diff options
Diffstat (limited to 'kernel/fs/f2fs/crypto_policy.c')
| -rw-r--r-- | kernel/fs/f2fs/crypto_policy.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/kernel/fs/f2fs/crypto_policy.c b/kernel/fs/f2fs/crypto_policy.c new file mode 100644 index 000000000..d4a96af51 --- /dev/null +++ b/kernel/fs/f2fs/crypto_policy.c @@ -0,0 +1,209 @@ +/* + * copied from linux/fs/ext4/crypto_policy.c + * + * Copyright (C) 2015, Google, Inc. + * Copyright (C) 2015, Motorola Mobility. + * + * This contains encryption policy functions for f2fs with some modifications + * to support f2fs-specific xattr APIs. + * + * Written by Michael Halcrow, 2015. + * Modified by Jaegeuk Kim, 2015. + */ +#include <linux/random.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/f2fs_fs.h> + +#include "f2fs.h" +#include "xattr.h" + +static int f2fs_inode_has_encryption_context(struct inode *inode) +{ + int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, + F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, NULL, 0, NULL); + return (res > 0); +} + +/* + * check whether the policy is consistent with the encryption context + * for the inode + */ +static int f2fs_is_encryption_context_consistent_with_policy( + struct inode *inode, const struct f2fs_encryption_policy *policy) +{ + struct f2fs_encryption_context ctx; + int res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, + F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, + sizeof(ctx), NULL); + + if (res != sizeof(ctx)) + return 0; + + return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor, + F2FS_KEY_DESCRIPTOR_SIZE) == 0 && + (ctx.flags == policy->flags) && + (ctx.contents_encryption_mode == + policy->contents_encryption_mode) && + (ctx.filenames_encryption_mode == + policy->filenames_encryption_mode)); +} + +static int f2fs_create_encryption_context_from_policy( + struct inode *inode, const struct f2fs_encryption_policy *policy) +{ + struct f2fs_encryption_context ctx; + + ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1; + memcpy(ctx.master_key_descriptor, policy->master_key_descriptor, + F2FS_KEY_DESCRIPTOR_SIZE); + + if (!f2fs_valid_contents_enc_mode(policy->contents_encryption_mode)) { + printk(KERN_WARNING + "%s: Invalid contents encryption mode %d\n", __func__, + policy->contents_encryption_mode); + return -EINVAL; + } + + if (!f2fs_valid_filenames_enc_mode(policy->filenames_encryption_mode)) { + printk(KERN_WARNING + "%s: Invalid filenames encryption mode %d\n", __func__, + policy->filenames_encryption_mode); + return -EINVAL; + } + + if (policy->flags & ~F2FS_POLICY_FLAGS_VALID) + return -EINVAL; + + ctx.contents_encryption_mode = policy->contents_encryption_mode; + ctx.filenames_encryption_mode = policy->filenames_encryption_mode; + ctx.flags = policy->flags; + BUILD_BUG_ON(sizeof(ctx.nonce) != F2FS_KEY_DERIVATION_NONCE_SIZE); + get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE); + + return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, + F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, + sizeof(ctx), NULL, XATTR_CREATE); +} + +int f2fs_process_policy(const struct f2fs_encryption_policy *policy, + struct inode *inode) +{ + if (policy->version != 0) + return -EINVAL; + + if (!S_ISDIR(inode->i_mode)) + return -EINVAL; + + if (!f2fs_inode_has_encryption_context(inode)) { + if (!f2fs_empty_dir(inode)) + return -ENOTEMPTY; + return f2fs_create_encryption_context_from_policy(inode, + policy); + } + + if (f2fs_is_encryption_context_consistent_with_policy(inode, policy)) + return 0; + + printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n", + __func__); + return -EINVAL; +} + +int f2fs_get_policy(struct inode *inode, struct f2fs_encryption_policy *policy) +{ + struct f2fs_encryption_context ctx; + int res; + + if (!f2fs_encrypted_inode(inode)) + return -ENODATA; + + res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION, + F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, + &ctx, sizeof(ctx), NULL); + if (res != sizeof(ctx)) + return -ENODATA; + if (ctx.format != F2FS_ENCRYPTION_CONTEXT_FORMAT_V1) + return -EINVAL; + + policy->version = 0; + policy->contents_encryption_mode = ctx.contents_encryption_mode; + policy->filenames_encryption_mode = ctx.filenames_encryption_mode; + policy->flags = ctx.flags; + memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor, + F2FS_KEY_DESCRIPTOR_SIZE); + return 0; +} + +int f2fs_is_child_context_consistent_with_parent(struct inode *parent, + struct inode *child) +{ + struct f2fs_crypt_info *parent_ci, *child_ci; + int res; + + if ((parent == NULL) || (child == NULL)) { + pr_err("parent %p child %p\n", parent, child); + BUG_ON(1); + } + + /* no restrictions if the parent directory is not encrypted */ + if (!f2fs_encrypted_inode(parent)) + return 1; + /* if the child directory is not encrypted, this is always a problem */ + if (!f2fs_encrypted_inode(child)) + return 0; + res = f2fs_get_encryption_info(parent); + if (res) + return 0; + res = f2fs_get_encryption_info(child); + if (res) + return 0; + parent_ci = F2FS_I(parent)->i_crypt_info; + child_ci = F2FS_I(child)->i_crypt_info; + if (!parent_ci && !child_ci) + return 1; + if (!parent_ci || !child_ci) + return 0; + + return (memcmp(parent_ci->ci_master_key, + child_ci->ci_master_key, + F2FS_KEY_DESCRIPTOR_SIZE) == 0 && + (parent_ci->ci_data_mode == child_ci->ci_data_mode) && + (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) && + (parent_ci->ci_flags == child_ci->ci_flags)); +} + +/** + * f2fs_inherit_context() - Sets a child context from its parent + * @parent: Parent inode from which the context is inherited. + * @child: Child inode that inherits the context from @parent. + * + * Return: Zero on success, non-zero otherwise + */ +int f2fs_inherit_context(struct inode *parent, struct inode *child, + struct page *ipage) +{ + struct f2fs_encryption_context ctx; + struct f2fs_crypt_info *ci; + int res; + + res = f2fs_get_encryption_info(parent); + if (res < 0) + return res; + + ci = F2FS_I(parent)->i_crypt_info; + BUG_ON(ci == NULL); + + ctx.format = F2FS_ENCRYPTION_CONTEXT_FORMAT_V1; + + ctx.contents_encryption_mode = ci->ci_data_mode; + ctx.filenames_encryption_mode = ci->ci_filename_mode; + ctx.flags = ci->ci_flags; + memcpy(ctx.master_key_descriptor, ci->ci_master_key, + F2FS_KEY_DESCRIPTOR_SIZE); + + get_random_bytes(ctx.nonce, F2FS_KEY_DERIVATION_NONCE_SIZE); + return f2fs_setxattr(child, F2FS_XATTR_INDEX_ENCRYPTION, + F2FS_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx, + sizeof(ctx), ipage, XATTR_CREATE); +} |