tls: Call SSL_CTX_set_default_verify_paths by default

This removes the hard dependency on a CA bundle file existing in the
default path (which seems to not be the case on Debian, for example),
but results in a subtle behaviour change: if the CA bundle file does not
exist, the CA directory will be used instead, rather than failing hard.

I believe the only reason libtls insists on loading a CA bundle file
itself is so that it can be sandboxed afterwards, given that a file is
loaded all at once while a directory is only loaded as needed. If the
default CA bundle file exists, SSL_CTX_set_default_verify_paths will
still immediately load it, so sandboxing will still work. If it doesn't
exist, then the CA directory will be used, which will work well for
unsandboxed applications, but will likely fail during verification as it
tries to search the directory. Either way, if the CA bundle file does
not exist, a sandboxed application will not work. Enabling the use of
the CA directory, however, will allow more unsandboxed applications to
work.

Finally, to restore the original behaviour, an application can call
tls_config_set_ca_file(3) with the path returned by
tls_default_ca_cert_file(3).

1 files changed, 11 insertions, 12 deletions

diff --git a/tls.c b/tls.c
index 90458c4..26adb2b 100644
--- a/tls.c
+++ b/tls.c
@@ -609,14 +609,6 @@ tls_configure_ssl_verify(struct tls *ctx, SSL_CTX *ssl_ctx, int verify)
 	if (ctx->config->verify_cert == 0)
 		goto done;
 
-	/* If no CA has been specified, attempt to load the default. */
-	if (ctx->config->ca_mem == NULL && ctx->config->ca_path == NULL) {
-		if (tls_config_load_file(&ctx->error, "CA", tls_default_ca_cert_file(),
-		    &ca_mem, &ca_len) != 0)
-			goto err;
-		ca_free = ca_mem;
-	}
-
 	if (ca_mem != NULL) {
 		if (ca_len > INT_MAX) {
 			tls_set_errorx(ctx, "ca too long");
@@ -626,10 +618,17 @@ tls_configure_ssl_verify(struct tls *ctx, SSL_CTX *ssl_ctx, int verify)
 			tls_set_errorx(ctx, "ssl verify memory setup failure");
 			goto err;
 		}
-	} else if (SSL_CTX_load_verify_locations(ssl_ctx, NULL,
-	    ctx->config->ca_path) != 1) {
-		tls_set_errorx(ctx, "ssl verify locations failure");
-		goto err;
+	} else if (ctx->config->ca_path != NULL) {
+		if (SSL_CTX_load_verify_locations(ssl_ctx, NULL,
+			ctx->config->ca_path) != 1) {
+			tls_set_errorx(ctx, "ssl verify locations failure");
+			goto err;
+		}
+	} else {
+		if (SSL_CTX_set_default_verify_paths(ssl_ctx) != 1) {
+			tls_set_errorx(ctx, "ssl verify locations failure");
+			goto err;
+		}
 	}
 
 	if (crl_mem != NULL) {