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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Ceph fscrypt functionality
*/
#ifndef _CEPH_CRYPTO_H
#define _CEPH_CRYPTO_H
#include <crypto/sha2.h>
#include <linux/fscrypt.h>
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;
u8 cfa_blob[FSCRYPT_SET_CONTEXT_MAX_SIZE];
} __packed;
#define CEPH_FSCRYPT_AUTH_VERSION 1
static inline u32 ceph_fscrypt_auth_len(struct ceph_fscrypt_auth *fa)
{
u32 ctxsize = le32_to_cpu(fa->cfa_blob_len);
return offsetof(struct ceph_fscrypt_auth, cfa_blob) + ctxsize;
}
#ifdef CONFIG_FS_ENCRYPTION
/*
* We want to encrypt filenames when creating them, but the encrypted
* versions of those names may have illegal characters in them. To mitigate
* that, we base64 encode them, but that gives us a result that can exceed
* NAME_MAX.
*
* Follow a similar scheme to fscrypt itself, and cap the filename to a
* smaller size. If the ciphertext name is longer than the value below, then
* sha256 hash the remaining bytes.
*
* For the fscrypt_nokey_name struct the dirhash[2] member is useless in ceph
* so the corresponding struct will be:
*
* struct fscrypt_ceph_nokey_name {
* u8 bytes[157];
* u8 sha256[SHA256_DIGEST_SIZE];
* }; // 180 bytes => 240 bytes base64-encoded, which is <= NAME_MAX (255)
*
* (240 bytes is the maximum size allowed for snapshot names to take into
* account the format: '_<SNAPSHOT-NAME>_<INODE-NUMBER>'.)
*
* Note that for long names that end up having their tail portion hashed, we
* must also store the full encrypted name (in the dentry's alternate_name
* field).
*/
#define CEPH_NOHASH_NAME_MAX (180 - SHA256_DIGEST_SIZE)
#define CEPH_BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
int ceph_base64_encode(const u8 *src, int srclen, char *dst);
int ceph_base64_decode(const char *src, int srclen, u8 *dst);
void ceph_fscrypt_set_ops(struct super_block *sb);
void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc);
int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
struct ceph_acl_sec_ctx *as);
void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
struct ceph_acl_sec_ctx *as);
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)
{
}
static inline void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
{
}
static inline int ceph_fscrypt_prepare_context(struct inode *dir,
struct inode *inode,
struct ceph_acl_sec_ctx *as)
{
if (IS_ENCRYPTED(dir))
return -EOPNOTSUPP;
return 0;
}
static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
struct ceph_acl_sec_ctx *as_ctx)
{
}
static inline int ceph_encode_encrypted_fname(const struct inode *parent,
struct dentry *dentry, char *buf)
{
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
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