| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* |
| * fscrypt.h: declarations for per-file encryption |
| * |
| * Filesystems that implement per-file encryption include this header |
| * file with the __FS_HAS_ENCRYPTION set according to whether that filesystem |
| * is being built with encryption support or not. |
| * |
| * Copyright (C) 2015, Google, Inc. |
| * |
| * Written by Michael Halcrow, 2015. |
| * Modified by Jaegeuk Kim, 2015. |
| */ |
| #ifndef _LINUX_FSCRYPT_H |
| #define _LINUX_FSCRYPT_H |
| |
| #include <linux/key.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/bio.h> |
| #include <linux/dcache.h> |
| #include <crypto/skcipher.h> |
| #include <uapi/linux/fs.h> |
| |
| #define FS_CRYPTO_BLOCK_SIZE 16 |
| |
| struct fscrypt_info; |
| |
| struct fscrypt_ctx { |
| union { |
| struct { |
| struct page *bounce_page; /* Ciphertext page */ |
| struct page *control_page; /* Original page */ |
| } w; |
| struct { |
| struct bio *bio; |
| struct work_struct work; |
| } r; |
| struct list_head free_list; /* Free list */ |
| }; |
| u8 flags; /* Flags */ |
| }; |
| |
| /** |
| * For encrypted symlinks, the ciphertext length is stored at the beginning |
| * of the string in little-endian format. |
| */ |
| struct fscrypt_symlink_data { |
| __le16 len; |
| char encrypted_path[1]; |
| } __packed; |
| |
| struct fscrypt_str { |
| unsigned char *name; |
| u32 len; |
| }; |
| |
| struct fscrypt_name { |
| const struct qstr *usr_fname; |
| struct fscrypt_str disk_name; |
| u32 hash; |
| u32 minor_hash; |
| struct fscrypt_str crypto_buf; |
| }; |
| |
| #define FSTR_INIT(n, l) { .name = n, .len = l } |
| #define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len) |
| #define fname_name(p) ((p)->disk_name.name) |
| #define fname_len(p) ((p)->disk_name.len) |
| |
| /* |
| * fscrypt superblock flags |
| */ |
| #define FS_CFLG_OWN_PAGES (1U << 1) |
| |
| /* |
| * crypto opertions for filesystems |
| */ |
| struct fscrypt_operations { |
| unsigned int flags; |
| const char *key_prefix; |
| int (*get_context)(struct inode *, void *, size_t); |
| int (*set_context)(struct inode *, const void *, size_t, void *); |
| bool (*dummy_context)(struct inode *); |
| bool (*empty_dir)(struct inode *); |
| unsigned (*max_namelen)(struct inode *); |
| }; |
| |
| /* Maximum value for the third parameter of fscrypt_operations.set_context(). */ |
| #define FSCRYPT_SET_CONTEXT_MAX_SIZE 28 |
| |
| static inline bool fscrypt_dummy_context_enabled(struct inode *inode) |
| { |
| if (inode->i_sb->s_cop->dummy_context && |
| inode->i_sb->s_cop->dummy_context(inode)) |
| return true; |
| return false; |
| } |
| |
| static inline bool fscrypt_valid_enc_modes(u32 contents_mode, |
| u32 filenames_mode) |
| { |
| if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC && |
| filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS) |
| return true; |
| |
| if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS && |
| filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS) |
| return true; |
| |
| return false; |
| } |
| |
| static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) |
| { |
| if (str->len == 1 && str->name[0] == '.') |
| return true; |
| |
| if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.') |
| return true; |
| |
| return false; |
| } |
| |
| #if __FS_HAS_ENCRYPTION |
| |
| static inline struct page *fscrypt_control_page(struct page *page) |
| { |
| return ((struct fscrypt_ctx *)page_private(page))->w.control_page; |
| } |
| |
| static inline bool fscrypt_has_encryption_key(const struct inode *inode) |
| { |
| return (inode->i_crypt_info != NULL); |
| } |
| |
| #include <linux/fscrypt_supp.h> |
| |
| #else /* !__FS_HAS_ENCRYPTION */ |
| |
| static inline struct page *fscrypt_control_page(struct page *page) |
| { |
| WARN_ON_ONCE(1); |
| return ERR_PTR(-EINVAL); |
| } |
| |
| static inline bool fscrypt_has_encryption_key(const struct inode *inode) |
| { |
| return 0; |
| } |
| |
| #include <linux/fscrypt_notsupp.h> |
| #endif /* __FS_HAS_ENCRYPTION */ |
| |
| /** |
| * fscrypt_require_key - require an inode's encryption key |
| * @inode: the inode we need the key for |
| * |
| * If the inode is encrypted, set up its encryption key if not already done. |
| * Then require that the key be present and return -ENOKEY otherwise. |
| * |
| * No locks are needed, and the key will live as long as the struct inode --- so |
| * it won't go away from under you. |
| * |
| * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code |
| * if a problem occurred while setting up the encryption key. |
| */ |
| static inline int fscrypt_require_key(struct inode *inode) |
| { |
| if (IS_ENCRYPTED(inode)) { |
| int err = fscrypt_get_encryption_info(inode); |
| |
| if (err) |
| return err; |
| if (!fscrypt_has_encryption_key(inode)) |
| return -ENOKEY; |
| } |
| return 0; |
| } |
| |
| /** |
| * fscrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory |
| * @old_dentry: an existing dentry for the inode being linked |
| * @dir: the target directory |
| * @dentry: negative dentry for the target filename |
| * |
| * A new link can only be added to an encrypted directory if the directory's |
| * encryption key is available --- since otherwise we'd have no way to encrypt |
| * the filename. Therefore, we first set up the directory's encryption key (if |
| * not already done) and return an error if it's unavailable. |
| * |
| * We also verify that the link will not violate the constraint that all files |
| * in an encrypted directory tree use the same encryption policy. |
| * |
| * Return: 0 on success, -ENOKEY if the directory's encryption key is missing, |
| * -EPERM if the link would result in an inconsistent encryption policy, or |
| * another -errno code. |
| */ |
| static inline int fscrypt_prepare_link(struct dentry *old_dentry, |
| struct inode *dir, |
| struct dentry *dentry) |
| { |
| if (IS_ENCRYPTED(dir)) |
| return __fscrypt_prepare_link(d_inode(old_dentry), dir); |
| return 0; |
| } |
| |
| /** |
| * fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories |
| * @old_dir: source directory |
| * @old_dentry: dentry for source file |
| * @new_dir: target directory |
| * @new_dentry: dentry for target location (may be negative unless exchanging) |
| * @flags: rename flags (we care at least about %RENAME_EXCHANGE) |
| * |
| * Prepare for ->rename() where the source and/or target directories may be |
| * encrypted. A new link can only be added to an encrypted directory if the |
| * directory's encryption key is available --- since otherwise we'd have no way |
| * to encrypt the filename. A rename to an existing name, on the other hand, |
| * *is* cryptographically possible without the key. However, we take the more |
| * conservative approach and just forbid all no-key renames. |
| * |
| * We also verify that the rename will not violate the constraint that all files |
| * in an encrypted directory tree use the same encryption policy. |
| * |
| * Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the |
| * rename would cause inconsistent encryption policies, or another -errno code. |
| */ |
| static inline int fscrypt_prepare_rename(struct inode *old_dir, |
| struct dentry *old_dentry, |
| struct inode *new_dir, |
| struct dentry *new_dentry, |
| unsigned int flags) |
| { |
| if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir)) |
| return __fscrypt_prepare_rename(old_dir, old_dentry, |
| new_dir, new_dentry, flags); |
| return 0; |
| } |
| |
| /** |
| * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory |
| * @dir: directory being searched |
| * @dentry: filename being looked up |
| * @flags: lookup flags |
| * |
| * Prepare for ->lookup() in a directory which may be encrypted. Lookups can be |
| * done with or without the directory's encryption key; without the key, |
| * filenames are presented in encrypted form. Therefore, we'll try to set up |
| * the directory's encryption key, but even without it the lookup can continue. |
| * |
| * To allow invalidating stale dentries if the directory's encryption key is |
| * added later, we also install a custom ->d_revalidate() method and use the |
| * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a |
| * plaintext name (flag set) or a ciphertext name (flag cleared). |
| * |
| * Return: 0 on success, -errno if a problem occurred while setting up the |
| * encryption key |
| */ |
| static inline int fscrypt_prepare_lookup(struct inode *dir, |
| struct dentry *dentry, |
| unsigned int flags) |
| { |
| if (IS_ENCRYPTED(dir)) |
| return __fscrypt_prepare_lookup(dir, dentry); |
| return 0; |
| } |
| |
| /** |
| * fscrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes |
| * @dentry: dentry through which the inode is being changed |
| * @attr: attributes to change |
| * |
| * Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file, |
| * most attribute changes are allowed even without the encryption key. However, |
| * without the encryption key we do have to forbid truncates. This is needed |
| * because the size being truncated to may not be a multiple of the filesystem |
| * block size, and in that case we'd have to decrypt the final block, zero the |
| * portion past i_size, and re-encrypt it. (We *could* allow truncating to a |
| * filesystem block boundary, but it's simpler to just forbid all truncates --- |
| * and we already forbid all other contents modifications without the key.) |
| * |
| * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code |
| * if a problem occurred while setting up the encryption key. |
| */ |
| static inline int fscrypt_prepare_setattr(struct dentry *dentry, |
| struct iattr *attr) |
| { |
| if (attr->ia_valid & ATTR_SIZE) |
| return fscrypt_require_key(d_inode(dentry)); |
| return 0; |
| } |
| |
| #endif /* _LINUX_FSCRYPT_H */ |