2 * copied from linux/fs/ext4/crypto_policy.c
4 * Copyright (C) 2015, Google, Inc.
5 * Copyright (C) 2015, Motorola Mobility.
7 * This contains encryption policy functions for f2fs with some modifications
8 * to support f2fs-specific xattr APIs.
10 * Written by Michael Halcrow, 2015.
11 * Modified by Jaegeuk Kim, 2015.
13 #include <linux/random.h>
14 #include <linux/string.h>
15 #include <linux/types.h>
16 #include <linux/f2fs_fs.h>
21 static int f2fs_inode_has_encryption_context(struct inode *inode)
23 int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
24 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL);
29 * check whether the policy is consistent with the encryption context
32 static int f2fs_is_encryption_context_consistent_with_policy(
33 struct inode *inode, const struct f2fs_encryption_policy *policy)
35 struct f2fs_encryption_context ctx;
36 int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
37 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
40 if (res != sizeof(ctx))
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));
52 static int f2fs_create_encryption_context_from_policy(
53 struct inode *inode, const struct f2fs_encryption_policy *policy)
55 struct f2fs_encryption_context ctx;
57 ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
58 memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
59 F2FS_KEY_DESCRIPTOR_SIZE);
61 if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) {
63 "%s: Invalid contents encryption mode %d\n", __func__,
64 policy->contents_encryption_mode);
68 if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
70 "%s: Invalid filenames encryption mode %d\n", __func__,
71 policy->filenames_encryption_mode);
75 if (policy->flags & ~F2FS_POLICY_FLAGS_VALID)
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);
84 return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
85 F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
86 sizeof(ctx), NULL, XATTR_CREATE);
89 int f2fs_process_policy(const struct f2fs_encryption_policy *policy,
92 if (policy->version != 0)
95 if (!S_ISDIR(inode->i_mode))
98 if (!f2fs_inode_has_encryption_context(inode)) {
99 if (!f2fs_empty_dir(inode))
101 return f2fs_create_encryption_context_from_policy(inode,
105 if (f2fs_is_encryption_context_consistent_with_policy(inode, policy))
108 printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
113 int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy)
115 struct f2fs_encryption_context ctx;
118 if (!f2fs_encrypted_inode(inode))
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))
126 if (ctx.format != F2FS_ENCRYPTION_CONTEXT_FORMAT_V1)
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);
138 int f2fs_is_child_context_consistent_with_parent(struct inode *parent,
141 struct f2fs_crypt_info *parent_ci, *child_ci;
144 if ((parent == NULL) || (child == NULL)) {
145 pr_err("parent %p child %p\n", parent, child);
149 /* no restrictions if the parent directory is not encrypted */
150 if (!f2fs_encrypted_inode(parent))
152 /* if the child directory is not encrypted, this is always a problem */
153 if (!f2fs_encrypted_inode(child))
155 res = f2fs_get_encryption_info(parent);
158 res = f2fs_get_encryption_info(child);
161 parent_ci = F2FS_I(parent)->i_crypt_info;
162 child_ci = F2FS_I(child)->i_crypt_info;
163 if (!parent_ci && !child_ci)
165 if (!parent_ci || !child_ci)
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));
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.
181 * Return: Zero on success, non-zero otherwise
183 int f2fs_inherit_context(struct inode *parent, struct inode *child,
186 struct f2fs_encryption_context ctx;
187 struct f2fs_crypt_info *ci;
190 res = f2fs_get_encryption_info(parent);
194 ci = F2FS_I(parent)->i_crypt_info;
197 ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1;
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);
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);