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net: split out functions related to registering inflight socket files

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We need this functionality for the io_uring file registration, but
we cannot rely on it since CONFIG_UNIX can be modular. Move the helpers
to a separate file, that's always builtin to the kernel if CONFIG_UNIX is
m/y.

No functional changes in this patch, just moving code around.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2019-02-08 09:01:44 -07:00
parent edafccee56
commit f4e65870e5
8 changed files with 174 additions and 131 deletions
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63
net/unix/af_unix.c
View file

@ -119,6 +119,8 @@
#include <linux/freezer.h>
#include <linux/file.h>
#include "scm.h"
struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
EXPORT_SYMBOL_GPL(unix_socket_table);
DEFINE_SPINLOCK(unix_table_lock);
@ -1486,67 +1488,6 @@ out:
return err;
}
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_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);
}
/*
* 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(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 int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
{
int err = 0;