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.

6 files changed, 62 insertions, 18 deletions

diff --git a/Kernel/Credentials.cpp b/Kernel/Credentials.cpp
index 935b4b107f..3fb155dbc1 100644
--- a/Kernel/Credentials.cpp
+++ b/Kernel/Credentials.cpp
@@ -10,13 +10,13 @@
 
 namespace Kernel {
 
-ErrorOr<NonnullRefPtr<Credentials>> Credentials::create(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, Span<GroupID const> extra_gids)
+ErrorOr<NonnullRefPtr<Credentials>> Credentials::create(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, Span<GroupID const> extra_gids, SessionID sid, ProcessGroupID pgid)
 {
     auto extra_gids_array = TRY(FixedArray<GroupID>::try_create(extra_gids));
-    return adopt_nonnull_ref_or_enomem(new (nothrow) Credentials(uid, gid, euid, egid, suid, sgid, move(extra_gids_array)));
+    return adopt_nonnull_ref_or_enomem(new (nothrow) Credentials(uid, gid, euid, egid, suid, sgid, move(extra_gids_array), sid, pgid));
 }
 
-Credentials::Credentials(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, FixedArray<GroupID> extra_gids)
+Credentials::Credentials(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, FixedArray<GroupID> extra_gids, SessionID sid, ProcessGroupID pgid)
     : m_uid(uid)
     , m_gid(gid)
     , m_euid(euid)
@@ -24,6 +24,8 @@ Credentials::Credentials(UserID uid, GroupID gid, UserID euid, GroupID egid, Use
     , m_suid(suid)
     , m_sgid(sgid)
     , m_extra_gids(move(extra_gids))
+    , m_sid(sid)
+    , m_pgid(pgid)
 {
 }
 
diff --git a/Kernel/Credentials.h b/Kernel/Credentials.h
index e951d57c21..25e002a25e 100644
--- a/Kernel/Credentials.h
+++ b/Kernel/Credentials.h
@@ -14,7 +14,7 @@ namespace Kernel {
 
 class Credentials final : public AtomicRefCounted<Credentials> {
 public:
-    static ErrorOr<NonnullRefPtr<Credentials>> create(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, Span<GroupID const> extra_gids);
+    static ErrorOr<NonnullRefPtr<Credentials>> create(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, Span<GroupID const> extra_gids, SessionID sid, ProcessGroupID pgid);
     ~Credentials();
 
     bool is_superuser() const { return euid() == 0; }
@@ -26,11 +26,13 @@ public:
     UserID suid() const { return m_suid; }
     GroupID sgid() const { return m_sgid; }
     Span<GroupID const> extra_gids() const { return m_extra_gids.span(); }
+    SessionID sid() const { return m_sid; };
+    ProcessGroupID pgid() const { return m_pgid; }
 
     bool in_group(GroupID) const;
 
 private:
-    Credentials(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, FixedArray<GroupID> extra_gids);
+    Credentials(UserID uid, GroupID gid, UserID euid, GroupID egid, UserID suid, GroupID sgid, FixedArray<GroupID> extra_gids, SessionID sid, ProcessGroupID pgid);
 
     UserID m_uid;
     GroupID m_gid;
@@ -39,6 +41,8 @@ private:
     UserID m_suid;
     GroupID m_sgid;
     FixedArray<GroupID> m_extra_gids;
+    SessionID m_sid;
+    ProcessGroupID m_pgid;
 };
 
 }
diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index d2fbf3f3f3..6f76b0537f 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -311,7 +311,7 @@ ErrorOr<NonnullLockRefPtr<Process>> Process::try_create(LockRefPtr<Thread>& firs
     }
     auto unveil_tree = UnveilNode { TRY(KString::try_create("/"sv)), UnveilMetadata(TRY(KString::try_create("/"sv))) };
     auto exec_unveil_tree = UnveilNode { TRY(KString::try_create("/"sv)), UnveilMetadata(TRY(KString::try_create("/"sv))) };
-    auto credentials = TRY(Credentials::create(uid, gid, uid, gid, uid, gid, {}));
+    auto credentials = TRY(Credentials::create(uid, gid, uid, gid, uid, gid, {}, fork_parent ? fork_parent->sid() : 0, fork_parent ? fork_parent->pgid() : 0));
     auto process = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Process(move(name), move(credentials), ppid, is_kernel_process, move(current_directory), move(executable), tty, move(unveil_tree), move(exec_unveil_tree))));
     TRY(process->attach_resources(new_address_space.release_nonnull(), first_thread, fork_parent));
     return process;
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;
     });
 }