summaryrefslogtreecommitdiff
path: root/fs/ceph/crypto.h
blob: a53645123248af3eaa6ac0119317d15e26037b8b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/* 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