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io_uring: handle multiple personalities in link chains

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If we have a chain of requests and they don't all use the same
credentials, then the head of the chain will be issued with the
credentails of the tail of the chain.

Ensure __io_queue_sqe() overrides the credentials, if they are different.

Once we do that, we can clean up the creds handling as well, by only
having io_submit_sqe() do the lookup of a personality. It doesn't need
to assign it, since __io_queue_sqe() now always does the right thing.

Fixes: 75c6a03904 ("io_uring: support using a registered personality for commands")
Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-02-22 23:22:19 -07:00
parent f8788d86ab
commit 193155c8c9
1 changed files with 15 additions and 10 deletions
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25
fs/io_uring.c
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@ -4705,11 +4705,21 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_kiocb *linked_timeout;
struct io_kiocb *nxt = NULL;
const struct cred *old_creds = NULL;
int ret;
again:
linked_timeout = io_prep_linked_timeout(req);
if (req->work.creds && req->work.creds != current_cred()) {
if (old_creds)
revert_creds(old_creds);
if (old_creds == req->work.creds)
old_creds = NULL; /* restored original creds */
else
old_creds = override_creds(req->work.creds);
}
ret = io_issue_sqe(req, sqe, &nxt, true);
/*
@ -4759,6 +4769,8 @@ done_req:
goto punt;
goto again;
}
if (old_creds)
revert_creds(old_creds);
}
static void io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)
@ -4803,7 +4815,6 @@ static inline void io_queue_link_head(struct io_kiocb *req)
static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
struct io_submit_state *state, struct io_kiocb **link)
{
const struct cred *old_creds = NULL;
struct io_ring_ctx *ctx = req->ctx;
unsigned int sqe_flags;
int ret, id;
@ -4818,14 +4829,12 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
id = READ_ONCE(sqe->personality);
if (id) {
const struct cred *personality_creds;
personality_creds = idr_find(&ctx->personality_idr, id);
if (unlikely(!personality_creds)) {
req->work.creds = idr_find(&ctx->personality_idr, id);
if (unlikely(!req->work.creds)) {
ret = -EINVAL;
goto err_req;
}
old_creds = override_creds(personality_creds);
get_cred(req->work.creds);
}
/* same numerical values with corresponding REQ_F_*, safe to copy */
@ -4837,8 +4846,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
err_req:
io_cqring_add_event(req, ret);
io_double_put_req(req);
if (old_creds)
revert_creds(old_creds);
return false;
}
@ -4899,8 +4906,6 @@ err_req:
}
}
if (old_creds)
revert_creds(old_creds);
return true;
}