[PATCH] Implement reading keys from stdin.

* [PATCH] Implement reading keys from stdin.
@ 2020-02-07 20:00 Hristo Venev
  2020-02-08 22:20 ` Jason A. Donenfeld
  0 siblings, 1 reply; 6+ messages in thread
From: Hristo Venev @ 2020-02-07 20:00 UTC (permalink / raw)
  To: wireguard

If "-" is specified as a path, the key is read as a single line from stdin. If
multiple "-" keys are specified, the order of the lines containing the keys is
the same as the order of the "-" arguments. An empty line means that there is
no key.
---
 src/config.c   | 68 +++++++++++++++++++++++++++++++++-----------------
 src/fuzz/set.c | 20 +++++++++++----
 2 files changed, 60 insertions(+), 28 deletions(-)

diff --git a/src/config.c b/src/config.c
index b8394a5..c5e5267 100644
--- a/src/config.c
+++ b/src/config.c
@@ -21,6 +21,7 @@
 #include "encoding.h"
 
 #define COMMENT_CHAR '#'
+#define KEY_LINE_MAX_LEN (WG_KEY_LEN_BASE64 + 1)
 
 static const char *get_value(const char *line, const char *key)
 {
@@ -118,42 +119,63 @@ static bool parse_keyfile(uint8_t key[static WG_KEY_LEN], const char *path)
 {
 	FILE *f;
 	int c;
-	char dst[WG_KEY_LEN_BASE64];
+	char dst[KEY_LINE_MAX_LEN];
+	bool is_file = false;
 	bool ret = false;
 
-	f = fopen(path, "r");
-	if (!f) {
-		perror("fopen");
-		return false;
+	if (!strcmp(path, "-"))
+		f = stdin;
+	else {
+		f = fopen(path, "r");
+		if (!f) {
+			perror("fopen");
+			return false;
+		}
+		is_file = true;
 	}
 
-	if (fread(dst, WG_KEY_LEN_BASE64 - 1, 1, f) != 1) {
-		/* If we're at the end and we didn't read anything, we're /dev/null or an empty file. */
-		if (!ferror(f) && feof(f) && !ftell(f)) {
-			memset(key, 0, WG_KEY_LEN);
-			ret = true;
-			goto out;
-		}
+	if (!fgets(dst, KEY_LINE_MAX_LEN, f)) {
+		dst[0] = '\0';
+	}
 
-		fprintf(stderr, "Invalid length key in key file\n");
+	if (ferror(f)) {
+		perror("fgets");
 		goto out;
 	}
-	dst[WG_KEY_LEN_BASE64 - 1] = '\0';
 
-	while ((c = getc(f)) != EOF) {
-		if (!isspace(c)) {
-			fprintf(stderr, "Found trailing character in key file: `%c'\n", c);
+	/* fgets stores the trailing newline into the buffer. If it is not there and
+	 * we have not hit EOF, there must be more of the line left. */
+	size_t n = strlen(dst);
+	if (n != 0 && dst[n - 1] == '\n') {
+		n--;
+		dst[n] = '\0';
+	} else if(!feof(f)) {
+		fprintf(stderr, "Key too long: `%s...'\n", dst);
+		goto out;
+	}
+
+	if (is_file) {
+		while ((c = getc(f)) != EOF) {
+			if (!isspace(c)) {
+				fprintf(stderr, "Found trailing character in key file: `%c'\n", c);
+				goto out;
+			}
+		}
+		if (ferror(f) && errno) {
+			perror("getc");
 			goto out;
 		}
 	}
-	if (ferror(f) && errno) {
-		perror("getc");
-		goto out;
-	}
-	ret = parse_key(key, dst);
+
+	if(n == 0) {
+		memset(key, 0, WG_KEY_LEN);
+		ret = true;
+	} else
+		ret = parse_key(key, dst);
 
 out:
-	fclose(f);
+	if (is_file)
+		fclose(f);
 	return ret;
 }
 
diff --git a/src/fuzz/set.c b/src/fuzz/set.c
index 2f40615..ded26e6 100644
--- a/src/fuzz/set.c
+++ b/src/fuzz/set.c
@@ -37,20 +37,30 @@ static FILE *hacked_fopen(const char *pathname, const char *mode)
 int LLVMFuzzerTestOneInput(const char *data, size_t data_len)
 {
 	char *argv[8192] = { "set", "wg0" }, *args;
-	size_t argc = 2;
+	size_t args_len, stdin_len, argc = 2;
+	FILE *input;
 
-	if (!data_len)
+	args_len = strnlen(data, data_len);
+	stdin_len = data_len - args_len;
+	/* POSIX (and therefore glibc) doesn't like fmemopen(_, 0, _) */
+	if (args_len == 0 || stdin_len == 0)
 		return 0;
 
-	assert((args = malloc(data_len)));
-	memcpy(args, data, data_len);
-	args[data_len - 1] = '\0';
+	assert((args = malloc(args_len + 1)));
+	memcpy(args, data, args_len);
+	args[args_len] = '\0';
+
+	assert((input = fmemopen((void*)(data + args_len), stdin_len, "r")));
+	/* discard null character, also permit tests where stdin is empty */
+	fgetc(input);
 
 	for (char *arg = strtok(args, " \t\n\r"); arg && argc < 8192; arg = strtok(NULL, " \t\n\r")) {
 		if (arg[0])
 			argv[argc++] = arg;
 	}
+	stdin = input;
 	set_main(argc, argv);
 	free(args);
+	fclose(stdin);
 	return 0;
 }
-- 
2.24.1

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