diff options
| author | Christian Brauner (Amutable) <brauner@kernel.org> | 2026-05-20 23:48:55 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-05-26 11:02:01 +0200 |
| commit | 6b1c66c9cca99bf00386481c7b2aa7394c26d8b8 (patch) | |
| tree | 4a0cefcb5798c8b96c2481271e3edd2ea9d08558 /kernel/sys.c | |
| parent | 92f829f6b2faad37a5582df73df01c93d4429821 (diff) | |
exec_state: relocate dumpable information
The dumpable flag captured at execve() is consulted by
__ptrace_may_access() and several /proc owner / visibility checks.
It lives on mm_struct today, which exit_mm() clears from the task
long before the task itself is reaped.
exec_state is anchored to the execve() that established the current
privilege domain. CLONE_VM siblings refcount-share the parent's
exec_state via copy_exec_state(); non-CLONE_VM clones allocate a
fresh exec_state inheriting the parent's dumpable mode and user_ns
reference via task_exec_state_copy(). execve() allocates a fresh
instance (via alloc_task_exec_state() in begin_new_exec()) and
installs it under task_lock + exec_update_lock with
task_exec_state_replace(). init_task uses a static instance.
The dumpable mode now lives on task->exec_state->dumpable.
task->mm->flags no longer carries dumpability; MMF_DUMPABLE_MASK is
removed, but MMF_DUMPABLE_BITS is reserved so MMF_DUMP_FILTER_* bit
positions remain stable for the /proc/<pid>/coredump_filter ABI. The
task->user_dumpable cache bit and its assignment in exit_mm() are
removed; readers go through get_dumpable(task) directly.
coredump_params gains a snapshot field cprm.dumpable, populated from
get_dumpable(current) at vfs_coredump() entry, replacing the previous
__get_dumpable(cprm->mm_flags) consumers in fs/coredump.c and
fs/pidfs.c.
The user namespace recorded at execve() is consulted by
__ptrace_may_access() and by /proc/PID/* owner derivation. Move the
captured user_ns onto task_exec_state, which stays attached to the task
past exit_mm() and across exit_files().
bprm grows a user_ns field staged in bprm_mm_init() with the caller's
user_ns, narrowed by would_dump() to the closest privileged ancestor,
and consumed by exec_mmap() via alloc_task_exec_state(bprm->user_ns).
free_bprm() releases the staging reference.
mm_struct loses ->user_ns entirely. Initializers in init-mm, efi_mm,
and the implicit one in mm_init()/dup_mm()/mm_alloc() are removed;
__mmdrop() drops the matching put_user_ns(). The kthread_use_mm()
WARN_ON_ONCE(!mm->user_ns) is no longer meaningful and goes too.
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-4-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'kernel/sys.c')
| -rw-r--r-- | kernel/sys.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index f1189f719db5..df69bd71de03 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2565,14 +2565,14 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = put_user(me->pdeath_signal, (int __user *)arg2); break; case PR_GET_DUMPABLE: - error = get_dumpable(me->mm); + error = task_exec_state_get_dumpable(me); break; case PR_SET_DUMPABLE: if (arg2 != TASK_DUMPABLE_OFF && arg2 != TASK_DUMPABLE_OWNER) { error = -EINVAL; break; } - set_dumpable(me->mm, arg2); + task_exec_state_set_dumpable(arg2); break; case PR_SET_UNALIGN: |