Git 2.19.5

This merges up the security fix from v2.17.5.

Signed-off-by: Jonathan Nieder <[email protected]>

Author: jrn

Documentation/RelNotes/2.17.5.txt

@@ -0,0 +1,22 @@
+Git v2.17.5 Release Notes
+=========================
+
+This release is to address a security issue: CVE-2020-11008
+
+Fixes since v2.17.4
+-------------------
+
+ * With a crafted URL that contains a newline or empty host, or lacks
+   a scheme, the credential helper machinery can be fooled into
+   providing credential information that is not appropriate for the
+   protocol in use and host being contacted.
+
+   Unlike the vulnerability CVE-2020-5260 fixed in v2.17.4, the
+   credentials are not for a host of the attacker's choosing; instead,
+   they are for some unspecified host (based on how the configured
+   credential helper handles an absent "host" parameter).
+
+   The attack has been made impossible by refusing to work with
+   under-specified credential patterns.
+
+Credit for finding the vulnerability goes to Carlo Arenas.

Documentation/RelNotes/2.18.4.txt

@@ -0,0 +1,5 @@
+Git v2.18.4 Release Notes
+=========================
+
+This release merges the security fix that appears in v2.17.5; see
+the release notes for that version for details.

Documentation/RelNotes/2.19.5.txt

@@ -0,0 +1,5 @@
+Git v2.19.5 Release Notes
+=========================
+
+This release merges the security fix that appears in v2.17.5; see
+the release notes for that version for details.

GIT-VERSION-GEN

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 GVF=GIT-VERSION-FILE
-DEF_VER=v2.19.4
+DEF_VER=v2.19.5
 
 LF='
 '

RelNotes

@@ -1 +1 @@
-Documentation/RelNotes/2.19.4.txt
+Documentation/RelNotes/2.19.5.txt

credential.c

@@ -89,6 +89,11 @@ static int proto_is_http(const char *s)
 
 static void credential_apply_config(struct credential *c)
 {
+	if (!c->host)
+		die(_("refusing to work with credential missing host field"));
+	if (!c->protocol)
+		die(_("refusing to work with credential missing protocol field"));
+
 	if (c->configured)
 		return;
 	git_config(credential_config_callback, c);
@@ -191,8 +196,11 @@ int credential_read(struct credential *c, FILE *fp)
 	return 0;
 }
 
-static void credential_write_item(FILE *fp, const char *key, const char *value)
+static void credential_write_item(FILE *fp, const char *key, const char *value,
+				  int required)
 {
+	if (!value && required)
+		BUG("credential value for %s is missing", key);
 	if (!value)
 		return;
 	if (strchr(value, '\n'))
@@ -202,11 +210,11 @@ static void credential_write_item(FILE *fp, const char *key, const char *value)
 
 void credential_write(const struct credential *c, FILE *fp)
 {
-	credential_write_item(fp, "protocol", c->protocol);
-	credential_write_item(fp, "host", c->host);
-	credential_write_item(fp, "path", c->path);
-	credential_write_item(fp, "username", c->username);
-	credential_write_item(fp, "password", c->password);
+	credential_write_item(fp, "protocol", c->protocol, 1);
+	credential_write_item(fp, "host", c->host, 1);
+	credential_write_item(fp, "path", c->path, 0);
+	credential_write_item(fp, "username", c->username, 0);
+	credential_write_item(fp, "password", c->password, 0);
 }
 
 static int run_credential_helper(struct credential *c,
@@ -352,8 +360,11 @@ int credential_from_url_gently(struct credential *c, const char *url,
 	 *   (3) proto://<user>:<pass>@<host>/...
 	 */
 	proto_end = strstr(url, "://");
-	if (!proto_end)
-		return 0;
+	if (!proto_end || proto_end == url) {
+		if (!quiet)
+			warning(_("url has no scheme: %s"), url);
+		return -1;
+	}
 	cp = proto_end + 3;
 	at = strchr(cp, '@');
 	colon = strchr(cp, ':');
@@ -374,10 +385,8 @@ int credential_from_url_gently(struct credential *c, const char *url,
 		host = at + 1;
 	}
 
-	if (proto_end - url > 0)
-		c->protocol = xmemdupz(url, proto_end - url);
-	if (slash - host > 0)
-		c->host = url_decode_mem(host, slash - host);
+	c->protocol = xmemdupz(url, proto_end - url);
+	c->host = url_decode_mem(host, slash - host);
 	/* Trim leading and trailing slashes from path */
 	while (*slash == '/')
 		slash++;
@@ -401,8 +410,6 @@ int credential_from_url_gently(struct credential *c, const char *url,
 
 void credential_from_url(struct credential *c, const char *url)
 {
-	if (credential_from_url_gently(c, url, 0) < 0) {
-		warning(_("skipping credential lookup for url: %s"), url);
-		credential_clear(c);
-	}
+	if (credential_from_url_gently(c, url, 0) < 0)
+		die(_("credential url cannot be parsed: %s"), url);
 }

fsck.c

@@ -9,6 +9,7 @@
 #include "tag.h"
 #include "fsck.h"
 #include "refs.h"
+#include "url.h"
 #include "utf8.h"
 #include "sha1-array.h"
 #include "decorate.h"
@@ -989,17 +990,147 @@ static int fsck_tag(struct tag *tag, const char *data,
 	return fsck_tag_buffer(tag, data, size, options);
 }
 
+/*
+ * Like builtin/submodule--helper.c's starts_with_dot_slash, but without
+ * relying on the platform-dependent is_dir_sep helper.
+ *
+ * This is for use in checking whether a submodule URL is interpreted as
+ * relative to the current directory on any platform, since \ is a
+ * directory separator on Windows but not on other platforms.
+ */
+static int starts_with_dot_slash(const char *str)
+{
+	return str[0] == '.' && (str[1] == '/' || str[1] == '\\');
+}
+
+/*
+ * Like starts_with_dot_slash, this is a variant of submodule--helper's
+ * helper of the same name with the twist that it accepts backslash as a
+ * directory separator even on non-Windows platforms.
+ */
+static int starts_with_dot_dot_slash(const char *str)
+{
+	return str[0] == '.' && starts_with_dot_slash(str + 1);
+}
+
+static int submodule_url_is_relative(const char *url)
+{
+	return starts_with_dot_slash(url) || starts_with_dot_dot_slash(url);
+}
+
+/*
+ * Count directory components that a relative submodule URL should chop
+ * from the remote_url it is to be resolved against.
+ *
+ * In other words, this counts "../" components at the start of a
+ * submodule URL.
+ *
+ * Returns the number of directory components to chop and writes a
+ * pointer to the next character of url after all leading "./" and
+ * "../" components to out.
+ */
+static int count_leading_dotdots(const char *url, const char **out)
+{
+	int result = 0;
+	while (1) {
+		if (starts_with_dot_dot_slash(url)) {
+			result++;
+			url += strlen("../");
+			continue;
+		}
+		if (starts_with_dot_slash(url)) {
+			url += strlen("./");
+			continue;
+		}
+		*out = url;
+		return result;
+	}
+}
+/*
+ * Check whether a transport is implemented by git-remote-curl.
+ *
+ * If it is, returns 1 and writes the URL that would be passed to
+ * git-remote-curl to the "out" parameter.
+ *
+ * Otherwise, returns 0 and leaves "out" untouched.
+ *
+ * Examples:
+ *   http::https://example.com/repo.git -> 1, https://example.com/repo.git
+ *   https://example.com/repo.git -> 1, https://example.com/repo.git
+ *   git://example.com/repo.git -> 0
+ *
+ * This is for use in checking for previously exploitable bugs that
+ * required a submodule URL to be passed to git-remote-curl.
+ */
+static int url_to_curl_url(const char *url, const char **out)
+{
+	/*
+	 * We don't need to check for case-aliases, "http.exe", and so
+	 * on because in the default configuration, is_transport_allowed
+	 * prevents URLs with those schemes from being cloned
+	 * automatically.
+	 */
+	if (skip_prefix(url, "http::", out) ||
+	    skip_prefix(url, "https::", out) ||
+	    skip_prefix(url, "ftp::", out) ||
+	    skip_prefix(url, "ftps::", out))
+		return 1;
+	if (starts_with(url, "http://") ||
+	    starts_with(url, "https://") ||
+	    starts_with(url, "ftp://") ||
+	    starts_with(url, "ftps://")) {
+		*out = url;
+		return 1;
+	}
+	return 0;
+}
+
 static int check_submodule_url(const char *url)
 {
-	struct credential c = CREDENTIAL_INIT;
-	int ret;
+	const char *curl_url;
 
 	if (looks_like_command_line_option(url))
 		return -1;
 
-	ret = credential_from_url_gently(&c, url, 1);
-	credential_clear(&c);
-	return ret;
+	if (submodule_url_is_relative(url)) {
+		char *decoded;
+		const char *next;
+		int has_nl;
+
+		/*
+		 * This could be appended to an http URL and url-decoded;
+		 * check for malicious characters.
+		 */
+		decoded = url_decode(url);
+		has_nl = !!strchr(decoded, '\n');
+
+		free(decoded);
+		if (has_nl)
+			return -1;
+
+		/*
+		 * URLs which escape their root via "../" can overwrite
+		 * the host field and previous components, resolving to
+		 * URLs like https::example.com/submodule.git and
+		 * https:///example.com/submodule.git that were
+		 * susceptible to CVE-2020-11008.
+		 */
+		if (count_leading_dotdots(url, &next) > 0 &&
+		    (*next == ':' || *next == '/'))
+			return -1;
+	}
+
+	else if (url_to_curl_url(url, &curl_url)) {
+		struct credential c = CREDENTIAL_INIT;
+		int ret = 0;
+		if (credential_from_url_gently(&c, curl_url, 1) ||
+		    !*c.host)
+			ret = -1;
+		credential_clear(&c);
+		return ret;
+	}
+
+	return 0;
 }
 
 struct fsck_gitmodules_data {

http.c

@@ -528,6 +528,7 @@ static int has_cert_password(void)
 		return 0;
 	if (!cert_auth.password) {
 		cert_auth.protocol = xstrdup("cert");
+		cert_auth.host = xstrdup("");
 		cert_auth.username = xstrdup("");
 		cert_auth.path = xstrdup(ssl_cert);
 		credential_fill(&cert_auth);