diff options
Diffstat (limited to 'net/unix')
| -rw-r--r-- | net/unix/Kconfig | 5 | ||||
| -rw-r--r-- | net/unix/Makefile | 2 | ||||
| -rw-r--r-- | net/unix/af_unix.c | 399 | ||||
| -rw-r--r-- | net/unix/diag.c | 16 | ||||
| -rw-r--r-- | net/unix/garbage.c | 677 | ||||
| -rw-r--r-- | net/unix/scm.c | 160 | ||||
| -rw-r--r-- | net/unix/scm.h | 10 | ||||
| -rw-r--r-- | net/unix/sysctl_net_unix.c | 6 | ||||
| -rw-r--r-- | net/unix/unix_bpf.c | 20 |
9 files changed, 736 insertions, 559 deletions
diff --git a/net/unix/Kconfig b/net/unix/Kconfig index 28b232f281ab..8b5d04210d7c 100644 --- a/net/unix/Kconfig +++ b/net/unix/Kconfig @@ -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 diff --git a/net/unix/Makefile b/net/unix/Makefile index 20491825b4d0..4ddd125c4642 100644 --- a/net/unix/Makefile +++ b/net/unix/Makefile @@ -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 diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 86930a8ed012..5e695a9a609c 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -116,8 +116,7 @@ #include <linux/freezer.h> #include <linux/file.h> #include <linux/btf_ids.h> - -#include "scm.h" +#include <linux/bpf-cgroup.h> static atomic_long_t unix_nr_socks; static struct hlist_head bsd_socket_buckets[UNIX_HASH_SIZE / 2]; @@ -212,8 +211,6 @@ static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb) } #endif /* CONFIG_SECURITY_NETWORK */ -#define unix_peer(sk) (unix_sk(sk)->peer) - static inline int unix_our_peer(struct sock *sk, struct sock *osk) { return unix_peer(osk) == sk; @@ -224,15 +221,9 @@ static inline int unix_may_send(struct sock *sk, struct sock *osk) return unix_peer(osk) == NULL || unix_our_peer(sk, osk); } -static inline int unix_recvq_full(const struct sock *sk) -{ - return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; -} - static inline int unix_recvq_full_lockless(const struct sock *sk) { - return skb_queue_len_lockless(&sk->sk_receive_queue) > - READ_ONCE(sk->sk_max_ack_backlog); + return skb_queue_len_lockless(&sk->sk_receive_queue) > sk->sk_max_ack_backlog; } struct sock *unix_peer_get(struct sock *s) @@ -533,10 +524,10 @@ static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other) return 0; } -static int unix_writable(const struct sock *sk) +static int unix_writable(const struct sock *sk, unsigned char state) { - return sk->sk_state != TCP_LISTEN && - (refcount_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf; + return state != TCP_LISTEN && + (refcount_read(&sk->sk_wmem_alloc) << 2) <= READ_ONCE(sk->sk_sndbuf); } static void unix_write_space(struct sock *sk) @@ -544,12 +535,12 @@ static void unix_write_space(struct sock *sk) struct socket_wq *wq; rcu_read_lock(); - if (unix_writable(sk)) { + if (unix_writable(sk, READ_ONCE(sk->sk_state))) { wq = rcu_dereference(sk->sk_wq); if (skwq_has_sleeper(wq)) wake_up_interruptible_sync_poll(&wq->wait, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND); - sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); + sk_wake_async_rcu(sk, SOCK_WAKE_SPACE, POLL_OUT); } rcu_read_unlock(); } @@ -573,7 +564,6 @@ static void unix_dgram_disconnected(struct sock *sk, struct sock *other) sk_error_report(other); } } - other->sk_state = TCP_CLOSE; } static void unix_sock_destructor(struct sock *sk) @@ -620,7 +610,7 @@ static void unix_release_sock(struct sock *sk, int embrion) u->path.dentry = NULL; u->path.mnt = NULL; state = sk->sk_state; - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); skpair = unix_peer(sk); unix_peer(sk) = NULL; @@ -641,7 +631,7 @@ static void unix_release_sock(struct sock *sk, int embrion) unix_state_lock(skpair); /* No more writes */ WRITE_ONCE(skpair->sk_shutdown, SHUTDOWN_MASK); - if (!skb_queue_empty(&sk->sk_receive_queue) || embrion) + if (!skb_queue_empty_lockless(&sk->sk_receive_queue) || embrion) WRITE_ONCE(skpair->sk_err, ECONNRESET); unix_state_unlock(skpair); skpair->sk_state_change(skpair); @@ -680,7 +670,7 @@ static void unix_release_sock(struct sock *sk, int embrion) * What the above comment does talk about? --ANK(980817) */ - if (unix_tot_inflight) + if (READ_ONCE(unix_tot_inflight)) unix_gc(); /* Garbage collect fds */ } @@ -734,7 +724,7 @@ static int unix_listen(struct socket *sock, int backlog) if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET) goto out; /* Only stream/seqpacket sockets accept */ err = -EINVAL; - if (!u->addr) + if (!READ_ONCE(u->addr)) goto out; /* No listens on an unbound socket */ unix_state_lock(sk); if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN) @@ -742,7 +732,8 @@ static int unix_listen(struct socket *sock, int backlog) if (backlog > sk->sk_max_ack_backlog) wake_up_interruptible_all(&u->peer_wait); sk->sk_max_ack_backlog = backlog; - sk->sk_state = TCP_LISTEN; + WRITE_ONCE(sk->sk_state, TCP_LISTEN); + /* set credentials so connect can copy them */ init_peercred(sk); err = 0; @@ -758,7 +749,7 @@ static int unix_bind(struct socket *, struct sockaddr *, int); static int unix_stream_connect(struct socket *, struct sockaddr *, int addr_len, int flags); static int unix_socketpair(struct socket *, struct socket *); -static int unix_accept(struct socket *, struct socket *, int, bool); +static int unix_accept(struct socket *, struct socket *, struct proto_accept_arg *arg); static int unix_getname(struct socket *, struct sockaddr *, int); static __poll_t unix_poll(struct file *, struct socket *, poll_table *); static __poll_t unix_dgram_poll(struct file *, struct socket *, @@ -783,19 +774,6 @@ static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t); static int unix_seqpacket_recvmsg(struct socket *, struct msghdr *, size_t, int); -static int unix_set_peek_off(struct sock *sk, int val) -{ - struct unix_sock *u = unix_sk(sk); - - if (mutex_lock_interruptible(&u->iolock)) - return -EINTR; - - WRITE_ONCE(sk->sk_peek_off, val); - mutex_unlock(&u->iolock); - - return 0; -} - #ifdef CONFIG_PROC_FS static int unix_count_nr_fds(struct sock *sk) { @@ -863,7 +841,7 @@ static const struct proto_ops unix_stream_ops = { .read_skb = unix_stream_read_skb, .mmap = sock_no_mmap, .splice_read = unix_stream_splice_read, - .set_peek_off = unix_set_peek_off, + .set_peek_off = sk_set_peek_off, .show_fdinfo = unix_show_fdinfo, }; @@ -887,7 +865,7 @@ static const struct proto_ops unix_dgram_ops = { .read_skb = unix_read_skb, .recvmsg = unix_dgram_recvmsg, .mmap = sock_no_mmap, - .set_peek_off = unix_set_peek_off, + .set_peek_off = sk_set_peek_off, .show_fdinfo = unix_show_fdinfo, }; @@ -910,7 +888,7 @@ static const struct proto_ops unix_seqpacket_ops = { .sendmsg = unix_seqpacket_sendmsg, .recvmsg = unix_seqpacket_recvmsg, .mmap = sock_no_mmap, - .set_peek_off = unix_set_peek_off, + .set_peek_off = sk_set_peek_off, .show_fdinfo = unix_show_fdinfo, }; @@ -992,14 +970,14 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, sk->sk_hash = unix_unbound_hash(sk); sk->sk_allocation = GFP_KERNEL_ACCOUNT; sk->sk_write_space = unix_write_space; - sk->sk_max_ack_backlog = net->unx.sysctl_max_dgram_qlen; + sk->sk_max_ack_backlog = READ_ONCE(net->unx.sysctl_max_dgram_qlen); sk->sk_destruct = unix_sock_destructor; - u = unix_sk(sk); + u = unix_sk(sk); + u->listener = NULL; + u->vertex = NULL; u->path.dentry = NULL; u->path.mnt = NULL; spin_lock_init(&u->lock); - atomic_long_set(&u->inflight, 0); - INIT_LIST_HEAD(&u->link); mutex_init(&u->iolock); /* single task reading lock */ mutex_init(&u->bindlock); /* single task binding lock */ init_waitqueue_head(&u->peer_wait); @@ -1147,8 +1125,8 @@ static struct sock *unix_find_other(struct net *net, static int unix_autobind(struct sock *sk) { - unsigned int new_hash, old_hash = sk->sk_hash; struct unix_sock *u = unix_sk(sk); + unsigned int new_hash, old_hash; struct net *net = sock_net(sk); struct unix_address *addr; u32 lastnum, ordernum; @@ -1171,6 +1149,7 @@ static int unix_autobind(struct sock *sk) addr->name->sun_family = AF_UNIX; refcount_set(&addr->refcnt, 1); + old_hash = sk->sk_hash; ordernum = get_random_u32(); lastnum = ordernum & 0xFFFFF; retry: @@ -1211,8 +1190,8 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr, { umode_t mode = S_IFSOCK | (SOCK_INODE(sk->sk_socket)->i_mode & ~current_umask()); - unsigned int new_hash, old_hash = sk->sk_hash; struct unix_sock *u = unix_sk(sk); + unsigned int new_hash, old_hash; struct net *net = sock_net(sk); struct mnt_idmap *idmap; struct unix_address *addr; @@ -1250,6 +1229,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr, if (u->addr) goto out_unlock; + old_hash = sk->sk_hash; new_hash = unix_bsd_hash(d_backing_inode(dentry)); unix_table_double_lock(net, old_hash, new_hash); u->path.mnt = mntget(parent.mnt); @@ -1277,8 +1257,8 @@ out: static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr, int addr_len) { - unsigned int new_hash, old_hash = sk->sk_hash; struct unix_sock *u = unix_sk(sk); + unsigned int new_hash, old_hash; struct net *net = sock_net(sk); struct unix_address *addr; int err; @@ -1296,6 +1276,7 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr, goto out_mutex; } + old_hash = sk->sk_hash; new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type); unix_table_double_lock(net, old_hash, new_hash); @@ -1345,13 +1326,11 @@ static void unix_state_double_lock(struct sock *sk1, struct sock *sk2) unix_state_lock(sk1); return; } - if (sk1 < sk2) { - unix_state_lock(sk1); - unix_state_lock_nested(sk2); - } else { - unix_state_lock(sk2); - unix_state_lock_nested(sk1); - } + if (sk1 > sk2) + swap(sk1, sk2); + + unix_state_lock(sk1); + unix_state_lock_nested(sk2, U_LOCK_SECOND); } static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2) @@ -1381,9 +1360,13 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr, if (err) goto out; + err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, addr, &alen); + if (err) + goto out; + if ((test_bit(SOCK_PASSCRED, &sock->flags) || test_bit(SOCK_PASSPIDFD, &sock->flags)) && - !unix_sk(sk)->addr) { + !READ_ONCE(unix_sk(sk)->addr)) { err = unix_autobind(sk); if (err) goto out; @@ -1413,7 +1396,8 @@ restart: if (err) goto out_unlock; - sk->sk_state = other->sk_state = TCP_ESTABLISHED; + WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED); + WRITE_ONCE(other->sk_state, TCP_ESTABLISHED); } else { /* * 1003.1g breaking connected state with AF_UNSPEC @@ -1430,13 +1414,20 @@ restart: unix_peer(sk) = other; if (!other) - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer); unix_state_double_unlock(sk, other); - if (other != old_peer) + if (other != old_peer) { unix_dgram_disconnected(sk, old_peer); + + unix_state_lock(old_peer); + if (!unix_peer(old_peer)) + WRITE_ONCE(old_peer->sk_state, TCP_CLOSE); + unix_state_unlock(old_peer); + } + sock_put(old_peer); } else { unix_peer(sk) = other; @@ -1484,14 +1475,18 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, struct sk_buff *skb = NULL; long timeo; int err; - int st; err = unix_validate_addr(sunaddr, addr_len); if (err) goto out; + err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, uaddr, &addr_len); + if (err) + goto out; + if ((test_bit(SOCK_PASSCRED, &sock->flags) || - test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { + test_bit(SOCK_PASSPIDFD, &sock->flags)) && + !READ_ONCE(u->addr)) { err = unix_autobind(sk); if (err) goto out; @@ -1544,7 +1539,7 @@ restart: if (other->sk_shutdown & RCV_SHUTDOWN) goto out_unlock; - if (unix_recvq_full(other)) { + if (unix_recvq_full_lockless(other)) { err = -EAGAIN; if (!timeo) goto out_unlock; @@ -1569,9 +1564,7 @@ restart: Well, and we have to recheck the state after socket locked. */ - st = sk->sk_state; - - switch (st) { + switch (READ_ONCE(sk->sk_state)) { case TCP_CLOSE: /* This is ok... continue with connect */ break; @@ -1584,9 +1577,9 @@ restart: goto out_unlock; } - unix_state_lock_nested(sk); + unix_state_lock_nested(sk, U_LOCK_SECOND); - if (sk->sk_state != st) { + if (sk->sk_state != TCP_CLOSE) { unix_state_unlock(sk); unix_state_unlock(other); sock_put(other); @@ -1607,6 +1600,7 @@ restart: newsk->sk_type = sk->sk_type; init_peercred(newsk); newu = unix_sk(newsk); + newu->listener = other; RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq); otheru = unix_sk(other); @@ -1638,7 +1632,7 @@ restart: copy_peercred(sk, other); sock->state = SS_CONNECTED; - sk->sk_state = TCP_ESTABLISHED; + WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED); sock_hold(newsk); smp_mb__after_atomic(); /* sock_hold() does an atomic_inc() */ @@ -1698,32 +1692,31 @@ static void unix_sock_inherit_flags(const struct socket *old, set_bit(SOCK_PASSSEC, &new->flags); } -static int unix_accept(struct socket *sock, struct socket *newsock, int flags, - bool kern) +static int unix_accept(struct socket *sock, struct socket *newsock, + struct proto_accept_arg *arg) { struct sock *sk = sock->sk; - struct sock *tsk; struct sk_buff *skb; - int err; + struct sock *tsk; - err = -EOPNOTSUPP; + arg->err = -EOPNOTSUPP; if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET) goto out; - err = -EINVAL; - if (sk->sk_state != TCP_LISTEN) + arg->err = -EINVAL; + if (READ_ONCE(sk->sk_state) != TCP_LISTEN) goto out; /* If socket state is TCP_LISTEN it cannot change (for now...), * so that no locks are necessary. */ - skb = skb_recv_datagram(sk, (flags & O_NONBLOCK) ? MSG_DONTWAIT : 0, - &err); + skb = skb_recv_datagram(sk, (arg->flags & O_NONBLOCK) ? MSG_DONTWAIT : 0, + &arg->err); if (!skb) { /* This means receive shutdown. */ - if (err == 0) - err = -EINVAL; + if (arg->err == 0) + arg->err = -EINVAL; goto out; } @@ -1733,6 +1726,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock, int flags, /* attach accepted sock to socket */ unix_state_lock(tsk); + unix_update_edges(unix_sk(tsk)); newsock->state = SS_CONNECTED; unix_sock_inherit_flags(sock, newsock); sock_graft(tsk, newsock); @@ -1740,7 +1734,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock, int flags, return 0; out: - return err; + return arg->err; } @@ -1770,57 +1764,73 @@ static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int peer) } else { err = addr->len; memcpy(sunaddr, addr->name, addr->len); + + if (peer) + BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err, + CGROUP_UNIX_GETPEERNAME); + else + BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err, + CGROUP_UNIX_GETSOCKNAME); } sock_put(sk); out: 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) +{ + if (too_many_unix_fds(current)) + return -ETOOMANYREFS; + + UNIXCB(skb).fp = scm->fp; + scm->fp = NULL; + + if (unix_prepare_fpl(UNIXCB(skb).fp)) + return -ENOMEM; + + return 0; +} + +static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb) +{ + scm->fp = UNIXCB(skb).fp; + UNIXCB(skb).fp = NULL; + + unix_destroy_fpl(scm->fp); +} + static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb) { scm->fp = scm_fp_dup(UNIXCB(skb).fp); +} - /* - * Garbage collection of unix sockets starts by selecting a set of - * candidate sockets which have reference only from being in flight - * (total_refs == inflight_refs). This condition is checked once during - * the candidate collection phase, and candidates are marked as such, so - * that non-candidates can later be ignored. While inflight_refs is - * protected by unix_gc_lock, total_refs (file count) is not, hence this - * is an instantaneous decision. - * - * Once a candidate, however, the socket must not be reinstalled into a - * file descriptor while the garbage collection is in progress. - * - * If the above conditions are met, then the directed graph of - * candidates (*) does not change while unix_gc_lock is held. - * - * Any operations that changes the file count through file descriptors - * (dup, close, sendmsg) does not change the graph since candidates are - * not installed in fds. - * - * Dequeing a candidate via recvmsg would install it into an fd, but - * that takes unix_gc_lock to decrement the inflight count, so it's - * serialized with garbage collection. - * - * MSG_PEEK is special in that it does not change the inflight count, - * yet does install the socket into an fd. The following lock/unlock - * pair is to ensure serialization with garbage collection. It must be - * done between incrementing the file count and installing the file into - * an fd. - * - * If garbage collection starts after the barrier provided by the - * lock/unlock, then it will see the elevated refcount and not mark this - * as a candidate. If a garbage collection is already in progress - * before the file count was incremented, then the lock/unlock pair will - * ensure that garbage collection is finished before progressing to - * installing the fd. - * - * (*) A -> B where B is on the queue of A or B is on the queue of C - * which is on the queue of listening socket A. - */ - spin_lock(&unix_gc_lock); - 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) @@ -1879,8 +1889,10 @@ static void scm_stat_add(struct sock *sk, struct sk_buff *skb) struct scm_fp_list *fp = UNIXCB(skb).fp; struct unix_sock *u = unix_sk(sk); - if (unlikely(fp && fp->count)) + if (unlikely(fp && fp->count)) { atomic_add(fp->count, &u->scm_stat.nr_fds); + unix_add_edges(fp, u); + } } static void scm_stat_del(struct sock *sk, struct sk_buff *skb) @@ -1888,8 +1900,10 @@ static void scm_stat_del(struct sock *sk, struct sk_buff *skb) struct scm_fp_list *fp = UNIXCB(skb).fp; struct unix_sock *u = unix_sk(sk); - if (unlikely(fp && fp->count)) + if (unlikely(fp && fp->count)) { atomic_sub(fp->count, &u->scm_stat.nr_fds); + unix_del_edges(fp); + } } /* @@ -1909,11 +1923,12 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, long timeo; int err; - wait_for_unix_gc(); err = scm_send(sock, msg, &scm, false); if (err < 0) return err; + wait_for_unix_gc(scm.fp); + err = -EOPNOTSUPP; if (msg->msg_flags&MSG_OOB) goto out; @@ -1922,6 +1937,13 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, err = unix_validate_addr(sunaddr, msg->msg_namelen); if (err) goto out; + + err = BPF_CGROUP_RUN_PROG_UNIX_SENDMSG_LOCK(sk, + msg->msg_name, + &msg->msg_namelen, + NULL); + if (err) + goto out; } else { sunaddr = NULL; err = -ENOTCONN; @@ -1931,14 +1953,15 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, } if ((test_bit(SOCK_PASSCRED, &sock->flags) || - test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { + test_bit(SOCK_PASSPIDFD, &sock->flags)) && + !READ_ONCE(u->addr)) { err = unix_autobind(sk); if (err) goto out; } err = -EMSGSIZE; - if (len > sk->sk_sndbuf - 32) + if (len > READ_ONCE(sk->sk_sndbuf) - 32) goto out; if (len > SKB_MAX_ALLOC) { @@ -2020,7 +2043,7 @@ restart_locked: unix_peer(sk) = NULL; unix_dgram_peer_wake_disconnect_wakeup(sk, other); - sk->sk_state = TCP_CLOSE; + WRITE_ONCE(sk->sk_state, TCP_CLOSE); unix_state_unlock(sk); unix_dgram_disconnected(sk, other); @@ -2151,13 +2174,15 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other maybe_add_creds(skb, sock, other); skb_get(skb); + scm_stat_add(other, skb); + + spin_lock(&other->sk_receive_queue.lock); if (ousk->oob_skb) consume_skb(ousk->oob_skb); - WRITE_ONCE(ousk->oob_skb, skb); + __skb_queue_tail(&other->sk_receive_queue, skb); + spin_unlock(&other->sk_receive_queue.lock); - scm_stat_add(other, skb); - skb_queue_tail(&other->sk_receive_queue, skb); sk_send_sigurg(other); unix_state_unlock(other); other->sk_data_ready(other); @@ -2178,11 +2203,12 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, bool fds_sent = false; int data_len; - wait_for_unix_gc(); err = scm_send(sock, msg, &scm, false); if (err < 0) return err; + wait_for_unix_gc(scm.fp); + err = -EOPNOTSUPP; if (msg->msg_flags & MSG_OOB) { #if IS_ENABLED(CONFIG_AF_UNIX_OOB) @@ -2194,7 +2220,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, } if (msg->msg_namelen) { - err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP; + err = READ_ONCE(sk->sk_state) == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP; goto out_err; } else { err = -ENOTCONN; @@ -2203,7 +2229,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, goto out_err; } - if (sk->sk_shutdown & SEND_SHUTDOWN) + if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) goto pipe_err; while (sent < len) { @@ -2215,7 +2241,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, &err, 0); } else { /* Keep two messages in the pipe so it schedules better */ - size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64); + size = min_t(int, size, (READ_ONCE(sk->sk_sndbuf) >> 1) - 64); /* allow fallback to order-0 allocations */ size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ); @@ -2308,7 +2334,7 @@ static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg, if (err) return err; - if (sk->sk_state != TCP_ESTABLISHED) + if (READ_ONCE(sk->sk_state) != TCP_ESTABLISHED) return -ENOTCONN; if (msg->msg_namelen) @@ -2322,7 +2348,7 @@ static int unix_seqpacket_recvmsg(struct socket *sock, struct msghdr *msg, { struct sock *sk = sock->sk; - if (sk->sk_state != TCP_ESTABLISHED) + if (READ_ONCE(sk->sk_state) != TCP_ESTABLISHED) return -ENOTCONN; return unix_dgram_recvmsg(sock, msg, size, flags); @@ -2390,9 +2416,14 @@ int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND); - if (msg->msg_name) + if (msg->msg_name) { unix_copy_addr(msg, skb->sk); + BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk, + msg->msg_name, + &msg->msg_namelen); + } + if (size > skb->len - skip) size = skb->len - skip; else if (size < skb->len - skip) @@ -2542,8 +2573,10 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state) mutex_lock(&u->iolock); unix_state_lock(sk); + spin_lock(&sk->sk_receive_queue.lock); if (sock_flag(sk, SOCK_URGINLINE) || !u->oob_skb) { + spin_unlock(&sk->sk_receive_queue.lock); unix_state_unlock(sk); mutex_unlock(&u->iolock); return -EINVAL; @@ -2553,15 +2586,18 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state) if (!(state->flags & MSG_PEEK)) WRITE_ONCE(u->oob_skb, NULL); + else + skb_get(oob_skb); + spin_unlock(&sk->sk_receive_queue.lock); unix_state_unlock(sk); chunk = state->recv_actor(oob_skb, 0, chunk, state); - if (!(state->flags & MSG_PEEK)) { + if (!(state->flags & MSG_PEEK)) UNIXCB(oob_skb).consumed += 1; - kfree_skb(oob_skb); - } + + consume_skb(oob_skb); mutex_unlock(&u->iolock); @@ -2582,20 +2618,34 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, consume_skb(skb); skb = NULL; } else { + struct sk_buff *unlinked_skb = NULL; + + spin_lock(&sk->sk_receive_queue.lock); + if (skb == u->oob_skb) { if (copied) { skb = NULL; - } else if (sock_flag(sk, SOCK_URGINLINE)) { - if (!(flags & MSG_PEEK)) { + } else if (!(flags & MSG_PEEK)) { + if (sock_flag(sk, SOCK_URGINLINE)) { WRITE_ONCE(u->oob_skb, NULL); consume_skb(skb); + } else { + __skb_unlink(skb, &sk->sk_receive_queue); + WRITE_ONCE(u->oob_skb, NULL); + unlinked_skb = skb; + skb = skb_peek(&sk->sk_receive_queue); } - } else if (!(flags & MSG_PEEK)) { - skb_unlink(skb, &sk->sk_receive_queue); - consume_skb(skb); - skb = skb_peek(&sk->sk_receive_queue); + } else if (!sock_flag(sk, SOCK_URGINLINE)) { + skb = skb_peek_next(skb, &sk->sk_receive_queue); } } + + spin_unlock(&sk->sk_receive_queue.lock); + + if (unlinked_skb) { + WARN_ON_ONCE(skb_unref(unlinked_skb)); + kfree_skb(unlinked_skb); + } } return skb; } @@ -2603,7 +2653,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) { - if (unlikely(sk->sk_state != TCP_ESTABLISHED)) + if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) return -ENOTCONN; return unix_read_skb(sk, recv_actor); @@ -2627,7 +2677,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state, size_t size = state->size; unsigned int last_len; - if (unlikely(sk->sk_state != TCP_ESTABLISHED)) { + if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) { err = -EINVAL; goto out; } @@ -2666,18 +2716,16 @@ redo: last = skb = skb_peek(&sk->sk_receive_queue); last_len = last ? last->len : 0; +again: #if IS_ENABLED(CONFIG_AF_UNIX_OOB) if (skb) { skb = manage_oob(skb, sk, flags, copied); - if (!skb) { + if (!skb && copied) { unix_state_unlock(sk); - if (copied) - break; - goto redo; + break; } } #endif -again: if (skb == NULL) { if (copied >= target) goto unlock; @@ -2744,6 +2792,11 @@ unlock: DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, state->msg->msg_name); unix_copy_addr(state->msg, skb->sk); + + BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk, + state->msg->msg_name, + &state->msg->msg_namelen); + sunaddr = NULL; } @@ -2955,7 +3008,7 @@ long unix_inq_len(struct sock *sk) struct sk_buff *skb; long amount = 0; - if (sk->sk_state == TCP_LISTEN) + if (READ_ONCE(sk->sk_state) == TCP_LISTEN) return -EINVAL; spin_lock(&sk->sk_receive_queue.lock); @@ -3067,12 +3120,14 @@ static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned lon static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wait) { struct sock *sk = sock->sk; + unsigned char state; __poll_t mask; u8 shutdown; sock_poll_wait(file, sock, wait); mask = 0; shutdown = READ_ONCE(sk->sk_shutdown); + state = READ_ONCE(sk->sk_state); /* exceptional events? */ if (READ_ONCE(sk->sk_err)) @@ -3094,14 +3149,14 @@ static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wa /* Connection-based need to check for termination and startup */ if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) && - sk->sk_state == TCP_CLOSE) + state == TCP_CLOSE) mask |= EPOLLHUP; /* * we set writable also when the other side has shut down the * connection. This prevents stuck sockets. */ - if (unix_writable(sk)) + if (unix_writable(sk, state)) mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND; return mask; @@ -3112,12 +3167,14 @@ static __poll_t unix_dgram_poll(struct file *file, struct socket *sock, { struct sock *sk = sock->sk, *other; unsigned int writable; + unsigned char state; __poll_t mask; u8 shutdown; sock_poll_wait(file, sock, wait); mask = 0; shutdown = READ_ONCE(sk->sk_shutdown); + state = READ_ONCE(sk->sk_state); /* exceptional events? */ if (READ_ONCE(sk->sk_err) || @@ -3137,19 +3194,14 @@ static __poll_t unix_dgram_poll(struct file *file, struct socket *sock, mask |= EPOLLIN | EPOLLRDNORM; /* Connection-based need to check for termination and startup */ - if (sk->sk_type == SOCK_SEQPACKET) { - if (sk->sk_state == TCP_CLOSE) - mask |= EPOLLHUP; - /* connection hasn't started yet? */ - if (sk->sk_state == TCP_SYN_SENT) - return mask; - } + if (sk->sk_type == SOCK_SEQPACKET && state == TCP_CLOSE) + mask |= EPOLLHUP; /* No write status requested, avoid expensive OUT tests. */ if (!(poll_requested_events(wait) & (EPOLLWRBAND|EPOLLWRNORM|EPOLLOUT))) return mask; - writable = unix_writable(sk); + writable = unix_writable(sk, state); if (writable) { unix_state_lock(sk); @@ -3311,7 +3363,7 @@ static const struct seq_operations unix_seq_ops = { .show = unix_seq_show, }; -#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) +#ifdef CONFIG_BPF_SYSCALL struct bpf_unix_iter_state { struct seq_net_private p; unsigned int cur_sk; @@ -3573,7 +3625,7 @@ static struct pernet_operations unix_net_ops = { .exit = unix_net_exit, }; -#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) +#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta, struct unix_sock *unix_sk, uid_t uid) @@ -3673,7 +3725,7 @@ static int __init af_unix_init(void) register_pernet_subsys(&unix_net_ops); unix_bpf_build_proto(); -#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) +#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) bpf_iter_register(); #endif @@ -3681,20 +3733,5 @@ out: return rc; } -static void __exit af_unix_exit(void) -{ - sock_unregister(PF_UNIX); - proto_unregister(&unix_dgram_proto); - proto_unregister(&unix_stream_proto); - unregister_pernet_subsys(&unix_net_ops); -} - -/* Earlier than device_initcall() so that other drivers invoking - request_module() don't end up in a loop when modprobe tries - to use a UNIX socket. But later than subsys_initcall() because - we depend on stuff initialised there */ +/* Later than subsys_initcall() because we depend on stuff initialised there */ fs_initcall(af_unix_init); -module_exit(af_unix_exit); - -MODULE_LICENSE("GPL"); -MODULE_ALIAS_NETPROTO(PF_UNIX); diff --git a/net/unix/diag.c b/net/unix/diag.c index 616b55c5b890..937edf4afed4 100644 --- a/net/unix/diag.c +++ b/net/unix/diag.c @@ -65,7 +65,7 @@ static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb) u32 *buf; int i; - if (sk->sk_state == TCP_LISTEN) { + if (READ_ONCE(sk->sk_state) == TCP_LISTEN) { spin_lock(&sk->sk_receive_queue.lock); attr = nla_reserve(nlskb, UNIX_DIAG_ICONS, @@ -84,7 +84,7 @@ static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb) * queue lock. With the other's queue locked it's * OK to lock the state. */ - unix_state_lock_nested(req); + unix_state_lock_nested(req, U_LOCK_DIAG); peer = unix_sk(req)->peer; buf[i++] = (peer ? sock_i_ino(peer) : 0); unix_state_unlock(req); @@ -103,8 +103,8 @@ static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb) { struct unix_diag_rqlen rql; - if (sk->sk_state == TCP_LISTEN) { - rql.udiag_rqueue = sk->sk_receive_queue.qlen; + if (READ_ONCE(sk->sk_state) == TCP_LISTEN) { + rql.udiag_rqueue = skb_queue_len_lockless(&sk->sk_receive_queue); rql.udiag_wqueue = sk->sk_max_ack_backlog; } else { rql.udiag_rqueue = (u32) unix_inq_len(sk); @@ -136,7 +136,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_r rep = nlmsg_data(nlh); rep->udiag_family = AF_UNIX; rep->udiag_type = sk->sk_type; - rep->udiag_state = sk->sk_state; + rep->udiag_state = READ_ONCE(sk->sk_state); rep->pad = 0; rep->udiag_ino = sk_ino; sock_diag_save_cookie(sk, rep->udiag_cookie); @@ -165,7 +165,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_r sock_diag_put_meminfo(sk, skb, UNIX_DIAG_MEMINFO)) goto out_nlmsg_trim; - if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, sk->sk_shutdown)) + if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, READ_ONCE(sk->sk_shutdown))) goto out_nlmsg_trim; if ((req->udiag_show & UDIAG_SHOW_UID) && @@ -215,7 +215,7 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb) sk_for_each(sk, &net->unx.table.buckets[slot]) { if (num < s_num) goto next; - if (!(req->udiag_states & (1 << sk->sk_state))) + if (!(req->udiag_states & (1 << READ_ONCE(sk->sk_state)))) goto next; if (sk_diag_dump(sk, skb, req, sk_user_ns(skb->sk), NETLINK_CB(cb->skb).portid, @@ -322,6 +322,7 @@ static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h) } static const struct sock_diag_handler unix_diag_handler = { + .owner = THIS_MODULE, .family = AF_UNIX, .dump = unix_diag_handler_dump, }; @@ -339,4 +340,5 @@ static void __exit unix_diag_exit(void) module_init(unix_diag_init); module_exit(unix_diag_exit); MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("UNIX socket monitoring via SOCK_DIAG"); MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 1 /* AF_LOCAL */); diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 2405f0f9af31..dfe94a90ece4 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -81,255 +81,550 @@ #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); + + /* 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; -/* Internal data structures and random procedures: */ + ops = READ_ONCE(sock->ops); -static LIST_HEAD(gc_candidates); -static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait); + /* PF_UNIX ? */ + if (sk && ops && ops->family == PF_UNIX) + return unix_sk(sk); + } -static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *), - struct sk_buff_head *hitlist) + return NULL; +} + +static struct unix_vertex *unix_edge_successor(struct unix_edge *edge) { - struct sk_buff *skb; - struct sk_buff *next; - - spin_lock(&x->sk_receive_queue.lock); - skb_queue_walk_safe(&x->sk_receive_queue, skb, next) { - /* Do we have file descriptors ? */ - if (UNIXCB(skb).fp) { - bool hit = false; - /* Process the descriptors of this socket */ - int nfd = UNIXCB(skb).fp->count; - struct file **fp = UNIXCB(skb).fp->fp; - - while (nfd--) { - /* Get the socket the fd matches if it indeed does so */ - struct sock *sk = unix_get_socket(*fp++); - - if (sk) { - struct unix_sock *u = unix_sk(sk); - - /* Ignore non-candidates, they could - * have been added to the queues after - * starting the garbage collection - */ - if (test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) { - hit = true; - - func(u); - } - } - } - if (hit && hitlist != NULL) { - __skb_unlink(skb, &x->sk_receive_queue); - __skb_queue_tail(hitlist, skb); - } - } + /* If an embryo socket has a fd, + * the listener indirectly holds the fd's refcnt. + */ + if (edge->successor->listener) + return unix_sk(edge->successor->listener)->vertex; + + return edge->successor->vertex; +} + +static bool unix_graph_maybe_cyclic; +static bool unix_graph_grouped; + +static void unix_update_graph(struct unix_vertex *vertex) +{ + /* If the receiver socket is not inflight, no cyclic + * reference could be formed. + */ + if (!vertex) + return; + + unix_graph_maybe_cyclic = true; + unix_graph_grouped = false; +} + +static LIST_HEAD(unix_unvisited_vertices); + +enum unix_vertex_index { + UNIX_VERTEX_INDEX_MARK1, + UNIX_VERTEX_INDEX_MARK2, + UNIX_VERTEX_INDEX_START, +}; + +static unsigned long unix_vertex_unvisited_index = UNIX_VERTEX_INDEX_MARK1; + +static void unix_add_edge(struct scm_fp_list *fpl, struct unix_edge *edge) +{ + struct unix_vertex *vertex = edge->predecessor->vertex; + + if (!vertex) { + vertex = list_first_entry(&fpl->vertices, typeof(*vertex), entry); + vertex->index = unix_vertex_unvisited_index; + vertex->out_degree = 0; + INIT_LIST_HEAD(&vertex->edges); + INIT_LIST_HEAD(&vertex->scc_entry); + + list_move_tail(&vertex->entry, &unix_unvisited_vertices); + edge->predecessor->vertex = vertex; } - spin_unlock(&x->sk_receive_queue.lock); + + vertex->out_degree++; + list_add_tail(&edge->vertex_entry, &vertex->edges); + + unix_update_graph(unix_edge_successor(edge)); } -static void scan_children(struct sock *x, void (*func)(struct unix_sock *), - struct sk_buff_head *hitlist) +static void unix_del_edge(struct scm_fp_list *fpl, struct unix_edge *edge) { - if (x->sk_state != TCP_LISTEN) { - scan_inflight(x, func, hitlist); - } else { - struct sk_buff *skb; - struct sk_buff *next; - struct unix_sock *u; - LIST_HEAD(embryos); + struct unix_vertex *vertex = edge->predecessor->vertex; - /* For a listening socket collect the queued embryos - * and perform a scan on them as well. - */ - spin_lock(&x->sk_receive_queue.lock); - skb_queue_walk_safe(&x->sk_receive_queue, skb, next) { - u = unix_sk(skb->sk); + if (!fpl->dead) + unix_update_graph(unix_edge_successor(edge)); - /* An embryo cannot be in-flight, so it's safe - * to use the list link. - */ - BUG_ON(!list_empty(&u->link)); - list_add_tail(&u->link, &embryos); - } - spin_unlock(&x->sk_receive_queue.lock); + list_del(&edge->vertex_entry); + vertex->out_degree--; - while (!list_empty(&embryos)) { - u = list_entry(embryos.next, struct unix_sock, link); - scan_inflight(&u->sk, func, hitlist); - list_del_init(&u->link); - } + if (!vertex->out_degree) { + edge->predecessor->vertex = NULL; + list_move_tail(&vertex->entry, &fpl->vertices); } } -static void dec_inflight(struct unix_sock *usk) +static void unix_free_vertices(struct scm_fp_list *fpl) { - atomic_long_dec(&usk->inflight); + struct unix_vertex *vertex, *next_vertex; + + list_for_each_entry_safe(vertex, next_vertex, &fpl->vertices, entry) { + list_del(&vertex->entry); + kfree(vertex); + } } -static void inc_inflight(struct unix_sock *usk) +static DEFINE_SPINLOCK(unix_gc_lock); +unsigned int unix_tot_inflight; + +void unix_add_edges(struct scm_fp_list *fpl, struct unix_sock *receiver) { - atomic_long_inc(&usk->inflight); + int i = 0, j = 0; + + spin_lock(&unix_gc_lock); + + if (!fpl->count_unix) + goto out; + + do { + struct unix_sock *inflight = unix_get_socket(fpl->fp[j++]); + struct unix_edge *edge; + + if (!inflight) + continue; + + edge = fpl->edges + i++; + edge->predecessor = inflight; + edge->successor = receiver; + + unix_add_edge(fpl, edge); + } while (i < fpl->count_unix); + + receiver->scm_stat.nr_unix_fds += fpl->count_unix; + WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + fpl->count_unix); +out: + WRITE_ONCE(fpl->user->unix_inflight, fpl->user->unix_inflight + fpl->count); + + spin_unlock(&unix_gc_lock); + + fpl->inflight = true; + + unix_free_vertices(fpl); } -static void inc_inflight_move_tail(struct unix_sock *u) +void unix_del_edges(struct scm_fp_list *fpl) { - atomic_long_inc(&u->inflight); - /* If this still might be part of a cycle, move it to the end - * of the list, so that it's checked even if it was already - * passed over + struct unix_sock *receiver; + int i = 0; + + spin_lock(&unix_gc_lock); + + if (!fpl->count_unix) + goto out; + + do { + struct unix_edge *edge = fpl->edges + i++; + + unix_del_edge(fpl, edge); + } while (i < fpl->count_unix); + + if (!fpl->dead) { + receiver = fpl->edges[0].successor; + receiver->scm_stat.nr_unix_fds -= fpl->count_unix; + } + WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - fpl->count_unix); +out: + WRITE_ONCE(fpl->user->unix_inflight, fpl->user->unix_inflight - fpl->count); + + spin_unlock(&unix_gc_lock); + + fpl->inflight = false; +} + +void unix_update_edges(struct unix_sock *receiver) +{ + /* nr_unix_fds is only updated under unix_state_lock(). + * If it's 0 here, the embryo socket is not part of the + * inflight graph, and GC will not see it, so no lock needed. */ - if (test_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags)) - list_move_tail(&u->link, &gc_candidates); + if (!receiver->scm_stat.nr_unix_fds) { + receiver->listener = NULL; + } else { + spin_lock(&unix_gc_lock); + unix_update_graph(unix_sk(receiver->listener)->vertex); + receiver->listener = NULL; + spin_unlock(&unix_gc_lock); + } } -static bool gc_in_progress; -#define UNIX_INFLIGHT_TRIGGER_GC 16000 +int unix_prepare_fpl(struct scm_fp_list *fpl) +{ + struct unix_vertex *vertex; + int i; + + if (!fpl->count_unix) + return 0; + + for (i = 0; i < fpl->count_unix; i++) { + vertex = kmalloc(sizeof(*vertex), GFP_KERNEL); + if (!vertex) + goto err; + + list_add(&vertex->entry, &fpl->vertices); + } + + fpl->edges = kvmalloc_array(fpl->count_unix, sizeof(*fpl->edges), + GFP_KERNEL_ACCOUNT); + if (!fpl->edges) + goto err; + + return 0; + +err: + unix_free_vertices(fpl); + return -ENOMEM; +} -void wait_for_unix_gc(void) +void unix_destroy_fpl(struct scm_fp_list *fpl) { - /* If number of inflight sockets is insane, - * force a garbage collect right now. - * Paired with the WRITE_ONCE() in unix_inflight(), - * unix_notinflight() and gc_in_progress(). - */ - if (READ_ONCE(unix_tot_inflight) > UNIX_INFLIGHT_TRIGGER_GC && - !READ_ONCE(gc_in_progress)) - unix_gc(); - wait_event(unix_gc_wait, gc_in_progress == false); + if (fpl->inflight) + unix_del_edges(fpl); + + kvfree(fpl->edges); + unix_free_vertices(fpl); } -/* The external entry point: unix_gc() */ -void unix_gc(void) +static bool unix_vertex_dead(struct unix_vertex *vertex) { - struct sk_buff *next_skb, *skb; + struct unix_edge *edge; struct unix_sock *u; - struct unix_sock *next; - struct sk_buff_head hitlist; - struct list_head cursor; - LIST_HEAD(not_cycle_list); + long total_ref; - spin_lock(&unix_gc_lock); + list_for_each_entry(edge, &vertex->edges, vertex_entry) { + struct unix_vertex *next_vertex = unix_edge_successor(edge); - /* Avoid a recursive GC. */ - if (gc_in_progress) - goto out; + /* The vertex's fd can be received by a non-inflight socket. */ + if (!next_vertex) + return false; - /* Paired with READ_ONCE() in wait_for_unix_gc(). */ - WRITE_ONCE(gc_in_progress, true); + /* The vertex's fd can be received by an inflight socket in + * another SCC. + */ + if (next_vertex->scc_index != vertex->scc_index) + return false; + } - /* First, select candidates for garbage collection. Only - * in-flight sockets are considered, and from those only ones - * which don't have any external reference. - * - * Holding unix_gc_lock will protect these candidates from - * being detached, and hence from gaining an external - * reference. Since there are no possible receivers, all - * buffers currently on the candidates' queues stay there - * during the garbage collection. - * - * We also know that no new candidate can be added onto the - * receive queues. Other, non candidate sockets _can_ be - * added to queue, so we must make sure only to touch - * candidates. - */ - list_for_each_entry_safe(u, next, &gc_inflight_list, link) { - long total_refs; - long inflight_refs; - - total_refs = file_count(u->sk.sk_socket->file); - inflight_refs = atomic_long_read(&u->inflight); - - BUG_ON(inflight_refs < 1); - BUG_ON(total_refs < inflight_refs); - if (total_refs == inflight_refs) { - list_move_tail(&u->link, &gc_candidates); - __set_bit(UNIX_GC_CANDIDATE, &u->gc_flags); - __set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags); + /* No receiver exists out of the same SCC. */ + + edge = list_first_entry(&vertex->edges, typeof(*edge), vertex_entry); + u = edge->predecessor; + total_ref = file_count(u->sk.sk_socket->file); + + /* If not close()d, total_ref > out_degree. */ + if (total_ref != vertex->out_degree) + return false; + + return true; +} + +enum unix_recv_queue_lock_class { + U_RECVQ_LOCK_NORMAL, + U_RECVQ_LOCK_EMBRYO, +}; + +static void unix_collect_queue(struct unix_sock *u, struct sk_buff_head *hitlist) +{ + skb_queue_splice_init(&u->sk.sk_receive_queue, hitlist); + +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) + if (u->oob_skb) { + WARN_ON_ONCE(skb_unref(u->oob_skb)); + u->oob_skb = NULL; + } +#endif +} + +static void unix_collect_skb(struct list_head *scc, struct sk_buff_head *hitlist) +{ + struct unix_vertex *vertex; + + list_for_each_entry_reverse(vertex, scc, scc_entry) { + struct sk_buff_head *queue; + struct unix_edge *edge; + struct unix_sock *u; + + edge = list_first_entry(&vertex->edges, typeof(*edge), vertex_entry); + u = edge->predecessor; + queue = &u->sk.sk_receive_queue; + + spin_lock(&queue->lock); + + if (u->sk.sk_state == TCP_LISTEN) { + struct sk_buff *skb; + + skb_queue_walk(queue, skb) { + struct sk_buff_head *embryo_queue = &skb->sk->sk_receive_queue; + + /* listener -> embryo order, the inversion never happens. */ + spin_lock_nested(&embryo_queue->lock, U_RECVQ_LOCK_EMBRYO); + unix_collect_queue(unix_sk(skb->sk), hitlist); + spin_unlock(&embryo_queue->lock); + } + } else { + unix_collect_queue(u, hitlist); } + + spin_unlock(&queue->lock); } +} - /* Now remove all internal in-flight reference to children of - * the candidates. - */ - list_for_each_entry(u, &gc_candidates, link) - scan_children(&u->sk, dec_inflight, NULL); +static bool unix_scc_cyclic(struct list_head *scc) +{ + struct unix_vertex *vertex; + struct unix_edge *edge; - /* Restore the references for children of all candidates, - * which have remaining references. Do this recursively, so - * only those remain, which form cyclic references. - * - * Use a "cursor" link, to make the list traversal safe, even - * though elements might be moved about. + /* SCC containing multiple vertices ? */ + if (!list_is_singular(scc)) + return true; + + vertex = list_first_entry(scc, typeof(*vertex), scc_entry); + + /* Self-reference or a embryo-listener circle ? */ + list_for_each_entry(edge, &vertex->edges, vertex_entry) { + if (unix_edge_successor(edge) == vertex) + return true; + } + + return false; +} + +static LIST_HEAD(unix_visited_vertices); +static unsigned long unix_vertex_grouped_index = UNIX_VERTEX_INDEX_MARK2; + +static void __unix_walk_scc(struct unix_vertex *vertex, unsigned long *last_index, + struct sk_buff_head *hitlist) +{ + LIST_HEAD(vertex_stack); + struct unix_edge *edge; + LIST_HEAD(edge_stack); + +next_vertex: + /* Push vertex to vertex_stack and mark it as on-stack + * (index >= UNIX_VERTEX_INDEX_START). + * The vertex will be popped when finalising SCC later. */ - list_add(&cursor, &gc_candidates); - while (cursor.next != &gc_candidates) { - u = list_entry(cursor.next, struct unix_sock, link); + list_add(&vertex->scc_entry, &vertex_stack); + + vertex->index = *last_index; + vertex->scc_index = *last_index; + (*last_index)++; - /* Move cursor to after the current position. */ - list_move(&cursor, &u->link); + /* Explore neighbour vertices (receivers of the current vertex's fd). */ + list_for_each_entry(edge, &vertex->edges, vertex_entry) { + struct unix_vertex *next_vertex = unix_edge_successor(edge); - if (atomic_long_read(&u->inflight) > 0) { - list_move_tail(&u->link, ¬_cycle_list); - __clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags); - scan_children(&u->sk, inc_inflight_move_tail, NULL); + if (!next_vertex) + continue; + + if (next_vertex->index == unix_vertex_unvisited_index) { + /* Iterative deepening depth first search + * + * 1. Push a forward edge to edge_stack and set + * the successor to vertex for the next iteration. + */ + list_add(&edge->stack_entry, &edge_stack); + + vertex = next_vertex; + goto next_vertex; + + /* 2. Pop the edge directed to the current vertex + * and restore the ancestor for backtracking. + */ +prev_vertex: + edge = list_first_entry(&edge_stack, typeof(*edge), stack_entry); + list_del_init(&edge->stack_entry); + + next_vertex = vertex; + vertex = edge->predecessor->vertex; + + /* If the successor has a smaller scc_index, two vertices + * are in the same SCC, so propagate the smaller scc_index + * to skip SCC finalisation. + */ + vertex->scc_index = min(vertex->scc_index, next_vertex->scc_index); + } else if (next_vertex->index != unix_vertex_grouped_index) { + /* Loop detected by a back/cross edge. + * + * The successor is on vertex_stack, so two vertices are in + * the same SCC. If the successor has a smaller *scc_index*, + * propagate it to skip SCC finalisation. + */ + vertex->scc_index = min(vertex->scc_index, next_vertex->scc_index); + } else { + /* The successor was already grouped as another SCC */ } } - list_del(&cursor); - /* Now gc_candidates contains only garbage. Restore original - * inflight counters for these as well, and remove the skbuffs - * which are creating the cycle(s). - */ - skb_queue_head_init(&hitlist); - list_for_each_entry(u, &gc_candidates, link) - scan_children(&u->sk, inc_inflight, &hitlist); + if (vertex->index == vertex->scc_index) { + struct list_head scc; + bool scc_dead = true; - /* not_cycle_list contains those sockets which do not make up a - * cycle. Restore these to the inflight list. - */ - while (!list_empty(¬_cycle_list)) { - u = list_entry(not_cycle_list.next, struct unix_sock, link); - __clear_bit(UNIX_GC_CANDIDATE, &u->gc_flags); - list_move_tail(&u->link, &gc_inflight_list); + /* SCC finalised. + * + * If the scc_index was not updated, all the vertices above on + * vertex_stack are in the same SCC. Group them using scc_entry. + */ + __list_cut_position(&scc, &vertex_stack, &vertex->scc_entry); + + list_for_each_entry_reverse(vertex, &scc, scc_entry) { + /* Don't restart DFS from this vertex in unix_walk_scc(). */ + list_move_tail(&vertex->entry, &unix_visited_vertices); + + /* Mark vertex as off-stack. */ + vertex->index = unix_vertex_grouped_index; + + if (scc_dead) + scc_dead = unix_vertex_dead(vertex); + } + + if (scc_dead) + unix_collect_skb(&scc, hitlist); + else if (!unix_graph_maybe_cyclic) + unix_graph_maybe_cyclic = unix_scc_cyclic(&scc); + + list_del(&scc); } - spin_unlock(&unix_gc_lock); + /* Need backtracking ? */ + if (!list_empty(&edge_stack)) + goto prev_vertex; +} + +static void unix_walk_scc(struct sk_buff_head *hitlist) +{ + unsigned long last_index = UNIX_VERTEX_INDEX_START; + + unix_graph_maybe_cyclic = false; - /* We need io_uring to clean its registered files, ignore all io_uring - * originated skbs. It's fine as io_uring doesn't keep references to - * other io_uring instances and so killing all other files in the cycle - * will put all io_uring references forcing it to go through normal - * release.path eventually putting registered files. + /* Visit every vertex exactly once. + * __unix_walk_scc() moves visited vertices to unix_visited_vertices. */ - skb_queue_walk_safe(&hitlist, skb, next_skb) { - if (skb->destructor == io_uring_destruct_scm) { - __skb_unlink(skb, &hitlist); - skb_queue_tail(&skb->sk->sk_receive_queue, skb); + while (!list_empty(&unix_unvisited_vertices)) { + struct unix_vertex *vertex; + + vertex = list_first_entry(&unix_unvisited_vertices, typeof(*vertex), entry); + __unix_walk_scc(vertex, &last_index, hitlist); + } + + list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices); + swap(unix_vertex_unvisited_index, unix_vertex_grouped_index); + + unix_graph_grouped = true; +} + +static void unix_walk_scc_fast(struct sk_buff_head *hitlist) +{ + unix_graph_maybe_cyclic = false; + + while (!list_empty(&unix_unvisited_vertices)) { + struct unix_vertex *vertex; + struct list_head scc; + bool scc_dead = true; + + vertex = list_first_entry(&unix_unvisited_vertices, typeof(*vertex), entry); + list_add(&scc, &vertex->scc_entry); + + list_for_each_entry_reverse(vertex, &scc, scc_entry) { + list_move_tail(&vertex->entry, &unix_visited_vertices); + + if (scc_dead) + scc_dead = unix_vertex_dead(vertex); } + + if (scc_dead) + unix_collect_skb(&scc, hitlist); + else if (!unix_graph_maybe_cyclic) + unix_graph_maybe_cyclic = unix_scc_cyclic(&scc); + + list_del(&scc); } - /* Here we are. Hitlist is filled. Die. */ - __skb_queue_purge(&hitlist); + list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices); +} + +static bool gc_in_progress; + +static void __unix_gc(struct work_struct *work) +{ + struct sk_buff_head hitlist; + struct sk_buff *skb; spin_lock(&unix_gc_lock); - /* There could be io_uring registered files, just push them back to - * the inflight list - */ - list_for_each_entry_safe(u, next, &gc_candidates, link) - list_move_tail(&u->link, &gc_inflight_list); + if (!unix_graph_maybe_cyclic) { + spin_unlock(&unix_gc_lock); + goto skip_gc; + } + + __skb_queue_head_init(&hitlist); + + if (unix_graph_grouped) + unix_walk_scc_fast(&hitlist); + else + unix_walk_scc(&hitlist); - /* All candidates should have been detached by now. */ - BUG_ON(!list_empty(&gc_candidates)); + spin_unlock(&unix_gc_lock); + + skb_queue_walk(&hitlist, skb) { + if (UNIXCB(skb).fp) + UNIXCB(skb).fp->dead = true; + } - /* Paired with READ_ONCE() in wait_for_unix_gc(). */ + __skb_queue_purge(&hitlist); +skip_gc: WRITE_ONCE(gc_in_progress, false); +} - wake_up(&unix_gc_wait); +static DECLARE_WORK(unix_gc_work, __unix_gc); - out: - spin_unlock(&unix_gc_lock); +void unix_gc(void) +{ + WRITE_ONCE(gc_in_progress, true); + queue_work(system_unbound_wq, &unix_gc_work); +} + +#define UNIX_INFLIGHT_TRIGGER_GC 16000 +#define UNIX_INFLIGHT_SANE_USER (SCM_MAX_FD * 8) + +void wait_for_unix_gc(struct scm_fp_list *fpl) +{ + /* If number of inflight sockets is insane, + * force a garbage collect right now. + * + * Paired with the WRITE_ONCE() in unix_inflight(), + * unix_notinflight(), and __unix_gc(). + */ + if (READ_ONCE(unix_tot_inflight) > UNIX_INFLIGHT_TRIGGER_GC && + !READ_ONCE(gc_in_progress)) + unix_gc(); + + /* Penalise users who want to send AF_UNIX sockets + * but whose sockets have not been received yet. + */ + if (!fpl || !fpl->count_unix || + READ_ONCE(fpl->user->unix_inflight) < UNIX_INFLIGHT_SANE_USER) + return; + + if (READ_ONCE(gc_in_progress)) + flush_work(&unix_gc_work); } diff --git a/net/unix/scm.c b/net/unix/scm.c deleted file mode 100644 index f9152881d77f..000000000000 --- a/net/unix/scm.c +++ /dev/null @@ -1,160 +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 sock *unix_get_socket(struct file *filp) -{ - struct sock *u_sock = NULL; - struct inode *inode = file_inode(filp); - - /* Socket ? */ - if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) { - struct socket *sock = SOCKET_I(inode); - struct sock *s = sock->sk; - - /* PF_UNIX ? */ - if (s && sock->ops && sock->ops->family == PF_UNIX) - u_sock = s; - } else { - /* Could be an io_uring instance */ - u_sock = io_uring_get_socket(filp); - } - return u_sock; -} -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 sock *s = unix_get_socket(fp); - - spin_lock(&unix_gc_lock); - - if (s) { - struct unix_sock *u = unix_sk(s); - - if (atomic_long_inc_return(&u->inflight) == 1) { - BUG_ON(!list_empty(&u->link)); - list_add_tail(&u->link, &gc_inflight_list); - } else { - BUG_ON(list_empty(&u->link)); - } - /* Paired with READ_ONCE() in wait_for_unix_gc() */ - WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1); - } - user->unix_inflight++; - spin_unlock(&unix_gc_lock); -} - -void unix_notinflight(struct user_struct *user, struct file *fp) -{ - struct sock *s = unix_get_socket(fp); - - spin_lock(&unix_gc_lock); - - if (s) { - struct unix_sock *u = unix_sk(s); - - BUG_ON(!atomic_long_read(&u->inflight)); - BUG_ON(list_empty(&u->link)); - - if (atomic_long_dec_and_test(&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); - } - user->unix_inflight--; - 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(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); - -void io_uring_destruct_scm(struct sk_buff *skb) -{ - unix_destruct_scm(skb); -} -EXPORT_SYMBOL(io_uring_destruct_scm); diff --git a/net/unix/scm.h b/net/unix/scm.h deleted file mode 100644 index 5a255a477f16..000000000000 --- a/net/unix/scm.h +++ /dev/null @@ -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 diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c index 500129aa710c..357b3e5f3847 100644 --- a/net/unix/sysctl_net_unix.c +++ b/net/unix/sysctl_net_unix.c @@ -19,7 +19,6 @@ static struct ctl_table unix_table[] = { .mode = 0644, .proc_handler = proc_dointvec }, - { } }; int __net_init unix_sysctl_register(struct net *net) @@ -36,7 +35,8 @@ int __net_init unix_sysctl_register(struct net *net) table[0].data = &net->unx.sysctl_max_dgram_qlen; } - net->unx.ctl = register_net_sysctl(net, "net/unix", table); + net->unx.ctl = register_net_sysctl_sz(net, "net/unix", table, + ARRAY_SIZE(unix_table)); if (net->unx.ctl == NULL) goto err_reg; @@ -51,7 +51,7 @@ err_alloc: void unix_sysctl_unregister(struct net *net) { - struct ctl_table *table; + const struct ctl_table *table; table = net->unx.ctl->ctl_table_arg; unregister_net_sysctl_table(net->unx.ctl); diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c index 2f9d8271c6ec..bd84785bf8d6 100644 --- a/net/unix/unix_bpf.c +++ b/net/unix/unix_bpf.c @@ -159,12 +159,32 @@ int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool re int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) { + struct sock *sk_pair; + + /* Restore does not decrement the sk_pair reference yet because we must + * keep the a reference to the socket until after an RCU grace period + * and any pending sends have completed. + */ if (restore) { sk->sk_write_space = psock->saved_write_space; sock_replace_proto(sk, psock->sk_proto); return 0; } + /* psock_update_sk_prot can be called multiple times if psock is + * added to multiple maps and/or slots in the same map. There is + * also an edge case where replacing a psock with itself can trigger + * an extra psock_update_sk_prot during the insert process. So it + * must be safe to do multiple calls. Here we need to ensure we don't + * increment the refcnt through sock_hold many times. There will only + * be a single matching destroy operation. + */ + if (!psock->sk_pair) { + sk_pair = unix_peer(sk); + sock_hold(sk_pair); + psock->sk_pair = sk_pair; + } + unix_stream_bpf_check_needs_rebuild(psock->sk_proto); sock_replace_proto(sk, &unix_stream_bpf_prot); return 0; |