Add per UID interface support to resolv cache
Add methods to attach/detach UID ranges to a specific dns cache/interface.
This mirrors the already existing code for attaching specific processes to
specific interfaces but will be used to push all processes from a given
user to a specific cache/interface.
Change-Id: Ic24391e92d3ca46fcb46cc4fc53e13984dec40b3
diff --git a/libc/netbsd/resolv/res_cache.c b/libc/netbsd/resolv/res_cache.c
index 3576202..b2d5f1b 100644
--- a/libc/netbsd/resolv/res_cache.c
+++ b/libc/netbsd/resolv/res_cache.c
@@ -1258,6 +1258,12 @@
char ifname[IF_NAMESIZE + 1];
struct resolv_pidiface_info* next;
} PidIfaceInfo;
+typedef struct resolv_uidiface_info {
+ int low;
+ int high;
+ char ifname[IF_NAMESIZE + 1];
+ struct resolv_uidiface_info* next;
+} UidIfaceInfo;
#define HTABLE_VALID(x) ((x) != NULL && (x) != HTABLE_DELETED)
@@ -1796,6 +1802,9 @@
// List of pid iface pairs
static struct resolv_pidiface_info _res_pidiface_list;
+// List of uid iface pairs
+static struct resolv_uidiface_info _res_uidiface_list;
+
// name of the current default inteface
static char _res_default_ifname[IF_NAMESIZE + 1];
@@ -1805,6 +1814,9 @@
// lock protecting the _res_pid_iface_list
static pthread_mutex_t _res_pidiface_list_lock;
+// lock protecting the _res_uidiface_list
+static pthread_mutex_t _res_uidiface_list_lock;
+
/* lookup the default interface name */
static char *_get_default_iface_locked();
/* find the first cache that has an associated interface and return the name of the interface */
@@ -1839,6 +1851,13 @@
/* get a resolv_pidiface_info structure from _res_pidiface_list with a certain pid */
static struct resolv_pidiface_info* _get_pid_iface_info_locked(int pid);
+/* remove a resolv_pidiface_info structure from _res_uidiface_list */
+static int _remove_uidiface_info_locked(int low, int high);
+/* check if a range [low,high] overlaps with any already existing ranges in the uid=>iface map*/
+static int _resolv_check_uid_range_overlap_locked(int low, int high);
+/* get a resolv_uidiface_info structure from _res_uidiface_list with a certain uid */
+static struct resolv_uidiface_info* _get_uid_iface_info_locked(int uid);
+
static void
_res_cache_init(void)
{
@@ -1852,8 +1871,10 @@
memset(&_res_default_ifname, 0, sizeof(_res_default_ifname));
memset(&_res_cache_list, 0, sizeof(_res_cache_list));
memset(&_res_pidiface_list, 0, sizeof(_res_pidiface_list));
+ memset(&_res_uidiface_list, 0, sizeof(_res_uidiface_list));
pthread_mutex_init(&_res_cache_list_lock, NULL);
pthread_mutex_init(&_res_pidiface_list_lock, NULL);
+ pthread_mutex_init(&_res_uidiface_list_lock, NULL);
}
struct resolv_cache*
@@ -2411,6 +2432,129 @@
return len;
}
+static int
+_remove_uidiface_info_locked(int low, int high) {
+ struct resolv_uidiface_info* result = &_res_uidiface_list.next;
+ struct resolv_uidiface_info* prev = NULL;
+
+ while (result != NULL && result->low != low && result->high != high) {
+ prev = result;
+ result = result->next;
+ }
+ if (prev != NULL && result != NULL) {
+ prev->next = result->next;
+ free(result);
+ return 0;
+ }
+ errno = EINVAL;
+ return -1;
+}
+
+static struct resolv_uidiface_info*
+_get_uid_iface_info_locked(int uid)
+{
+ struct resolv_uidiface_info* result = &_res_uidiface_list.next;
+ while (result != NULL && !(result->low <= uid && result->high >= uid)) {
+ result = result->next;
+ }
+
+ return result;
+}
+
+static int
+_resolv_check_uid_range_overlap_locked(int low, int high)
+{
+ struct resolv_uidiface_info* cur = &_res_uidiface_list.next;
+ while (cur != NULL) {
+ if (cur->low <= high && cur->high >= low) {
+ return -1;
+ }
+ cur = cur->next;
+ }
+ return 0;
+}
+
+int
+_resolv_set_iface_for_uid_range(const char* ifname, int low, int high)
+{
+ int rv = 0;
+ struct resolv_uidiface_info* uidiface_info;
+ // make sure the uid iface list is created
+ pthread_once(&_res_cache_once, _res_cache_init);
+ pthread_mutex_lock(&_res_uidiface_list_lock);
+ //check that we aren't adding an overlapping range
+ if (!_resolv_check_uid_range_overlap_locked(low,high)) {
+ uidiface_info = calloc(sizeof(*uidiface_info), 1);
+ if (uidiface_info) {
+ uidiface_info->low = low;
+ uidiface_info->high = high;
+ int len = sizeof(uidiface_info->ifname);
+ strncpy(uidiface_info->ifname, ifname, len - 1);
+ uidiface_info->ifname[len - 1] = '\0';
+
+ uidiface_info->next = _res_uidiface_list.next;
+ _res_uidiface_list.next = uidiface_info;
+
+ XLOG("_resolv_set_iface_for_uid_range: [%d,%d], iface %s\n", low, high, ifname);
+ } else {
+ XLOG("_resolv_set_iface_for_uid_range failing calloc\n");
+ rv = -1;
+ errno = EINVAL;
+ }
+ } else {
+ XLOG("_resolv_set_iface_for_uid_range range [%d,%d] overlaps\n", low, high);
+ rv = -1;
+ errno = EINVAL;
+ }
+
+ pthread_mutex_unlock(&_res_uidiface_list_lock);
+ return rv;
+}
+
+int
+_resolv_clear_iface_for_uid_range(int low, int high)
+{
+ pthread_once(&_res_cache_once, _res_cache_init);
+ pthread_mutex_lock(&_res_uidiface_list_lock);
+
+ int rv = _remove_uidiface_info_locked(low, high);
+
+ XLOG("_resolv_clear_iface_for_uid_range: low %d high %d\n", low, high);
+
+ pthread_mutex_unlock(&_res_uidiface_list_lock);
+
+ return rv;
+}
+
+int
+_resolv_get_uids_associated_interface(int uid, char* buff, int buffLen)
+{
+ int len = 0;
+
+ if (!buff) {
+ return -1;
+ }
+
+ pthread_once(&_res_cache_once, _res_cache_init);
+ pthread_mutex_lock(&_res_uidiface_list_lock);
+
+ struct resolv_uidiface_info* uidiface_info = _get_uid_iface_info_locked(uid);
+ buff[0] = '\0';
+ if (uidiface_info) {
+ len = strlen(uidiface_info->ifname);
+ if (len < buffLen) {
+ strncpy(buff, uidiface_info->ifname, len);
+ buff[len] = '\0';
+ }
+ }
+
+ XLOG("_resolv_get_uids_associated_interface buff: %s\n", buff);
+
+ pthread_mutex_unlock(&_res_uidiface_list_lock);
+
+ return len;
+}
+
size_t
_resolv_get_default_iface(char* buff, size_t buffLen)
{