[PATCH 5.15 002/317] io_uring: drop any code related to SCM_RIGHTS

Sasha Levin
2024-03-24T23:35:02Z

From: Jens Axboe <axboe@kernel.dk>

Commit 6e5e6d274956305f1fc0340522b38f5f5be74bdb upstream.

This is dead code after we dropped support for passing io_uring fds
over SCM_RIGHTS, get rid of it.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
io_uring/io_uring.c | 211 +-------------------------------------------
1 file changed, 3 insertions(+), 208 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 541e6a6985ecc..386b32e6fd9a8 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -62,7 +62,6 @@
#include <linux/net.h>
#include <net/sock.h>
#include <net/af_unix.h>
-#include <net/scm.h>
#include <linux/anon_inodes.h>
#include <linux/sched/mm.h>
#include <linux/uaccess.h>
@@ -440,9 +439,6 @@ struct io_ring_ctx {

/* Keep this last, we don't need it for the fast path */
struct {
- #if defined(CONFIG_UNIX)
- struct socket *ring_sock;
- #endif
/* hashed buffered write serialization */
struct io_wq_hash *hash_map;

@@ -8151,15 +8147,6 @@ static void io_free_file_tables(struct io_file_table *table)

static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
-#if defined(CONFIG_UNIX)
- if (ctx->ring_sock) {
- struct sock *sock = ctx->ring_sock->sk;
- struct sk_buff *skb;
-
- while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
- kfree_skb(skb);
- }
-#else
int i;

for (i = 0; i < ctx->nr_user_files; i++) {
@@ -8169,7 +8156,6 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
if (file)
fput(file);
}
-#endif
io_free_file_tables(&ctx->file_table);
io_rsrc_data_free(ctx->file_data);
ctx->file_data = NULL;
@@ -8321,170 +8307,11 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
return sqd;
}

-#if defined(CONFIG_UNIX)
-/*
- * Ensure the UNIX gc is aware of our file set, so we are certain that
- * the io_uring can be safely unregistered on process exit, even if we have
- * loops in the file referencing.
- */
-static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
-{
- struct sock *sk = ctx->ring_sock->sk;
- struct scm_fp_list *fpl;
- struct sk_buff *skb;
- int i, nr_files;
-
- fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
- if (!fpl)
- return -ENOMEM;
-
- skb = alloc_skb(0, GFP_KERNEL);
- if (!skb) {
- kfree(fpl);
- return -ENOMEM;
- }
-
- skb->sk = sk;
- skb->scm_io_uring = 1;
-
- nr_files = 0;
- fpl->user = get_uid(current_user());
- for (i = 0; i < nr; i++) {
- struct file *file = io_file_from_index(ctx, i + offset);
-
- if (!file)
- continue;
- fpl->fp[nr_files] = get_file(file);
- unix_inflight(fpl->user, fpl->fp[nr_files]);
- nr_files++;
- }
-
- if (nr_files) {
- fpl->max = SCM_MAX_FD;
- fpl->count = nr_files;
- UNIXCB(skb).fp = fpl;
- skb->destructor = unix_destruct_scm;
- refcount_add(skb->truesize, &sk->sk_wmem_alloc);
- skb_queue_head(&sk->sk_receive_queue, skb);
-
- for (i = 0; i < nr; i++) {
- struct file *file = io_file_from_index(ctx, i + offset);
-
- if (file)
- fput(file);
- }
- } else {
- kfree_skb(skb);
- free_uid(fpl->user);
- kfree(fpl);
- }
-
- return 0;
-}
-
-/*
- * If UNIX sockets are enabled, fd passing can cause a reference cycle which
- * causes regular reference counting to break down. We rely on the UNIX
- * garbage collection to take care of this problem for us.
- */
-static int io_sqe_files_scm(struct io_ring_ctx *ctx)
-{
- unsigned left, total;
- int ret = 0;
-
- total = 0;
- left = ctx->nr_user_files;
- while (left) {
- unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
-
- ret = __io_sqe_files_scm(ctx, this_files, total);
- if (ret)
- break;
- left -= this_files;
- total += this_files;
- }
-
- if (!ret)
- return 0;
-
- while (total < ctx->nr_user_files) {
- struct file *file = io_file_from_index(ctx, total);
-
- if (file)
- fput(file);
- total++;
- }
-
- return ret;
-}
-#else
-static int io_sqe_files_scm(struct io_ring_ctx *ctx)
-{
- return 0;
-}
-#endif
-
static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
{
struct file *file = prsrc->file;
-#if defined(CONFIG_UNIX)
- struct sock *sock = ctx->ring_sock->sk;
- struct sk_buff_head list, *head = &sock->sk_receive_queue;
- struct sk_buff *skb;
- int i;

- __skb_queue_head_init(&list);
-
- /*
- * Find the skb that holds this file in its SCM_RIGHTS. When found,
- * remove this entry and rearrange the file array.
- */
- skb = skb_dequeue(head);
- while (skb) {
- struct scm_fp_list *fp;
-
- fp = UNIXCB(skb).fp;
- for (i = 0; i < fp->count; i++) {
- int left;
-
- if (fp->fp[i] != file)
- continue;
-
- unix_notinflight(fp->user, fp->fp[i]);
- left = fp->count - 1 - i;
- if (left) {
- memmove(&fp->fp[i], &fp->fp[i + 1],
- left * sizeof(struct file *));
- }
- fp->count--;
- if (!fp->count) {
- kfree_skb(skb);
- skb = NULL;
- } else {
- __skb_queue_tail(&list, skb);
- }
- fput(file);
- file = NULL;
- break;
- }
-
- if (!file)
- break;
-
- __skb_queue_tail(&list, skb);
-
- skb = skb_dequeue(head);
- }
-
- if (skb_peek(&list)) {
- spin_lock_irq(&head->lock);
- while ((skb = __skb_dequeue(&list)) != NULL)
- __skb_queue_tail(head, skb);
- spin_unlock_irq(&head->lock);
- }
-#else
fput(file);
-#endif
}

static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
@@ -8595,12 +8422,6 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
io_fixed_file_set(io_fixed_file_slot(&ctx->file_table, i), file);
}

- ret = io_sqe_files_scm(ctx);
- if (ret) {
- __io_sqe_files_unregister(ctx);
- return ret;
- }
-
io_rsrc_node_switch(ctx, NULL);
return ret;
out_fput:
@@ -9557,12 +9378,6 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
WARN_ON_ONCE(!llist_empty(&ctx->rsrc_put_llist));

-#if defined(CONFIG_UNIX)
- if (ctx->ring_sock) {
- ctx->ring_sock->file = NULL; /* so that iput() is called */
- sock_release(ctx->ring_sock);
- }
-#endif
WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));

if (ctx->mm_account) {
@@ -10499,32 +10314,12 @@ static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
/*
* Allocate an anonymous fd, this is what constitutes the application
* visible backing of an io_uring instance. The application mmaps this
- * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
- * we have to tie this fd to a socket for file garbage collection purposes.
+ * fd to gain access to the SQ/CQ ring details.
*/
static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
{
- struct file *file;
-#if defined(CONFIG_UNIX)
- int ret;
-
- ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
- &ctx->ring_sock);
- if (ret)
- return ERR_PTR(ret);
-#endif
-
- file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
- O_RDWR | O_CLOEXEC);
-#if defined(CONFIG_UNIX)
- if (IS_ERR(file)) {
- sock_release(ctx->ring_sock);
- ctx->ring_sock = NULL;
- } else {
- ctx->ring_sock->file = file;
- }
-#endif
- return file;
+ return anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
+ O_RDWR | O_CLOEXEC);
}

static int io_uring_create(unsigned entries, struct io_uring_params *p,
--
2.43.0