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