util/shm: clear mode permission bits in allocate_shm_file_pair

This ensures the file cannot be re-opened with write permissions.

Closes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3429
This commit is contained in:
Simon Ser 2022-05-12 19:58:50 +02:00
parent e646d882cf
commit 19896e7fb6

View file

@ -3,6 +3,7 @@
#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>
#include <wlr/config.h>
@ -73,6 +74,14 @@ bool allocate_shm_file_pair(size_t size, int *rw_fd_ptr, int *ro_fd_ptr) {
shm_unlink(name);
// Make sure the file cannot be re-opened in read-write mode (e.g. via
// "/proc/self/fd/" on Linux)
if (fchmod(rw_fd, 0) != 0) {
close(rw_fd);
close(ro_fd);
return false;
}
int ret;
do {
ret = ftruncate(rw_fd, size);