[iOS][GPUP] Block unused system calls

https://bugs.webkit.org/show_bug.cgi?id=240960
<rdar://84826074>

Reviewed by Chris Dumez.

* Source/WebKit/Resources/SandboxProfiles/ios/com.apple.WebKit.GPU.sb.in:

Canonical link: https://commits.webkit.org/251022@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@294899 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebKit/Resources/SandboxProfiles/ios/com.apple.WebKit.GPU.sb.in

@@ -714,12 +714,14 @@
 )
 
 (when (defined? 'syscall-unix)
-    (allow syscall-unix (with telemetry))
+    (deny syscall-unix (with telemetry))
     (allow syscall-unix (syscall-number
         SYS___disable_threadsignal
         SYS___mac_syscall
         SYS___pthread_sigmask
+        SYS___pthread_kill
         SYS___semwait_signal
+        SYS_abort_with_payload
         SYS_access
         SYS_bsdthread_create
         SYS_bsdthread_ctl
@@ -804,6 +806,7 @@
         SYS_shared_region_check_np
         SYS_shm_open
         SYS_sigaction
+        SYS_sigprocmask
         SYS_socket
         SYS_stat64
         SYS_statfs64
@@ -822,7 +825,7 @@
     (allow syscall-unix (syscall-number SYS_map_with_linking_np)))
 
 (when (defined? 'syscall-mach)
-    (allow syscall-mach (with telemetry))
+    (deny syscall-mach (with telemetry))
     (allow syscall-mach
         (machtrap-number
             MSC__kernelrpc_mach_port_allocate_trap