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Kernel: Handle promise violations in the syscall handler

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Previously we would crash the process immediately when a promise
violation was found during a syscall. This is error prone, as we
don't unwind the stack. This means that in certain cases we can
leak resources, like an OwnPtr / RefPtr tracked on the stack. Or
even leak a lock acquired in a ScopeLockLocker.

To remedy this situation we move the promise violation handling to
the syscall handler, right before we return to user space. This
allows the code to follow the normal unwind path, and grantees
there is no longer any cleanup that needs to occur.

The Process::require_promise() and Process::require_no_promises()
functions were modified to return ErrorOr<void> so we enforce that
the errors are always propagated by the caller.
This commit is contained in:
Brian Gianforcaro 2021-12-29 01:11:45 -08:00 • committed by Andreas Kling
parent c444a3fc9e
commit 54b9a4ec1e
66 changed files with 156 additions and 148 deletions
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16
Kernel/Syscalls/setuid.cpp
View file

@ -11,7 +11,7 @@ namespace Kernel {
ErrorOr<FlatPtr> Process::sys$seteuid(UserID new_euid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_euid == (uid_t)-1)
return EINVAL;
@ -31,7 +31,7 @@ ErrorOr<FlatPtr> Process::sys$seteuid(UserID new_euid)
ErrorOr<FlatPtr> Process::sys$setegid(GroupID new_egid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_egid == (uid_t)-1)
return EINVAL;
@ -50,7 +50,7 @@ ErrorOr<FlatPtr> Process::sys$setegid(GroupID new_egid)
ErrorOr<FlatPtr> Process::sys$setuid(UserID new_uid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_uid == (uid_t)-1)
return EINVAL;
@ -71,7 +71,7 @@ ErrorOr<FlatPtr> Process::sys$setuid(UserID new_uid)
ErrorOr<FlatPtr> Process::sys$setgid(GroupID new_gid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_gid == (uid_t)-1)
return EINVAL;
@ -92,7 +92,7 @@ ErrorOr<FlatPtr> Process::sys$setgid(GroupID new_gid)
ErrorOr<FlatPtr> Process::sys$setreuid(UserID new_ruid, UserID new_euid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_ruid == (uid_t)-1)
new_ruid = uid();
@ -118,7 +118,7 @@ ErrorOr<FlatPtr> Process::sys$setreuid(UserID new_ruid, UserID new_euid)
ErrorOr<FlatPtr> Process::sys$setresuid(UserID new_ruid, UserID new_euid, UserID new_suid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_ruid == (uid_t)-1)
new_ruid = uid();
@ -144,7 +144,7 @@ ErrorOr<FlatPtr> Process::sys$setresuid(UserID new_ruid, UserID new_euid, UserID
ErrorOr<FlatPtr> Process::sys$setresgid(GroupID new_rgid, GroupID new_egid, GroupID new_sgid)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (new_rgid == (gid_t)-1)
new_rgid = gid();
@ -170,7 +170,7 @@ ErrorOr<FlatPtr> Process::sys$setresgid(GroupID new_rgid, GroupID new_egid, Grou
ErrorOr<FlatPtr> Process::sys$setgroups(size_t count, Userspace<const gid_t*> user_gids)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
require_promise(Pledge::id);
TRY(require_promise(Pledge::id));
if (!is_superuser())
return EPERM;