io_uring: async workers should inherit the user creds
If we don't inherit the original task creds, then we can confuse users
like fuse that pass creds in the request header. See link below on
identical aio issue.
Link: https://lore.kernel.org/linux-fsdevel/26f0d78e-99ca-2f1b-78b9-433088053a61@scylladb.com/T/#u
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index fabae84..b6c6fdc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -237,6 +237,8 @@ struct io_ring_ctx {
struct user_struct *user;
+ struct cred *creds;
+
/* 0 is for ctx quiesce/reinit/free, 1 is for sqo_thread started */
struct completion *completions;
@@ -3267,6 +3269,7 @@ static int io_sq_thread(void *data)
{
struct io_ring_ctx *ctx = data;
struct mm_struct *cur_mm = NULL;
+ const struct cred *old_cred;
mm_segment_t old_fs;
DEFINE_WAIT(wait);
unsigned inflight;
@@ -3277,6 +3280,7 @@ static int io_sq_thread(void *data)
old_fs = get_fs();
set_fs(USER_DS);
+ old_cred = override_creds(ctx->creds);
ret = timeout = inflight = 0;
while (!kthread_should_park()) {
@@ -3383,6 +3387,7 @@ static int io_sq_thread(void *data)
unuse_mm(cur_mm);
mmput(cur_mm);
}
+ revert_creds(old_cred);
kthread_parkme();
@@ -4009,6 +4014,7 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
data.mm = ctx->sqo_mm;
data.user = ctx->user;
+ data.creds = ctx->creds;
data.get_work = io_get_work;
data.put_work = io_put_work;
@@ -4363,6 +4369,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
io_unaccount_mem(ctx->user,
ring_pages(ctx->sq_entries, ctx->cq_entries));
free_uid(ctx->user);
+ put_cred(ctx->creds);
kfree(ctx->completions);
kmem_cache_free(req_cachep, ctx->fallback_req);
kfree(ctx);
@@ -4715,6 +4722,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p)
ctx->compat = in_compat_syscall();
ctx->account_mem = account_mem;
ctx->user = user;
+ ctx->creds = prepare_creds();
ret = io_allocate_scq_urings(ctx, p);
if (ret)