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1 : /* SPDX-License-Identifier: GPL-2.0-or-later */
2 : /* Credentials management - see Documentation/security/credentials.rst
3 : *
4 : * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
5 : * Written by David Howells (dhowells@redhat.com)
6 : */
7 :
8 : #ifndef _LINUX_CRED_H
9 : #define _LINUX_CRED_H
10 :
11 : #include <linux/capability.h>
12 : #include <linux/init.h>
13 : #include <linux/key.h>
14 : #include <linux/atomic.h>
15 : #include <linux/uidgid.h>
16 : #include <linux/sched.h>
17 : #include <linux/sched/user.h>
18 :
19 : struct cred;
20 : struct inode;
21 :
22 : /*
23 : * COW Supplementary groups list
24 : */
25 : struct group_info {
26 : atomic_t usage;
27 : int ngroups;
28 : kgid_t gid[];
29 : } __randomize_layout;
30 :
31 : /**
32 : * get_group_info - Get a reference to a group info structure
33 : * @group_info: The group info to reference
34 : *
35 : * This gets a reference to a set of supplementary groups.
36 : *
37 : * If the caller is accessing a task's credentials, they must hold the RCU read
38 : * lock when reading.
39 : */
40 6232 : static inline struct group_info *get_group_info(struct group_info *gi)
41 : {
42 6232 : atomic_inc(&gi->usage);
43 6232 : return gi;
44 : }
45 :
46 : /**
47 : * put_group_info - Release a reference to a group info structure
48 : * @group_info: The group info to release
49 : */
50 : #define put_group_info(group_info) \
51 : do { \
52 : if (atomic_dec_and_test(&(group_info)->usage)) \
53 : groups_free(group_info); \
54 : } while (0)
55 :
56 : extern struct group_info init_groups;
57 : #ifdef CONFIG_MULTIUSER
58 : extern struct group_info *groups_alloc(int);
59 : extern void groups_free(struct group_info *);
60 :
61 : extern int in_group_p(kgid_t);
62 : extern int in_egroup_p(kgid_t);
63 : extern int groups_search(const struct group_info *, kgid_t);
64 :
65 : extern int set_current_groups(struct group_info *);
66 : extern void set_groups(struct cred *, struct group_info *);
67 : extern bool may_setgroups(void);
68 : extern void groups_sort(struct group_info *);
69 : #else
70 : static inline void groups_free(struct group_info *group_info)
71 : {
72 : }
73 :
74 : static inline int in_group_p(kgid_t grp)
75 : {
76 : return 1;
77 : }
78 : static inline int in_egroup_p(kgid_t grp)
79 : {
80 : return 1;
81 : }
82 : static inline int groups_search(const struct group_info *group_info, kgid_t grp)
83 : {
84 : return 1;
85 : }
86 : #endif
87 :
88 : /*
89 : * The security context of a task
90 : *
91 : * The parts of the context break down into two categories:
92 : *
93 : * (1) The objective context of a task. These parts are used when some other
94 : * task is attempting to affect this one.
95 : *
96 : * (2) The subjective context. These details are used when the task is acting
97 : * upon another object, be that a file, a task, a key or whatever.
98 : *
99 : * Note that some members of this structure belong to both categories - the
100 : * LSM security pointer for instance.
101 : *
102 : * A task has two security pointers. task->real_cred points to the objective
103 : * context that defines that task's actual details. The objective part of this
104 : * context is used whenever that task is acted upon.
105 : *
106 : * task->cred points to the subjective context that defines the details of how
107 : * that task is going to act upon another object. This may be overridden
108 : * temporarily to point to another security context, but normally points to the
109 : * same context as task->real_cred.
110 : */
111 : struct cred {
112 : atomic_t usage;
113 : #ifdef CONFIG_DEBUG_CREDENTIALS
114 : atomic_t subscribers; /* number of processes subscribed */
115 : void *put_addr;
116 : unsigned magic;
117 : #define CRED_MAGIC 0x43736564
118 : #define CRED_MAGIC_DEAD 0x44656144
119 : #endif
120 : kuid_t uid; /* real UID of the task */
121 : kgid_t gid; /* real GID of the task */
122 : kuid_t suid; /* saved UID of the task */
123 : kgid_t sgid; /* saved GID of the task */
124 : kuid_t euid; /* effective UID of the task */
125 : kgid_t egid; /* effective GID of the task */
126 : kuid_t fsuid; /* UID for VFS ops */
127 : kgid_t fsgid; /* GID for VFS ops */
128 : unsigned securebits; /* SUID-less security management */
129 : kernel_cap_t cap_inheritable; /* caps our children can inherit */
130 : kernel_cap_t cap_permitted; /* caps we're permitted */
131 : kernel_cap_t cap_effective; /* caps we can actually use */
132 : kernel_cap_t cap_bset; /* capability bounding set */
133 : kernel_cap_t cap_ambient; /* Ambient capability set */
134 : #ifdef CONFIG_KEYS
135 : unsigned char jit_keyring; /* default keyring to attach requested
136 : * keys to */
137 : struct key *session_keyring; /* keyring inherited over fork */
138 : struct key *process_keyring; /* keyring private to this process */
139 : struct key *thread_keyring; /* keyring private to this thread */
140 : struct key *request_key_auth; /* assumed request_key authority */
141 : #endif
142 : #ifdef CONFIG_SECURITY
143 : void *security; /* subjective LSM security */
144 : #endif
145 : struct user_struct *user; /* real user ID subscription */
146 : struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
147 : struct group_info *group_info; /* supplementary groups for euid/fsgid */
148 : /* RCU deletion */
149 : union {
150 : int non_rcu; /* Can we skip RCU deletion? */
151 : struct rcu_head rcu; /* RCU deletion hook */
152 : };
153 : } __randomize_layout;
154 :
155 : extern void __put_cred(struct cred *);
156 : extern void exit_creds(struct task_struct *);
157 : extern int copy_creds(struct task_struct *, unsigned long);
158 : extern const struct cred *get_task_cred(struct task_struct *);
159 : extern struct cred *cred_alloc_blank(void);
160 : extern struct cred *prepare_creds(void);
161 : extern struct cred *prepare_exec_creds(void);
162 : extern int commit_creds(struct cred *);
163 : extern void abort_creds(struct cred *);
164 : extern const struct cred *override_creds(const struct cred *);
165 : extern void revert_creds(const struct cred *);
166 : extern struct cred *prepare_kernel_cred(struct task_struct *);
167 : extern int change_create_files_as(struct cred *, struct inode *);
168 : extern int set_security_override(struct cred *, u32);
169 : extern int set_security_override_from_ctx(struct cred *, const char *);
170 : extern int set_create_files_as(struct cred *, struct inode *);
171 : extern int cred_fscmp(const struct cred *, const struct cred *);
172 : extern void __init cred_init(void);
173 :
174 : /*
175 : * check for validity of credentials
176 : */
177 : #ifdef CONFIG_DEBUG_CREDENTIALS
178 : extern void __invalid_creds(const struct cred *, const char *, unsigned);
179 : extern void __validate_process_creds(struct task_struct *,
180 : const char *, unsigned);
181 :
182 : extern bool creds_are_invalid(const struct cred *cred);
183 :
184 : static inline void __validate_creds(const struct cred *cred,
185 : const char *file, unsigned line)
186 : {
187 : if (unlikely(creds_are_invalid(cred)))
188 : __invalid_creds(cred, file, line);
189 : }
190 :
191 : #define validate_creds(cred) \
192 : do { \
193 : __validate_creds((cred), __FILE__, __LINE__); \
194 : } while(0)
195 :
196 : #define validate_process_creds() \
197 : do { \
198 : __validate_process_creds(current, __FILE__, __LINE__); \
199 : } while(0)
200 :
201 : extern void validate_creds_for_do_exit(struct task_struct *);
202 : #else
203 147535 : static inline void validate_creds(const struct cred *cred)
204 : {
205 131844 : }
206 0 : static inline void validate_creds_for_do_exit(struct task_struct *tsk)
207 : {
208 0 : }
209 6183 : static inline void validate_process_creds(void)
210 : {
211 6183 : }
212 : #endif
213 :
214 4578 : static inline bool cap_ambient_invariant_ok(const struct cred *cred)
215 : {
216 4578 : return cap_issubset(cred->cap_ambient,
217 : cap_intersect(cred->cap_permitted,
218 : cred->cap_inheritable));
219 : }
220 :
221 : /**
222 : * get_new_cred - Get a reference on a new set of credentials
223 : * @cred: The new credentials to reference
224 : *
225 : * Get a reference on the specified set of new credentials. The caller must
226 : * release the reference.
227 : */
228 67756 : static inline struct cred *get_new_cred(struct cred *cred)
229 : {
230 67756 : atomic_inc(&cred->usage);
231 67756 : return cred;
232 : }
233 :
234 : /**
235 : * get_cred - Get a reference on a set of credentials
236 : * @cred: The credentials to reference
237 : *
238 : * Get a reference on the specified set of credentials. The caller must
239 : * release the reference. If %NULL is passed, it is returned with no action.
240 : *
241 : * This is used to deal with a committed set of credentials. Although the
242 : * pointer is const, this will temporarily discard the const and increment the
243 : * usage count. The purpose of this is to attempt to catch at compile time the
244 : * accidental alteration of a set of credentials that should be considered
245 : * immutable.
246 : */
247 64564 : static inline const struct cred *get_cred(const struct cred *cred)
248 : {
249 64564 : struct cred *nonconst_cred = (struct cred *) cred;
250 63606 : if (!cred)
251 : return cred;
252 64564 : validate_creds(cred);
253 64564 : nonconst_cred->non_rcu = 0;
254 64564 : return get_new_cred(nonconst_cred);
255 : }
256 :
257 152 : static inline const struct cred *get_cred_rcu(const struct cred *cred)
258 : {
259 152 : struct cred *nonconst_cred = (struct cred *) cred;
260 152 : if (!cred)
261 : return NULL;
262 304 : if (!atomic_inc_not_zero(&nonconst_cred->usage))
263 : return NULL;
264 152 : validate_creds(cred);
265 152 : nonconst_cred->non_rcu = 0;
266 152 : return cred;
267 : }
268 :
269 : /**
270 : * put_cred - Release a reference to a set of credentials
271 : * @cred: The credentials to release
272 : *
273 : * Release a reference to a set of credentials, deleting them when the last ref
274 : * is released. If %NULL is passed, nothing is done.
275 : *
276 : * This takes a const pointer to a set of credentials because the credentials
277 : * on task_struct are attached by const pointers to prevent accidental
278 : * alteration of otherwise immutable credential sets.
279 : */
280 73699 : static inline void put_cred(const struct cred *_cred)
281 : {
282 73699 : struct cred *cred = (struct cred *) _cred;
283 :
284 73699 : if (cred) {
285 73699 : validate_creds(cred);
286 147407 : if (atomic_dec_and_test(&(cred)->usage))
287 6708 : __put_cred(cred);
288 : }
289 73707 : }
290 :
291 : /**
292 : * current_cred - Access the current task's subjective credentials
293 : *
294 : * Access the subjective credentials of the current task. RCU-safe,
295 : * since nobody else can modify it.
296 : */
297 : #define current_cred() \
298 : rcu_dereference_protected(current->cred, 1)
299 :
300 : /**
301 : * current_real_cred - Access the current task's objective credentials
302 : *
303 : * Access the objective credentials of the current task. RCU-safe,
304 : * since nobody else can modify it.
305 : */
306 : #define current_real_cred() \
307 : rcu_dereference_protected(current->real_cred, 1)
308 :
309 : /**
310 : * __task_cred - Access a task's objective credentials
311 : * @task: The task to query
312 : *
313 : * Access the objective credentials of a task. The caller must hold the RCU
314 : * readlock.
315 : *
316 : * The result of this function should not be passed directly to get_cred();
317 : * rather get_task_cred() should be used instead.
318 : */
319 : #define __task_cred(task) \
320 : rcu_dereference((task)->real_cred)
321 :
322 : /**
323 : * get_current_cred - Get the current task's subjective credentials
324 : *
325 : * Get the subjective credentials of the current task, pinning them so that
326 : * they can't go away. Accessing the current task's credentials directly is
327 : * not permitted.
328 : */
329 : #define get_current_cred() \
330 : (get_cred(current_cred()))
331 :
332 : /**
333 : * get_current_user - Get the current task's user_struct
334 : *
335 : * Get the user record of the current task, pinning it so that it can't go
336 : * away.
337 : */
338 : #define get_current_user() \
339 : ({ \
340 : struct user_struct *__u; \
341 : const struct cred *__cred; \
342 : __cred = current_cred(); \
343 : __u = get_uid(__cred->user); \
344 : __u; \
345 : })
346 :
347 : /**
348 : * get_current_groups - Get the current task's supplementary group list
349 : *
350 : * Get the supplementary group list of the current task, pinning it so that it
351 : * can't go away.
352 : */
353 : #define get_current_groups() \
354 : ({ \
355 : struct group_info *__groups; \
356 : const struct cred *__cred; \
357 : __cred = current_cred(); \
358 : __groups = get_group_info(__cred->group_info); \
359 : __groups; \
360 : })
361 :
362 : #define task_cred_xxx(task, xxx) \
363 : ({ \
364 : __typeof__(((struct cred *)NULL)->xxx) ___val; \
365 : rcu_read_lock(); \
366 : ___val = __task_cred((task))->xxx; \
367 : rcu_read_unlock(); \
368 : ___val; \
369 : })
370 :
371 : #define task_uid(task) (task_cred_xxx((task), uid))
372 : #define task_euid(task) (task_cred_xxx((task), euid))
373 :
374 : #define current_cred_xxx(xxx) \
375 : ({ \
376 : current_cred()->xxx; \
377 : })
378 :
379 : #define current_uid() (current_cred_xxx(uid))
380 : #define current_gid() (current_cred_xxx(gid))
381 : #define current_euid() (current_cred_xxx(euid))
382 : #define current_egid() (current_cred_xxx(egid))
383 : #define current_suid() (current_cred_xxx(suid))
384 : #define current_sgid() (current_cred_xxx(sgid))
385 : #define current_fsuid() (current_cred_xxx(fsuid))
386 : #define current_fsgid() (current_cred_xxx(fsgid))
387 : #define current_cap() (current_cred_xxx(cap_effective))
388 : #define current_user() (current_cred_xxx(user))
389 :
390 : extern struct user_namespace init_user_ns;
391 : #ifdef CONFIG_USER_NS
392 : #define current_user_ns() (current_cred_xxx(user_ns))
393 : #else
394 98969 : static inline struct user_namespace *current_user_ns(void)
395 : {
396 52493 : return &init_user_ns;
397 : }
398 : #endif
399 :
400 :
401 : #define current_uid_gid(_uid, _gid) \
402 : do { \
403 : const struct cred *__cred; \
404 : __cred = current_cred(); \
405 : *(_uid) = __cred->uid; \
406 : *(_gid) = __cred->gid; \
407 : } while(0)
408 :
409 : #define current_euid_egid(_euid, _egid) \
410 : do { \
411 : const struct cred *__cred; \
412 : __cred = current_cred(); \
413 : *(_euid) = __cred->euid; \
414 : *(_egid) = __cred->egid; \
415 : } while(0)
416 :
417 : #define current_fsuid_fsgid(_fsuid, _fsgid) \
418 : do { \
419 : const struct cred *__cred; \
420 : __cred = current_cred(); \
421 : *(_fsuid) = __cred->fsuid; \
422 : *(_fsgid) = __cred->fsgid; \
423 : } while(0)
424 :
425 : #endif /* _LINUX_CRED_H */
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