From: Matt Caswell Date: Tue, 27 Jan 2015 10:03:29 +0000 (+0000) Subject: In certain situations the server provided certificate chain may no longer be valid... X-Git-Tag: OpenSSL_1_0_1n~52 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=f7bf8e02dfcb2c02bc12a59276d0a3ba43e6c204;p=oweals%2Fopenssl.git In certain situations the server provided certificate chain may no longer be valid. However the issuer of the leaf, or some intermediate cert is in fact in the trust store. When building a trust chain if the first attempt fails, then try to see if alternate chains could be constructed that are trusted. RT3637 RT3621 Reviewed-by: Kurt Roeckx --- diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c index 559b5cdeb5..5c67ae6c57 100644 --- a/crypto/x509/x509_vfy.c +++ b/crypto/x509/x509_vfy.c @@ -151,11 +151,11 @@ static int x509_subject_cmp(X509 **a, X509 **b) int X509_verify_cert(X509_STORE_CTX *ctx) { - X509 *x, *xtmp, *chain_ss = NULL; + X509 *x, *xtmp, *xtmp2, *chain_ss = NULL; int bad_chain = 0; X509_VERIFY_PARAM *param = ctx->param; int depth, i, ok = 0; - int num; + int num, j, retry; int (*cb) (int xok, X509_STORE_CTX *xctx); STACK_OF(X509) *sktmp = NULL; if (ctx->cert == NULL) { @@ -224,85 +224,116 @@ int X509_verify_cert(X509_STORE_CTX *ctx) 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. */ - /* - * 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 (ctx->check_issued(ctx, x, 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; + 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 (ctx->check_issued(ctx, x, 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 { /* - * We have a match: replace certificate with store version so - * we get any trust settings. + * extract and save self signed certificate for later use */ - X509_free(x); - x = xtmp; - (void)sk_X509_set(ctx->chain, i - 1, x); - ctx->last_untrusted = 0; + chain_ss = sk_X509_pop(ctx->chain); + ctx->last_untrusted--; + num--; + j--; + x = sk_X509_value(ctx->chain, num - 1); } - } else { - /* - * extract and save self signed certificate for later use - */ - chain_ss = sk_X509_pop(ctx->chain); - ctx->last_untrusted--; - num--; - 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 (ctx->check_issued(ctx, x, x)) - break; - - ok = ctx->get_issuer(&xtmp, ctx, x); + /* 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 (ctx->check_issued(ctx, x, x)) + break; + ok = ctx->get_issuer(&xtmp, ctx, x); + if (ok < 0) + return ok; + 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); + return 0; + } + num++; + } - if (ok < 0) - return ok; - if (ok == 0) - break; + /* + * If we haven't got a least one certificate from our store then check + * if there is an alternative chain that could be used. + */ + retry = 0; + if (j == ctx->last_untrusted) { + while (j-- > 1) { + xtmp2 = sk_X509_value(ctx->chain, j - 1); + ok = ctx->get_issuer(&xtmp, ctx, xtmp2); + 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); - x = xtmp; - if (!sk_X509_push(ctx->chain, x)) { - X509_free(xtmp); - X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE); - return 0; + /* + * 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--; + } + retry = 1; + break; + } + } } - num++; - } - - /* we now have our chain, lets check it... */ + } while (retry); /* Is last certificate looked up self signed? */ if (!ctx->check_issued(ctx, x, x)) {