include/linux/fscrypt_common.h

   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
  23 struct fscrypt_info;
  24
  25 struct 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  */
  44 struct fscrypt_symlink_data {
  45         __le16 len;
  46         char encrypted_path[1];
  47 } __packed;
  48
  49 struct fscrypt_str {
  50         unsigned char *name;
  51         u32 len;
  52 };
  53
  54 struct 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  */
  75 struct 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
  89 static 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
  97 static 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
 111 static 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
 122 static 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
 132 static 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 */