Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6c988f57 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ecryptfs: use vfs_get_link() 



Here again we are copying form one buffer to another, while jumping through
hoops to make kernel memory look like userspace memory.

For no good reason, since vfs_get_link() provides exactly what is needed.

As a bonus, now the security hook for readlink is also called on the
underlying inode.

Note: this can be called from link-following context.  But this is okay:

 - not in RCU mode

 - commit e54ad7f1 ("proc: prevent stacking filesystems on top")

 - ecryptfs is *reading* the underlying symlink not following it, so the
   right security hook is being called

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
parent 3f9ca755

fs/ecryptfs/inode.c

+12 −17
Original line number Diff line number Diff line
@@ -631,28 +631,23 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry, 


static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)

{

	DEFINE_DELAYED_CALL(done);

	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);

	char *lower_buf;

	const char *link;

	char *buf;

	mm_segment_t old_fs;

	int rc;



	lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);

	if (!lower_buf)

		return ERR_PTR(-ENOMEM);

	old_fs = get_fs();

	set_fs(get_ds());

	rc = d_inode(lower_dentry)->i_op->readlink(lower_dentry,

						   (char __user *)lower_buf,

						   PATH_MAX);

	set_fs(old_fs);

	if (rc < 0)

		goto out;

	link = vfs_get_link(lower_dentry, &done);

	if (IS_ERR(link))

		return ERR_CAST(link);



	rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,

						  lower_buf, rc);

out:

	kfree(lower_buf);

	return rc ? ERR_PTR(rc) : buf;

						  link, strlen(link));

	do_delayed_call(&done);

	if (rc)

		return ERR_PTR(rc);



	return buf;

}



static const char *ecryptfs_get_link(struct dentry *dentry,