From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- fs/autofs/waitq.c | 513 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 513 insertions(+) create mode 100644 fs/autofs/waitq.c (limited to 'fs/autofs/waitq.c') 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 + */ + +#include +#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(¤t->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(¤t->sighand->siglock, flags); + sigdelset(¤t->pending.signal, SIGPIPE); + recalc_sigpending(); + spin_unlock_irqrestore(¤t->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; +} -- cgit v1.2.3