In conf() we parse a MAC address in two places, for the --ns-mac-addr and
the -M options. As well as duplicating code, the logic for this parsing
has several bugs:
* The most serious is that if the given string is shorter than a MAC
address should be, we'll access past the end of it.
* We don't check the endptr supplied by strtol() which means we could
ignore certain erroneous contents
* We never check the separator characters between each octet
* We ignore certain sorts of garbage that follow the MAC address
Correct all these bugs in a new parse_mac() helper.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
conf.c | 53 ++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 36 insertions(+), 17 deletions(-)
diff --git a/conf.c b/conf.c
index 72ca1fc8..fdeb9db7 100644
--- a/conf.c
+++ b/conf.c
@@ -1124,6 +1124,39 @@ static void conf_open_files(struct ctx *c)
c->pidfile_fd = pidfile_open(c->pidfile);
}
+/**
+ * parse_mac - Parse a MAC address from a string
+ * @mac: Binary MAC address, initialised on success
+ * @str: String to parse
+ *
+ * Parses @str as an Ethernet MAC address stored in @mac on success. Exits on
+ * failure.
+ */
+static void parse_mac(unsigned char mac[ETH_ALEN], const char *str)
+{
+ size_t i;
+
+ if (strlen(str) != (ETH_ALEN * 3 - 1))
+ goto fail;
+
+ for (i = 0; i < ETH_ALEN; i++) {
+ const char *octet = str + 3 * i;
+ unsigned long b;
+ char *end;
+
+ errno = 0;
+ b = strtoul(octet, &end, 16);
+ if (b > UCHAR_MAX || errno || end != octet + 2 ||
+ *end != ((i == ETH_ALEN - 1) ? '\0' : ':'))
+ goto fail;
+ mac[i] = b;
+ }
+ return;
+
+fail:
+ die("Invalid MAC address: %s", str);
+}
+
/**
* conf() - Process command-line arguments and set configuration
* @c: Execution context
@@ -1200,9 +1233,9 @@ void conf(struct ctx *c, int argc, char **argv)
unsigned int ifi4 = 0, ifi6 = 0;
const char *logfile = NULL;
const char *optstring;
- int name, ret, b, i;
size_t logsize = 0;
char *runas = NULL;
+ int name, ret;
uid_t uid;
gid_t gid;
@@ -1243,14 +1276,7 @@ void conf(struct ctx *c, int argc, char **argv)
if (c->mode != MODE_PASTA)
die("--ns-mac-addr is for pasta mode only");
- for (i = 0; i < ETH_ALEN; i++) {
- errno = 0;
- b = strtol(optarg + (intptr_t)i * 3, NULL, 16);
- if (b < 0 || b > UCHAR_MAX || errno)
- die("Invalid MAC address: %s", optarg);
-
- c->mac_guest[i] = b;
- }
+ parse_mac(c->mac_guest, optarg);
break;
case 5:
if (c->mode != MODE_PASTA)
@@ -1510,14 +1536,7 @@ void conf(struct ctx *c, int argc, char **argv)
break;
case 'M':
- for (i = 0; i < ETH_ALEN; i++) {
- errno = 0;
- b = strtol(optarg + (intptr_t)i * 3, NULL, 16);
- if (b < 0 || b > UCHAR_MAX || errno)
- die("Invalid MAC address: %s", optarg);
-
- c->mac[i] = b;
- }
+ parse_mac(c->mac, optarg);
break;
case 'g':
if (c->mode == MODE_PASTA)
--
2.45.2