commit:7a1c06730feac986e1bf29f202b6afe910b56f14
author:Chip Black
committer:Chip Black
date:Sat Jun 28 23:55:15 2014 -0500
parents:abeaeafe6860bef22ab8469261d3198efc8358c1
Update password storage to a more compact form

Instead of using three files to store version, password, and salt, pack
it all into a struct and write it as a single file.  Also added locking
for password updates, and removed raw password get functions from the
exposed functions in common/auth.h.
diff --git a/common/auth.c b/common/auth.c
line changes: +98/-31
index ef548ec..6638748
--- a/common/auth.c
+++ b/common/auth.c
@@ -18,8 +18,7 @@
 
 int auth_set_password(const char *username, const char *password) {
 	char filename[FILENAME_MAX];
-	uint8_t pwhash[SCRYPT_OUTPUT_SIZE];
-	uint8_t salt[SCRYPT_SALT_SIZE];
+	struct auth_v2 auth;
 	int fd, n, r;
 
 	if (!valid_name(username) || !blerg_exists(username))
@@ -29,39 +28,35 @@ int auth_set_password(const char *username, const char *password) {
 	if (n > MAX_PASSWORD_LENGTH)
 		return 0;
 
+	/* Clear the auth structure */
+	memset(&auth, 0, sizeof(struct auth_v2));
+
+	/* Set the auth version */
+	auth.header.version = 2;
+
 	/* Gather some salt */
 	fd = open("/dev/urandom", O_RDONLY);
 	if (fd == -1) {
-		perror("Could not open /dev/urandom\n");
+		perror("Could not open /dev/urandom");
 		return 0;
 	}
-	read(fd, salt, SCRYPT_SALT_SIZE);
+	read(fd, auth.salt, SCRYPT_SALT_SIZE);
 	close(fd);
 
-	r = crypto_scrypt((const uint8_t *)password, n, salt, SCRYPT_SALT_SIZE, SCRYPT_N, SCRYPT_r, SCRYPT_p, pwhash, SCRYPT_OUTPUT_SIZE);
+	r = crypto_scrypt((const uint8_t *)password, n, auth.salt, SCRYPT_SALT_SIZE, SCRYPT_N, SCRYPT_r, SCRYPT_p, auth.password, SCRYPT_OUTPUT_SIZE);
 	if (r != 0) {
 		fprintf(stderr, "Failure in scrypt for %s\n", username);
 		return 0;
 	}
 
-	/* Write the password */
-	snprintf(filename, FILENAME_MAX, "%s/%s/password", blergconf.data_path, username);
-	fd = open(filename, O_WRONLY | O_CREAT, 0600);
-	write(fd, pwhash, SCRYPT_OUTPUT_SIZE);
-	close(fd);
-
-	/* Write the salt */
-	snprintf(filename, FILENAME_MAX, "%s/%s/password_salt", blergconf.data_path, username);
+	/* Write the data */
+	snprintf(filename, FILENAME_MAX, "%s/%s/auth", blergconf.data_path, username);
 	fd = open(filename, O_WRONLY | O_CREAT, 0600);
-	write(fd, salt, SCRYPT_SALT_SIZE);
+	flock(fd, LOCK_EX);
+	write(fd, &auth, sizeof(struct auth_v2));
+	flock(fd, LOCK_UN);
 	close(fd);
 
-	/* Mark this as a version 1 password */
-	snprintf(filename, FILENAME_MAX, "%s/%s/password_version", blergconf.data_path, username);
-	fd = open(filename, O_WRONLY | O_CREAT, 0600);
-	write(fd, "1\n", 2);
-	close(fd);
-	
 	return 1;
 }
 
@@ -69,8 +64,28 @@ int auth_get_password_version(const char *username) {
 	char filename[FILENAME_MAX];
 	int fd;
 	char str[4];
+	struct auth_header ah;
 	int len = 0;
 
+	snprintf(filename, FILENAME_MAX, "%s/%s/auth", blergconf.data_path, username);
+	if (access(filename, F_OK) == 0) {
+		fd = open(filename, O_RDONLY);
+		if (fd == -1)
+			return -1;
+		len = read(fd, &ah, sizeof(struct auth_header));
+		close(fd);
+
+		if (len < 0) {
+			perror("reading auth file");
+			return -1;
+		} else if (len < sizeof(struct auth_header)) {
+			fprintf(stderr, "Short read on while determining auth version for %s", username);
+			return -1;
+		}
+
+		return ah.version;
+	}
+
 	snprintf(filename, FILENAME_MAX, "%s/%s/password_version", blergconf.data_path, username);
 	if (access(filename, F_OK) != 0) {
 		return 0;
@@ -82,7 +97,7 @@ int auth_get_password_version(const char *username) {
 	len = read(fd, str, 4);
 	close(fd);
 
-	if (len < -1) {
+	if (len < 0) {
 		perror("auth_get_password_version");
 		return -1;
 	}
@@ -178,30 +193,73 @@ int auth_check_password_v0(const char *username, const char *password) {
 		return 0;
 }
 
-int auth_check_password_v1(const char *username, const char *password) {
-	unsigned char epw[SCRYPT_OUTPUT_SIZE];
-	uint8_t esalt[SCRYPT_SALT_SIZE];
-	unsigned char givenpw[SCRYPT_OUTPUT_SIZE];
-	int r;
+int auth_get_data(const char *username, void *data, size_t data_len) {
+	char filename[FILENAME_MAX];
+	int fd;
+	int len = 0;
 
-	if (auth_get_password(username, (char *)epw) == 0)
+	if (!valid_name(username))
 		return 0;
 
-	if (auth_get_salt(username, esalt) == 0)
+	snprintf(filename, FILENAME_MAX, "%s/%s/auth", blergconf.data_path, username);
+	fd = open(filename, O_RDONLY);
+	if (fd == -1)
 		return 0;
+	flock(fd, LOCK_SH);
+	len = read(fd, data, data_len);
+	flock(fd, LOCK_UN);
+	close(fd);
 
-	r = crypto_scrypt((const uint8_t *)password, strlen(password), esalt, SCRYPT_SALT_SIZE, SCRYPT_N, SCRYPT_r, SCRYPT_p, givenpw, SCRYPT_OUTPUT_SIZE);
+	if (len < 0) {
+		perror("auth_get_data");
+		return 0;
+	} else if (len < data_len) {
+		fprintf(stderr, "Short read getting auth data\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+int auth_check_scrypt(struct auth_v2 *auth, const char *username, const char *password) {
+	unsigned char givenpw[SCRYPT_OUTPUT_SIZE];
+	int r;
+
+	r = crypto_scrypt(password, strlen(password), auth->salt, SCRYPT_SALT_SIZE, SCRYPT_N, SCRYPT_r, SCRYPT_p, givenpw, SCRYPT_OUTPUT_SIZE);
 	if (r != 0) {
 		fprintf(stderr, "Failure in scrypt for %s\n", username);
 		return 0;
 	}
 
-	if (memcmp(givenpw, epw, SCRYPT_OUTPUT_SIZE) == 0)
+	if (memcmp(givenpw, auth->password, SCRYPT_OUTPUT_SIZE) == 0)
 		return 1;
 	else
 		return 0;
 }
 
+int auth_check_password_v1(const char *username, const char *password) {
+	struct auth_v2 auth;
+	int r;
+
+	if (auth_get_password(username, (char *)auth.password) == 0)
+		return 0;
+
+	if (auth_get_salt(username, auth.salt) == 0)
+		return 0;
+
+	return auth_check_scrypt(&auth, username, password);
+}
+
+int auth_check_password_v2(const char *username, const char *password) {
+	struct auth_v2 auth;
+	int r;
+
+	if (auth_get_data(username, (void *) &auth, sizeof(struct auth_v2)) == 0)
+		return 0;
+
+	return auth_check_scrypt(&auth, username, password);
+}
+
 int auth_check_password(const char *username, const char *password) {
 	int version = auth_get_password_version(username);
 
@@ -216,7 +274,16 @@ int auth_check_password(const char *username, const char *password) {
 		}
 		break;
 	case 1:
-		return auth_check_password_v1(username, password);
+		if (auth_check_password_v1(username, password)) {
+			/* Refresh to the newest version */
+			auth_set_password(username, password);
+			return 1;
+		} else {
+			return 0;
+		}
+		break;
+	case 2:
+		return auth_check_password_v2(username, password);
 	}
 	fprintf(stderr, "auth_check_password fell through. Bad password version?\n");
 	return 0;

diff --git a/common/auth.h b/common/auth.h
line changes: +12/-3
index 9d3fe49..4a16776
--- a/common/auth.h
+++ b/common/auth.h
@@ -14,10 +14,19 @@
 #define SCRYPT_r 8
 #define SCRYPT_p 1
 
+struct auth_header {
+	uint8_t version;
+	uint8_t reserved1;
+	uint16_t reserved2;
+};
+
+struct auth_v2 {
+	struct auth_header header;
+	uint8_t password[SCRYPT_OUTPUT_SIZE];
+	uint8_t salt[SCRYPT_SALT_SIZE];
+};
+
 int auth_set_password(const char *username, const char *password);
-int auth_get_password_version(const char *username);
-int auth_get_password(const char *username, char *password);
-int auth_get_salt(const char *username, uint8_t *salt);
 int auth_check_password(const char *username, const char *password);
 char * auth_login(const char *username, const char *password);
 int auth_logout(const char *username, const char *token);