From 457117f077c6749d1e28469eae91fb69c9806768 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 26 Mar 2021 12:26:18 -0400 Subject: [PATCH] ceph: add helpers for converting names for userland presentation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Jeff Layton Reviewed-by: Xiubo Li Reviewed-and-tested-by: Luís Henriques Reviewed-by: Milind Changire Signed-off-by: Ilya Dryomov --- fs/ceph/crypto.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/ceph/crypto.h | 46 +++++++++++++++++++++++++++++++++ 2 files changed, 123 insertions(+) diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c index 6dc723e..e2a4619 100644 --- a/fs/ceph/crypto.c +++ b/fs/ceph/crypto.c @@ -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; +} diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h index 176731f..a536451 100644 --- a/fs/ceph/crypto.h +++ b/fs/ceph/crypto.h @@ -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 -- 2.7.4