1/* Credentials management - see Documentation/security/credentials.txt 2 * 3 * Copyright (C) 2008 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 Licence 8 * as published by the Free Software Foundation; either version 9 * 2 of the Licence, or (at your option) any later version. 10 */ 11 12#ifndef _LINUX_CRED_H 13#define _LINUX_CRED_H 14 15#include <linux/capability.h> 16#include <linux/init.h> 17#include <linux/key.h> 18#include <linux/selinux.h> 19#include <linux/atomic.h> 20#include <linux/uidgid.h> 21 22struct user_struct; 23struct cred; 24struct inode; 25 26/* 27 * COW Supplementary groups list 28 */ 29#define NGROUPS_SMALL 32 30#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t))) 31 32struct group_info { 33 atomic_t usage; 34 int ngroups; 35 int nblocks; 36 kgid_t small_block[NGROUPS_SMALL]; 37 kgid_t *blocks[0]; 38}; 39 40/** 41 * get_group_info - Get a reference to a group info structure 42 * @group_info: The group info to reference 43 * 44 * This gets a reference to a set of supplementary groups. 45 * 46 * If the caller is accessing a task's credentials, they must hold the RCU read 47 * lock when reading. 48 */ 49static inline struct group_info *get_group_info(struct group_info *gi) 50{ 51 atomic_inc(&gi->usage); 52 return gi; 53} 54 55/** 56 * put_group_info - Release a reference to a group info structure 57 * @group_info: The group info to release 58 */ 59#define put_group_info(group_info) \ 60do { \ 61 if (atomic_dec_and_test(&(group_info)->usage)) \ 62 groups_free(group_info); \ 63} while (0) 64 65extern struct group_info *groups_alloc(int); 66extern struct group_info init_groups; 67extern void groups_free(struct group_info *); 68extern int set_current_groups(struct group_info *); 69extern void set_groups(struct cred *, struct group_info *); 70extern int groups_search(const struct group_info *, kgid_t); 71 72/* access the groups "array" with this macro */ 73#define GROUP_AT(gi, i) \ 74 ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK]) 75 76extern int in_group_p(kgid_t); 77extern int in_egroup_p(kgid_t); 78 79/* 80 * The security context of a task 81 * 82 * The parts of the context break down into two categories: 83 * 84 * (1) The objective context of a task. These parts are used when some other 85 * task is attempting to affect this one. 86 * 87 * (2) The subjective context. These details are used when the task is acting 88 * upon another object, be that a file, a task, a key or whatever. 89 * 90 * Note that some members of this structure belong to both categories - the 91 * LSM security pointer for instance. 92 * 93 * A task has two security pointers. task->real_cred points to the objective 94 * context that defines that task's actual details. The objective part of this 95 * context is used whenever that task is acted upon. 96 * 97 * task->cred points to the subjective context that defines the details of how 98 * that task is going to act upon another object. This may be overridden 99 * temporarily to point to another security context, but normally points to the 100 * same context as task->real_cred. 101 */ 102struct cred { 103 atomic_t usage; 104#ifdef CONFIG_DEBUG_CREDENTIALS 105 atomic_t subscribers; /* number of processes subscribed */ 106 void *put_addr; 107 unsigned magic; 108#define CRED_MAGIC 0x43736564 109#define CRED_MAGIC_DEAD 0x44656144 110#endif 111 kuid_t uid; /* real UID of the task */ 112 kgid_t gid; /* real GID of the task */ 113 kuid_t suid; /* saved UID of the task */ 114 kgid_t sgid; /* saved GID of the task */ 115 kuid_t euid; /* effective UID of the task */ 116 kgid_t egid; /* effective GID of the task */ 117 kuid_t fsuid; /* UID for VFS ops */ 118 kgid_t fsgid; /* GID for VFS ops */ 119 unsigned securebits; /* SUID-less security management */ 120 kernel_cap_t cap_inheritable; /* caps our children can inherit */ 121 kernel_cap_t cap_permitted; /* caps we're permitted */ 122 kernel_cap_t cap_effective; /* caps we can actually use */ 123 kernel_cap_t cap_bset; /* capability bounding set */ 124#ifdef CONFIG_KEYS 125 unsigned char jit_keyring; /* default keyring to attach requested 126 * keys to */ 127 struct key __rcu *session_keyring; /* keyring inherited over fork */ 128 struct key *process_keyring; /* keyring private to this process */ 129 struct key *thread_keyring; /* keyring private to this thread */ 130 struct key *request_key_auth; /* assumed request_key authority */ 131#endif 132#ifdef CONFIG_SECURITY 133 void *security; /* subjective LSM security */ 134#endif 135 struct user_struct *user; /* real user ID subscription */ 136 struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */ 137 struct group_info *group_info; /* supplementary groups for euid/fsgid */ 138 struct rcu_head rcu; /* RCU deletion hook */ 139}; 140 141extern void __put_cred(struct cred *); 142extern void exit_creds(struct task_struct *); 143extern int copy_creds(struct task_struct *, unsigned long); 144extern const struct cred *get_task_cred(struct task_struct *); 145extern struct cred *cred_alloc_blank(void); 146extern struct cred *prepare_creds(void); 147extern struct cred *prepare_exec_creds(void); 148extern int commit_creds(struct cred *); 149extern void abort_creds(struct cred *); 150extern const struct cred *override_creds(const struct cred *); 151extern void revert_creds(const struct cred *); 152extern struct cred *prepare_kernel_cred(struct task_struct *); 153extern int change_create_files_as(struct cred *, struct inode *); 154extern int set_security_override(struct cred *, u32); 155extern int set_security_override_from_ctx(struct cred *, const char *); 156extern int set_create_files_as(struct cred *, struct inode *); 157extern void __init cred_init(void); 158 159/* 160 * check for validity of credentials 161 */ 162#ifdef CONFIG_DEBUG_CREDENTIALS 163extern void __invalid_creds(const struct cred *, const char *, unsigned); 164extern void __validate_process_creds(struct task_struct *, 165 const char *, unsigned); 166 167extern bool creds_are_invalid(const struct cred *cred); 168 169static inline void __validate_creds(const struct cred *cred, 170 const char *file, unsigned line) 171{ 172 if (unlikely(creds_are_invalid(cred))) 173 __invalid_creds(cred, file, line); 174} 175 176#define validate_creds(cred) \ 177do { \ 178 __validate_creds((cred), __FILE__, __LINE__); \ 179} while(0) 180 181#define validate_process_creds() \ 182do { \ 183 __validate_process_creds(current, __FILE__, __LINE__); \ 184} while(0) 185 186extern void validate_creds_for_do_exit(struct task_struct *); 187#else 188static inline void validate_creds(const struct cred *cred) 189{ 190} 191static inline void validate_creds_for_do_exit(struct task_struct *tsk) 192{ 193} 194static inline void validate_process_creds(void) 195{ 196} 197#endif 198 199/** 200 * get_new_cred - Get a reference on a new set of credentials 201 * @cred: The new credentials to reference 202 * 203 * Get a reference on the specified set of new credentials. The caller must 204 * release the reference. 205 */ 206static inline struct cred *get_new_cred(struct cred *cred) 207{ 208 atomic_inc(&cred->usage); 209 return cred; 210} 211 212/** 213 * get_cred - Get a reference on a set of credentials 214 * @cred: The credentials to reference 215 * 216 * Get a reference on the specified set of credentials. The caller must 217 * release the reference. 218 * 219 * This is used to deal with a committed set of credentials. Although the 220 * pointer is const, this will temporarily discard the const and increment the 221 * usage count. The purpose of this is to attempt to catch at compile time the 222 * accidental alteration of a set of credentials that should be considered 223 * immutable. 224 */ 225static inline const struct cred *get_cred(const struct cred *cred) 226{ 227 struct cred *nonconst_cred = (struct cred *) cred; 228 validate_creds(cred); 229 return get_new_cred(nonconst_cred); 230} 231 232/** 233 * put_cred - Release a reference to a set of credentials 234 * @cred: The credentials to release 235 * 236 * Release a reference to a set of credentials, deleting them when the last ref 237 * is released. 238 * 239 * This takes a const pointer to a set of credentials because the credentials 240 * on task_struct are attached by const pointers to prevent accidental 241 * alteration of otherwise immutable credential sets. 242 */ 243static inline void put_cred(const struct cred *_cred) 244{ 245 struct cred *cred = (struct cred *) _cred; 246 247 validate_creds(cred); 248 if (atomic_dec_and_test(&(cred)->usage)) 249 __put_cred(cred); 250} 251 252/** 253 * current_cred - Access the current task's subjective credentials 254 * 255 * Access the subjective credentials of the current task. RCU-safe, 256 * since nobody else can modify it. 257 */ 258#define current_cred() \ 259 rcu_dereference_protected(current->cred, 1) 260 261/** 262 * current_real_cred - Access the current task's objective credentials 263 * 264 * Access the objective credentials of the current task. RCU-safe, 265 * since nobody else can modify it. 266 */ 267#define current_real_cred() \ 268 rcu_dereference_protected(current->real_cred, 1) 269 270/** 271 * __task_cred - Access a task's objective credentials 272 * @task: The task to query 273 * 274 * Access the objective credentials of a task. The caller must hold the RCU 275 * readlock. 276 * 277 * The result of this function should not be passed directly to get_cred(); 278 * rather get_task_cred() should be used instead. 279 */ 280#define __task_cred(task) \ 281 rcu_dereference((task)->real_cred) 282 283/** 284 * get_current_cred - Get the current task's subjective credentials 285 * 286 * Get the subjective credentials of the current task, pinning them so that 287 * they can't go away. Accessing the current task's credentials directly is 288 * not permitted. 289 */ 290#define get_current_cred() \ 291 (get_cred(current_cred())) 292 293/** 294 * get_current_user - Get the current task's user_struct 295 * 296 * Get the user record of the current task, pinning it so that it can't go 297 * away. 298 */ 299#define get_current_user() \ 300({ \ 301 struct user_struct *__u; \ 302 const struct cred *__cred; \ 303 __cred = current_cred(); \ 304 __u = get_uid(__cred->user); \ 305 __u; \ 306}) 307 308/** 309 * get_current_groups - Get the current task's supplementary group list 310 * 311 * Get the supplementary group list of the current task, pinning it so that it 312 * can't go away. 313 */ 314#define get_current_groups() \ 315({ \ 316 struct group_info *__groups; \ 317 const struct cred *__cred; \ 318 __cred = current_cred(); \ 319 __groups = get_group_info(__cred->group_info); \ 320 __groups; \ 321}) 322 323#define task_cred_xxx(task, xxx) \ 324({ \ 325 __typeof__(((struct cred *)NULL)->xxx) ___val; \ 326 rcu_read_lock(); \ 327 ___val = __task_cred((task))->xxx; \ 328 rcu_read_unlock(); \ 329 ___val; \ 330}) 331 332#define task_uid(task) (task_cred_xxx((task), uid)) 333#define task_euid(task) (task_cred_xxx((task), euid)) 334 335#define current_cred_xxx(xxx) \ 336({ \ 337 current_cred()->xxx; \ 338}) 339 340#define current_uid() (current_cred_xxx(uid)) 341#define current_gid() (current_cred_xxx(gid)) 342#define current_euid() (current_cred_xxx(euid)) 343#define current_egid() (current_cred_xxx(egid)) 344#define current_suid() (current_cred_xxx(suid)) 345#define current_sgid() (current_cred_xxx(sgid)) 346#define current_fsuid() (current_cred_xxx(fsuid)) 347#define current_fsgid() (current_cred_xxx(fsgid)) 348#define current_cap() (current_cred_xxx(cap_effective)) 349#define current_user() (current_cred_xxx(user)) 350#define current_security() (current_cred_xxx(security)) 351 352extern struct user_namespace init_user_ns; 353#ifdef CONFIG_USER_NS 354#define current_user_ns() (current_cred_xxx(user_ns)) 355#else 356#define current_user_ns() (&init_user_ns) 357#endif 358 359 360#define current_uid_gid(_uid, _gid) \ 361do { \ 362 const struct cred *__cred; \ 363 __cred = current_cred(); \ 364 *(_uid) = __cred->uid; \ 365 *(_gid) = __cred->gid; \ 366} while(0) 367 368#define current_euid_egid(_euid, _egid) \ 369do { \ 370 const struct cred *__cred; \ 371 __cred = current_cred(); \ 372 *(_euid) = __cred->euid; \ 373 *(_egid) = __cred->egid; \ 374} while(0) 375 376#define current_fsuid_fsgid(_fsuid, _fsgid) \ 377do { \ 378 const struct cred *__cred; \ 379 __cred = current_cred(); \ 380 *(_fsuid) = __cred->fsuid; \ 381 *(_fsgid) = __cred->fsgid; \ 382} while(0) 383 384#endif /* _LINUX_CRED_H */ 385