1 files changed, 265 insertions, 103 deletions

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 1fe28e4754c..116fd38ee47 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -28,6 +28,12 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
 {
 	struct autofs_wait_queue *wq, *nwq;
 
+	mutex_lock(&sbi->wq_mutex);
+	if (sbi->catatonic) {
+		mutex_unlock(&sbi->wq_mutex);
+		return;
+	}
+
 	DPRINTK("entering catatonic mode");
 
 	sbi->catatonic = 1;
@@ -36,35 +42,39 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
 	while (wq) {
 		nwq = wq->next;
 		wq->status = -ENOENT; /* Magic is gone - report failure */
-		kfree(wq->name);
-		wq->name = NULL;
+		kfree(wq->name.name);
+		wq->name.name = NULL;
+		wq->wait_ctr--;
 		wake_up_interruptible(&wq->queue);
 		wq = nwq;
 	}
 	fput(sbi->pipe);	/* Close the pipe */
 	sbi->pipe = NULL;
+	sbi->pipefd = -1;
+	mutex_unlock(&sbi->wq_mutex);
 }
 
-static int autofs4_write(struct file *file, const void *addr, int bytes)
+static int autofs4_write(struct autofs_sb_info *sbi,
+			 struct file *file, const void *addr, int bytes)
 {
 	unsigned long sigpipe, flags;
 	mm_segment_t fs;
 	const char *data = (const char *)addr;
 	ssize_t wr = 0;
 
-	/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
-
 	sigpipe = sigismember(&current->pending.signal, SIGPIPE);
 
 	/* Save pointer to user space and point back to kernel space */
 	fs = get_fs();
 	set_fs(KERNEL_DS);
 
+	mutex_lock(&sbi->pipe_mutex);
 	while (bytes &&
 	       (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
 		data += wr;
 		bytes -= wr;
 	}
+	mutex_unlock(&sbi->pipe_mutex);
 
 	set_fs(fs);
 
@@ -89,15 +99,17 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 		union autofs_packet_union v4_pkt;
 		union autofs_v5_packet_union v5_pkt;
 	} pkt;
+	struct file *pipe = NULL;
 	size_t pktsz;
 
 	DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
-		wq->wait_queue_token, wq->len, wq->name, type);
+		(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:
@@ -107,9 +119,9 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 		pktsz = sizeof(*mp);
 
 		mp->wait_queue_token = wq->wait_queue_token;
-		mp->len = wq->len;
-		memcpy(mp->name, wq->name, wq->len);
-		mp->name[wq->len] = '\0';
+		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:
@@ -119,9 +131,9 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 		pktsz = sizeof(*ep);
 
 		ep->wait_queue_token = wq->wait_queue_token;
-		ep->len = wq->len;
-		memcpy(ep->name, wq->name, wq->len);
-		ep->name[wq->len] = '\0';
+		ep->len = wq->name.len;
+		memcpy(ep->name, wq->name.name, wq->name.len);
+		ep->name[wq->name.len] = '\0';
 		break;
 	}
 	/*
@@ -134,28 +146,35 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
 	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->len;
-		memcpy(packet->name, wq->name, wq->len);
-		packet->name[wq->len] = '\0';
+		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 = wq->uid;
-		packet->gid = wq->gid;
+		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:
 		printk("autofs4_notify_daemon: bad type %d!\n", type);
+		mutex_unlock(&sbi->wq_mutex);
 		return;
 	}
 
-	if (autofs4_write(sbi->pipe, &pkt, pktsz))
+	pipe = get_file(sbi->pipe);
+
+	mutex_unlock(&sbi->wq_mutex);
+
+	if (autofs4_write(sbi, pipe, &pkt, pktsz))
 		autofs4_catatonic_mode(sbi);
+	fput(pipe);
 }
 
 static int autofs4_getpath(struct autofs_sb_info *sbi,
@@ -163,16 +182,26 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
 {
 	struct dentry *root = sbi->sb->s_root;
 	struct dentry *tmp;
-	char *buf = *name;
+	char *buf;
 	char *p;
-	int len = 0;
+	int len;
+	unsigned seq;
+
+rename_retry:
+	buf = *name;
+	len = 0;
 
-	spin_lock(&dcache_lock);
+	seq = read_seqbegin(&rename_lock);
+	rcu_read_lock();
+	spin_lock(&sbi->fs_lock);
 	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
 		len += tmp->d_name.len + 1;
 
-	if (--len > NAME_MAX) {
-		spin_unlock(&dcache_lock);
+	if (!len || --len > NAME_MAX) {
+		spin_unlock(&sbi->fs_lock);
+		rcu_read_unlock();
+		if (read_seqretry(&rename_lock, seq))
+			goto rename_retry;
 		return 0;
 	}
 
@@ -185,64 +214,67 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
 		p -= tmp->d_name.len;
 		strncpy(p, tmp->d_name.name, tmp->d_name.len);
 	}
-	spin_unlock(&dcache_lock);
+	spin_unlock(&sbi->fs_lock);
+	rcu_read_unlock();
+	if (read_seqretry(&rename_lock, seq))
+		goto rename_retry;
 
 	return len;
 }
 
 static struct autofs_wait_queue *
-autofs4_find_wait(struct autofs_sb_info *sbi,
-		  char *name, unsigned int hash, unsigned int len)
+autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
 {
 	struct autofs_wait_queue *wq;
 
 	for (wq = sbi->queues; wq; wq = wq->next) {
-		if (wq->hash == hash &&
-		    wq->len == len &&
-		    wq->name && !memcmp(wq->name, name, len))
+		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;
 }
 
-int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
-		enum autofs_notify notify)
+/*
+ * 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,
+			    struct qstr *qstr,
+			    struct dentry*dentry, enum autofs_notify notify)
 {
-	struct autofs_info *ino;
 	struct autofs_wait_queue *wq;
-	char *name;
-	unsigned int len = 0;
-	unsigned int hash = 0;
-	int status, type;
+	struct autofs_info *ino;
 
-	/* In catatonic mode, we don't wait for nobody */
 	if (sbi->catatonic)
 		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) && (sbi->type & AUTOFS_TYPE_DIRECT))
-		len = sprintf(name, "%p", dentry);
-	else {
-		len = autofs4_getpath(sbi, dentry, &name);
-		if (!len) {
-			kfree(name);
-			return -ENOENT;
-		}
+	/* Wait in progress, continue; */
+	wq = autofs4_find_wait(sbi, qstr);
+	if (wq) {
+		*wait = wq;
+		return 1;
 	}
-	hash = full_name_hash(name, len);
 
-	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
-		kfree(name);
-		return -EINTR;
-	}
+	*wait = NULL;
 
-	wq = autofs4_find_wait(sbi, name, hash, len);
+	/* If we don't yet have any info this is a new request */
 	ino = autofs4_dentry_ino(dentry);
-	if (!wq && ino && notify == NFY_NONE) {
+	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.
@@ -253,13 +285,17 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 		while (ino->flags & AUTOFS_INF_EXPIRING) {
 			mutex_unlock(&sbi->wq_mutex);
 			schedule_timeout_interruptible(HZ/10);
-			if (mutex_lock_interruptible(&sbi->wq_mutex)) {
-				kfree(name);
+			if (mutex_lock_interruptible(&sbi->wq_mutex))
 				return -EINTR;
+
+			if (sbi->catatonic)
+				return -ENOENT;
+
+			wq = autofs4_find_wait(sbi, qstr);
+			if (wq) {
+				*wait = wq;
+				return 1;
 			}
-			wq = autofs4_find_wait(sbi, name, hash, len);
-			if (wq)
-				break;
 		}
 
 		/*
@@ -267,18 +303,117 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 		 * cases where we wait on NFY_NONE neither depend on the
 		 * return status of the wait.
 		 */
-		if (!wq) {
+		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;
+		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 (dentry->d_inode && d_unhashed(dentry)) {
+				struct dentry *parent = dentry->d_parent;
+				new = d_lookup(parent, &dentry->d_name);
+				if (new)
+					dentry = new;
+			}
+		}
+		if (have_submounts(dentry))
+			valid = 0;
+
+		if (new)
+			dput(new);
+		return valid;
+	}
+
+	return 1;
+}
+
+int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
+		enum autofs_notify notify)
+{
+	struct autofs_wait_queue *wq;
+	struct qstr qstr;
+	char *name;
+	int status, ret, type;
+	pid_t pid;
+	pid_t tgid;
+
+	/* In catatonic mode, we don't wait for nobody */
+	if (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 (!dentry->d_inode) {
+		/*
+		 * 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.len = sprintf(name, "%p", dentry);
+	else {
+		qstr.len = autofs4_getpath(sbi, dentry, &name);
+		if (!qstr.len) {
 			kfree(name);
-			mutex_unlock(&sbi->wq_mutex);
-			return 0;
+			return -ENOENT;
 		}
 	}
+	qstr.name = name;
+	qstr.hash = full_name_hash(name, qstr.len);
+
+	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
+		kfree(qstr.name);
+		return -EINTR;
+	}
+
+	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
+	if (ret <= 0) {
+		if (ret != -EINTR)
+			mutex_unlock(&sbi->wq_mutex);
+		kfree(qstr.name);
+		return ret;
+	}
 
 	if (!wq) {
 		/* Create a new wait queue */
 		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
 		if (!wq) {
-			kfree(name);
+			kfree(qstr.name);
 			mutex_unlock(&sbi->wq_mutex);
 			return -ENOMEM;
 		}
@@ -289,18 +424,15 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 		wq->next = sbi->queues;
 		sbi->queues = wq;
 		init_waitqueue_head(&wq->queue);
-		wq->hash = hash;
-		wq->name = name;
-		wq->len = len;
+		memcpy(&wq->name, &qstr, sizeof(struct qstr));
 		wq->dev = autofs4_get_dev(sbi);
 		wq->ino = autofs4_get_ino(sbi);
-		wq->uid = current->uid;
-		wq->gid = current->gid;
-		wq->pid = current->pid;
-		wq->tgid = current->tgid;
+		wq->uid = current_uid();
+		wq->gid = current_gid();
+		wq->pid = pid;
+		wq->tgid = tgid;
 		wq->status = -EINTR; /* Status return if interrupted */
-		atomic_set(&wq->wait_ctr, 2);
-		mutex_unlock(&sbi->wq_mutex);
+		wq->wait_ctr = 2;
 
 		if (sbi->version < 5) {
 			if (notify == NFY_MOUNT)
@@ -309,38 +441,35 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 				type = autofs_ptype_expire_multi;
 		} else {
 			if (notify == NFY_MOUNT)
-				type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
+				type = autofs_type_trigger(sbi->type) ?
 					autofs_ptype_missing_direct :
 					 autofs_ptype_missing_indirect;
 			else
-				type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
+				type = autofs_type_trigger(sbi->type) ?
 					autofs_ptype_expire_direct :
 					autofs_ptype_expire_indirect;
 		}
 
 		DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
-			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
+			(unsigned long) wq->wait_queue_token, wq->name.len,
+			wq->name.name, notify);
 
-		/* autofs4_notify_daemon() may block */
+		/* autofs4_notify_daemon() may block; it will unlock ->wq_mutex */
 		autofs4_notify_daemon(sbi, wq, type);
 	} else {
-		atomic_inc(&wq->wait_ctr);
-		mutex_unlock(&sbi->wq_mutex);
-		kfree(name);
+		wq->wait_ctr++;
 		DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
-			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
-	}
-
-	/* wq->name is NULL if and only if the lock is already released */
-
-	if (sbi->catatonic) {
-		/* We might have slept, so check again for catatonic mode */
-		wq->status = -ENOENT;
-		kfree(wq->name);
-		wq->name = NULL;
+			(unsigned long) wq->wait_queue_token, wq->name.len,
+			wq->name.name, notify);
+		mutex_unlock(&sbi->wq_mutex);
+		kfree(qstr.name);
 	}
 
-	if (wq->name) {
+	/*
+	 * wq->name.name is NULL iff the lock is already released
+	 * or the mount has been made catatonic.
+	 */
+	if (wq->name.name) {
 		/* Block all but "shutdown" signals while waiting */
 		sigset_t oldset;
 		unsigned long irqflags;
@@ -351,7 +480,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 		recalc_sigpending();
 		spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
 
-		wait_event_interruptible(wq->queue, wq->name == NULL);
+		wait_event_interruptible(wq->queue, wq->name.name == NULL);
 
 		spin_lock_irqsave(&current->sighand->siglock, irqflags);
 		current->blocked = oldset;
@@ -363,9 +492,45 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 
 	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 = autofs4_dentry_ino(dentry);
+		if (!ino) {
+			/* If not lookup actual dentry used */
+			de = d_lookup(dentry->d_parent, &dentry->d_name);
+			if (de)
+				ino = autofs4_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? */
-	if (atomic_dec_and_test(&wq->wait_ctr))
+	mutex_lock(&sbi->wq_mutex);
+	if (!--wq->wait_ctr)
 		kfree(wq);
+	mutex_unlock(&sbi->wq_mutex);
 
 	return status;
 }
@@ -387,16 +552,13 @@ int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_tok
 	}
 
 	*wql = wq->next;	/* Unlink from chain */
-	mutex_unlock(&sbi->wq_mutex);
-	kfree(wq->name);
-	wq->name = NULL;	/* Do not wait on this queue */
-
+	kfree(wq->name.name);
+	wq->name.name = NULL;	/* Do not wait on this queue */
 	wq->status = status;
-
-	if (atomic_dec_and_test(&wq->wait_ctr))	/* Is anyone still waiting for this guy? */
+	wake_up_interruptible(&wq->queue);
+	if (!--wq->wait_ctr)
 		kfree(wq);
-	else
-		wake_up_interruptible(&wq->queue);
+	mutex_unlock(&sbi->wq_mutex);
 
 	return 0;
 }