Commit 071698e1 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: allow registering credentials 



If an application wants to use a ring with different kinds of
credentials, it can register them upfront. We don't lookup credentials,
the credentials of the task calling IORING_REGISTER_PERSONALITY is used.

An 'id' is returned for the application to use in subsequent personality
support.

Reviewed-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 24369c2e

fs/io_uring.c

+68 −7
Original line number Diff line number Diff line
@@ -273,6 +273,8 @@ struct io_ring_ctx { 
	struct socket		*ring_sock;

#endif



	struct idr		personality_idr;



	struct {

		unsigned		cached_cq_tail;

		unsigned		cq_entries;
@@ -796,6 +798,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) 
	INIT_LIST_HEAD(&ctx->cq_overflow_list);

	init_completion(&ctx->completions[0]);

	init_completion(&ctx->completions[1]);

	idr_init(&ctx->personality_idr);

	mutex_init(&ctx->uring_lock);

	init_waitqueue_head(&ctx->wait);

	spin_lock_init(&ctx->completion_lock);
@@ -6177,6 +6180,17 @@ static int io_uring_fasync(int fd, struct file *file, int on) 
	return fasync_helper(fd, file, on, &ctx->cq_fasync);

}



static int io_remove_personalities(int id, void *p, void *data)

{

	struct io_ring_ctx *ctx = data;

	const struct cred *cred;



	cred = idr_remove(&ctx->personality_idr, id);

	if (cred)

		put_cred(cred);

	return 0;

}



static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)

{

	mutex_lock(&ctx->uring_lock);
@@ -6193,6 +6207,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx) 
	/* if we failed setting up the ctx, we might not have any rings */

	if (ctx->rings)

		io_cqring_overflow_flush(ctx, true);

	idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);

	wait_for_completion(&ctx->completions[0]);

	io_ring_ctx_free(ctx);

}
@@ -6683,6 +6698,45 @@ out: 
	return ret;

}



static int io_register_personality(struct io_ring_ctx *ctx)

{

	const struct cred *creds = get_current_cred();

	int id;



	id = idr_alloc_cyclic(&ctx->personality_idr, (void *) creds, 1,

				USHRT_MAX, GFP_KERNEL);

	if (id < 0)

		put_cred(creds);

	return id;

}



static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)

{

	const struct cred *old_creds;



	old_creds = idr_remove(&ctx->personality_idr, id);

	if (old_creds) {

		put_cred(old_creds);

		return 0;

	}



	return -EINVAL;

}



static bool io_register_op_must_quiesce(int op)

{

	switch (op) {

	case IORING_UNREGISTER_FILES:

	case IORING_REGISTER_FILES_UPDATE:

	case IORING_REGISTER_PROBE:

	case IORING_REGISTER_PERSONALITY:

	case IORING_UNREGISTER_PERSONALITY:

		return false;

	default:

		return true;

	}

}



static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,

			       void __user *arg, unsigned nr_args)

	__releases(ctx->uring_lock)
@@ -6698,9 +6752,7 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, 
	if (percpu_ref_is_dying(&ctx->refs))

		return -ENXIO;



	if (opcode != IORING_UNREGISTER_FILES &&

	    opcode != IORING_REGISTER_FILES_UPDATE &&

	    opcode != IORING_REGISTER_PROBE) {

	if (io_register_op_must_quiesce(opcode)) {

		percpu_ref_kill(&ctx->refs);



		/*
@@ -6768,15 +6820,24 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, 
			break;

		ret = io_probe(ctx, arg, nr_args);

		break;

	case IORING_REGISTER_PERSONALITY:

		ret = -EINVAL;

		if (arg || nr_args)

			break;

		ret = io_register_personality(ctx);

		break;

	case IORING_UNREGISTER_PERSONALITY:

		ret = -EINVAL;

		if (arg)

			break;

		ret = io_unregister_personality(ctx, nr_args);

		break;

	default:

		ret = -EINVAL;

		break;

	}





	if (opcode != IORING_UNREGISTER_FILES &&

	    opcode != IORING_REGISTER_FILES_UPDATE &&

	    opcode != IORING_REGISTER_PROBE) {

	if (io_register_op_must_quiesce(opcode)) {

		/* bring the ctx back to life */

		percpu_ref_reinit(&ctx->refs);

out:

include/uapi/linux/io_uring.h

+2 −0
Original line number Diff line number Diff line
@@ -211,6 +211,8 @@ struct io_uring_params { 
#define IORING_REGISTER_FILES_UPDATE	6

#define IORING_REGISTER_EVENTFD_ASYNC	7

#define IORING_REGISTER_PROBE		8

#define IORING_REGISTER_PERSONALITY	9

#define IORING_UNREGISTER_PERSONALITY	10



struct io_uring_files_update {

	__u32 offset;

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