Allow overlap in resolv uid => DNS iface mapping
When multiple rules exist covering a given uid the one added most
recently will be used.
This allows us to handle the simultaneous tuns case where a new tun is
coming online for an already running VPN.
_resolv_clear_iface_for_uid_range now also takes the iface and removes
only that matching (iface, uid range) entry.
Bug: 12134439
Change-Id: I9b9cfcfae2f38c409022a8c76ccadad7e2babd78
diff --git a/libc/netbsd/resolv/res_cache.c b/libc/netbsd/resolv/res_cache.c
index 8a6dc83..1a0c40c 100644
--- a/libc/netbsd/resolv/res_cache.c
+++ b/libc/netbsd/resolv/res_cache.c
@@ -1852,9 +1852,7 @@
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 uid_start, int uid_end);
-/* 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 uid_start, int uid_end);
+static int _remove_uidiface_info_locked(const char* iface, int uid_start, int uid_end);
/* 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);
@@ -2433,11 +2431,11 @@
}
static int
-_remove_uidiface_info_locked(int uid_start, int uid_end) {
+_remove_uidiface_info_locked(const char* ifname, int uid_start, int uid_end) {
struct resolv_uidiface_info* result = _res_uidiface_list.next;
struct resolv_uidiface_info* prev = &_res_uidiface_list;
-
- while (result != NULL && result->uid_start != uid_start && result->uid_end != uid_end) {
+ while (result != NULL && !(result->uid_start == uid_start && result->uid_end == uid_end &&
+ !strcmp(result->ifname, ifname))) {
prev = result;
result = result->next;
}
@@ -2461,19 +2459,6 @@
return result;
}
-static int
-_resolv_check_uid_range_overlap_locked(int uid_start, int uid_end)
-{
- struct resolv_uidiface_info* cur = _res_uidiface_list.next;
- while (cur != NULL) {
- if (cur->uid_start <= uid_end && cur->uid_end >= uid_start) {
- return -1;
- }
- cur = cur->next;
- }
- return 0;
-}
-
void
_resolv_clear_iface_uid_range_mapping()
{
@@ -2518,28 +2503,21 @@
return -1;
}
pthread_mutex_lock(&_res_uidiface_list_lock);
- //check that we aren't adding an overlapping range
- if (!_resolv_check_uid_range_overlap_locked(uid_start, uid_end)) {
- uidiface_info = calloc(sizeof(*uidiface_info), 1);
- if (uidiface_info) {
- uidiface_info->uid_start = uid_start;
- uidiface_info->uid_end = uid_end;
- int len = sizeof(uidiface_info->ifname);
- strncpy(uidiface_info->ifname, ifname, len - 1);
- uidiface_info->ifname[len - 1] = '\0';
+ uidiface_info = calloc(sizeof(*uidiface_info), 1);
+ if (uidiface_info) {
+ uidiface_info->uid_start = uid_start;
+ uidiface_info->uid_end = uid_end;
+ 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;
+ 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", uid_start, uid_end,
- ifname);
- } else {
- XLOG("_resolv_set_iface_for_uid_range failing calloc\n");
- rv = -1;
- errno = EINVAL;
- }
+ XLOG("_resolv_set_iface_for_uid_range: [%d,%d], iface %s\n", uid_start, uid_end,
+ ifname);
} else {
- XLOG("_resolv_set_iface_for_uid_range range [%d,%d] overlaps\n", uid_start, uid_end);
+ XLOG("_resolv_set_iface_for_uid_range failing calloc\n");
rv = -1;
errno = EINVAL;
}
@@ -2549,14 +2527,14 @@
}
int
-_resolv_clear_iface_for_uid_range(int uid_start, int uid_end)
+_resolv_clear_iface_for_uid_range(const char* ifname, int uid_start, int uid_end)
{
pthread_once(&_res_cache_once, _res_cache_init);
pthread_mutex_lock(&_res_uidiface_list_lock);
- int rv = _remove_uidiface_info_locked(uid_start, uid_end);
+ int rv = _remove_uidiface_info_locked(ifname, uid_start, uid_end);
- XLOG("_resolv_clear_iface_for_uid_range: [%d,%d]\n", uid_start, uid_end);
+ XLOG("_resolv_clear_iface_for_uid_range: [%d,%d] iface %s\n", uid_start, uid_end, ifname);
pthread_mutex_unlock(&_res_uidiface_list_lock);
diff --git a/libc/private/resolv_iface.h b/libc/private/resolv_iface.h
index ad42793..5d24124 100644
--- a/libc/private/resolv_iface.h
+++ b/libc/private/resolv_iface.h
@@ -79,13 +79,12 @@
extern int _resolv_get_pids_associated_interface(int pid, char* buff, int buffLen);
-/** set a uid range to use the name servers of the specified interface
- * If [low,high] overlaps with an already existing rule -1 is returned */
+/** set a uid range to use the name servers of the specified interface */
extern int _resolv_set_iface_for_uid_range(const char* ifname, int uid_start, int uid_end);
-/* clear a uid range from being associated with an interface
- * If the range given is not mapped -1 is returned. */
-extern int _resolv_clear_iface_for_uid_range(int uid_start, int uid_end);
+/** Remove a mapping added by _resolv_set_iface_for_uid_range.
+ * If no such rule exists -1 is returned. */
+extern int _resolv_clear_iface_for_uid_range(const char* ifname, int uid_start, int uid_end);
/* clear the entire mapping of uid ranges to interfaces. */
extern void _resolv_clear_iface_uid_range_mapping();
@@ -94,6 +93,7 @@
* On error, -1 is returned.
* If no interface is found, 0 is returned and buff is set to empty ('\0').
* If an interface is found, the name is copied to buff and the length of the name is returned.
+ * If there are multiple rules covering uid the most recently added rule will be returned.
* Arguments: uid The uid to find an interface for
* buff A buffer to copy the result to
* buffLen Length of buff. An interface is at most IF_NAMESIZE in length */
