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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[0];
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 : : static inline struct group_info *get_group_info(struct group_info *gi)
41 : : {
42 : 1929192 : atomic_inc(&gi->usage);
43 : : 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 : : static inline void validate_creds(const struct cred *cred)
204 : : {
205 : : }
206 : : static inline void validate_creds_for_do_exit(struct task_struct *tsk)
207 : : {
208 : : }
209 : : static inline void validate_process_creds(void)
210 : : {
211 : : }
212 : : #endif
213 : :
214 : 1198681 : static inline bool cap_ambient_invariant_ok(const struct cred *cred)
215 : : {
216 : 1198681 : 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 : : static inline struct cred *get_new_cred(struct cred *cred)
229 : : {
230 : 22909913 : atomic_inc(&cred->usage);
231 : : 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 : 21450314 : static inline const struct cred *get_cred(const struct cred *cred)
248 : : {
249 : : struct cred *nonconst_cred = (struct cred *) cred;
250 [ + + ]: 21450314 : if (!cred)
251 : : return cred;
252 : : validate_creds(cred);
253 : 21451597 : nonconst_cred->non_rcu = 0;
254 : 21450307 : return get_new_cred(nonconst_cred);
255 : : }
256 : :
257 : 101570 : static inline const struct cred *get_cred_rcu(const struct cred *cred)
258 : : {
259 : : struct cred *nonconst_cred = (struct cred *) cred;
260 [ + + ]: 101570 : if (!cred)
261 : : return NULL;
262 [ + - ]: 203136 : if (!atomic_inc_not_zero(&nonconst_cred->usage))
263 : : return NULL;
264 : : validate_creds(cred);
265 : 101569 : nonconst_cred->non_rcu = 0;
266 : 101569 : 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 : 24441638 : static inline void put_cred(const struct cred *_cred)
281 : : {
282 : : struct cred *cred = (struct cred *) _cred;
283 : :
284 [ + + ]: 24441638 : if (cred) {
285 : : validate_creds(cred);
286 [ + + ]: 49024771 : if (atomic_dec_and_test(&(cred)->usage))
287 : 2163551 : __put_cred(cred);
288 : : }
289 : 24448610 : }
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 : : static inline struct user_namespace *current_user_ns(void)
395 : : {
396 : : 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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