bsd/sys/cprotect.h

   1 /*
   2  * Copyright (c) 2009-2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #ifndef _SYS_CPROTECT_H_
  30 #define _SYS_CPROTECT_H_
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 #if KERNEL_PRIVATE
  37
  38 #include <sys/cdefs.h>
  39 #include <sys/content_protection.h>
  40 #include <sys/kernel_types.h>
  41 #include <crypto/aes.h>
  42
  43 #define CP_IV_KEYSIZE             20    /* 16x8 = 128, but SHA1 pushes 20 bytes so keep space for that */
  44 #define CP_MAX_KEYSIZE            32    /* 8x4 = 32, 32x8 = 256 */
  45 #define CP_MAX_WRAPPEDKEYSIZE     128   /* The size of the largest allowed key */
  46 #define CP_INITIAL_WRAPPEDKEYSIZE 40
  47 #define CP_V2_WRAPPEDKEYSIZE      40    /* Size of the wrapped key in a v2 EA */
  48 #define CP_V4_RESERVEDBYTES       20    /* Number of reserved bytes in EA still present */
  49
  50 /* lock events from AppleKeyStore */
  51 #define CP_LOCKED_STATE           0     /* Device is locked */
  52 #define CP_UNLOCKED_STATE         1     /* Device is unlocked */
  53
  54 #define CP_MAX_STATE                      1     /* uint8_t ; maximum # of states is 255 */
  55
  56 #define CP_LOCKED_KEYCHAIN        0
  57 #define CP_UNLOCKED_KEYCHAIN      1
  58
  59 /* For struct cprotect: cp_flags */
  60 #define CP_NEEDS_KEYS             0x01  /* File needs persistent keys */
  61 #define CP_KEY_FLUSHED            0x02  /* File's unwrapped key has been purged from memory */
  62 #define CP_NO_XATTR               0x04  /* Key info has not been saved as EA to the FS */
  63 #define CP_OFF_IV_ENABLED         0x08  /* Only go down relative IV route if this flag is set */
  64 #define CP_RELOCATION_INFLIGHT    0x10  /* File with offset IVs is in the process of being relocated. */
  65 #define CP_SEP_WRAPPEDKEY                 0x20  /* Wrapped key delivered from keybag */
  66
  67 /* Content Protection VNOP Operation flags */
  68 #define CP_READ_ACCESS            0x1
  69 #define CP_WRITE_ACCESS           0x2
  70
  71 /*
  72  * Check for this version when deciding to enable features
  73  * For iOS 4, CP_CURRENT_MAJOR_VERS = 2.0
  74  * For iOS 5, CP_CURRENT_MAJOR_VERS = 4.0
  75  */
  76 #define CONTENT_PROTECTION_XATTR_NAME   "com.apple.system.cprotect"
  77 #define CP_NEW_MAJOR_VERS         4
  78 #define CP_PREV_MAJOR_VERS        2
  79 #define CP_MINOR_VERS             0
  80
  81 typedef struct cprotect *cprotect_t;
  82 typedef struct cp_wrap_func *cp_wrap_func_t;
  83 typedef struct cp_global_state *cp_global_state_t;
  84 typedef struct cp_xattr *cp_xattr_t;
  85
  86 typedef struct cnode * cnode_ptr_t;
  87 //forward declare the struct.
  88 struct hfsmount;
  89
  90 /* Structures passed between HFS and AKS kext */
  91 typedef struct {
  92         void     *key;
  93         unsigned key_len;
  94         void     *iv_key;
  95         unsigned iv_key_len;
  96         uint32_t flags;
  97 } cp_raw_key_s, *cp_raw_key_t;
  98
  99 typedef struct {
 100         void     *key;
 101         unsigned key_len;
 102         uint32_t dp_class;
 103 } cp_wrapped_key_s, *cp_wrapped_key_t;
 104
 105 typedef struct {
 106         ino64_t  inode;
 107         uint32_t volume;
 108         pid_t    pid;
 109         uid_t    uid;
 110 } cp_cred_s, *cp_cred_t;
 111
 112 /* The wrappers are invoked on the AKS kext */
 113 typedef int unwrapper_t(cp_cred_t access, const cp_wrapped_key_t wrapped_key_in, cp_raw_key_t key_out);
 114 typedef int rewrapper_t(cp_cred_t access, uint32_t dp_class, const cp_wrapped_key_t wrapped_key_in, cp_wrapped_key_t wrapped_key_out);
 115 typedef int new_key_t(cp_cred_t access, uint32_t dp_class, cp_raw_key_t key_out, cp_wrapped_key_t wrapped_key_out);
 116 typedef int invalidater_t(cp_cred_t access); /* invalidates keys */
 117
 118
 119 /* Flags for Interaction between AKS / Kernel */
 120 #define CP_RAW_KEY_WRAPPEDKEY 0x00000001
 121
 122
 123 /*
 124  * Runtime-only structure containing the content protection status
 125  * for the given file.  This is contained within the cnode
 126  * This is passed down to IOStorageFamily via the bufattr struct
 127  *
 128  ******************************************************
 129  * Some Key calculation information for offset based IV
 130  ******************************************************
 131  * Kf  = original 256 bit per file key
 132  * Kiv = SHA1(Kf), use full Kf, but truncate Kiv to 128 bits
 133  * Kiv can be cached in the cprotect, so it only has to be calculated once for the file init
 134  *
 135  * IVb = Encrypt(Kiv, offset)
 136  *
 137  */
 138 struct cprotect {
 139         uint32_t        cp_flags;
 140         uint32_t        cp_pclass;
 141         aes_encrypt_ctx cp_cache_iv_ctx;
 142         uint32_t        cp_cache_key_len;
 143         uint8_t         cp_cache_key[CP_MAX_KEYSIZE];
 144         uint32_t        cp_persistent_key_len;
 145         void*           cp_backing_cnode;
 146         uint8_t         cp_persistent_key[];
 147 };
 148
 149 struct cp_wrap_func {
 150         new_key_t       *new_key;
 151         unwrapper_t     *unwrapper;
 152         rewrapper_t     *rewrapper;
 153         invalidater_t   *invalidater;
 154 };
 155
 156 struct cp_global_state {
 157         uint8_t wrap_functions_set;
 158         uint8_t lock_state;
 159         u_int16_t reserved;
 160 };
 161
 162 /*
 163  * On-disk structure written as the per-file EA payload
 164  * All on-disk multi-byte fields for the CP XATTR must be stored
 165  * little-endian on-disk.  This means they must be endian swapped to
 166  * L.E on getxattr() and converted to LE on setxattr().
 167  *
 168  * This structure is a fixed length and is tightly packed.
 169  * 56 bytes total.
 170  */
 171 struct cp_xattr_v2 {
 172         u_int16_t xattr_major_version;
 173         u_int16_t xattr_minor_version;
 174         u_int32_t flags;
 175         u_int32_t persistent_class;
 176         u_int32_t key_size;
 177         uint8_t   persistent_key[CP_V2_WRAPPEDKEYSIZE];
 178 } __attribute__((aligned(2), packed));
 179
 180
 181 /*
 182  * V4 Content Protection EA On-Disk Layout.
 183  *
 184  * This structure must be tightly packed, but the *size can vary*
 185  * depending on the length of the key.  At MOST, the key length will be
 186  * CP_MAX_WRAPPEDKEYSIZE, but the length is defined by the key_size field.
 187  *
 188  * Either way, the packing must be applied to ensure that the key data is
 189  * retrievable in the right location relative to the start of the struct.
 190  *
 191  * Fully packed, this structure can range from :
 192  *              MIN: 36 bytes (no key -- used with directories)
 193  *              MAX: 164 bytes (with 128 byte key)
 194  *
 195  * During runtime we always allocate with the full 128 byte key, but only
 196  * use as much of the key buffer as needed. It must be tightly packed, though.
 197  */
 198
 199 struct cp_xattr_v4 {
 200         u_int16_t xattr_major_version;
 201         u_int16_t xattr_minor_version;
 202         u_int32_t flags;
 203         u_int32_t persistent_class;
 204         u_int32_t key_size;
 205         /* CP V4 Reserved Bytes == 20 */
 206         u_int8_t reserved[CP_V4_RESERVEDBYTES];
 207         /* All above fields are fixed regardless of key length (36 bytes) */
 208         /* Max Wrapped Size == 128 */
 209         uint8_t   persistent_key[CP_MAX_WRAPPEDKEYSIZE];
 210 } __attribute__((aligned(2), packed));
 211
 212
 213 /*
 214  * The Root Directory's EA (fileid 1) is special; it defines information about
 215  * what capabilities the filesystem is using.
 216  *
 217  * The data is still stored little endian.
 218  *
 219  * Note that this structure is tightly packed: 28 bytes total.
 220  */
 221  struct cp_root_xattr {
 222         u_int16_t major_version;
 223         u_int16_t minor_version;
 224         u_int64_t flags;
 225         u_int8_t reserved[16];
 226 } __attribute__((aligned(2), packed));
 227
 228
 229 /*
 230  * Functions to check the status of a CP and to query
 231  * the containing filesystem to see if it is supported.
 232  */
 233 int cp_vnode_getclass(vnode_t, int *);
 234 int cp_vnode_setclass(vnode_t, uint32_t);
 235 int cp_vnode_transcode(vnode_t);
 236
 237 int cp_key_store_action(int);
 238 int cp_register_wraps(cp_wrap_func_t);
 239
 240 int cp_entry_init(cnode_ptr_t, struct mount *);
 241 int cp_entry_gentempkeys(struct cprotect **entry_ptr, struct hfsmount *hfsmp);
 242 int cp_needs_tempkeys (struct hfsmount *hfsmp, int* needs);
 243 void cp_entry_destroy(struct cprotect *entry_ptr);
 244 void cp_replace_entry (struct cnode *cp, struct cprotect *newentry);
 245 cnode_ptr_t cp_get_protected_cnode(vnode_t);
 246 int cp_handle_vnop(vnode_t, int, int);
 247 int cp_fs_protected (mount_t);
 248 int cp_getrootxattr (struct hfsmount *hfsmp, struct cp_root_xattr *outxattr);
 249 int cp_setrootxattr (struct hfsmount *hfsmp, struct cp_root_xattr *newxattr);
 250 int cp_setxattr(struct cnode *cp, struct cprotect *entry, struct hfsmount *hfsmp, uint32_t fileid, int options);
 251 int cp_generate_keys (struct hfsmount *hfsmp, struct cnode *cp, int targetclass, struct cprotect **newentry);
 252 int cp_setup_newentry (struct hfsmount *hfsmp, struct cnode *dcp, int32_t suppliedclass,
 253                 mode_t cmode, struct cprotect **tmpentry);
 254 int cp_handle_relocate (cnode_ptr_t cp, struct hfsmount *hfsmp);
 255 int cp_handle_open(struct vnode *vp, int mode);
 256 int cp_get_root_major_vers (struct vnode *vp, uint32_t *level);
 257 int cp_get_default_level (struct vnode *vp, uint32_t *level);
 258 int cp_is_valid_class (int isdir, int32_t protectionclass);
 259
 260 #endif  /* KERNEL_PRIVATE */
 261
 262 #ifdef __cplusplus
 263 };
 264 #endif
 265
 266 #endif /* !_SYS_CPROTECT_H_ */