From: Jens Axboe axboe@kernel.dk
[ Upstream commit 181e448d8709e517c9c7b523fcd209f24eb38ca7 ]
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@s... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 56c23dee98117..f563a581b924c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -260,6 +260,8 @@ struct io_ring_ctx {
struct user_struct *user;
+ struct cred *creds; + struct completion ctx_done;
struct { @@ -1633,8 +1635,11 @@ static void io_poll_complete_work(struct work_struct *work) struct io_poll_iocb *poll = &req->poll; struct poll_table_struct pt = { ._key = poll->events }; struct io_ring_ctx *ctx = req->ctx; + const struct cred *old_cred; __poll_t mask = 0;
+ old_cred = override_creds(ctx->creds); + if (!READ_ONCE(poll->canceled)) mask = vfs_poll(poll->file, &pt) & poll->events;
@@ -1649,7 +1654,7 @@ static void io_poll_complete_work(struct work_struct *work) if (!mask && !READ_ONCE(poll->canceled)) { add_wait_queue(poll->head, &poll->wait); spin_unlock_irq(&ctx->completion_lock); - return; + goto out; } list_del_init(&req->list); io_poll_complete(ctx, req, mask); @@ -1657,6 +1662,8 @@ static void io_poll_complete_work(struct work_struct *work)
io_cqring_ev_posted(ctx); io_put_req(req); +out: + revert_creds(old_cred); }
static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, @@ -1906,10 +1913,12 @@ static void io_sq_wq_submit_work(struct work_struct *work) struct io_ring_ctx *ctx = req->ctx; struct mm_struct *cur_mm = NULL; struct async_list *async_list; + const struct cred *old_cred; LIST_HEAD(req_list); mm_segment_t old_fs; int ret;
+ old_cred = override_creds(ctx->creds); async_list = io_async_list_from_sqe(ctx, req->submit.sqe); restart: do { @@ -2017,6 +2026,7 @@ static void io_sq_wq_submit_work(struct work_struct *work) unuse_mm(cur_mm); mmput(cur_mm); } + revert_creds(old_cred); }
/* @@ -2354,6 +2364,7 @@ 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; @@ -2363,6 +2374,7 @@ static int io_sq_thread(void *data)
old_fs = get_fs(); set_fs(USER_DS); + old_cred = override_creds(ctx->creds);
timeout = inflight = 0; while (!kthread_should_park()) { @@ -2473,6 +2485,7 @@ static int io_sq_thread(void *data) unuse_mm(cur_mm); mmput(cur_mm); } + revert_creds(old_cred);
kthread_parkme();
@@ -3142,6 +3155,8 @@ 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); + if (ctx->creds) + put_cred(ctx->creds); kfree(ctx); }
@@ -3419,6 +3434,12 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) ctx->account_mem = account_mem; ctx->user = user;
+ ctx->creds = prepare_creds(); + if (!ctx->creds) { + ret = -ENOMEM; + goto err; + } + ret = io_allocate_scq_urings(ctx, p); if (ret) goto err;