ARI authentication.

This patch adds authentication support to ARI.

Two authentication methods are supported. The first is HTTP Basic
authentication, as specified in RFC 2617[1]. The second is by simply
passing the username and password as an ?api_key query parameter
(which allows swagger-ui[2] to authenticate more easily).

ARI usernames and passwords are configured in the ari.conf file
(formerly known as stasis_http.conf). The user may be set to
`read_only`, which will prohibit the user from issuing POST, DELETE,
etc. Also, the user's password may be specified in either plaintext,
or encrypted using the crypt() function.

Several other notes about the patch.

 * A few command line commands for seeing ARI config and status were
   also added.
 * The configuration parsing grew big enough that I extracted it to
   its own file.

 [1]: http://www.ietf.org/rfc/rfc2617.txt [2]:
 https://github.com/wordnik/swagger-ui

(closes issue ASTERISK-21277)
Review: https://reviewboard.asterisk.org/r/2649/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@393530 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 170 insertions, 3 deletions

diff --git a/main/utils.c b/main/utils.c
index 100725487..208a4d326 100644
--- a/main/utils.c
+++ b/main/utils.c
@@ -32,12 +32,14 @@
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include <ctype.h>
+#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/stat.h>
-
-#include <fcntl.h>
-
 #include <sys/syscall.h>
+#include <unistd.h>
+#if defined(HAVE_CRYPT_R)
+#include <crypt.h>
+#endif
 #if defined(__APPLE__)
 #include <mach/mach.h>
 #elif defined(HAVE_SYS_THR_H)
@@ -2271,6 +2273,171 @@ int ast_get_tid(void)
 	return ret;
 }
 
+/*!
+ * \brief Max length of a salt string.
+ *
+ * $[1,5,6]$[a–zA–Z0–9./]{1,16}$, plus null terminator
+ */
+#define MAX_SALT_LEN 21
+
+static char salt_chars[] =
+	"abcdefghijklmnopqrstuvwxyz"
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	"0123456789"
+	"./";
+
+/*! Randomly select a character for a salt string */
+static char gen_salt_char(void)
+{
+	int which = ast_random_double() * 64;
+	return salt_chars[which];
+}
+
+/*!
+ * \brief Generates a salt to try with crypt.
+ *
+ * If given an empty string, will generate a salt for the most secure algorithm
+ * to try with crypt(). If given a previously generated salt, the algorithm will
+ * be lowered by one level of security.
+ *
+ * \param[out] current_salt Output string in which to generate the salt.
+ *                          This can be an empty string, or the results of a
+ *                          prior gen_salt call.
+ * \param max_len Length of \a current_salt.
+ * \return 0 on success.
+ * \return Non-zero on error.
+ */
+static int gen_salt(char *current_salt, size_t maxlen)
+{
+	int i;
+
+	if (maxlen < MAX_SALT_LEN || current_salt == NULL) {
+		return -1;
+	}
+
+	switch (current_salt[0]) {
+	case '\0':
+		/* Initial generation; $6$ = SHA-512 */
+		*current_salt++ = '$';
+		*current_salt++ = '6';
+		*current_salt++ = '$';
+		for (i = 0; i < 16; ++i) {
+			*current_salt++ = gen_salt_char();
+		}
+		*current_salt++ = '$';
+		*current_salt++ = '\0';
+		return 0;
+	case '$':
+		switch (current_salt[1]) {
+		case '6':
+			/* Downgrade to SHA-256 */
+			current_salt[1] = '5';
+			return 0;
+		case '5':
+			/* Downgrade to MD5 */
+			current_salt[1] = '1';
+			return 0;
+		case '1':
+			/* Downgrade to traditional crypt */
+			*current_salt++ = gen_salt_char();
+			*current_salt++ = gen_salt_char();
+			*current_salt++ = '\0';
+			return 0;
+		default:
+			/* Unrecognized algorithm */
+			return -1;
+		}
+	default:
+		/* Was already as insecure as it gets */
+		return -1;
+	}
+
+}
+
+#if defined(HAVE_CRYPT_R)
+
+char *ast_crypt(const char *key, const char *salt)
+{
+	struct crypt_data data = {};
+	const char *crypted = crypt_r(key, salt, &data);
+
+	/* Crypt may return success even if it doesn't recognize the salt. But
+	 * in those cases it always mangles the salt in some way.
+	 */
+	if (!crypted || !ast_begins_with(crypted, salt)) {
+		return NULL;
+	}
+
+	return ast_strdup(crypted);
+}
+
+int ast_crypt_validate(const char *key, const char *expected)
+{
+	struct crypt_data data = {};
+	return strcmp(expected, crypt_r(key, expected, &data)) == 0;
+}
+
+#elif defined(HAVE_CRYPT)
+
+/* crypt is not reentrant. A global mutex is neither ideal nor perfect, but good
+ * enough if crypt_r support is unavailable
+ */
+AST_MUTEX_DEFINE_STATIC(crypt_mutex);
+
+char *ast_crypt(const char *key, const char *salt)
+{
+	const char *crypted;
+	SCOPED_MUTEX(lock, &crypt_mutex);
+
+	crypted = crypt(key, salt);
+
+	/* Crypt may return success even if it doesn't recognize the salt. But
+	 * in those cases it always mangles the salt in some way.
+	 */
+	if (!crypted || !ast_begins_with(crypted, salt)) {
+		return NULL;
+	}
+
+	return ast_strdup(crypted);
+}
+
+int ast_crypt_validate(const char *key, const char *expected)
+{
+	SCOPED_MUTEX(lock, &crypt_mutex);
+	return strcmp(expected, crypt(key, expected)) == 0;
+}
+
+#else /* No crypt support */
+
+char *ast_crypt(const char *key, const char *salt)
+{
+	ast_log(LOG_WARNING,
+		"crypt() support not available; cannot encrypt password\n");
+	return NULL;
+}
+
+int ast_crypt_validate(const char *key, const char *expected)
+{
+	ast_log(LOG_WARNING,
+		"crypt() support not available; cannot validate password\n");
+	return 0;
+}
+
+#endif  /* No crypt support */
+
+char *ast_crypt_encrypt(const char *key)
+{
+	char salt[MAX_SALT_LEN] = {};
+	while (gen_salt(salt, sizeof(salt)) == 0) {
+		char *crypted = ast_crypt(key, salt);
+		if (crypted) {
+			return crypted;
+		}
+	}
+	return NULL;
+}
+
+
 char *ast_utils_which(const char *binary, char *fullpath, size_t fullpath_size)
 {
 	const char *envPATH = getenv("PATH");