LXR linux/include/linux/key.h

   1/* key.h: authentication token and access key management
   2 *
   3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 *
  11 *
  12 * See Documentation/keys.txt for information on keys/keyrings.
  13 */
  14
  15#ifndef _LINUX_KEY_H
  16#define _LINUX_KEY_H
  17
  18#include <linux/types.h>
  19#include <linux/list.h>
  20#include <linux/rbtree.h>
  21#include <linux/rcupdate.h>
  22#include <asm/atomic.h>
  23
  24#ifdef __KERNEL__
  25
  26/* key handle serial number */
  27typedef int32_t key_serial_t;
  28
  29/* key handle permissions mask */
  30typedef uint32_t key_perm_t;
  31
  32struct key;
  33
  34#ifdef CONFIG_KEYS
  35
  36#undef KEY_DEBUGGING
  37
  38#define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  39#define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  40#define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  41#define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  42#define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  43#define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  44#define KEY_POS_ALL     0x3f000000
  45
  46#define KEY_USR_VIEW    0x00010000      /* user permissions... */
  47#define KEY_USR_READ    0x00020000
  48#define KEY_USR_WRITE   0x00040000
  49#define KEY_USR_SEARCH  0x00080000
  50#define KEY_USR_LINK    0x00100000
  51#define KEY_USR_SETATTR 0x00200000
  52#define KEY_USR_ALL     0x003f0000
  53
  54#define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  55#define KEY_GRP_READ    0x00000200
  56#define KEY_GRP_WRITE   0x00000400
  57#define KEY_GRP_SEARCH  0x00000800
  58#define KEY_GRP_LINK    0x00001000
  59#define KEY_GRP_SETATTR 0x00002000
  60#define KEY_GRP_ALL     0x00003f00
  61
  62#define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  63#define KEY_OTH_READ    0x00000002
  64#define KEY_OTH_WRITE   0x00000004
  65#define KEY_OTH_SEARCH  0x00000008
  66#define KEY_OTH_LINK    0x00000010
  67#define KEY_OTH_SETATTR 0x00000020
  68#define KEY_OTH_ALL     0x0000003f
  69
  70struct seq_file;
  71struct user_struct;
  72struct signal_struct;
  73
  74struct key_type;
  75struct key_owner;
  76struct keyring_list;
  77struct keyring_name;
  78
  79/*****************************************************************************/
  80/*
  81 * key reference with possession attribute handling
  82 *
  83 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
  84 * defined. This is because we abuse the bottom bit of the reference to carry a
  85 * flag to indicate whether the calling process possesses that key in one of
  86 * its keyrings.
  87 *
  88 * the key_ref_t has been made a separate type so that the compiler can reject
  89 * attempts to dereference it without proper conversion.
  90 *
  91 * the three functions are used to assemble and disassemble references
  92 */
  93typedef struct __key_reference_with_attributes *key_ref_t;
  94
  95static inline key_ref_t make_key_ref(const struct key *key,
  96                                     unsigned long possession)
  97{
  98        return (key_ref_t) ((unsigned long) key | possession);
  99}
 100
 101static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 102{
 103        return (struct key *) ((unsigned long) key_ref & ~1UL);
 104}
 105
 106static inline unsigned long is_key_possessed(const key_ref_t key_ref)
 107{
 108        return (unsigned long) key_ref & 1UL;
 109}
 110
 111/*****************************************************************************/
 112/*
 113 * authentication token / access credential / keyring
 114 * - types of key include:
 115 *   - keyrings
 116 *   - disk encryption IDs
 117 *   - Kerberos TGTs and tickets
 118 */
 119struct key {
 120        atomic_t                usage;          /* number of references */
 121        key_serial_t            serial;         /* key serial number */
 122        struct rb_node          serial_node;
 123        struct key_type         *type;          /* type of key */
 124        struct rw_semaphore     sem;            /* change vs change sem */
 125        struct key_user         *user;          /* owner of this key */
 126        void                    *security;      /* security data for this key */
 127        time_t                  expiry;         /* time at which key expires (or 0) */
 128        uid_t                   uid;
 129        gid_t                   gid;
 130        key_perm_t              perm;           /* access permissions */
 131        unsigned short          quotalen;       /* length added to quota */
 132        unsigned short          datalen;        /* payload data length
 133                                                 * - may not match RCU dereferenced payload
 134                                                 * - payload should contain own length
 135                                                 */
 136
 137#ifdef KEY_DEBUGGING
 138        unsigned                magic;
 139#define KEY_DEBUG_MAGIC         0x18273645u
 140#define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 141#endif
 142
 143        unsigned long           flags;          /* status flags (change with bitops) */
 144#define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 145#define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 146#define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 147#define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 148#define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 149#define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 150
 151        /* the description string
 152         * - this is used to match a key against search criteria
 153         * - this should be a printable string
 154         * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 155         */
 156        char                    *description;
 157
 158        /* type specific data
 159         * - this is used by the keyring type to index the name
 160         */
 161        union {
 162                struct list_head        link;
 163        } type_data;
 164
 165        /* key data
 166         * - this is used to hold the data actually used in cryptography or
 167         *   whatever
 168         */
 169        union {
 170                unsigned long           value;
 171                void                    *data;
 172                struct keyring_list     *subscriptions;
 173        } payload;
 174};
 175
 176/*****************************************************************************/
 177/*
 178 * kernel managed key type definition
 179 */
 180typedef int (*request_key_actor_t)(struct key *key, struct key *authkey,
 181                                   const char *op, void *aux);
 182
 183struct key_type {
 184        /* name of the type */
 185        const char *name;
 186
 187        /* default payload length for quota precalculation (optional)
 188         * - this can be used instead of calling key_payload_reserve(), that
 189         *   function only needs to be called if the real datalen is different
 190         */
 191        size_t def_datalen;
 192
 193        /* instantiate a key of this type
 194         * - this method should call key_payload_reserve() to determine if the
 195         *   user's quota will hold the payload
 196         */
 197        int (*instantiate)(struct key *key, const void *data, size_t datalen);
 198
 199        /* update a key of this type (optional)
 200         * - this method should call key_payload_reserve() to recalculate the
 201         *   quota consumption
 202         * - the key must be locked against read when modifying
 203         */
 204        int (*update)(struct key *key, const void *data, size_t datalen);
 205
 206        /* match a key against a description */
 207        int (*match)(const struct key *key, const void *desc);
 208
 209        /* clear some of the data from a key on revokation (optional)
 210         * - the key's semaphore will be write-locked by the caller
 211         */
 212        void (*revoke)(struct key *key);
 213
 214        /* clear the data from a key (optional) */
 215        void (*destroy)(struct key *key);
 216
 217        /* describe a key */
 218        void (*describe)(const struct key *key, struct seq_file *p);
 219
 220        /* read a key's data (optional)
 221         * - permission checks will be done by the caller
 222         * - the key's semaphore will be readlocked by the caller
 223         * - should return the amount of data that could be read, no matter how
 224         *   much is copied into the buffer
 225         * - shouldn't do the copy if the buffer is NULL
 226         */
 227        long (*read)(const struct key *key, char __user *buffer, size_t buflen);
 228
 229        /* handle request_key() for this type instead of invoking
 230         * /sbin/request-key (optional)
 231         * - key is the key to instantiate
 232         * - authkey is the authority to assume when instantiating this key
 233         * - op is the operation to be done, usually "create"
 234         * - the call must not return until the instantiation process has run
 235         *   its course
 236         */
 237        request_key_actor_t request_key;
 238
 239        /* internal fields */
 240        struct list_head        link;           /* link in types list */
 241};
 242
 243extern struct key_type key_type_keyring;
 244
 245extern int register_key_type(struct key_type *ktype);
 246extern void unregister_key_type(struct key_type *ktype);
 247
 248extern struct key *key_alloc(struct key_type *type,
 249                             const char *desc,
 250                             uid_t uid, gid_t gid,
 251                             struct task_struct *ctx,
 252                             key_perm_t perm,
 253                             unsigned long flags);
 254
 255
 256#define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 257#define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 258#define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 259
 260extern int key_payload_reserve(struct key *key, size_t datalen);
 261extern int key_instantiate_and_link(struct key *key,
 262                                    const void *data,
 263                                    size_t datalen,
 264                                    struct key *keyring,
 265                                    struct key *instkey);
 266extern int key_negate_and_link(struct key *key,
 267                               unsigned timeout,
 268                               struct key *keyring,
 269                               struct key *instkey);
 270extern void key_revoke(struct key *key);
 271extern void key_put(struct key *key);
 272
 273static inline struct key *key_get(struct key *key)
 274{
 275        if (key)
 276                atomic_inc(&key->usage);
 277        return key;
 278}
 279
 280static inline void key_ref_put(key_ref_t key_ref)
 281{
 282        key_put(key_ref_to_ptr(key_ref));
 283}
 284
 285extern struct key *request_key(struct key_type *type,
 286                               const char *description,
 287                               const char *callout_info);
 288
 289extern struct key *request_key_with_auxdata(struct key_type *type,
 290                                            const char *description,
 291                                            const char *callout_info,
 292                                            void *aux);
 293
 294extern int key_validate(struct key *key);
 295
 296extern key_ref_t key_create_or_update(key_ref_t keyring,
 297                                      const char *type,
 298                                      const char *description,
 299                                      const void *payload,
 300                                      size_t plen,
 301                                      unsigned long flags);
 302
 303extern int key_update(key_ref_t key,
 304                      const void *payload,
 305                      size_t plen);
 306
 307extern int key_link(struct key *keyring,
 308                    struct key *key);
 309
 310extern int key_unlink(struct key *keyring,
 311                      struct key *key);
 312
 313extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 314                                 struct task_struct *ctx,
 315                                 unsigned long flags,
 316                                 struct key *dest);
 317
 318extern int keyring_clear(struct key *keyring);
 319
 320extern key_ref_t keyring_search(key_ref_t keyring,
 321                                struct key_type *type,
 322                                const char *description);
 323
 324extern int keyring_add_key(struct key *keyring,
 325                           struct key *key);
 326
 327extern struct key *key_lookup(key_serial_t id);
 328
 329extern void keyring_replace_payload(struct key *key, void *replacement);
 330
 331#define key_serial(key) ((key) ? (key)->serial : 0)
 332
 333/*
 334 * the userspace interface
 335 */
 336extern struct key root_user_keyring, root_session_keyring;
 337extern int alloc_uid_keyring(struct user_struct *user,
 338                             struct task_struct *ctx);
 339extern void switch_uid_keyring(struct user_struct *new_user);
 340extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
 341extern int copy_thread_group_keys(struct task_struct *tsk);
 342extern void exit_keys(struct task_struct *tsk);
 343extern void exit_thread_group_keys(struct signal_struct *tg);
 344extern int suid_keys(struct task_struct *tsk);
 345extern int exec_keys(struct task_struct *tsk);
 346extern void key_fsuid_changed(struct task_struct *tsk);
 347extern void key_fsgid_changed(struct task_struct *tsk);
 348extern void key_init(void);
 349
 350#define __install_session_keyring(tsk, keyring)                 \
 351({                                                              \
 352        struct key *old_session = tsk->signal->session_keyring; \
 353        tsk->signal->session_keyring = keyring;                 \
 354        old_session;                                            \
 355})
 356
 357#else /* CONFIG_KEYS */
 358
 359#define key_validate(k)                 0
 360#define key_serial(k)                   0
 361#define key_get(k)                      ({ NULL; })
 362#define key_put(k)                      do { } while(0)
 363#define key_ref_put(k)                  do { } while(0)
 364#define make_key_ref(k)                 ({ NULL; })
 365#define key_ref_to_ptr(k)               ({ NULL; })
 366#define is_key_possessed(k)             0
 367#define alloc_uid_keyring(u,c)          0
 368#define switch_uid_keyring(u)           do { } while(0)
 369#define __install_session_keyring(t, k) ({ NULL; })
 370#define copy_keys(f,t)                  0
 371#define copy_thread_group_keys(t)       0
 372#define exit_keys(t)                    do { } while(0)
 373#define exit_thread_group_keys(tg)      do { } while(0)
 374#define suid_keys(t)                    do { } while(0)
 375#define exec_keys(t)                    do { } while(0)
 376#define key_fsuid_changed(t)            do { } while(0)
 377#define key_fsgid_changed(t)            do { } while(0)
 378#define key_init()                      do { } while(0)
 379
 380/* Initial keyrings */
 381extern struct key root_user_keyring;
 382extern struct key root_session_keyring;
 383
 384#endif /* CONFIG_KEYS */
 385#endif /* __KERNEL__ */
 386#endif /* _LINUX_KEY_H */
 387