Merge branch 'jk/transfer-limit-redirection' into maint-2.3

Documentation/git.txt

@@ -1071,11 +1071,6 @@ GIT_ICASE_PATHSPECS::
 
 	  - any external helpers are named by their protocol (e.g., use
 	    `hg` to allow the `git-remote-hg` helper)
-+
-Note that this controls only git's internal protocol selection.
-If libcurl is used (e.g., by the `http` transport), it may
-redirect to other protocols. There is not currently any way to
-restrict this.
 
 
 Discussion[[Discussion]]

http.c

@@ -8,6 +8,7 @@
 #include "credential.h"
 #include "version.h"
 #include "pkt-line.h"
+#include "transport.h"
 
 int active_requests;
 int http_is_verbose;
@@ -303,6 +304,7 @@ static void set_curl_keepalive(CURL *c)
 static CURL *get_curl_handle(void)
 {
 	CURL *result = curl_easy_init();
+	long allowed_protocols = 0;
 
 	if (!result)
 		die("curl_easy_init failed");
@@ -350,11 +352,27 @@ static CURL *get_curl_handle(void)
 	}
 
 	curl_easy_setopt(result, CURLOPT_FOLLOWLOCATION, 1);
+	curl_easy_setopt(result, CURLOPT_MAXREDIRS, 20);
 #if LIBCURL_VERSION_NUM >= 0x071301
 	curl_easy_setopt(result, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 #elif LIBCURL_VERSION_NUM >= 0x071101
 	curl_easy_setopt(result, CURLOPT_POST301, 1);
 #endif
+#if LIBCURL_VERSION_NUM >= 0x071304
+	if (is_transport_allowed("http"))
+		allowed_protocols |= CURLPROTO_HTTP;
+	if (is_transport_allowed("https"))
+		allowed_protocols |= CURLPROTO_HTTPS;
+	if (is_transport_allowed("ftp"))
+		allowed_protocols |= CURLPROTO_FTP;
+	if (is_transport_allowed("ftps"))
+		allowed_protocols |= CURLPROTO_FTPS;
+	curl_easy_setopt(result, CURLOPT_REDIR_PROTOCOLS, allowed_protocols);
+#else
+	if (transport_restrict_protocols())
+		warning("protocol restrictions not applied to curl redirects because\n"
+			"your curl version is too old (>= 7.19.4)");
+#endif
 
 	if (getenv("GIT_CURL_VERBOSE"))
 		curl_easy_setopt(result, CURLOPT_VERBOSE, 1);

t/lib-httpd/apache.conf

@@ -119,6 +119,10 @@ RewriteRule ^/smart-redir-perm/(.*)$ /smart/$1 [R=301]
 RewriteRule ^/smart-redir-temp/(.*)$ /smart/$1 [R=302]
 RewriteRule ^/smart-redir-auth/(.*)$ /auth/smart/$1 [R=301]
 RewriteRule ^/smart-redir-limited/(.*)/info/refs$ /smart/$1/info/refs [R=301]
+RewriteRule ^/ftp-redir/(.*)$ ftp://localhost:1000/$1 [R=302]
+
+RewriteRule ^/loop-redir/x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-(.*) /$1 [R=302]
+RewriteRule ^/loop-redir/(.*)$ /loop-redir/x-$1 [R=302]
 
 <IfDefine SSL>
 LoadModule ssl_module modules/mod_ssl.so

t/t5812-proto-disable-http.sh

@@ -16,5 +16,18 @@ test_expect_success 'create git-accessible repo' '
 
 test_proto "smart http" http "$HTTPD_URL/smart/repo.git"
 
+test_expect_success 'curl redirects respect whitelist' '
+	test_must_fail env GIT_ALLOW_PROTOCOL=http:https \
+		git clone "$HTTPD_URL/ftp-redir/repo.git" 2>stderr &&
+	{
+		test_i18ngrep "ftp.*disabled" stderr ||
+		test_i18ngrep "your curl version is too old"
+	}
+'
+
+test_expect_success 'curl limits redirects' '
+	test_must_fail git clone "$HTTPD_URL/loop-redir/smart/repo.git"
+'
+
 stop_httpd
 test_done

transport.c

@@ -909,18 +909,40 @@ static int external_specification_len(const char *url)
 	return strchr(url, ':') - url;
 }
 
-void transport_check_allowed(const char *type)
+static const struct string_list *protocol_whitelist(void)
 {
-	struct string_list allowed = STRING_LIST_INIT_DUP;
+	static int enabled = -1;
+	static struct string_list allowed = STRING_LIST_INIT_DUP;
+
+	if (enabled < 0) {
 		const char *v = getenv("GIT_ALLOW_PROTOCOL");
+		if (v) {
+			string_list_split(&allowed, v, ':', -1);
+			string_list_sort(&allowed);
+			enabled = 1;
+		} else {
+			enabled = 0;
+		}
+	}
 
-	if (!v)
-		return;
+	return enabled ? &allowed : NULL;
+}
 
-	string_list_split(&allowed, v, ':', -1);
-	if (!unsorted_string_list_has_string(&allowed, type))
+int is_transport_allowed(const char *type)
+{
+	const struct string_list *allowed = protocol_whitelist();
+	return !allowed || string_list_has_string(allowed, type);
+}
+
+void transport_check_allowed(const char *type)
+{
+	if (!is_transport_allowed(type))
 		die("transport '%s' not allowed", type);
-	string_list_clear(&allowed, 0);
+}
+
+int transport_restrict_protocols(void)
+{
+	return !!protocol_whitelist();
 }
 
 struct transport *transport_get(struct remote *remote, const char *url)

transport.h

@@ -132,13 +132,24 @@ struct transport {
 /* Returns a transport suitable for the url */
 struct transport *transport_get(struct remote *, const char *);
 
+/*
+ * Check whether a transport is allowed by the environment. Type should
+ * generally be the URL scheme, as described in Documentation/git.txt
+ */
+int is_transport_allowed(const char *type);
+
 /*
  * Check whether a transport is allowed by the environment,
- * and die otherwise. type should generally be the URL scheme,
- * as described in Documentation/git.txt
+ * and die otherwise.
  */
 void transport_check_allowed(const char *type);
 
+/*
+ * Returns true if the user has attempted to turn on protocol
+ * restrictions at all.
+ */
+int transport_restrict_protocols(void);
+
 /* Transport options which apply to git:// and scp-style URLs */
 
 /* The program to use on the remote side to send a pack */