LCOV - code coverage report
Current view: top level - lkbce/include/linux - cred.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 6 6 100.0 %
Date: 2017-01-25 Functions: 0 0 -

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

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