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gluon-status-page-api: support batadv-in-VLAN on ibss interface

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introduce function to recurse down to the lowest layer-2 interface
corresponding to a given interface.
also re-introduce some of the previously removed input validation plus
some more to protect against glob and path based exploits.
This commit is contained in:
Daniel Golle 2015-12-11 02:53:09 +01:00
parent e012e67bf1
commit 4ce85afc22
1 changed files with 63 additions and 2 deletions
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65
package/gluon-status-page-api/src/stations.c
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@ -4,7 +4,12 @@
#include <json-c/json.h>
#include <iwinfo.h>
#include <net/if.h>
#include <glob.h>
#include <alloca.h>
#define NETIF_PREFIX "/sys/class/net/"
#define VIRTIF_PREFIX "/sys/devices/virtual/net/"
#define LOWERGLOB_SUFFIX "/lower_*"
static struct json_object *get_stations(const struct iwinfo_ops *iw, const char *ifname) {
int len;
@ -40,12 +45,68 @@ static void badrequest() {
exit(1);
}
// recurse down to the lowest layer-2 interface
static int interface_get_lowest(const char *ifname, char *hwifname);
static int interface_get_lowest(const char *ifname, char *hwifname) {
glob_t globbuf;
char *fnamebuf = alloca(1 + strlen(VIRTIF_PREFIX) + IF_NAMESIZE +
strlen(LOWERGLOB_SUFFIX));
char *lowentry = NULL;
sprintf(fnamebuf, "%s%s%s", VIRTIF_PREFIX, ifname, LOWERGLOB_SUFFIX);
glob(fnamebuf, GLOB_NOSORT | GLOB_NOESCAPE, NULL, &globbuf);
if (globbuf.gl_pathc == 1) {
lowentry = alloca(1 + strlen(globbuf.gl_pathv[0]));
strncpy(lowentry, globbuf.gl_pathv[0], 1 + strlen(globbuf.gl_pathv[0]));
}
globfree(&globbuf);
if (!lowentry) {
char *path = alloca(1 + strlen(NETIF_PREFIX) + strlen(ifname));
sprintf(path, "%s%s", NETIF_PREFIX, ifname);
if(access(path, F_OK) != 0)
return false;
strncpy(hwifname, ifname, IF_NAMESIZE - 1);
return true;
} else {
char buf[PATH_MAX];
ssize_t len;
if ((len = readlink(lowentry, buf, sizeof(buf)-1)) != -1)
buf[len] = '\0';
else
return false;
if (strncmp(buf, "../", 3) == 0) {
return interface_get_lowest(strrchr(buf, '/') + 1, hwifname);
} else {
return false;
}
}
}
int main(int argc, char *argv[]) {
if (argc != 2)
badrequest();
const char *ifname = argv[1];
const struct iwinfo_ops *iw = iwinfo_backend(ifname);
char hwifname[IF_NAMESIZE] = "";
if (strlen(ifname) >= IF_NAMESIZE)
badrequest();
if (strcspn(ifname, "/\\[]{}*?") != strlen(ifname))
badrequest();
if (!interface_get_lowest(ifname, hwifname))
badrequest();
const struct iwinfo_ops *iw = iwinfo_backend(hwifname);
if (iw == NULL)
badrequest();
@ -54,7 +115,7 @@ int main(int argc, char *argv[]) {
while (true) {
struct json_object *obj;
obj = get_stations(iw, ifname);
obj = get_stations(iw, hwifname);
printf("data: %s\n\n", json_object_to_json_string_ext(obj, JSON_C_TO_STRING_PLAIN));
fflush(stdout);
json_object_put(obj);