok = ctx->check_revocation(ctx);
- if (!ok)
- goto end;
-
- i = X509_chain_check_suiteb(&ctx->error_depth, NULL, ctx->chain,
- ctx->param->flags);
- if (i != X509_V_OK) {
- ctx->error = i;
- ctx->current_cert = sk_X509_value(ctx->chain, ctx->error_depth);
- ok = cb(0, ctx);
- if (!ok)
- goto end;
- }
-
- /* At this point, we have a chain and need to verify it */
- if (ctx->verify != NULL)
- ok = ctx->verify(ctx);
- else
- ok = internal_verify(ctx);
- if (!ok)
- goto end;
+ ctx->num_untrusted = 1;
-#ifndef OPENSSL_NO_RFC3779
- /* RFC 3779 path validation, now that CRL check has been done */
- ok = v3_asid_validate_path(ctx);
- if (!ok)
- goto end;
- ok = v3_addr_validate_path(ctx);
- if (!ok)
- goto end;
-#endif
-
- /* If we get this far evaluate policies */
- if (!bad_chain && (ctx->param->flags & X509_V_FLAG_POLICY_CHECK))
- ok = ctx->check_policy(ctx);
- if (ok)
- goto done;
-
- end:
- X509_get_pubkey_parameters(NULL, ctx->chain);
- done:
- sk_X509_free(sktmp);
- X509_free(chain_ss);
- return ok;
+ return verify_chain(ctx);
}
/*
@@ -618,7 +375,7 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
}
/* Check all untrusted certificates */
- for (i = 0; i < ctx->last_untrusted; i++) {
+ for (i = 0; i == 0 || i < ctx->num_untrusted; i++) {
int ret;
x = sk_X509_value(ctx->chain, i);
if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL)
@@ -801,48 +558,66 @@ static int check_id(X509_STORE_CTX *ctx)
return 1;
}
-static int check_trust(X509_STORE_CTX *ctx)
+static int check_trust(X509_STORE_CTX *ctx, int num_untrusted)
{
- int i, ok;
+ int i, ok = 0;
X509 *x = NULL;
- int (*cb) (int xok, X509_STORE_CTX *xctx);
- cb = ctx->verify_cb;
- /* Check all trusted certificates in chain */
- for (i = ctx->last_untrusted; i < sk_X509_num(ctx->chain); i++) {
+ X509 *mx;
+ int (*cb) (int xok, X509_STORE_CTX *xctx) = ctx->verify_cb;
+ int num = sk_X509_num(ctx->chain);
+ int trust;
+
+ /*
+ * Check trusted certificates in chain at depth num_untrusted and up.
+ * Note, that depths 0..num_untrusted-1 may also contain trusted
+ * certificates, but the caller is expected to have already checked those,
+ * and wants to incrementally check just any added since.
+ */
+ for (i = num_untrusted; i < num; i++) {
x = sk_X509_value(ctx->chain, i);
- ok = X509_check_trust(x, ctx->param->trust, 0);
+ trust = X509_check_trust(x, ctx->param->trust, 0);
/* If explicitly trusted return trusted */
- if (ok == X509_TRUST_TRUSTED)
- return X509_TRUST_TRUSTED;
- /*
- * If explicitly rejected notify callback and reject if not
- * overridden.
- */
- if (ok == X509_TRUST_REJECTED) {
- ctx->error_depth = i;
- ctx->current_cert = x;
- ctx->error = X509_V_ERR_CERT_REJECTED;
- ok = cb(0, ctx);
- if (!ok)
- return X509_TRUST_REJECTED;
- }
+ if (trust == X509_TRUST_TRUSTED)
+ goto trusted;
+ if (trust == X509_TRUST_REJECTED)
+ goto rejected;
}
+
/*
- * If we accept partial chains and have at least one trusted certificate
- * return success.
+ * If we are looking at a trusted certificate, and accept partial chains,
+ * the chain is PKIX trusted.
*/
+ if (num_untrusted < num) {
+ if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN)
+ goto trusted;
+ return X509_TRUST_UNTRUSTED;
+ }
+
if (ctx->param->flags & X509_V_FLAG_PARTIAL_CHAIN) {
- X509 *mx;
- if (ctx->last_untrusted < sk_X509_num(ctx->chain))
- return X509_TRUST_TRUSTED;
+ /*
+ * Last-resort call with no new trusted certificates, check the leaf
+ * for a direct trust store match.
+ */
x = sk_X509_value(ctx->chain, 0);
mx = lookup_cert_match(ctx, x);
- if (mx) {
- (void)sk_X509_set(ctx->chain, 0, mx);
- X509_free(x);
- ctx->last_untrusted = 0;
- return X509_TRUST_TRUSTED;
+ if (!mx)
+ return X509_TRUST_UNTRUSTED;
+
+ /*
+ * Check explicit auxiliary trust/reject settings. If none are set,
+ * we'll accept X509_TRUST_UNTRUSTED when not self-signed.
+ */
+ trust = X509_check_trust(mx, ctx->param->trust, 0);
+ if (trust == X509_TRUST_REJECTED) {
+ X509_free(mx);
+ goto rejected;
}
+
+ /* Replace leaf with trusted match */
+ (void) sk_X509_set(ctx->chain, 0, mx);
+ X509_free(x);
+ ctx->num_untrusted = 0;
+ goto trusted;
}
/*
@@ -850,6 +625,18 @@ static int check_trust(X509_STORE_CTX *ctx)
* standard (no issuer cert) etc errors to be indicated.
*/
return X509_TRUST_UNTRUSTED;
+
+ rejected:
+ ctx->error_depth = i;
+ ctx->current_cert = x;
+ ctx->error = X509_V_ERR_CERT_REJECTED;
+ ok = cb(0, ctx);
+ if (!ok)
+ return X509_TRUST_REJECTED;
+ return X509_TRUST_UNTRUSTED;
+
+ trusted:
+ return X509_TRUST_TRUSTED;
}
static int check_revocation(X509_STORE_CTX *ctx)
@@ -1732,9 +1519,8 @@ static int internal_verify(X509_STORE_CTX *ctx)
cb = ctx->verify_cb;
- n = sk_X509_num(ctx->chain);
- ctx->error_depth = n - 1;
- n--;
+ n = sk_X509_num(ctx->chain) - 1;
+ ctx->error_depth = n;
xi = sk_X509_value(ctx->chain, n);
if (ctx->check_issued(ctx, xi, xi))
@@ -1756,7 +1542,10 @@ static int internal_verify(X509_STORE_CTX *ctx)
}
}
-/* ctx->error=0; not needed */
+ /*
+ * Do not clear ctx->error=0, it must be "sticky", only the user's callback
+ * is allowed to reset errors (at its own peril).
+ */
while (n >= 0) {
ctx->error_depth = n;
@@ -2269,7 +2058,7 @@ int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *store, X509 *x509,
ctx->cert = x509;
ctx->untrusted = chain;
ctx->crls = NULL;
- ctx->last_untrusted = 0;
+ ctx->num_untrusted = 0;
ctx->other_ctx = NULL;
ctx->valid = 0;
ctx->chain = NULL;
@@ -2380,7 +2169,7 @@ int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *store, X509 *x509,
}
return 1;
-err:
+ err:
X509_STORE_CTX_cleanup(ctx);
return 0;
}
@@ -2447,7 +2236,7 @@ int X509_STORE_CTX_get_explicit_policy(X509_STORE_CTX *ctx)
int X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx)
{
- return ctx->last_untrusted;
+ return ctx->num_untrusted;
}
int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name)
@@ -2469,3 +2258,267 @@ void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param)
X509_VERIFY_PARAM_free(ctx->param);
ctx->param = param;
}
+
+static int build_chain(X509_STORE_CTX *ctx)
+{
+ int (*cb) (int, X509_STORE_CTX *) = ctx->verify_cb;
+ int num = sk_X509_num(ctx->chain);
+ X509 *cert = sk_X509_value(ctx->chain, num - 1);
+ int ss = cert_self_signed(cert);
+ STACK_OF(X509) *sktmp = NULL;
+ unsigned int search;
+ int may_trusted = 1;
+ int may_alternate = 0;
+ int trust = X509_TRUST_UNTRUSTED;
+ int alt_untrusted = 0;
+ int depth;
+ int ok = 0;
+ int i;
+
+ /* Our chain starts with a single untrusted element. */
+ OPENSSL_assert(num == 1 && ctx->num_untrusted == num);
+
+#define S_DOUNTRUSTED (1 << 0) /* Search untrusted chain */
+#define S_DOTRUSTED (1 << 1) /* Search trusted store */
+#define S_DOALTERNATE (1 << 2) /* Retry with pruned alternate chain */
+ /*
+ * Set up search policy, untrusted if possible, trusted-first if enabled.
+ * If not trusted-first, and alternate chains are not disabled, try
+ * building an alternate chain if no luck with untrusted first.
+ */
+ search = (ctx->untrusted != NULL) ? S_DOUNTRUSTED : 0;
+ if (search == 0 || ctx->param->flags & X509_V_FLAG_TRUSTED_FIRST)
+ search |= S_DOTRUSTED;
+ else if (!(ctx->param->flags & X509_V_FLAG_NO_ALT_CHAINS))
+ may_alternate = 1;
+
+ /*
+ * Shallow-copy the stack of untrusted certificates (with TLS, this is
+ * typically the content of the peer's certificate message) so can make
+ * multiple passes over it, while free to remove elements as we go.
+ */
+ if (ctx->untrusted && (sktmp = sk_X509_dup(ctx->untrusted)) == NULL) {
+ X509err(X509_F_BUILD_CHAIN, ERR_R_MALLOC_FAILURE);
+ return 0;
+ }
+
+ /*
+ * Still absurdly large, but arithmetically safe, a lower hard upper bound
+ * might be reasonable.
+ */
+ if (ctx->param->depth > INT_MAX/2)
+ ctx->param->depth = INT_MAX/2;
+
+ /*
+ * Try to Extend the chain until we reach an ultimately trusted issuer.
+ * Build chains up to one longer the limit, later fail if we hit the limit,
+ * with an X509_V_ERR_CERT_CHAIN_TOO_LONG error code.
+ */
+ depth = ctx->param->depth + 1;
+
+ while (search != 0) {
+ X509 *x;
+ X509 *xtmp = NULL;
+
+ /*
+ * Look in the trust store if enabled for first lookup, or we've run
+ * out of untrusted issuers and search here is not disabled. When
+ * we exceed the depth limit, we simulate absence of a match.
+ */
+ if ((search & S_DOTRUSTED) != 0) {
+ STACK_OF(X509) *hide = ctx->chain;
+
+ i = num = sk_X509_num(ctx->chain);
+ if ((search & S_DOALTERNATE) != 0) {
+ /*
+ * As high up the chain as we can, look for an alternative
+ * trusted issuer of an untrusted certificate that currently
+ * has an untrusted issuer. We use the alt_untrusted variable
+ * to track how far up the chain we find the first match. It
+ * is only if and when we find a match, that we prune the chain
+ * and reset ctx->num_untrusted to the reduced count of
+ * untrusted certificates. While we're searching for such a
+ * match (which may never be found), it is neither safe nor
+ * wise to preemptively modify either the chain or
+ * ctx->num_untrusted.
+ *
+ * Note, like ctx->num_untrusted, alt_untrusted is a count of
+ * untrusted certificates, not a "depth".
+ */
+ i = alt_untrusted;
+ }
+ x = sk_X509_value(ctx->chain, i-1);
+
+ /* Suppress duplicate suppression */
+ ctx->chain = NULL;
+ ok = (depth < num) ? 0 : ctx->get_issuer(&xtmp, ctx, x);
+ ctx->chain = hide;
+
+ if (ok < 0) {
+ trust = X509_TRUST_REJECTED;
+ search = 0;
+ continue;
+ }
+
+ if (ok > 0) {
+ /*
+ * Alternative trusted issuer for a mid-chain untrusted cert?
+ * Pop the untrusted cert's successors and retry. We might now
+ * be able to complete a valid chain via the trust store. Note
+ * that despite the current trust-store match we might still
+ * fail complete the chain to a suitable trust-anchor, in which
+ * case we may prune some more untrusted certificates and try
+ * again. Thus the S_DOALTERNATE bit may yet be turned on
+ * again with an even shorter untrusted chain!
+ */
+ if ((search & S_DOALTERNATE) != 0) {
+ OPENSSL_assert(num > i && i > 0 && ss == 0);
+ search &= ~S_DOALTERNATE;
+ for (; num > i; --num)
+ X509_free(sk_X509_pop(ctx->chain));
+ ctx->num_untrusted = num;
+ }
+
+ /*
+ * Self-signed untrusted certificates get replaced by their
+ * trusted matching issuer. Otherwise, grow the chain.
+ */
+ if (ss == 0) {
+ if (!sk_X509_push(ctx->chain, x = xtmp)) {
+ X509_free(xtmp);
+ X509err(X509_F_BUILD_CHAIN, ERR_R_MALLOC_FAILURE);
+ trust = X509_TRUST_REJECTED;
+ search = 0;
+ continue;
+ }
+ ss = cert_self_signed(x);
+ } else if (num == ctx->num_untrusted) {
+ /*
+ * We have a self-signed certificate that has the same
+ * subject name (and perhaps keyid and/or serial number) as
+ * a trust-anchor. We must have an exact match to avoid
+ * possible impersonation via key substitution etc.
+ */
+ if (X509_cmp(x, xtmp) != 0) {
+ /* Self-signed untrusted mimic. */
+ X509_free(xtmp);
+ ok = 0;
+ } else {
+ X509_free(x);
+ ctx->num_untrusted = --num;
+ (void) sk_X509_set(ctx->chain, num, x = xtmp);
+ }
+ }
+
+ /*
+ * We've added a new trusted certificate to the chain, recheck
+ * trust. If not done, and not self-signed look deeper.
+ * Whether or not we're doing "trusted first", we no longer
+ * look for untrusted certificates from the peer's chain.
+ */
+ if (ok) {
+ OPENSSL_assert(ctx->num_untrusted <= num);
+ search &= ~S_DOUNTRUSTED;
+ switch (trust = check_trust(ctx, num)) {
+ case X509_TRUST_TRUSTED:
+ case X509_TRUST_REJECTED:
+ search = 0;
+ continue;
+ }
+ if (ss == 0)
+ continue;
+ }
+ }
+
+ /*
+ * No dispositive decision, and either self-signed or no match, if
+ * we were doing untrusted-first, and alt-chains are not disabled,
+ * do that, by repeatedly losing one untrusted element at a time,
+ * and trying to extend the shorted chain.
+ */
+ if ((search & S_DOUNTRUSTED) == 0) {
+ /* Continue search for a trusted issuer of a shorter chain? */
+ if ((search & S_DOALTERNATE) != 0 && --alt_untrusted > 0)
+ continue;
+ /* Still no luck and no fallbacks left? */
+ if (!may_alternate || (search & S_DOALTERNATE) != 0 ||
+ ctx->num_untrusted < 2)
+ break;
+ /* Search for a trusted issuer of a shorter chain */
+ search |= S_DOALTERNATE;
+ alt_untrusted = ctx->num_untrusted - 1;
+ ss = 0;
+ }
+ }
+
+ /*
+ * Extend chain with peer-provided certificates
+ */
+ if ((search & S_DOUNTRUSTED) != 0) {
+ num = sk_X509_num(ctx->chain);
+ OPENSSL_assert(num == ctx->num_untrusted);
+ x = sk_X509_value(ctx->chain, num-1);
+ xtmp = (depth < num) ? NULL : find_issuer(ctx, sktmp, x);
+
+ /*
+ * Once we run out of untrusted issuers, we stop looking for more
+ * and start looking only in the trust store if enabled.
+ */
+ if (xtmp == NULL) {
+ search &= ~S_DOUNTRUSTED;
+ if (may_trusted)
+ search |= S_DOTRUSTED;
+ continue;
+ }
+
+ if (!sk_X509_push(ctx->chain, x = xtmp)) {
+ X509err(X509_F_BUILD_CHAIN, ERR_R_MALLOC_FAILURE);
+ trust = X509_TRUST_REJECTED;
+ search = 0;
+ continue;
+ }
+ X509_up_ref(x);
+ ++ctx->num_untrusted;
+ ss = cert_self_signed(xtmp);
+
+ /*
+ * Not strictly necessary, but saves cycles looking at the same
+ * certificates over and over.
+ */
+ (void) sk_X509_delete_ptr(sktmp, x);
+ }
+ }
+ sk_X509_free(sktmp);
+
+ /*
+ * Last chance to make a trusted chain, check for direct leaf PKIX trust.
+ */
+ if (sk_X509_num(ctx->chain) <= depth) {
+ if (trust == X509_TRUST_UNTRUSTED &&
+ sk_X509_num(ctx->chain) == ctx->num_untrusted)
+ trust = check_trust(ctx, 1);
+ }
+
+ switch (trust) {
+ case X509_TRUST_TRUSTED:
+ return 1;
+ case X509_TRUST_REJECTED:
+ return 0;
+ case X509_TRUST_UNTRUSTED:
+ default:
+ num = sk_X509_num(ctx->chain);
+ ctx->current_cert = sk_X509_value(ctx->chain, num - 1);
+ ctx->error_depth = num-1;
+ if (num > depth)
+ ctx->error = X509_V_ERR_CERT_CHAIN_TOO_LONG;
+ else if (ss && sk_X509_num(ctx->chain) == 1)
+ ctx->error = X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT;
+ else if (ss)
+ ctx->error = X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN;
+ else if (ctx->num_untrusted == num)
+ ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY;
+ else
+ ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT;
+ return cb(0, ctx);
+ }
+}
diff --git a/include/openssl/x509.h b/include/openssl/x509.h
index 167aae8..4133fc1 100644
--- a/include/openssl/x509.h
+++ b/include/openssl/x509.h
@@ -1070,6 +1070,7 @@ void ERR_load_X509_strings(void);
/* Function codes. */
# define X509_F_ADD_CERT_DIR 100
+# define X509_F_BUILD_CHAIN 106
# define X509_F_BY_FILE_CTRL 101
# define X509_F_CHECK_POLICY 145
# define X509_F_DIR_CTRL 102
diff --git a/include/openssl/x509_vfy.h b/include/openssl/x509_vfy.h
index f949bd9..b78b59c 100644
--- a/include/openssl/x509_vfy.h
+++ b/include/openssl/x509_vfy.h
@@ -240,8 +240,8 @@ struct x509_store_ctx_st { /* X509_STORE_CTX */
/* The following is built up */
/* if 0, rebuild chain */
int valid;
- /* index of last untrusted cert */
- int last_untrusted;
+ /* number of untrusted certs */
+ int num_untrusted;
/* chain of X509s - built up and trusted */
STACK_OF(X509) *chain;
/* Valid policy tree */
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