Kernel: Allow sending `SIGCONT` to processes in the same group

Allow sending `SIGCONT` to processes that share the same `pgid`.
This is allowed in Linux aswell.

Also fixes a FIXME :^)

1 files changed, 6 insertions, 2 deletions

diff --git a/Kernel/Syscalls/kill.cpp b/Kernel/Syscalls/kill.cpp
index 84291d515e..a9b72d2e37 100644
--- a/Kernel/Syscalls/kill.cpp
+++ b/Kernel/Syscalls/kill.cpp
@@ -11,11 +11,15 @@ namespace Kernel {
 
 ErrorOr<void> Process::do_kill(Process& process, int signal)
 {
-    // FIXME: Allow sending SIGCONT to everyone in the process group.
     // FIXME: Should setuid processes have some special treatment here?
     auto credentials = this->credentials();
     auto kill_process_credentials = process.credentials();
-    if (!credentials->is_superuser() && credentials->euid() != kill_process_credentials->uid() && credentials->uid() != kill_process_credentials->uid())
+
+    bool can_send_signal = credentials->is_superuser()
+        || credentials->euid() == kill_process_credentials->uid()
+        || credentials->uid() == kill_process_credentials->uid()
+        || (signal == SIGCONT && credentials->pgid() == kill_process_credentials->pgid());
+    if (!can_send_signal)
         return EPERM;
     if (process.is_kernel_process()) {
         dbgln("Attempted to send signal {} to kernel process {} ({})", signal, process.name(), process.pid());