LXR linux/include/linux/fscrypt

   1/*
   2 * fscrypt_common.h: common declarations for per-file encryption
   3 *
   4 * Copyright (C) 2015, Google, Inc.
   5 *
   6 * Written by Michael Halcrow, 2015.
   7 * Modified by Jaegeuk Kim, 2015.
   8 */
   9
  10#ifndef _LINUX_FSCRYPT_COMMON_H
  11#define _LINUX_FSCRYPT_COMMON_H
  12
  13#include <linux/key.h>
  14#include <linux/fs.h>
  15#include <linux/mm.h>
  16#include <linux/bio.h>
  17#include <linux/dcache.h>
  18#include <crypto/skcipher.h>
  19#include <uapi/linux/fs.h>
  20
  21#define FS_CRYPTO_BLOCK_SIZE            16
  22
  23struct fscrypt_info;
  24
  25struct fscrypt_ctx {
  26        union {
  27                struct {
  28                        struct page *bounce_page;       /* Ciphertext page */
  29                        struct page *control_page;      /* Original page  */
  30                } w;
  31                struct {
  32                        struct bio *bio;
  33                        struct work_struct work;
  34                } r;
  35                struct list_head free_list;     /* Free list */
  36        };
  37        u8 flags;                               /* Flags */
  38};
  39
  40/**
  41 * For encrypted symlinks, the ciphertext length is stored at the beginning
  42 * of the string in little-endian format.
  43 */
  44struct fscrypt_symlink_data {
  45        __le16 len;
  46        char encrypted_path[1];
  47} __packed;
  48
  49struct fscrypt_str {
  50        unsigned char *name;
  51        u32 len;
  52};
  53
  54struct fscrypt_name {
  55        const struct qstr *usr_fname;
  56        struct fscrypt_str disk_name;
  57        u32 hash;
  58        u32 minor_hash;
  59        struct fscrypt_str crypto_buf;
  60};
  61
  62#define FSTR_INIT(n, l)         { .name = n, .len = l }
  63#define FSTR_TO_QSTR(f)         QSTR_INIT((f)->name, (f)->len)
  64#define fname_name(p)           ((p)->disk_name.name)
  65#define fname_len(p)            ((p)->disk_name.len)
  66
  67/*
  68 * fscrypt superblock flags
  69 */
  70#define FS_CFLG_OWN_PAGES (1U << 1)
  71
  72/*
  73 * crypto opertions for filesystems
  74 */
  75struct fscrypt_operations {
  76        unsigned int flags;
  77        const char *key_prefix;
  78        int (*get_context)(struct inode *, void *, size_t);
  79        int (*set_context)(struct inode *, const void *, size_t, void *);
  80        bool (*dummy_context)(struct inode *);
  81        bool (*is_encrypted)(struct inode *);
  82        bool (*empty_dir)(struct inode *);
  83        unsigned (*max_namelen)(struct inode *);
  84};
  85
  86/* Maximum value for the third parameter of fscrypt_operations.set_context(). */
  87#define FSCRYPT_SET_CONTEXT_MAX_SIZE    28
  88
  89static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
  90{
  91        if (inode->i_sb->s_cop->dummy_context &&
  92                                inode->i_sb->s_cop->dummy_context(inode))
  93                return true;
  94        return false;
  95}
  96
  97static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
  98                                        u32 filenames_mode)
  99{
 100        if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC &&
 101            filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS)
 102                return true;
 103
 104        if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS &&
 105            filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS)
 106                return true;
 107
 108        return false;
 109}
 110
 111static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
 112{
 113        if (str->len == 1 && str->name[0] == '.')
 114                return true;
 115
 116        if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
 117                return true;
 118
 119        return false;
 120}
 121
 122static inline struct page *fscrypt_control_page(struct page *page)
 123{
 124#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
 125        return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
 126#else
 127        WARN_ON_ONCE(1);
 128        return ERR_PTR(-EINVAL);
 129#endif
 130}
 131
 132static inline int fscrypt_has_encryption_key(const struct inode *inode)
 133{
 134#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
 135        return (inode->i_crypt_info != NULL);
 136#else
 137        return 0;
 138#endif
 139}
 140
 141#endif  /* _LINUX_FSCRYPT_COMMON_H */
 142