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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>5 */6 7#include <linux/sched/signal.h>8#include "autofs_i.h"9 10/* We make this a static variable rather than a part of the superblock; it11 * is better if we don't reassign numbers easily even across filesystems12 */13static autofs_wqt_t autofs_next_wait_queue = 1;14 15void autofs_catatonic_mode(struct autofs_sb_info *sbi)16{17 struct autofs_wait_queue *wq, *nwq;18 19 mutex_lock(&sbi->wq_mutex);20 if (sbi->flags & AUTOFS_SBI_CATATONIC) {21 mutex_unlock(&sbi->wq_mutex);22 return;23 }24 25 pr_debug("entering catatonic mode\n");26 27 sbi->flags |= AUTOFS_SBI_CATATONIC;28 wq = sbi->queues;29 sbi->queues = NULL; /* Erase all wait queues */30 while (wq) {31 nwq = wq->next;32 wq->status = -ENOENT; /* Magic is gone - report failure */33 kfree(wq->name.name - wq->offset);34 wq->name.name = NULL;35 wake_up(&wq->queue);36 if (!--wq->wait_ctr)37 kfree(wq);38 wq = nwq;39 }40 fput(sbi->pipe); /* Close the pipe */41 sbi->pipe = NULL;42 sbi->pipefd = -1;43 mutex_unlock(&sbi->wq_mutex);44}45 46static int autofs_write(struct autofs_sb_info *sbi,47 struct file *file, const void *addr, int bytes)48{49 unsigned long sigpipe, flags;50 const char *data = (const char *)addr;51 ssize_t wr = 0;52 53 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);54 55 mutex_lock(&sbi->pipe_mutex);56 while (bytes) {57 wr = __kernel_write(file, data, bytes, NULL);58 if (wr <= 0)59 break;60 data += wr;61 bytes -= wr;62 }63 mutex_unlock(&sbi->pipe_mutex);64 65 /* Keep the currently executing process from receiving a66 * SIGPIPE unless it was already supposed to get one67 */68 if (wr == -EPIPE && !sigpipe) {69 spin_lock_irqsave(¤t->sighand->siglock, flags);70 sigdelset(¤t->pending.signal, SIGPIPE);71 recalc_sigpending();72 spin_unlock_irqrestore(¤t->sighand->siglock, flags);73 }74 75 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */76 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;77}78 79static void autofs_notify_daemon(struct autofs_sb_info *sbi,80 struct autofs_wait_queue *wq,81 int type)82{83 union {84 struct autofs_packet_hdr hdr;85 union autofs_packet_union v4_pkt;86 union autofs_v5_packet_union v5_pkt;87 } pkt;88 struct file *pipe = NULL;89 size_t pktsz;90 int ret;91 92 pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",93 (unsigned long) wq->wait_queue_token,94 wq->name.len, wq->name.name, type);95 96 memset(&pkt, 0, sizeof(pkt)); /* For security reasons */97 98 pkt.hdr.proto_version = sbi->version;99 pkt.hdr.type = type;100 101 switch (type) {102 /* Kernel protocol v4 missing and expire packets */103 case autofs_ptype_missing:104 {105 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;106 107 pktsz = sizeof(*mp);108 109 mp->wait_queue_token = wq->wait_queue_token;110 mp->len = wq->name.len;111 memcpy(mp->name, wq->name.name, wq->name.len);112 mp->name[wq->name.len] = '\0';113 break;114 }115 case autofs_ptype_expire_multi:116 {117 struct autofs_packet_expire_multi *ep =118 &pkt.v4_pkt.expire_multi;119 120 pktsz = sizeof(*ep);121 122 ep->wait_queue_token = wq->wait_queue_token;123 ep->len = wq->name.len;124 memcpy(ep->name, wq->name.name, wq->name.len);125 ep->name[wq->name.len] = '\0';126 break;127 }128 /*129 * Kernel protocol v5 packet for handling indirect and direct130 * mount missing and expire requests131 */132 case autofs_ptype_missing_indirect:133 case autofs_ptype_expire_indirect:134 case autofs_ptype_missing_direct:135 case autofs_ptype_expire_direct:136 {137 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;138 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;139 140 pktsz = sizeof(*packet);141 142 packet->wait_queue_token = wq->wait_queue_token;143 packet->len = wq->name.len;144 memcpy(packet->name, wq->name.name, wq->name.len);145 packet->name[wq->name.len] = '\0';146 packet->dev = wq->dev;147 packet->ino = wq->ino;148 packet->uid = from_kuid_munged(user_ns, wq->uid);149 packet->gid = from_kgid_munged(user_ns, wq->gid);150 packet->pid = wq->pid;151 packet->tgid = wq->tgid;152 break;153 }154 default:155 pr_warn("bad type %d!\n", type);156 mutex_unlock(&sbi->wq_mutex);157 return;158 }159 160 pipe = get_file(sbi->pipe);161 162 mutex_unlock(&sbi->wq_mutex);163 164 switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {165 case 0:166 break;167 case -ENOMEM:168 case -ERESTARTSYS:169 /* Just fail this one */170 autofs_wait_release(sbi, wq->wait_queue_token, ret);171 break;172 default:173 autofs_catatonic_mode(sbi);174 break;175 }176 fput(pipe);177}178 179static struct autofs_wait_queue *180autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)181{182 struct autofs_wait_queue *wq;183 184 for (wq = sbi->queues; wq; wq = wq->next) {185 if (wq->name.hash == qstr->hash &&186 wq->name.len == qstr->len &&187 wq->name.name &&188 !memcmp(wq->name.name, qstr->name, qstr->len))189 break;190 }191 return wq;192}193 194/*195 * Check if we have a valid request.196 * Returns197 * 1 if the request should continue.198 * In this case we can return an autofs_wait_queue entry if one is199 * found or NULL to idicate a new wait needs to be created.200 * 0 or a negative errno if the request shouldn't continue.201 */202static int validate_request(struct autofs_wait_queue **wait,203 struct autofs_sb_info *sbi,204 const struct qstr *qstr,205 const struct path *path, enum autofs_notify notify)206{207 struct dentry *dentry = path->dentry;208 struct autofs_wait_queue *wq;209 struct autofs_info *ino;210 211 if (sbi->flags & AUTOFS_SBI_CATATONIC)212 return -ENOENT;213 214 /* Wait in progress, continue; */215 wq = autofs_find_wait(sbi, qstr);216 if (wq) {217 *wait = wq;218 return 1;219 }220 221 *wait = NULL;222 223 /* If we don't yet have any info this is a new request */224 ino = autofs_dentry_ino(dentry);225 if (!ino)226 return 1;227 228 /*229 * If we've been asked to wait on an existing expire (NFY_NONE)230 * but there is no wait in the queue ...231 */232 if (notify == NFY_NONE) {233 /*234 * Either we've betean the pending expire to post it's235 * wait or it finished while we waited on the mutex.236 * So we need to wait till either, the wait appears237 * or the expire finishes.238 */239 240 while (ino->flags & AUTOFS_INF_EXPIRING) {241 mutex_unlock(&sbi->wq_mutex);242 schedule_timeout_interruptible(HZ/10);243 if (mutex_lock_interruptible(&sbi->wq_mutex))244 return -EINTR;245 246 if (sbi->flags & AUTOFS_SBI_CATATONIC)247 return -ENOENT;248 249 wq = autofs_find_wait(sbi, qstr);250 if (wq) {251 *wait = wq;252 return 1;253 }254 }255 256 /*257 * Not ideal but the status has already gone. Of the two258 * cases where we wait on NFY_NONE neither depend on the259 * return status of the wait.260 */261 return 0;262 }263 264 /*265 * If we've been asked to trigger a mount and the request266 * completed while we waited on the mutex ...267 */268 if (notify == NFY_MOUNT) {269 struct dentry *new = NULL;270 struct path this;271 int valid = 1;272 273 /*274 * If the dentry was successfully mounted while we slept275 * on the wait queue mutex we can return success. If it276 * isn't mounted (doesn't have submounts for the case of277 * a multi-mount with no mount at it's base) we can278 * continue on and create a new request.279 */280 if (!IS_ROOT(dentry)) {281 if (d_unhashed(dentry) &&282 d_really_is_positive(dentry)) {283 struct dentry *parent = dentry->d_parent;284 285 new = d_lookup(parent, &dentry->d_name);286 if (new)287 dentry = new;288 }289 }290 this.mnt = path->mnt;291 this.dentry = dentry;292 if (path_has_submounts(&this))293 valid = 0;294 295 if (new)296 dput(new);297 return valid;298 }299 300 return 1;301}302 303int autofs_wait(struct autofs_sb_info *sbi,304 const struct path *path, enum autofs_notify notify)305{306 struct dentry *dentry = path->dentry;307 struct autofs_wait_queue *wq;308 struct qstr qstr;309 char *name;310 int status, ret, type;311 unsigned int offset = 0;312 pid_t pid;313 pid_t tgid;314 315 /* In catatonic mode, we don't wait for nobody */316 if (sbi->flags & AUTOFS_SBI_CATATONIC)317 return -ENOENT;318 319 /*320 * Try translating pids to the namespace of the daemon.321 *322 * Zero means failure: we are in an unrelated pid namespace.323 */324 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));325 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));326 if (pid == 0 || tgid == 0)327 return -ENOENT;328 329 if (d_really_is_negative(dentry)) {330 /*331 * A wait for a negative dentry is invalid for certain332 * cases. A direct or offset mount "always" has its mount333 * point directory created and so the request dentry must334 * be positive or the map key doesn't exist. The situation335 * is very similar for indirect mounts except only dentrys336 * in the root of the autofs file system may be negative.337 */338 if (autofs_type_trigger(sbi->type))339 return -ENOENT;340 else if (!IS_ROOT(dentry->d_parent))341 return -ENOENT;342 }343 344 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);345 if (!name)346 return -ENOMEM;347 348 /* If this is a direct mount request create a dummy name */349 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) {350 qstr.name = name;351 qstr.len = sprintf(name, "%p", dentry);352 } else {353 char *p = dentry_path_raw(dentry, name, NAME_MAX);354 if (IS_ERR(p)) {355 kfree(name);356 return -ENOENT;357 }358 qstr.name = ++p; // skip the leading slash359 qstr.len = strlen(p);360 offset = p - name;361 }362 qstr.hash = full_name_hash(dentry, qstr.name, qstr.len);363 364 if (mutex_lock_interruptible(&sbi->wq_mutex)) {365 kfree(name);366 return -EINTR;367 }368 369 ret = validate_request(&wq, sbi, &qstr, path, notify);370 if (ret <= 0) {371 if (ret != -EINTR)372 mutex_unlock(&sbi->wq_mutex);373 kfree(name);374 return ret;375 }376 377 if (!wq) {378 /* Create a new wait queue */379 wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);380 if (!wq) {381 kfree(name);382 mutex_unlock(&sbi->wq_mutex);383 return -ENOMEM;384 }385 386 wq->wait_queue_token = autofs_next_wait_queue;387 if (++autofs_next_wait_queue == 0)388 autofs_next_wait_queue = 1;389 wq->next = sbi->queues;390 sbi->queues = wq;391 init_waitqueue_head(&wq->queue);392 memcpy(&wq->name, &qstr, sizeof(struct qstr));393 wq->offset = offset;394 wq->dev = autofs_get_dev(sbi);395 wq->ino = autofs_get_ino(sbi);396 wq->uid = current_uid();397 wq->gid = current_gid();398 wq->pid = pid;399 wq->tgid = tgid;400 wq->status = -EINTR; /* Status return if interrupted */401 wq->wait_ctr = 2;402 403 if (sbi->version < 5) {404 if (notify == NFY_MOUNT)405 type = autofs_ptype_missing;406 else407 type = autofs_ptype_expire_multi;408 } else {409 if (notify == NFY_MOUNT)410 type = autofs_type_trigger(sbi->type) ?411 autofs_ptype_missing_direct :412 autofs_ptype_missing_indirect;413 else414 type = autofs_type_trigger(sbi->type) ?415 autofs_ptype_expire_direct :416 autofs_ptype_expire_indirect;417 }418 419 pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",420 (unsigned long) wq->wait_queue_token, wq->name.len,421 wq->name.name, notify);422 423 /*424 * autofs_notify_daemon() may block; it will unlock ->wq_mutex425 */426 autofs_notify_daemon(sbi, wq, type);427 } else {428 wq->wait_ctr++;429 pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",430 (unsigned long) wq->wait_queue_token, wq->name.len,431 wq->name.name, notify);432 mutex_unlock(&sbi->wq_mutex);433 kfree(name);434 }435 436 /*437 * wq->name.name is NULL iff the lock is already released438 * or the mount has been made catatonic.439 */440 wait_event_killable(wq->queue, wq->name.name == NULL);441 status = wq->status;442 443 /*444 * For direct and offset mounts we need to track the requester's445 * uid and gid in the dentry info struct. This is so it can be446 * supplied, on request, by the misc device ioctl interface.447 * This is needed during daemon resatart when reconnecting448 * to existing, active, autofs mounts. The uid and gid (and449 * related string values) may be used for macro substitution450 * in autofs mount maps.451 */452 if (!status) {453 struct autofs_info *ino;454 struct dentry *de = NULL;455 456 /* direct mount or browsable map */457 ino = autofs_dentry_ino(dentry);458 if (!ino) {459 /* If not lookup actual dentry used */460 de = d_lookup(dentry->d_parent, &dentry->d_name);461 if (de)462 ino = autofs_dentry_ino(de);463 }464 465 /* Set mount requester */466 if (ino) {467 spin_lock(&sbi->fs_lock);468 ino->uid = wq->uid;469 ino->gid = wq->gid;470 spin_unlock(&sbi->fs_lock);471 }472 473 if (de)474 dput(de);475 }476 477 /* Are we the last process to need status? */478 mutex_lock(&sbi->wq_mutex);479 if (!--wq->wait_ctr)480 kfree(wq);481 mutex_unlock(&sbi->wq_mutex);482 483 return status;484}485 486 487int autofs_wait_release(struct autofs_sb_info *sbi,488 autofs_wqt_t wait_queue_token, int status)489{490 struct autofs_wait_queue *wq, **wql;491 492 mutex_lock(&sbi->wq_mutex);493 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {494 if (wq->wait_queue_token == wait_queue_token)495 break;496 }497 498 if (!wq) {499 mutex_unlock(&sbi->wq_mutex);500 return -EINVAL;501 }502 503 *wql = wq->next; /* Unlink from chain */504 kfree(wq->name.name - wq->offset);505 wq->name.name = NULL; /* Do not wait on this queue */506 wq->status = status;507 wake_up(&wq->queue);508 if (!--wq->wait_ctr)509 kfree(wq);510 mutex_unlock(&sbi->wq_mutex);511 512 return 0;513}514