Kernel: Add support for jails

Our implementation for Jails resembles much of how FreeBSD jails are
working - it's essentially only a matter of using a RefPtr in the
Process class to a Jail object. Then, when we iterate over all processes
in various cases, we could ensure if either the current process is in
jail and therefore should be restricted what is visible in terms of
PID isolation, and also to be able to expose metadata about Jails in
/sys/kernel/jails node (which does not reveal anything to a process
which is in jail).

A lifetime model for the Jail object is currently plain simple - there's
simpy no way to manually delete a Jail object once it was created. Such
feature should be carefully designed to allow safe destruction of a Jail
without the possibility of releasing a process which is in Jail from the
actual jail. Each process which is attached into a Jail cannot leave it
until the end of a Process (i.e. when finalizing a Process). All jails
are kept being referenced in the JailManagement. When a last attached
process is finalized, the Jail is automatically destroyed.

1 files changed, 9 insertions, 9 deletions

diff --git a/Kernel/Syscalls/setpgid.cpp b/Kernel/Syscalls/setpgid.cpp
index 8ff0b70bbf..4a52aaf9b8 100644
--- a/Kernel/Syscalls/setpgid.cpp
+++ b/Kernel/Syscalls/setpgid.cpp
@@ -16,7 +16,7 @@ ErrorOr<FlatPtr> Process::sys$getsid(pid_t pid)
     TRY(require_promise(Pledge::stdio));
     if (pid == 0)
         return sid().value();
-    auto process = Process::from_pid(pid);
+    auto process = Process::from_pid_in_same_jail(pid);
     if (!process)
         return ESRCH;
     if (sid() != process->sid())
@@ -30,10 +30,10 @@ ErrorOr<FlatPtr> Process::sys$setsid()
     TRY(require_promise(Pledge::proc));
     InterruptDisabler disabler;
     bool found_process_with_same_pgid_as_my_pid = false;
-    Process::for_each_in_pgrp(pid().value(), [&](auto&) {
+    TRY(Process::for_each_in_pgrp_in_same_jail(pid().value(), [&](auto&) -> ErrorOr<void> {
         found_process_with_same_pgid_as_my_pid = true;
-        return IterationDecision::Break;
-    });
+        return {};
+    }));
     if (found_process_with_same_pgid_as_my_pid)
         return EPERM;
     // Create a new Session and a new ProcessGroup.
@@ -52,7 +52,7 @@ ErrorOr<FlatPtr> Process::sys$getpgid(pid_t pid)
     TRY(require_promise(Pledge::stdio));
     if (pid == 0)
         return pgid().value();
-    auto process = Process::from_pid(pid);
+    auto process = Process::from_pid_in_same_jail(pid);
     if (!process)
         return ESRCH;
     return process->pgid().value();
@@ -70,10 +70,10 @@ SessionID Process::get_sid_from_pgid(ProcessGroupID pgid)
     // FIXME: This xor sys$setsid() uses the wrong locking mechanism.
 
     SessionID sid { -1 };
-    Process::for_each_in_pgrp(pgid, [&](auto& process) {
+    MUST(Process::current().for_each_in_pgrp_in_same_jail(pgid, [&](auto& process) -> ErrorOr<void> {
         sid = process.sid();
-        return IterationDecision::Break;
-    });
+        return {};
+    }));
 
     return sid;
 }
@@ -87,7 +87,7 @@ ErrorOr<FlatPtr> Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
         // The value of the pgid argument is less than 0, or is not a value supported by the implementation.
         return EINVAL;
     }
-    auto process = Process::from_pid(pid);
+    auto process = Process::from_pid_in_same_jail(pid);
     if (!process)
         return ESRCH;
     if (process != this && process->ppid() != this->pid()) {