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af_unix: Remove CONFIG_UNIX_SCM.

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Originally, the code related to garbage collection was all in garbage.c.

Commit f4e65870e5 ("net: split out functions related to registering
inflight socket files") moved some functions to scm.c for io_uring and
added CONFIG_UNIX_SCM just in case AF_UNIX was built as module.

However, since commit 97154bcf4d ("af_unix: Kconfig: make CONFIG_UNIX
bool"), AF_UNIX is no longer built separately.  Also, io_uring does not
support SCM_RIGHTS now.

Let's move the functions back to garbage.c

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20240129190435.57228-4-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2024-01-29 11:04:35 -08:00 committed by Jakub Kicinski
parent 11498715f2
commit 99a7a5b994
8 changed files with 137 additions and 175 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
include/net/af_unix.h
View File

@ -17,19 +17,20 @@ static inline struct unix_sock *unix_get_socket(struct file *filp)
}
#endif
extern spinlock_t unix_gc_lock;
extern unsigned int unix_tot_inflight;
void unix_inflight(struct user_struct *user, struct file *fp);
void unix_notinflight(struct user_struct *user, struct file *fp);
void unix_destruct_scm(struct sk_buff *skb);
void unix_gc(void);
void wait_for_unix_gc(struct scm_fp_list *fpl);
struct sock *unix_peer_get(struct sock *sk);
#define UNIX_HASH_MOD (256 - 1)
#define UNIX_HASH_SIZE (256 * 2)
#define UNIX_HASH_BITS 8
extern unsigned int unix_tot_inflight;
struct unix_address {
refcount_t refcnt;
int len;

2
net/Makefile
View File

@ -17,7 +17,7 @@ obj-$(CONFIG_NETFILTER) += netfilter/
obj-$(CONFIG_INET) += ipv4/
obj-$(CONFIG_TLS) += tls/
obj-$(CONFIG_XFRM) += xfrm/
obj-$(CONFIG_UNIX_SCM) += unix/
obj-$(CONFIG_UNIX) += unix/
obj-y += ipv6/
obj-$(CONFIG_PACKET) += packet/
obj-$(CONFIG_NET_KEY) += key/

5
net/unix/Kconfig
View File

@ -16,11 +16,6 @@ config UNIX
Say Y unless you know what you are doing.
config UNIX_SCM
bool
depends on UNIX
default y
config AF_UNIX_OOB
bool
depends on UNIX

2
net/unix/Makefile
View File

@ -11,5 +11,3 @@ unix-$(CONFIG_BPF_SYSCALL) += unix_bpf.o
obj-$(CONFIG_UNIX_DIAG) += unix_diag.o
unix_diag-y := diag.o
obj-$(CONFIG_UNIX_SCM) += scm.o

63
net/unix/af_unix.c
View File

@ -118,8 +118,6 @@
#include <linux/btf_ids.h>
#include <linux/bpf-cgroup.h>
#include "scm.h"
static atomic_long_t unix_nr_socks;
static struct hlist_head bsd_socket_buckets[UNIX_HASH_SIZE / 2];
static spinlock_t bsd_socket_locks[UNIX_HASH_SIZE / 2];
@ -1790,6 +1788,52 @@ static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
return err;
}
/* The "user->unix_inflight" variable is protected by the garbage
* collection lock, and we just read it locklessly here. If you go
* over the limit, there might be a tiny race in actually noticing
* it across threads. Tough.
*/
static inline bool too_many_unix_fds(struct task_struct *p)
{
struct user_struct *user = current_user();
if (unlikely(READ_ONCE(user->unix_inflight) > task_rlimit(p, RLIMIT_NOFILE)))
return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
return false;
}
static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
int i;
if (too_many_unix_fds(current))
return -ETOOMANYREFS;
/* Need to duplicate file references for the sake of garbage
* collection. Otherwise a socket in the fps might become a
* candidate for GC while the skb is not yet queued.
*/
UNIXCB(skb).fp = scm_fp_dup(scm->fp);
if (!UNIXCB(skb).fp)
return -ENOMEM;
for (i = scm->fp->count - 1; i >= 0; i--)
unix_inflight(scm->fp->user, scm->fp->fp[i]);
return 0;
}
static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
int i;
scm->fp = UNIXCB(skb).fp;
UNIXCB(skb).fp = NULL;
for (i = scm->fp->count - 1; i >= 0; i--)
unix_notinflight(scm->fp->user, scm->fp->fp[i]);
}
static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
scm->fp = scm_fp_dup(UNIXCB(skb).fp);
@ -1837,6 +1881,21 @@ static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
spin_unlock(&unix_gc_lock);
}
static void unix_destruct_scm(struct sk_buff *skb)
{
struct scm_cookie scm;
memset(&scm, 0, sizeof(scm));
scm.pid = UNIXCB(skb).pid;
if (UNIXCB(skb).fp)
unix_detach_fds(&scm, skb);
/* Alas, it calls VFS */
/* So fscking what? fput() had been SMP-safe since the last Summer */
scm_destroy(&scm);
sock_wfree(skb);
}
static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
{
int err = 0;

73
net/unix/garbage.c
View File

@ -81,11 +81,80 @@
#include <net/scm.h>
#include <net/tcp_states.h>
#include "scm.h"
struct unix_sock *unix_get_socket(struct file *filp)
{
struct inode *inode = file_inode(filp);
/* Internal data structures and random procedures: */
/* Socket ? */
if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) {
struct socket *sock = SOCKET_I(inode);
const struct proto_ops *ops;
struct sock *sk = sock->sk;
ops = READ_ONCE(sock->ops);
/* PF_UNIX ? */
if (sk && ops && ops->family == PF_UNIX)
return unix_sk(sk);
}
return NULL;
}
DEFINE_SPINLOCK(unix_gc_lock);
unsigned int unix_tot_inflight;
static LIST_HEAD(gc_candidates);
static LIST_HEAD(gc_inflight_list);
/* Keep the number of times in flight count for the file
* descriptor if it is for an AF_UNIX socket.
*/
void unix_inflight(struct user_struct *user, struct file *filp)
{
struct unix_sock *u = unix_get_socket(filp);
spin_lock(&unix_gc_lock);
if (u) {
if (!u->inflight) {
WARN_ON_ONCE(!list_empty(&u->link));
list_add_tail(&u->link, &gc_inflight_list);
} else {
WARN_ON_ONCE(list_empty(&u->link));
}
u->inflight++;
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
}
WRITE_ONCE(user->unix_inflight, user->unix_inflight + 1);
spin_unlock(&unix_gc_lock);
}
void unix_notinflight(struct user_struct *user, struct file *filp)
{
struct unix_sock *u = unix_get_socket(filp);
spin_lock(&unix_gc_lock);
if (u) {
WARN_ON_ONCE(!u->inflight);
WARN_ON_ONCE(list_empty(&u->link));
u->inflight--;
if (!u->inflight)
list_del_init(&u->link);
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);
}
WRITE_ONCE(user->unix_inflight, user->unix_inflight - 1);
spin_unlock(&unix_gc_lock);
}
static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
struct sk_buff_head *hitlist)

150
net/unix/scm.c
View File

@ -1,150 +0,0 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/net.h>
#include <linux/fs.h>
#include <net/af_unix.h>
#include <net/scm.h>
#include <linux/init.h>
#include <linux/io_uring.h>
#include "scm.h"
unsigned int unix_tot_inflight;
EXPORT_SYMBOL(unix_tot_inflight);
LIST_HEAD(gc_inflight_list);
EXPORT_SYMBOL(gc_inflight_list);
DEFINE_SPINLOCK(unix_gc_lock);
EXPORT_SYMBOL(unix_gc_lock);
struct unix_sock *unix_get_socket(struct file *filp)
{
struct inode *inode = file_inode(filp);
/* Socket ? */
if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) {
struct socket *sock = SOCKET_I(inode);
const struct proto_ops *ops = READ_ONCE(sock->ops);
struct sock *s = sock->sk;
/* PF_UNIX ? */
if (s && ops && ops->family == PF_UNIX)
return unix_sk(s);
}
return NULL;
}
EXPORT_SYMBOL(unix_get_socket);
/* Keep the number of times in flight count for the file
* descriptor if it is for an AF_UNIX socket.
*/
void unix_inflight(struct user_struct *user, struct file *fp)
{
struct unix_sock *u = unix_get_socket(fp);
spin_lock(&unix_gc_lock);
if (u) {
if (!u->inflight) {
WARN_ON_ONCE(!list_empty(&u->link));
list_add_tail(&u->link, &gc_inflight_list);
} else {
WARN_ON_ONCE(list_empty(&u->link));
}
u->inflight++;
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
}
WRITE_ONCE(user->unix_inflight, user->unix_inflight + 1);
spin_unlock(&unix_gc_lock);
}
void unix_notinflight(struct user_struct *user, struct file *fp)
{
struct unix_sock *u = unix_get_socket(fp);
spin_lock(&unix_gc_lock);
if (u) {
WARN_ON_ONCE(!u->inflight);
WARN_ON_ONCE(list_empty(&u->link));
u->inflight--;
if (!u->inflight)
list_del_init(&u->link);
/* Paired with READ_ONCE() in wait_for_unix_gc() */
WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);
}
WRITE_ONCE(user->unix_inflight, user->unix_inflight - 1);
spin_unlock(&unix_gc_lock);
}
/*
* The "user->unix_inflight" variable is protected by the garbage
* collection lock, and we just read it locklessly here. If you go
* over the limit, there might be a tiny race in actually noticing
* it across threads. Tough.
*/
static inline bool too_many_unix_fds(struct task_struct *p)
{
struct user_struct *user = current_user();
if (unlikely(READ_ONCE(user->unix_inflight) > task_rlimit(p, RLIMIT_NOFILE)))
return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
return false;
}
int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
int i;
if (too_many_unix_fds(current))
return -ETOOMANYREFS;
/*
* Need to duplicate file references for the sake of garbage
* collection. Otherwise a socket in the fps might become a
* candidate for GC while the skb is not yet queued.
*/
UNIXCB(skb).fp = scm_fp_dup(scm->fp);
if (!UNIXCB(skb).fp)
return -ENOMEM;
for (i = scm->fp->count - 1; i >= 0; i--)
unix_inflight(scm->fp->user, scm->fp->fp[i]);
return 0;
}
EXPORT_SYMBOL(unix_attach_fds);
void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
int i;
scm->fp = UNIXCB(skb).fp;
UNIXCB(skb).fp = NULL;
for (i = scm->fp->count-1; i >= 0; i--)
unix_notinflight(scm->fp->user, scm->fp->fp[i]);
}
EXPORT_SYMBOL(unix_detach_fds);
void unix_destruct_scm(struct sk_buff *skb)
{
struct scm_cookie scm;
memset(&scm, 0, sizeof(scm));
scm.pid = UNIXCB(skb).pid;
if (UNIXCB(skb).fp)
unix_detach_fds(&scm, skb);
/* Alas, it calls VFS */
/* So fscking what? fput() had been SMP-safe since the last Summer */
scm_destroy(&scm);
sock_wfree(skb);
}
EXPORT_SYMBOL(unix_destruct_scm);

10
net/unix/scm.h
View File

@ -1,10 +0,0 @@
#ifndef NET_UNIX_SCM_H
#define NET_UNIX_SCM_H
extern struct list_head gc_inflight_list;
extern spinlock_t unix_gc_lock;
int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb);
void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb);
#endif