Kernel: Add `sid` and `pgid` to `Credentials`

There are places in the kernel that would like to have access
to `pgid` credentials in certain circumstances.

I haven't found any use cases for `sid` yet, but `sid` and `pgid` are
both changed with `sys$setpgid`, so it seemed sensical to add it.

In Linux, `man 7 credentials` also mentions both the session id and
process group id, so this isn't unprecedented.

3 files changed, 50 insertions, 12 deletions

diff --git a/Kernel/Syscalls/execve.cpp b/Kernel/Syscalls/execve.cpp
index 4f1e06d149..43218c1134 100644
--- a/Kernel/Syscalls/execve.cpp
+++ b/Kernel/Syscalls/execve.cpp
@@ -540,7 +540,9 @@ ErrorOr<void> Process::do_exec(NonnullLockRefPtr<OpenFileDescription> main_progr
                 new_egid,
                 new_suid,
                 new_sgid,
-                old_credentials->extra_gids()));
+                old_credentials->extra_gids(),
+                old_credentials->sid(),
+                old_credentials->pgid()));
         }
     }
 
diff --git a/Kernel/Syscalls/setpgid.cpp b/Kernel/Syscalls/setpgid.cpp
index 4a52aaf9b8..fffdecd749 100644
--- a/Kernel/Syscalls/setpgid.cpp
+++ b/Kernel/Syscalls/setpgid.cpp
@@ -120,7 +120,23 @@ ErrorOr<FlatPtr> Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
     }
     // FIXME: There are more EPERM conditions to check for here..
     process->m_pg = TRY(ProcessGroup::try_find_or_create(new_pgid));
-    return 0;
+    return with_mutable_protected_data([&](auto& protected_data) -> ErrorOr<FlatPtr> {
+        auto credentials = this->credentials();
+
+        auto new_credentials = TRY(Credentials::create(
+            credentials->uid(),
+            credentials->gid(),
+            credentials->euid(),
+            credentials->egid(),
+            credentials->suid(),
+            credentials->sgid(),
+            credentials->extra_gids(),
+            new_sid,
+            new_pgid));
+
+        protected_data.credentials = move(new_credentials);
+        return 0;
+    });
 }
 
 }
diff --git a/Kernel/Syscalls/setuid.cpp b/Kernel/Syscalls/setuid.cpp
index 71070bdacf..20d8948eef 100644
--- a/Kernel/Syscalls/setuid.cpp
+++ b/Kernel/Syscalls/setuid.cpp
@@ -30,7 +30,9 @@ ErrorOr<FlatPtr> Process::sys$seteuid(UserID new_euid)
             credentials->egid(),
             credentials->suid(),
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->euid() != new_euid)
             protected_data.dumpable = false;
@@ -61,7 +63,9 @@ ErrorOr<FlatPtr> Process::sys$setegid(GroupID new_egid)
             new_egid,
             credentials->suid(),
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->egid() != new_egid)
             protected_data.dumpable = false;
@@ -92,7 +96,9 @@ ErrorOr<FlatPtr> Process::sys$setuid(UserID new_uid)
             credentials->egid(),
             new_uid,
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->euid() != new_uid)
             protected_data.dumpable = false;
@@ -123,7 +129,9 @@ ErrorOr<FlatPtr> Process::sys$setgid(GroupID new_gid)
             new_gid,
             credentials->suid(),
             new_gid,
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->egid() != new_gid)
             protected_data.dumpable = false;
@@ -160,7 +168,9 @@ ErrorOr<FlatPtr> Process::sys$setreuid(UserID new_ruid, UserID new_euid)
             credentials->egid(),
             credentials->suid(),
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->euid() != new_euid)
             protected_data.dumpable = false;
@@ -196,7 +206,9 @@ ErrorOr<FlatPtr> Process::sys$setresuid(UserID new_ruid, UserID new_euid, UserID
             credentials->egid(),
             new_suid,
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->euid() != new_euid)
             protected_data.dumpable = false;
@@ -230,7 +242,9 @@ ErrorOr<FlatPtr> Process::sys$setregid(GroupID new_rgid, GroupID new_egid)
             new_egid,
             credentials->suid(),
             credentials->sgid(),
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->egid() != new_egid)
             protected_data.dumpable = false;
@@ -266,7 +280,9 @@ ErrorOr<FlatPtr> Process::sys$setresgid(GroupID new_rgid, GroupID new_egid, Grou
             new_egid,
             credentials->suid(),
             new_sgid,
-            credentials->extra_gids()));
+            credentials->extra_gids(),
+            credentials->sid(),
+            credentials->pgid()));
 
         if (credentials->egid() != new_egid)
             protected_data.dumpable = false;
@@ -298,7 +314,9 @@ ErrorOr<FlatPtr> Process::sys$setgroups(size_t count, Userspace<GroupID const*>
                 credentials->egid(),
                 credentials->suid(),
                 credentials->sgid(),
-                {}));
+                {},
+                credentials->sid(),
+                credentials->pgid()));
             return 0;
         }
 
@@ -324,7 +342,9 @@ ErrorOr<FlatPtr> Process::sys$setgroups(size_t count, Userspace<GroupID const*>
             credentials->egid(),
             credentials->suid(),
             credentials->sgid(),
-            new_extra_gids.span()));
+            new_extra_gids.span(),
+            credentials->sid(),
+            credentials->pgid()));
         return 0;
     });
 }