^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) #include <linux/kernel.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) #include <linux/string.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) #include <linux/socket.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) #include <linux/net.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) #include <linux/fs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <net/af_unix.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <net/scm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/init.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <linux/io_uring.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include "scm.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) unsigned int unix_tot_inflight;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) EXPORT_SYMBOL(unix_tot_inflight);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) LIST_HEAD(gc_inflight_list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) EXPORT_SYMBOL(gc_inflight_list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) DEFINE_SPINLOCK(unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) EXPORT_SYMBOL(unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) struct sock *unix_get_socket(struct file *filp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) struct sock *u_sock = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) struct inode *inode = file_inode(filp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) /* Socket ? */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) struct socket *sock = SOCKET_I(inode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) struct sock *s = sock->sk;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) /* PF_UNIX ? */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) if (s && sock->ops && sock->ops->family == PF_UNIX)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) u_sock = s;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) /* Could be an io_uring instance */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) u_sock = io_uring_get_socket(filp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) return u_sock;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) EXPORT_SYMBOL(unix_get_socket);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) /* Keep the number of times in flight count for the file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * descriptor if it is for an AF_UNIX socket.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) void unix_inflight(struct user_struct *user, struct file *fp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) struct sock *s = unix_get_socket(fp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) spin_lock(&unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) if (s) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) struct unix_sock *u = unix_sk(s);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) if (atomic_long_inc_return(&u->inflight) == 1) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) BUG_ON(!list_empty(&u->link));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) list_add_tail(&u->link, &gc_inflight_list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) BUG_ON(list_empty(&u->link));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) /* Paired with READ_ONCE() in wait_for_unix_gc() */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) user->unix_inflight++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) spin_unlock(&unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) void unix_notinflight(struct user_struct *user, struct file *fp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) struct sock *s = unix_get_socket(fp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) spin_lock(&unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) if (s) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) struct unix_sock *u = unix_sk(s);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) BUG_ON(!atomic_long_read(&u->inflight));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) BUG_ON(list_empty(&u->link));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) if (atomic_long_dec_and_test(&u->inflight))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) list_del_init(&u->link);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) /* Paired with READ_ONCE() in wait_for_unix_gc() */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) user->unix_inflight--;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) spin_unlock(&unix_gc_lock);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) * The "user->unix_inflight" variable is protected by the garbage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) * collection lock, and we just read it locklessly here. If you go
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * over the limit, there might be a tiny race in actually noticing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) * it across threads. Tough.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) static inline bool too_many_unix_fds(struct task_struct *p)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) struct user_struct *user = current_user();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) if (too_many_unix_fds(current))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) return -ETOOMANYREFS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) * Need to duplicate file references for the sake of garbage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) * collection. Otherwise a socket in the fps might become a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) * candidate for GC while the skb is not yet queued.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) UNIXCB(skb).fp = scm_fp_dup(scm->fp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) if (!UNIXCB(skb).fp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) for (i = scm->fp->count - 1; i >= 0; i--)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) unix_inflight(scm->fp->user, scm->fp->fp[i]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) EXPORT_SYMBOL(unix_attach_fds);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) scm->fp = UNIXCB(skb).fp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) UNIXCB(skb).fp = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) for (i = scm->fp->count-1; i >= 0; i--)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) unix_notinflight(scm->fp->user, scm->fp->fp[i]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) EXPORT_SYMBOL(unix_detach_fds);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) void unix_destruct_scm(struct sk_buff *skb)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) struct scm_cookie scm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) memset(&scm, 0, sizeof(scm));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) scm.pid = UNIXCB(skb).pid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) if (UNIXCB(skb).fp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) unix_detach_fds(&scm, skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) /* Alas, it calls VFS */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) /* So fscking what? fput() had been SMP-safe since the last Summer */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) scm_destroy(&scm);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) sock_wfree(skb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) EXPORT_SYMBOL(unix_destruct_scm);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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