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-rw-r--r--fs/autofs/waitq.c513
1 files changed, 513 insertions, 0 deletions
diff --git a/fs/autofs/waitq.c b/fs/autofs/waitq.c
new file mode 100644
index 0000000000..33dd4660d8
--- /dev/null
+++ b/fs/autofs/waitq.c
@@ -0,0 +1,513 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ * Copyright 2001-2006 Ian Kent <raven@themaw.net>
+ */
+
+#include <linux/sched/signal.h>
+#include "autofs_i.h"
+
+/* We make this a static variable rather than a part of the superblock; it
+ * is better if we don't reassign numbers easily even across filesystems
+ */
+static autofs_wqt_t autofs_next_wait_queue = 1;
+
+void autofs_catatonic_mode(struct autofs_sb_info *sbi)
+{
+ struct autofs_wait_queue *wq, *nwq;
+
+ mutex_lock(&sbi->wq_mutex);
+ if (sbi->flags & AUTOFS_SBI_CATATONIC) {
+ mutex_unlock(&sbi->wq_mutex);
+ return;
+ }
+
+ pr_debug("entering catatonic mode\n");
+
+ sbi->flags |= AUTOFS_SBI_CATATONIC;
+ wq = sbi->queues;
+ sbi->queues = NULL; /* Erase all wait queues */
+ while (wq) {
+ nwq = wq->next;
+ wq->status = -ENOENT; /* Magic is gone - report failure */
+ kfree(wq->name.name - wq->offset);
+ wq->name.name = NULL;
+ wake_up(&wq->queue);
+ if (!--wq->wait_ctr)
+ kfree(wq);
+ wq = nwq;
+ }
+ fput(sbi->pipe); /* Close the pipe */
+ sbi->pipe = NULL;
+ sbi->pipefd = -1;
+ mutex_unlock(&sbi->wq_mutex);
+}
+
+static int autofs_write(struct autofs_sb_info *sbi,
+ struct file *file, const void *addr, int bytes)
+{
+ unsigned long sigpipe, flags;
+ const char *data = (const char *)addr;
+ ssize_t wr = 0;
+
+ sigpipe = sigismember(&current->pending.signal, SIGPIPE);
+
+ mutex_lock(&sbi->pipe_mutex);
+ while (bytes) {
+ wr = __kernel_write(file, data, bytes, NULL);
+ if (wr <= 0)
+ break;
+ data += wr;
+ bytes -= wr;
+ }
+ mutex_unlock(&sbi->pipe_mutex);
+
+ /* Keep the currently executing process from receiving a
+ * SIGPIPE unless it was already supposed to get one
+ */
+ if (wr == -EPIPE && !sigpipe) {
+ spin_lock_irqsave(&current->sighand->siglock, flags);
+ sigdelset(&current->pending.signal, SIGPIPE);
+ recalc_sigpending();
+ spin_unlock_irqrestore(&current->sighand->siglock, flags);
+ }
+
+ /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
+ return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
+}
+
+static void autofs_notify_daemon(struct autofs_sb_info *sbi,
+ struct autofs_wait_queue *wq,
+ int type)
+{
+ union {
+ struct autofs_packet_hdr hdr;
+ union autofs_packet_union v4_pkt;
+ union autofs_v5_packet_union v5_pkt;
+ } pkt;
+ struct file *pipe = NULL;
+ size_t pktsz;
+ int ret;
+
+ pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
+ (unsigned long) wq->wait_queue_token,
+ wq->name.len, wq->name.name, type);
+
+ memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
+
+ pkt.hdr.proto_version = sbi->version;
+ pkt.hdr.type = type;
+
+ switch (type) {
+ /* Kernel protocol v4 missing and expire packets */
+ case autofs_ptype_missing:
+ {
+ struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
+
+ pktsz = sizeof(*mp);
+
+ mp->wait_queue_token = wq->wait_queue_token;
+ mp->len = wq->name.len;
+ memcpy(mp->name, wq->name.name, wq->name.len);
+ mp->name[wq->name.len] = '\0';
+ break;
+ }
+ case autofs_ptype_expire_multi:
+ {
+ struct autofs_packet_expire_multi *ep =
+ &pkt.v4_pkt.expire_multi;
+
+ pktsz = sizeof(*ep);
+
+ ep->wait_queue_token = wq->wait_queue_token;
+ ep->len = wq->name.len;
+ memcpy(ep->name, wq->name.name, wq->name.len);
+ ep->name[wq->name.len] = '\0';
+ break;
+ }
+ /*
+ * Kernel protocol v5 packet for handling indirect and direct
+ * mount missing and expire requests
+ */
+ case autofs_ptype_missing_indirect:
+ case autofs_ptype_expire_indirect:
+ case autofs_ptype_missing_direct:
+ case autofs_ptype_expire_direct:
+ {
+ struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
+ struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
+
+ pktsz = sizeof(*packet);
+
+ packet->wait_queue_token = wq->wait_queue_token;
+ packet->len = wq->name.len;
+ memcpy(packet->name, wq->name.name, wq->name.len);
+ packet->name[wq->name.len] = '\0';
+ packet->dev = wq->dev;
+ packet->ino = wq->ino;
+ packet->uid = from_kuid_munged(user_ns, wq->uid);
+ packet->gid = from_kgid_munged(user_ns, wq->gid);
+ packet->pid = wq->pid;
+ packet->tgid = wq->tgid;
+ break;
+ }
+ default:
+ pr_warn("bad type %d!\n", type);
+ mutex_unlock(&sbi->wq_mutex);
+ return;
+ }
+
+ pipe = get_file(sbi->pipe);
+
+ mutex_unlock(&sbi->wq_mutex);
+
+ switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
+ case 0:
+ break;
+ case -ENOMEM:
+ case -ERESTARTSYS:
+ /* Just fail this one */
+ autofs_wait_release(sbi, wq->wait_queue_token, ret);
+ break;
+ default:
+ autofs_catatonic_mode(sbi);
+ break;
+ }
+ fput(pipe);
+}
+
+static struct autofs_wait_queue *
+autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
+{
+ struct autofs_wait_queue *wq;
+
+ for (wq = sbi->queues; wq; wq = wq->next) {
+ if (wq->name.hash == qstr->hash &&
+ wq->name.len == qstr->len &&
+ wq->name.name &&
+ !memcmp(wq->name.name, qstr->name, qstr->len))
+ break;
+ }
+ return wq;
+}
+
+/*
+ * Check if we have a valid request.
+ * Returns
+ * 1 if the request should continue.
+ * In this case we can return an autofs_wait_queue entry if one is
+ * found or NULL to idicate a new wait needs to be created.
+ * 0 or a negative errno if the request shouldn't continue.
+ */
+static int validate_request(struct autofs_wait_queue **wait,
+ struct autofs_sb_info *sbi,
+ const struct qstr *qstr,
+ const struct path *path, enum autofs_notify notify)
+{
+ struct dentry *dentry = path->dentry;
+ struct autofs_wait_queue *wq;
+ struct autofs_info *ino;
+
+ if (sbi->flags & AUTOFS_SBI_CATATONIC)
+ return -ENOENT;
+
+ /* Wait in progress, continue; */
+ wq = autofs_find_wait(sbi, qstr);
+ if (wq) {
+ *wait = wq;
+ return 1;
+ }
+
+ *wait = NULL;
+
+ /* If we don't yet have any info this is a new request */
+ ino = autofs_dentry_ino(dentry);
+ if (!ino)
+ return 1;
+
+ /*
+ * If we've been asked to wait on an existing expire (NFY_NONE)
+ * but there is no wait in the queue ...
+ */
+ if (notify == NFY_NONE) {
+ /*
+ * Either we've betean the pending expire to post it's
+ * wait or it finished while we waited on the mutex.
+ * So we need to wait till either, the wait appears
+ * or the expire finishes.
+ */
+
+ while (ino->flags & AUTOFS_INF_EXPIRING) {
+ mutex_unlock(&sbi->wq_mutex);
+ schedule_timeout_interruptible(HZ/10);
+ if (mutex_lock_interruptible(&sbi->wq_mutex))
+ return -EINTR;
+
+ if (sbi->flags & AUTOFS_SBI_CATATONIC)
+ return -ENOENT;
+
+ wq = autofs_find_wait(sbi, qstr);
+ if (wq) {
+ *wait = wq;
+ return 1;
+ }
+ }
+
+ /*
+ * Not ideal but the status has already gone. Of the two
+ * cases where we wait on NFY_NONE neither depend on the
+ * return status of the wait.
+ */
+ return 0;
+ }
+
+ /*
+ * If we've been asked to trigger a mount and the request
+ * completed while we waited on the mutex ...
+ */
+ if (notify == NFY_MOUNT) {
+ struct dentry *new = NULL;
+ struct path this;
+ int valid = 1;
+
+ /*
+ * If the dentry was successfully mounted while we slept
+ * on the wait queue mutex we can return success. If it
+ * isn't mounted (doesn't have submounts for the case of
+ * a multi-mount with no mount at it's base) we can
+ * continue on and create a new request.
+ */
+ if (!IS_ROOT(dentry)) {
+ if (d_unhashed(dentry) &&
+ d_really_is_positive(dentry)) {
+ struct dentry *parent = dentry->d_parent;
+
+ new = d_lookup(parent, &dentry->d_name);
+ if (new)
+ dentry = new;
+ }
+ }
+ this.mnt = path->mnt;
+ this.dentry = dentry;
+ if (path_has_submounts(&this))
+ valid = 0;
+
+ if (new)
+ dput(new);
+ return valid;
+ }
+
+ return 1;
+}
+
+int autofs_wait(struct autofs_sb_info *sbi,
+ const struct path *path, enum autofs_notify notify)
+{
+ struct dentry *dentry = path->dentry;
+ struct autofs_wait_queue *wq;
+ struct qstr qstr;
+ char *name;
+ int status, ret, type;
+ unsigned int offset = 0;
+ pid_t pid;
+ pid_t tgid;
+
+ /* In catatonic mode, we don't wait for nobody */
+ if (sbi->flags & AUTOFS_SBI_CATATONIC)
+ return -ENOENT;
+
+ /*
+ * Try translating pids to the namespace of the daemon.
+ *
+ * Zero means failure: we are in an unrelated pid namespace.
+ */
+ pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
+ tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
+ if (pid == 0 || tgid == 0)
+ return -ENOENT;
+
+ if (d_really_is_negative(dentry)) {
+ /*
+ * A wait for a negative dentry is invalid for certain
+ * cases. A direct or offset mount "always" has its mount
+ * point directory created and so the request dentry must
+ * be positive or the map key doesn't exist. The situation
+ * is very similar for indirect mounts except only dentrys
+ * in the root of the autofs file system may be negative.
+ */
+ if (autofs_type_trigger(sbi->type))
+ return -ENOENT;
+ else if (!IS_ROOT(dentry->d_parent))
+ return -ENOENT;
+ }
+
+ name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!name)
+ return -ENOMEM;
+
+ /* If this is a direct mount request create a dummy name */
+ if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) {
+ qstr.name = name;
+ qstr.len = sprintf(name, "%p", dentry);
+ } else {
+ char *p = dentry_path_raw(dentry, name, NAME_MAX);
+ if (IS_ERR(p)) {
+ kfree(name);
+ return -ENOENT;
+ }
+ qstr.name = ++p; // skip the leading slash
+ qstr.len = strlen(p);
+ offset = p - name;
+ }
+ qstr.hash = full_name_hash(dentry, qstr.name, qstr.len);
+
+ if (mutex_lock_interruptible(&sbi->wq_mutex)) {
+ kfree(name);
+ return -EINTR;
+ }
+
+ ret = validate_request(&wq, sbi, &qstr, path, notify);
+ if (ret <= 0) {
+ if (ret != -EINTR)
+ mutex_unlock(&sbi->wq_mutex);
+ kfree(name);
+ return ret;
+ }
+
+ if (!wq) {
+ /* Create a new wait queue */
+ wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
+ if (!wq) {
+ kfree(name);
+ mutex_unlock(&sbi->wq_mutex);
+ return -ENOMEM;
+ }
+
+ wq->wait_queue_token = autofs_next_wait_queue;
+ if (++autofs_next_wait_queue == 0)
+ autofs_next_wait_queue = 1;
+ wq->next = sbi->queues;
+ sbi->queues = wq;
+ init_waitqueue_head(&wq->queue);
+ memcpy(&wq->name, &qstr, sizeof(struct qstr));
+ wq->offset = offset;
+ wq->dev = autofs_get_dev(sbi);
+ wq->ino = autofs_get_ino(sbi);
+ wq->uid = current_uid();
+ wq->gid = current_gid();
+ wq->pid = pid;
+ wq->tgid = tgid;
+ wq->status = -EINTR; /* Status return if interrupted */
+ wq->wait_ctr = 2;
+
+ if (sbi->version < 5) {
+ if (notify == NFY_MOUNT)
+ type = autofs_ptype_missing;
+ else
+ type = autofs_ptype_expire_multi;
+ } else {
+ if (notify == NFY_MOUNT)
+ type = autofs_type_trigger(sbi->type) ?
+ autofs_ptype_missing_direct :
+ autofs_ptype_missing_indirect;
+ else
+ type = autofs_type_trigger(sbi->type) ?
+ autofs_ptype_expire_direct :
+ autofs_ptype_expire_indirect;
+ }
+
+ pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
+ (unsigned long) wq->wait_queue_token, wq->name.len,
+ wq->name.name, notify);
+
+ /*
+ * autofs_notify_daemon() may block; it will unlock ->wq_mutex
+ */
+ autofs_notify_daemon(sbi, wq, type);
+ } else {
+ wq->wait_ctr++;
+ pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
+ (unsigned long) wq->wait_queue_token, wq->name.len,
+ wq->name.name, notify);
+ mutex_unlock(&sbi->wq_mutex);
+ kfree(name);
+ }
+
+ /*
+ * wq->name.name is NULL iff the lock is already released
+ * or the mount has been made catatonic.
+ */
+ wait_event_killable(wq->queue, wq->name.name == NULL);
+ status = wq->status;
+
+ /*
+ * For direct and offset mounts we need to track the requester's
+ * uid and gid in the dentry info struct. This is so it can be
+ * supplied, on request, by the misc device ioctl interface.
+ * This is needed during daemon resatart when reconnecting
+ * to existing, active, autofs mounts. The uid and gid (and
+ * related string values) may be used for macro substitution
+ * in autofs mount maps.
+ */
+ if (!status) {
+ struct autofs_info *ino;
+ struct dentry *de = NULL;
+
+ /* direct mount or browsable map */
+ ino = autofs_dentry_ino(dentry);
+ if (!ino) {
+ /* If not lookup actual dentry used */
+ de = d_lookup(dentry->d_parent, &dentry->d_name);
+ if (de)
+ ino = autofs_dentry_ino(de);
+ }
+
+ /* Set mount requester */
+ if (ino) {
+ spin_lock(&sbi->fs_lock);
+ ino->uid = wq->uid;
+ ino->gid = wq->gid;
+ spin_unlock(&sbi->fs_lock);
+ }
+
+ if (de)
+ dput(de);
+ }
+
+ /* Are we the last process to need status? */
+ mutex_lock(&sbi->wq_mutex);
+ if (!--wq->wait_ctr)
+ kfree(wq);
+ mutex_unlock(&sbi->wq_mutex);
+
+ return status;
+}
+
+
+int autofs_wait_release(struct autofs_sb_info *sbi,
+ autofs_wqt_t wait_queue_token, int status)
+{
+ struct autofs_wait_queue *wq, **wql;
+
+ mutex_lock(&sbi->wq_mutex);
+ for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
+ if (wq->wait_queue_token == wait_queue_token)
+ break;
+ }
+
+ if (!wq) {
+ mutex_unlock(&sbi->wq_mutex);
+ return -EINVAL;
+ }
+
+ *wql = wq->next; /* Unlink from chain */
+ kfree(wq->name.name - wq->offset);
+ wq->name.name = NULL; /* Do not wait on this queue */
+ wq->status = status;
+ wake_up(&wq->queue);
+ if (!--wq->wait_ctr)
+ kfree(wq);
+ mutex_unlock(&sbi->wq_mutex);
+
+ return 0;
+}
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