Commit 457117f0 authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
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ceph: add helpers for converting names for userland presentation 



Define a new ceph_fname struct that we can use to carry information
about encrypted dentry names. Add helpers for working with these
objects, including ceph_fname_to_usr which formats an encrypted filename
for userland presentation.

[ xiubli: fix resulting name length check -- neither name_len nor
  ctext_len should exceed NAME_MAX ]

Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-and-tested-by: default avatarLuís Henriques <lhenriques@suse.de>
Reviewed-by: default avatarMilind Changire <mchangir@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent c5267601

fs/ceph/crypto.c

+77 −0
Original line number Diff line number Diff line
@@ -244,3 +244,80 @@ int ceph_encode_encrypted_fname(const struct inode *parent, 
	dout("base64-encoded ciphertext name = %.*s\n", elen, buf);

	return elen;

}



/**

 * ceph_fname_to_usr - convert a filename for userland presentation

 * @fname: ceph_fname to be converted

 * @tname: temporary name buffer to use for conversion (may be NULL)

 * @oname: where converted name should be placed

 * @is_nokey: set to true if key wasn't available during conversion (may be NULL)

 *

 * Given a filename (usually from the MDS), format it for presentation to

 * userland. If @parent is not encrypted, just pass it back as-is.

 *

 * Otherwise, base64 decode the string, and then ask fscrypt to format it

 * for userland presentation.

 *

 * Returns 0 on success or negative error code on error.

 */

int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,

		      struct fscrypt_str *oname, bool *is_nokey)

{

	int ret;

	struct fscrypt_str _tname = FSTR_INIT(NULL, 0);

	struct fscrypt_str iname;



	if (!IS_ENCRYPTED(fname->dir)) {

		oname->name = fname->name;

		oname->len = fname->name_len;

		return 0;

	}



	/* Sanity check that the resulting name will fit in the buffer */

	if (fname->name_len > NAME_MAX || fname->ctext_len > NAME_MAX)

		return -EIO;



	ret = __fscrypt_prepare_readdir(fname->dir);

	if (ret)

		return ret;



	/*

	 * Use the raw dentry name as sent by the MDS instead of

	 * generating a nokey name via fscrypt.

	 */

	if (!fscrypt_has_encryption_key(fname->dir)) {

		memcpy(oname->name, fname->name, fname->name_len);

		oname->len = fname->name_len;

		if (is_nokey)

			*is_nokey = true;

		return 0;

	}



	if (fname->ctext_len == 0) {

		int declen;



		if (!tname) {

			ret = fscrypt_fname_alloc_buffer(NAME_MAX, &_tname);

			if (ret)

				return ret;

			tname = &_tname;

		}



		declen = ceph_base64_decode(fname->name, fname->name_len,

					    tname->name);

		if (declen <= 0) {

			ret = -EIO;

			goto out;

		}

		iname.name = tname->name;

		iname.len = declen;

	} else {

		iname.name = fname->ctext;

		iname.len = fname->ctext_len;

	}



	ret = fscrypt_fname_disk_to_usr(fname->dir, 0, 0, &iname, oname);

out:

	fscrypt_fname_free_buffer(&_tname);

	return ret;

}

fs/ceph/crypto.h

+46 −0
Original line number Diff line number Diff line
@@ -13,6 +13,14 @@ struct ceph_fs_client; 
struct ceph_acl_sec_ctx;

struct ceph_mds_request;



struct ceph_fname {

	struct inode	*dir;

	char		*name;		// b64 encoded, possibly hashed

	unsigned char	*ctext;		// binary crypttext (if any)

	u32		name_len;	// length of name buffer

	u32		ctext_len;	// length of crypttext

};



struct ceph_fscrypt_auth {

	__le32	cfa_version;

	__le32	cfa_blob_len;
@@ -71,6 +79,24 @@ void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req, 
int ceph_encode_encrypted_fname(const struct inode *parent,

				struct dentry *dentry, char *buf);



static inline int ceph_fname_alloc_buffer(struct inode *parent,

					  struct fscrypt_str *fname)

{

	if (!IS_ENCRYPTED(parent))

		return 0;

	return fscrypt_fname_alloc_buffer(NAME_MAX, fname);

}



static inline void ceph_fname_free_buffer(struct inode *parent,

					  struct fscrypt_str *fname)

{

	if (IS_ENCRYPTED(parent))

		fscrypt_fname_free_buffer(fname);

}



int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,

		      struct fscrypt_str *oname, bool *is_nokey);



#else /* CONFIG_FS_ENCRYPTION */



static inline void ceph_fscrypt_set_ops(struct super_block *sb)
@@ -100,6 +126,26 @@ static inline int ceph_encode_encrypted_fname(const struct inode *parent, 
{

	return -EOPNOTSUPP;

}



static inline int ceph_fname_alloc_buffer(struct inode *parent,

					  struct fscrypt_str *fname)

{

	return 0;

}



static inline void ceph_fname_free_buffer(struct inode *parent,

					  struct fscrypt_str *fname)

{

}



static inline int ceph_fname_to_usr(const struct ceph_fname *fname,

				    struct fscrypt_str *tname,

				    struct fscrypt_str *oname, bool *is_nokey)

{

	oname->name = fname->name;

	oname->len = fname->name_len;

	return 0;

}

#endif /* CONFIG_FS_ENCRYPTION */



#endif