allowlist new Linux close_range() system call, use it in posix_spawn() am: 436980d31c
Original change: https://googleplex-android-review.googlesource.com/c/platform/bionic/+/18092494
Change-Id: I16c8b93587667162c586de1fd56c9c6a73ae83b8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/libc/SECCOMP_ALLOWLIST_COMMON.TXT b/libc/SECCOMP_ALLOWLIST_COMMON.TXT
index 6650d7e..c440f9b 100644
--- a/libc/SECCOMP_ALLOWLIST_COMMON.TXT
+++ b/libc/SECCOMP_ALLOWLIST_COMMON.TXT
@@ -74,3 +74,5 @@
int sched_rr_get_interval_time64(pid_t, timespec64*) lp32
# Since Linux 5.4, not in glibc. Probed for and conditionally used by ART.
int userfaultfd(int) all
+# Since Linux 5.9, used by POSIX_SPAWN_CLOEXEC_DEFAULT
+int close_range(unsigned int, unsigned int, int) all
diff --git a/libc/bionic/spawn.cpp b/libc/bionic/spawn.cpp
index 314a056..59f7631 100644
--- a/libc/bionic/spawn.cpp
+++ b/libc/bionic/spawn.cpp
@@ -30,10 +30,12 @@
#include <errno.h>
#include <fcntl.h>
+#include <linux/close_range.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
+#include <sys/syscall.h>
#include <unistd.h>
#include <android/fdsan.h>
@@ -49,6 +51,9 @@
// mark all open fds except stdin/out/err as close-on-exec
static int cloexec_except_stdioe() {
+ // requires 5.11+ or ACK 5.10-T kernel, otherwise returns ENOSYS or EINVAL
+ if (!syscall(SYS_close_range, 3, ~0U, CLOSE_RANGE_CLOEXEC)) return 0;
+
// unfortunately getrlimit can lie:
// - both soft and hard limits can be lowered to 0, with fds still open, so it can underestimate
// - in practice it usually is some really large value (like 32K or more)