From: Alberto Leiva Popper <ydahhrk@gmail.com>
Date: Mon, 11 Mar 2024 20:22:38 +0000 (-0600)
Subject: Reject HTTP redirects to different origins
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f29f9e6421feb9f57e74f408af797b38013b84be;p=thirdparty%2FFORT-validator.git

Reject HTTP redirects to different origins

Prevents malicious RRDP servers from wasting other servers' bandwidth.

Second half of draft-spaghetti-sidrops-rrdp-same-origin-00.

Thanks to Job Snijders for reporting this.
---

diff --git a/src/http/http.c b/src/http/http.c
index 0de473bb..b783ba1b 100644
--- a/src/http/http.c
+++ b/src/http/http.c
@@ -131,9 +131,6 @@ http_easy_init(struct http_handler *handler, curl_off_t ims)
 
 	setopt_str(result, CURLOPT_USERAGENT, config_get_http_user_agent());
 
-	setopt_long(result, CURLOPT_FOLLOWLOCATION, 1);
-	setopt_long(result, CURLOPT_MAXREDIRS, config_get_max_redirs());
-
 	setopt_long(result, CURLOPT_CONNECTTIMEOUT,
 	    config_get_http_connect_timeout());
 	setopt_long(result, CURLOPT_TIMEOUT,
@@ -197,7 +194,7 @@ curl_err_string(struct http_handler *handler, CURLcode res)
 }
 
 static int
-validate_file_size(char const *uri, struct write_callback_arg *args)
+validate_file_size(struct write_callback_arg *args)
 {
 	float ratio;
 
@@ -254,72 +251,107 @@ http_fetch(char const *src, char const *dst, curl_off_t ims, bool *changed)
 	struct write_callback_arg args;
 	CURLcode res;
 	long http_code;
+	char *redirect;
+	unsigned int r;
 	int error;
 
 	error = http_easy_init(&handler, ims);
 	if (error)
 		return error;
 
-	handler.errbuf[0] = 0;
-	setopt_str(handler.curl, CURLOPT_URL, src);
+	redirect = NULL;
+	r = 0;
 
-	args.total_bytes = 0;
-	args.error = 0;
-	args.file_name = dst;
-	args.file = NULL;
-	setopt_writedata(handler.curl, &args);
+	do {
+		handler.errbuf[0] = 0;
+		setopt_str(handler.curl, CURLOPT_URL, (redirect != NULL) ? redirect : src);
 
-	res = curl_easy_perform(handler.curl); /* write_callback() */
-	if (args.file != NULL)
-		file_close(args.file);
-	pr_val_debug("Done. Total bytes transferred: %zu", args.total_bytes);
+		args.total_bytes = 0;
+		args.error = 0;
+		args.file_name = dst;
+		args.file = NULL;
+		setopt_writedata(handler.curl, &args);
 
-	args.error = validate_file_size(src, &args);
-	if (args.error) {
-		error = args.error;
-		goto end;
-	}
+		res = curl_easy_perform(handler.curl); /* write_callback() */
+		if (args.file != NULL)
+			file_close(args.file);
+		pr_val_debug("Done. Total bytes transferred: %zu", args.total_bytes);
 
-	args.error = get_http_response_code(&handler, &http_code, src);
-	if (args.error) {
-		error = args.error;
-		goto end;
-	}
+		args.error = validate_file_size(&args);
+		if (args.error) {
+			error = args.error;
+			goto end;
+		}
 
-	if (res != CURLE_OK) {
-		pr_val_err("Error requesting URL: %s. (HTTP code: %ld)",
-		    curl_err_string(&handler, res), http_code);
+		args.error = get_http_response_code(&handler, &http_code, src);
+		if (args.error) {
+			error = args.error;
+			goto end;
+		}
+
+		if (res != CURLE_OK) {
+			pr_val_err("Error requesting URL: %s. (HTTP code: %ld)",
+			    curl_err_string(&handler, res), http_code);
+
+			switch (res) {
+			case CURLE_FILESIZE_EXCEEDED:
+				error = -EFBIG; /* Do not retry */
+				goto end;
+			case CURLE_OPERATION_TIMEDOUT:
+			case CURLE_COULDNT_RESOLVE_HOST:
+			case CURLE_COULDNT_RESOLVE_PROXY:
+			case CURLE_FTP_ACCEPT_TIMEOUT:
+				error = EAGAIN; /* Retry */
+				goto end;
+			default:
+				error = handle_http_response_code(http_code);
+				goto end;
+			}
+		}
 
-		switch (res) {
-		case CURLE_FILESIZE_EXCEEDED:
-			error = -EFBIG; /* Do not retry */
+		if (http_code >= 400 || http_code == 204) {
+			pr_val_err("HTTP result code: %ld", http_code);
+			error = handle_http_response_code(http_code);
+			goto end;
+		}
+		if (http_code == 304) {
+			/* Write callback not called, no file to remove. */
+			pr_val_debug("Not modified.");
+			error = 0;
 			goto end;
-		case CURLE_OPERATION_TIMEDOUT:
-		case CURLE_COULDNT_RESOLVE_HOST:
-		case CURLE_COULDNT_RESOLVE_PROXY:
-		case CURLE_FTP_ACCEPT_TIMEOUT:
-			error = EAGAIN; /* Retry */
+		}
+
+		if (redirect != NULL) {
+			free(redirect);
+			redirect = NULL;
+		}
+
+		res = curl_easy_getinfo(handler.curl, CURLINFO_REDIRECT_URL, &redirect);
+		if (res != CURLE_OK) {
+			error = pr_op_err("curl_easy_getinfo(CURLINFO_REDIRECT_URL) returned %u.", res);
+			redirect = NULL;
 			goto end;
-		case CURLE_TOO_MANY_REDIRECTS:
-			error = -EINVAL;
+		}
+
+		if (redirect == NULL)
+			break;
+		if (!str_same_origin(src, redirect)) {
+			error = pr_val_err("%s is redirecting to %s; disallowing because of different origin.",
+			   src, redirect);
+			redirect = NULL;
 			goto end;
-		default:
-			error = handle_http_response_code(http_code);
+		}
+
+		r++;
+		if (r > config_get_max_redirs()) {
+			error = pr_val_err("Too many redirects.");
+			redirect = NULL;
 			goto end;
 		}
-	}
 
-	if (http_code >= 400 || http_code == 204) {
-		pr_val_err("HTTP result code: %ld", http_code);
-		error = handle_http_response_code(http_code);
-		goto end;
-	}
-	if (http_code == 304) {
-		/* Write callback not called, no file to remove. */
-		pr_val_debug("Not modified.");
-		error = 0;
-		goto end;
-	}
+		/* The original redirect is destroyed during the next curl_easy_perform(). */
+		redirect = pstrdup(redirect);
+	} while (true);
 
 	pr_val_debug("HTTP result code: %ld", http_code);
 	error = 0;
@@ -329,6 +361,8 @@ http_fetch(char const *src, char const *dst, curl_off_t ims, bool *changed)
 end:	http_easy_cleanup(&handler);
 	if (error)
 		file_rm_f(dst);
+	if (redirect != NULL)
+		free(redirect);
 	return error;
 }
 
diff --git a/src/types/uri.c b/src/types/uri.c
index 4b64d863..ee6854e5 100644
--- a/src/types/uri.c
+++ b/src/types/uri.c
@@ -530,15 +530,11 @@ uri_equals(struct rpki_uri *u1, struct rpki_uri *u2)
 }
 
 bool
-uri_same_origin(struct rpki_uri *u1, struct rpki_uri *u2)
+str_same_origin(char const *g1, char const *g2)
 {
-	char const *g1, *g2;
 	size_t c, slashes;
 
-	g1 = u1->global;
-	g2 = u2->global;
 	slashes = 0;
-
 	for (c = 0; g1[c] == g2[c]; c++) {
 		switch (g1[c]) {
 		case '/':
@@ -559,6 +555,12 @@ uri_same_origin(struct rpki_uri *u1, struct rpki_uri *u2)
 	return false;
 }
 
+bool
+uri_same_origin(struct rpki_uri *u1, struct rpki_uri *u2)
+{
+	return str_same_origin(u1->global, u2->global);
+}
+
 /* @ext must include the period. */
 bool
 uri_has_extension(struct rpki_uri *uri, char const *ext)
diff --git a/src/types/uri.h b/src/types/uri.h
index 3105757c..8cc93824 100644
--- a/src/types/uri.h
+++ b/src/types/uri.h
@@ -71,6 +71,7 @@ char const *uri_get_global(struct rpki_uri *);
 char const *uri_get_local(struct rpki_uri *);
 
 bool uri_equals(struct rpki_uri *, struct rpki_uri *);
+bool str_same_origin(char const *, char const *);
 bool uri_same_origin(struct rpki_uri *, struct rpki_uri *);
 bool uri_has_extension(struct rpki_uri *, char const *);
 bool uri_is_certificate(struct rpki_uri *);
diff --git a/test/types/uri_test.c b/test/types/uri_test.c
index fcc47a5a..35dfe018 100644
--- a/test/types/uri_test.c
+++ b/test/types/uri_test.c
@@ -196,35 +196,25 @@ START_TEST(check_caged)
 }
 END_TEST
 
-static bool
-same_origin(char *g1, char *g2)
-{
-	struct rpki_uri u1 = { .type = UT_NOTIF, .references = 1 };
-	struct rpki_uri u2 = { .type = UT_TMP,   .references = 1 };
-	u1.global = g1;
-	u2.global = g2;
-	return uri_same_origin(&u1, &u2);
-}
-
 START_TEST(test_same_origin)
 {
-	ck_assert_int_eq(true,	same_origin("https://a.b.c/d/e/f",	"https://a.b.c/g/h/i"));
-	ck_assert_int_eq(false,	same_origin("https://a.b.cc/d/e/f",	"https://a.b.c/g/h/i"));
-	ck_assert_int_eq(false,	same_origin("https://a.b.c/d/e/f",	"https://a.b.cc/g/h/i"));
-	ck_assert_int_eq(true,	same_origin("https://a.b.c",		"https://a.b.c"));
-	ck_assert_int_eq(true,	same_origin("https://a.b.c/",		"https://a.b.c"));
-	ck_assert_int_eq(true,	same_origin("https://a.b.c",		"https://a.b.c/"));
-	ck_assert_int_eq(true,	same_origin("https://",			"https://"));
-	ck_assert_int_eq(false,	same_origin("https://",			"https://a"));
-	ck_assert_int_eq(false,	same_origin("https://a",		"https://b"));
+	ck_assert_int_eq(true,	str_same_origin("https://a.b.c/d/e/f",	"https://a.b.c/g/h/i"));
+	ck_assert_int_eq(false,	str_same_origin("https://a.b.cc/d/e/f",	"https://a.b.c/g/h/i"));
+	ck_assert_int_eq(false,	str_same_origin("https://a.b.c/d/e/f",	"https://a.b.cc/g/h/i"));
+	ck_assert_int_eq(true,	str_same_origin("https://a.b.c",	"https://a.b.c"));
+	ck_assert_int_eq(true,	str_same_origin("https://a.b.c/",	"https://a.b.c"));
+	ck_assert_int_eq(true,	str_same_origin("https://a.b.c",	"https://a.b.c/"));
+	ck_assert_int_eq(true,	str_same_origin("https://",		"https://"));
+	ck_assert_int_eq(false,	str_same_origin("https://",		"https://a"));
+	ck_assert_int_eq(false,	str_same_origin("https://a",		"https://b"));
 
 	/* Undefined, but manhandle the code anyway */
-	ck_assert_int_eq(false,	same_origin("",				""));
-	ck_assert_int_eq(false,	same_origin("ht",			"ht"));
-	ck_assert_int_eq(false,	same_origin("https:",			"https:"));
-	ck_assert_int_eq(false,	same_origin("https:/",			"https:/"));
-	ck_assert_int_eq(false,	same_origin("https:/a",			"https:/a"));
-	ck_assert_int_eq(true,	same_origin("https:/a/",		"https:/a/"));
+	ck_assert_int_eq(false,	str_same_origin("",			""));
+	ck_assert_int_eq(false,	str_same_origin("ht",			"ht"));
+	ck_assert_int_eq(false,	str_same_origin("https:",		"https:"));
+	ck_assert_int_eq(false,	str_same_origin("https:/",		"https:/"));
+	ck_assert_int_eq(false,	str_same_origin("https:/a",		"https:/a"));
+	ck_assert_int_eq(true,	str_same_origin("https:/a/",		"https:/a/"));
 }
 END_TEST