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Allow overlap in resolv uid => DNS iface mapping

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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
This commit is contained in:
Chad Brubaker 2014-02-21 10:39:41 -08:00
parent 04583ce9b9
commit 081db840be
2 changed files with 24 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
libc/netbsd/resolv/res_cache.c
View File

@ -1852,9 +1852,7 @@ static void _remove_pidiface_info_locked(int 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 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 @@ _resolv_get_pids_associated_interface(int pid, char* buff, int buffLen)
}
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 @@ _get_uid_iface_info_locked(int uid)
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 @@ _resolv_set_iface_for_uid_range(const char* ifname, int uid_start, int uid_end)
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 @@ _resolv_set_iface_for_uid_range(const char* ifname, int uid_start, int uid_end)
}
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);

10
libc/private/resolv_iface.h
View File

@ -79,13 +79,12 @@ extern void _resolv_clear_iface_pid_mapping();
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 @@ extern void _resolv_clear_iface_uid_range_mapping();
* 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 */