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Linux kernel mirror (for testing)
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linux
1/*
2 * copied from linux/fs/ext4/crypto_policy.c
3 *
4 * Copyright (C) 2015, Google, Inc.
5 * Copyright (C) 2015, Motorola Mobility.
6 *
7 * This contains encryption policy functions for f2fs with some modifications
8 * to support f2fs-specific xattr APIs.
9 *
10 * Written by Michael Halcrow, 2015.
11 * Modified by Jaegeuk Kim, 2015.
12 */
13#include <linux/random.h>
14#include <linux/string.h>
15#include <linux/types.h>
16#include <linux/f2fs_fs.h>
17
18#include "f2fs.h"
19#include "xattr.h"
20
21static int f2fs_inode_has_encryption_context(struct inode *inode)
22{
23 int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
24 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL);
25 return (res > 0);
26}
27
28/*
29 * check whether the policy is consistent with the encryption context
30 * for the inode
31 */
32static int f2fs_is_encryption_context_consistent_with_policy(
33 struct inode *inode, const struct f2fs_encryption_policy *policy)
34{
35 struct f2fs_encryption_context ctx;
36 int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
37 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
38 sizeof(ctx), NULL);
39
40 if (res != sizeof(ctx))
41 return 0;
42
43 return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
44 F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
45 (ctx.flags == policy->flags) &&
46 (ctx.contents_encryption_mode ==
47 policy->contents_encryption_mode) &&
48 (ctx.filenames_encryption_mode ==
49 policy->filenames_encryption_mode));
50}
51
52static int f2fs_create_encryption_context_from_policy(
53 struct inode *inode, const struct f2fs_encryption_policy *policy)
54{
55 struct f2fs_encryption_context ctx;
56
57 ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
58 memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
59 F2FS_KEY_DESCRIPTOR_SIZE);
60
61 if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) {
62 printk(KERN_WARNING
63 "%s: Invalid contents encryption mode %d\n", __func__,
64 policy->contents_encryption_mode);
65 return -EINVAL;
66 }
67
68 if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
69 printk(KERN_WARNING
70 "%s: Invalid filenames encryption mode %d\n", __func__,
71 policy->filenames_encryption_mode);
72 return -EINVAL;
73 }
74
75 if (policy->flags & ~F2FS_POLICY_FLAGS_VALID)
76 return -EINVAL;
77
78 ctx.contents_encryption_mode = policy->contents_encryption_mode;
79 ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
80 ctx.flags = policy->flags;
81 BUILD_BUG_ON(sizeof(ctx.nonce) != F2FS_KEY_DERIVATION_NONCE_SIZE);
82 get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
83
84 return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
85 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
86 sizeof(ctx), NULL, XATTR_CREATE);
87}
88
89int f2fs_process_policy(const struct f2fs_encryption_policy *policy,
90 struct inode *inode)
91{
92 if (policy->version != 0)
93 return -EINVAL;
94
95 if (!S_ISDIR(inode->i_mode))
96 return -EINVAL;
97
98 if (!f2fs_inode_has_encryption_context(inode)) {
99 if (!f2fs_empty_dir(inode))
100 return -ENOTEMPTY;
101 return f2fs_create_encryption_context_from_policy(inode,
102 policy);
103 }
104
105 if (f2fs_is_encryption_context_consistent_with_policy(inode, policy))
106 return 0;
107
108 printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
109 __func__);
110 return -EINVAL;
111}
112
113int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy)
114{
115 struct f2fs_encryption_context ctx;
116 int res;
117
118 if (!f2fs_encrypted_inode(inode))
119 return -ENODATA;
120
121 res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
122 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
123 &ctx, sizeof(ctx), NULL);
124 if (res != sizeof(ctx))
125 return -ENODATA;
126 if (ctx.format != F2FS_ENCRYPTION_CONTEXT_FORMAT_V1)
127 return -EINVAL;
128
129 policy->version = 0;
130 policy->contents_encryption_mode = ctx.contents_encryption_mode;
131 policy->filenames_encryption_mode = ctx.filenames_encryption_mode;
132 policy->flags = ctx.flags;
133 memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
134 F2FS_KEY_DESCRIPTOR_SIZE);
135 return 0;
136}
137
138int f2fs_is_child_context_consistent_with_parent(struct inode *parent,
139 struct inode *child)
140{
141 struct f2fs_crypt_info *parent_ci, *child_ci;
142 int res;
143
144 if ((parent == NULL) || (child == NULL)) {
145 pr_err("parent %p child %p\n", parent, child);
146 BUG_ON(1);
147 }
148
149 /* no restrictions if the parent directory is not encrypted */
150 if (!f2fs_encrypted_inode(parent))
151 return 1;
152 /* if the child directory is not encrypted, this is always a problem */
153 if (!f2fs_encrypted_inode(child))
154 return 0;
155 res = f2fs_get_encryption_info(parent);
156 if (res)
157 return 0;
158 res = f2fs_get_encryption_info(child);
159 if (res)
160 return 0;
161 parent_ci = F2FS_I(parent)->i_crypt_info;
162 child_ci = F2FS_I(child)->i_crypt_info;
163 if (!parent_ci && !child_ci)
164 return 1;
165 if (!parent_ci || !child_ci)
166 return 0;
167
168 return (memcmp(parent_ci->ci_master_key,
169 child_ci->ci_master_key,
170 F2FS_KEY_DESCRIPTOR_SIZE) == 0 &&
171 (parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
172 (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
173 (parent_ci->ci_flags == child_ci->ci_flags));
174}
175
176/**
177 * f2fs_inherit_context() - Sets a child context from its parent
178 * @parent: Parent inode from which the context is inherited.
179 * @child: Child inode that inherits the context from @parent.
180 *
181 * Return: Zero on success, non-zero otherwise
182 */
183int f2fs_inherit_context(struct inode *parent, struct inode *child,
184 struct page *ipage)
185{
186 struct f2fs_encryption_context ctx;
187 struct f2fs_crypt_info *ci;
188 int res;
189
190 res = f2fs_get_encryption_info(parent);
191 if (res < 0)
192 return res;
193
194 ci = F2FS_I(parent)->i_crypt_info;
195 BUG_ON(ci == NULL);
196
197 ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
198
199 ctx.contents_encryption_mode = ci->ci_data_mode;
200 ctx.filenames_encryption_mode = ci->ci_filename_mode;
201 ctx.flags = ci->ci_flags;
202 memcpy(ctx.master_key_descriptor, ci->ci_master_key,
203 F2FS_KEY_DESCRIPTOR_SIZE);
204
205 get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE);
206 return f2fs_setxattr(child, F2FS_XATTR_INDEX_ENCRYPTION,
207 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
208 sizeof(ctx), ipage, XATTR_CREATE);
209}