Commit 87ce955b authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: add ->show_fdinfo() for the io_uring file descriptor 



It can be hard to know exactly what is registered with the ring.
Especially for credentials, it'd be handy to be able to see which
ones are registered, what personalities they have, and what the ID
of each of them is.

This adds support for showing information registered in the ring from
the fdinfo of the io_uring fd. Here's an example from a test case that
registers 4 files (two of them sparse), 4 buffers, and 2 personalities:

pos:	0
flags:	02000002
mnt_id:	14
UserFiles:	4
    0: file-no-1
    1: file-no-2
    2: <none>
    3: <none>
UserBufs:	4
    0: 0x563817c46000/128
    1: 0x563817c47000/256
    2: 0x563817c48000/512
    3: 0x563817c49000/1024
Personalities:
    1
	Uid:	0		0		0		0
	Gid:	0		0		0		0
	Groups:	0
	CapEff:	0000003fffffffff
    2
	Uid:	0		0		0		0
	Gid:	0		0		0		0
	Groups:	0
	CapEff:	0000003fffffffff

Suggested-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 39bed42d

fs/io_uring.c

+75 −0
Original line number Diff line number Diff line
@@ -6501,6 +6501,80 @@ out_fput: 
	return submitted ? submitted : ret;

}



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

{

	const struct cred *cred = p;

	struct seq_file *m = data;

	struct user_namespace *uns = seq_user_ns(m);

	struct group_info *gi;

	kernel_cap_t cap;

	unsigned __capi;

	int g;



	seq_printf(m, "%5d\n", id);

	seq_put_decimal_ull(m, "\tUid:\t", from_kuid_munged(uns, cred->uid));

	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->euid));

	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->suid));

	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->fsuid));

	seq_put_decimal_ull(m, "\n\tGid:\t", from_kgid_munged(uns, cred->gid));

	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->egid));

	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->sgid));

	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->fsgid));

	seq_puts(m, "\n\tGroups:\t");

	gi = cred->group_info;

	for (g = 0; g < gi->ngroups; g++) {

		seq_put_decimal_ull(m, g ? " " : "",

					from_kgid_munged(uns, gi->gid[g]));

	}

	seq_puts(m, "\n\tCapEff:\t");

	cap = cred->cap_effective;

	CAP_FOR_EACH_U32(__capi)

		seq_put_hex_ll(m, NULL, cap.cap[CAP_LAST_U32 - __capi], 8);

	seq_putc(m, '\n');

	return 0;

}



static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)

{

	int i;



	mutex_lock(&ctx->uring_lock);

	seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files);

	for (i = 0; i < ctx->nr_user_files; i++) {

		struct fixed_file_table *table;

		struct file *f;



		table = &ctx->file_data->table[i >> IORING_FILE_TABLE_SHIFT];

		f = table->files[i & IORING_FILE_TABLE_MASK];

		if (f)

			seq_printf(m, "%5u: %s\n", i, file_dentry(f)->d_iname);

		else

			seq_printf(m, "%5u: <none>\n", i);

	}

	seq_printf(m, "UserBufs:\t%u\n", ctx->nr_user_bufs);

	for (i = 0; i < ctx->nr_user_bufs; i++) {

		struct io_mapped_ubuf *buf = &ctx->user_bufs[i];



		seq_printf(m, "%5u: 0x%llx/%u\n", i, buf->ubuf,

						(unsigned int) buf->len);

	}

	if (!idr_is_empty(&ctx->personality_idr)) {

		seq_printf(m, "Personalities:\n");

		idr_for_each(&ctx->personality_idr, io_uring_show_cred, m);

	}

	mutex_unlock(&ctx->uring_lock);

}



static void io_uring_show_fdinfo(struct seq_file *m, struct file *f)

{

	struct io_ring_ctx *ctx = f->private_data;



	if (percpu_ref_tryget(&ctx->refs)) {

		__io_uring_show_fdinfo(ctx, m);

		percpu_ref_put(&ctx->refs);

	}

}



static const struct file_operations io_uring_fops = {

	.release	= io_uring_release,

	.flush		= io_uring_flush,
@@ -6511,6 +6585,7 @@ static const struct file_operations io_uring_fops = { 
#endif

	.poll		= io_uring_poll,

	.fasync		= io_uring_fasync,

	.show_fdinfo	= io_uring_show_fdinfo,

};



static int io_allocate_scq_urings(struct io_ring_ctx *ctx,

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