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Commit fd3b36d2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull vfs namei updates from Al Viro:

 - make lookup_one_len() safe with parent locked only shared(incoming
   afs series wants that)

 - fix of getname_kernel() regression from 2015 (-stable fodder, that
   one).

* 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  getname_kernel() needs to make sure that ->name != ->iname in long case
  make lookup_one_len() safe to use with directory locked shared
  new helper: __lookup_slow()
  merge common parts of lookup_one_len{,_unlocked} into common helper
parents 8ea4a5d8 30ce4d19

fs/namei.c

+57 −67
Original line number Diff line number Diff line
@@ -224,9 +224,10 @@ getname_kernel(const char * filename) 
	if (len <= EMBEDDED_NAME_MAX) {

		result->name = (char *)result->iname;

	} else if (len <= PATH_MAX) {

		const size_t size = offsetof(struct filename, iname[1]);

		struct filename *tmp;



		tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);

		tmp = kmalloc(size, GFP_KERNEL);

		if (unlikely(!tmp)) {

			__putname(result);

			return ERR_PTR(-ENOMEM);
@@ -1597,22 +1598,21 @@ static int lookup_fast(struct nameidata *nd, 
}



/* Fast lookup failed, do it the slow way */

static struct dentry *lookup_slow(const struct qstr *name,

static struct dentry *__lookup_slow(const struct qstr *name,

				    struct dentry *dir,

				    unsigned int flags)

{

	struct dentry *dentry = ERR_PTR(-ENOENT), *old;

	struct dentry *dentry, *old;

	struct inode *inode = dir->d_inode;

	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);



	inode_lock_shared(inode);

	/* Don't go there if it's already dead */

	if (unlikely(IS_DEADDIR(inode)))

		goto out;

		return ERR_PTR(-ENOENT);

again:

	dentry = d_alloc_parallel(dir, name, &wq);

	if (IS_ERR(dentry))

		goto out;

		return dentry;

	if (unlikely(!d_in_lookup(dentry))) {

		if (!(flags & LOOKUP_NO_REVAL)) {

			int error = d_revalidate(dentry, flags);
@@ -1634,11 +1634,21 @@ static struct dentry *lookup_slow(const struct qstr *name, 
			dentry = old;

		}

	}

out:

	inode_unlock_shared(inode);

	return dentry;

}



static struct dentry *lookup_slow(const struct qstr *name,

				  struct dentry *dir,

				  unsigned int flags)

{

	struct inode *inode = dir->d_inode;

	struct dentry *res;

	inode_lock_shared(inode);

	res = __lookup_slow(name, dir, flags);

	inode_unlock_shared(inode);

	return res;

}



static inline int may_lookup(struct nameidata *nd)

{

	if (nd->flags & LOOKUP_RCU) {
@@ -2421,56 +2431,63 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 
}

EXPORT_SYMBOL(vfs_path_lookup);



/**

 * lookup_one_len - filesystem helper to lookup single pathname component

 * @name:	pathname component to lookup

 * @base:	base directory to lookup from

 * @len:	maximum length @len should be interpreted to

 *

 * Note that this routine is purely a helper for filesystem usage and should

 * not be called by generic code.

 *

 * The caller must hold base->i_mutex.

 */

struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)

static int lookup_one_len_common(const char *name, struct dentry *base,

				 int len, struct qstr *this)

{

	struct qstr this;

	unsigned int c;

	int err;



	WARN_ON_ONCE(!inode_is_locked(base->d_inode));



	this.name = name;

	this.len = len;

	this.hash = full_name_hash(base, name, len);

	this->name = name;

	this->len = len;

	this->hash = full_name_hash(base, name, len);

	if (!len)

		return ERR_PTR(-EACCES);

		return -EACCES;



	if (unlikely(name[0] == '.')) {

		if (len < 2 || (len == 2 && name[1] == '.'))

			return ERR_PTR(-EACCES);

			return -EACCES;

	}



	while (len--) {

		c = *(const unsigned char *)name++;

		unsigned int c = *(const unsigned char *)name++;

		if (c == '/' || c == '\0')

			return ERR_PTR(-EACCES);

			return -EACCES;

	}

	/*

	 * See if the low-level filesystem might want

	 * to use its own hash..

	 */

	if (base->d_flags & DCACHE_OP_HASH) {

		int err = base->d_op->d_hash(base, &this);

		int err = base->d_op->d_hash(base, this);

		if (err < 0)

			return ERR_PTR(err);

			return err;

	}



	return inode_permission(base->d_inode, MAY_EXEC);

}



	err = inode_permission(base->d_inode, MAY_EXEC);

/**

 * lookup_one_len - filesystem helper to lookup single pathname component

 * @name:	pathname component to lookup

 * @base:	base directory to lookup from

 * @len:	maximum length @len should be interpreted to

 *

 * Note that this routine is purely a helper for filesystem usage and should

 * not be called by generic code.

 *

 * The caller must hold base->i_mutex.

 */

struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)

{

	struct dentry *dentry;

	struct qstr this;

	int err;



	WARN_ON_ONCE(!inode_is_locked(base->d_inode));



	err = lookup_one_len_common(name, base, len, &this);

	if (err)

		return ERR_PTR(err);



	return __lookup_hash(&this, base, 0);

	dentry = lookup_dcache(&this, base, 0);

	return dentry ? dentry : __lookup_slow(&this, base, 0);

}

EXPORT_SYMBOL(lookup_one_len);
@@ -2490,37 +2507,10 @@ struct dentry *lookup_one_len_unlocked(const char *name, 
				       struct dentry *base, int len)

{

	struct qstr this;

	unsigned int c;

	int err;

	struct dentry *ret;



	this.name = name;

	this.len = len;

	this.hash = full_name_hash(base, name, len);

	if (!len)

		return ERR_PTR(-EACCES);



	if (unlikely(name[0] == '.')) {

		if (len < 2 || (len == 2 && name[1] == '.'))

			return ERR_PTR(-EACCES);

	}



	while (len--) {

		c = *(const unsigned char *)name++;

		if (c == '/' || c == '\0')

			return ERR_PTR(-EACCES);

	}

	/*

	 * See if the low-level filesystem might want

	 * to use its own hash..

	 */

	if (base->d_flags & DCACHE_OP_HASH) {

		int err = base->d_op->d_hash(base, &this);

		if (err < 0)

			return ERR_PTR(err);

	}



	err = inode_permission(base->d_inode, MAY_EXEC);

	err = lookup_one_len_common(name, base, len, &this);

	if (err)

		return ERR_PTR(err);