Commit ac22ba23 authored by Tyler Hicks's avatar Tyler Hicks
Browse files

eCryptfs: Check for O_RDONLY lower inodes when opening lower files 



If the lower inode is read-only, don't attempt to open the lower file
read/write and don't hand off the open request to the privileged
eCryptfs kthread for opening it read/write.  Instead, only try an
unprivileged, read-only open of the file and give up if that fails.
This patch fixes an oops when eCryptfs is mounted on top of a read-only
mount.

Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Cc: Eric Sandeen <esandeen@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: ecryptfs-devel@lists.launchpad.net
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent b0105eae

fs/ecryptfs/kthread.c

+8 −16
Original line number Diff line number Diff line
@@ -136,6 +136,7 @@ int ecryptfs_privileged_open(struct file **lower_file, 
			     const struct cred *cred)

{

	struct ecryptfs_open_req *req;

	int flags = O_LARGEFILE;

	int rc = 0;



	/* Corresponding dput() and mntput() are done when the
@@ -143,10 +144,14 @@ int ecryptfs_privileged_open(struct file **lower_file, 
	 * destroyed. */

	dget(lower_dentry);

	mntget(lower_mnt);

	(*lower_file) = dentry_open(lower_dentry, lower_mnt,

				    (O_RDWR | O_LARGEFILE), cred);

	flags |= IS_RDONLY(lower_dentry->d_inode) ? O_RDONLY : O_RDWR;

	(*lower_file) = dentry_open(lower_dentry, lower_mnt, flags, cred);

	if (!IS_ERR(*lower_file))

		goto out;

	if (flags & O_RDONLY) {

		rc = PTR_ERR((*lower_file));

		goto out;

	}

	req = kmem_cache_alloc(ecryptfs_open_req_cache, GFP_KERNEL);

	if (!req) {

		rc = -ENOMEM;
@@ -180,21 +185,8 @@ int ecryptfs_privileged_open(struct file **lower_file, 
		       __func__);

		goto out_unlock;

	}

	if (IS_ERR(*req->lower_file)) {

	if (IS_ERR(*req->lower_file))

		rc = PTR_ERR(*req->lower_file);

		dget(lower_dentry);

		mntget(lower_mnt);

		(*lower_file) = dentry_open(lower_dentry, lower_mnt,

					    (O_RDONLY | O_LARGEFILE), cred);

		if (IS_ERR(*lower_file)) {

			rc = PTR_ERR(*req->lower_file);

			(*lower_file) = NULL;

			printk(KERN_WARNING "%s: Error attempting privileged "

			       "open of lower file with either RW or RO "

			       "perms; rc = [%d]. Giving up.\n",

			       __func__, rc);

		}

	}

out_unlock:

	mutex_unlock(&req->mux);

out_free:

fs/ecryptfs/main.c

+1 −2
Original line number Diff line number Diff line
@@ -129,11 +129,10 @@ int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry) 
		lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);

		rc = ecryptfs_privileged_open(&inode_info->lower_file,

					      lower_dentry, lower_mnt, cred);

		if (rc || IS_ERR(inode_info->lower_file)) {

		if (rc) {

			printk(KERN_ERR "Error opening lower persistent file "

			       "for lower_dentry [0x%p] and lower_mnt [0x%p]; "

			       "rc = [%d]\n", lower_dentry, lower_mnt, rc);

			rc = PTR_ERR(inode_info->lower_file);

			inode_info->lower_file = NULL;

		}

	}

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