diff options
Diffstat (limited to 'include/linux/cred.h')
| -rw-r--r-- | include/linux/cred.h | 342 |
1 files changed, 319 insertions, 23 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h index b69222cc1fd..3282ee4318e 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -1,4 +1,4 @@ -/* Credentials management +/* Credentials management - see Documentation/credentials.txt * * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -12,39 +12,335 @@ #ifndef _LINUX_CRED_H #define _LINUX_CRED_H -#define get_current_user() (get_uid(current->user)) +#include <linux/capability.h> +#include <linux/key.h> +#include <asm/atomic.h> -#define task_uid(task) ((task)->uid) -#define task_gid(task) ((task)->gid) -#define task_euid(task) ((task)->euid) -#define task_egid(task) ((task)->egid) +struct user_struct; +struct cred; +struct inode; -#define current_uid() (current->uid) -#define current_gid() (current->gid) -#define current_euid() (current->euid) -#define current_egid() (current->egid) -#define current_suid() (current->suid) -#define current_sgid() (current->sgid) -#define current_fsuid() (current->fsuid) -#define current_fsgid() (current->fsgid) -#define current_cap() (current->cap_effective) +/* + * COW Supplementary groups list + */ +#define NGROUPS_SMALL 32 +#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(gid_t))) + +struct group_info { + atomic_t usage; + int ngroups; + int nblocks; + gid_t small_block[NGROUPS_SMALL]; + gid_t *blocks[0]; +}; + +/** + * get_group_info - Get a reference to a group info structure + * @group_info: The group info to reference + * + * This gets a reference to a set of supplementary groups. + * + * If the caller is accessing a task's credentials, they must hold the RCU read + * lock when reading. + */ +static inline struct group_info *get_group_info(struct group_info *gi) +{ + atomic_inc(&gi->usage); + return gi; +} + +/** + * put_group_info - Release a reference to a group info structure + * @group_info: The group info to release + */ +#define put_group_info(group_info) \ +do { \ + if (atomic_dec_and_test(&(group_info)->usage)) \ + groups_free(group_info); \ +} while (0) + +extern struct group_info *groups_alloc(int); +extern struct group_info init_groups; +extern void groups_free(struct group_info *); +extern int set_current_groups(struct group_info *); +extern int set_groups(struct cred *, struct group_info *); +extern int groups_search(const struct group_info *, gid_t); + +/* access the groups "array" with this macro */ +#define GROUP_AT(gi, i) \ + ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK]) + +extern int in_group_p(gid_t); +extern int in_egroup_p(gid_t); + +/* + * The common credentials for a thread group + * - shared by CLONE_THREAD + */ +#ifdef CONFIG_KEYS +struct thread_group_cred { + atomic_t usage; + pid_t tgid; /* thread group process ID */ + spinlock_t lock; + struct key *session_keyring; /* keyring inherited over fork */ + struct key *process_keyring; /* keyring private to this process */ + struct rcu_head rcu; /* RCU deletion hook */ +}; +#endif + +/* + * The security context of a task + * + * The parts of the context break down into two categories: + * + * (1) The objective context of a task. These parts are used when some other + * task is attempting to affect this one. + * + * (2) The subjective context. These details are used when the task is acting + * upon another object, be that a file, a task, a key or whatever. + * + * Note that some members of this structure belong to both categories - the + * LSM security pointer for instance. + * + * A task has two security pointers. task->real_cred points to the objective + * context that defines that task's actual details. The objective part of this + * context is used whenever that task is acted upon. + * + * task->cred points to the subjective context that defines the details of how + * that task is going to act upon another object. This may be overridden + * temporarily to point to another security context, but normally points to the + * same context as task->real_cred. + */ +struct cred { + atomic_t usage; + uid_t uid; /* real UID of the task */ + gid_t gid; /* real GID of the task */ + uid_t suid; /* saved UID of the task */ + gid_t sgid; /* saved GID of the task */ + uid_t euid; /* effective UID of the task */ + gid_t egid; /* effective GID of the task */ + uid_t fsuid; /* UID for VFS ops */ + gid_t fsgid; /* GID for VFS ops */ + unsigned securebits; /* SUID-less security management */ + kernel_cap_t cap_inheritable; /* caps our children can inherit */ + kernel_cap_t cap_permitted; /* caps we're permitted */ + kernel_cap_t cap_effective; /* caps we can actually use */ + kernel_cap_t cap_bset; /* capability bounding set */ +#ifdef CONFIG_KEYS + unsigned char jit_keyring; /* default keyring to attach requested + * keys to */ + struct key *thread_keyring; /* keyring private to this thread */ + struct key *request_key_auth; /* assumed request_key authority */ + struct thread_group_cred *tgcred; /* thread-group shared credentials */ +#endif +#ifdef CONFIG_SECURITY + void *security; /* subjective LSM security */ +#endif + struct user_struct *user; /* real user ID subscription */ + struct group_info *group_info; /* supplementary groups for euid/fsgid */ + struct rcu_head rcu; /* RCU deletion hook */ +}; + +extern void __put_cred(struct cred *); +extern int copy_creds(struct task_struct *, unsigned long); +extern struct cred *prepare_creds(void); +extern struct cred *prepare_exec_creds(void); +extern struct cred *prepare_usermodehelper_creds(void); +extern int commit_creds(struct cred *); +extern void abort_creds(struct cred *); +extern const struct cred *override_creds(const struct cred *); +extern void revert_creds(const struct cred *); +extern struct cred *prepare_kernel_cred(struct task_struct *); +extern int change_create_files_as(struct cred *, struct inode *); +extern int set_security_override(struct cred *, u32); +extern int set_security_override_from_ctx(struct cred *, const char *); +extern int set_create_files_as(struct cred *, struct inode *); +extern void __init cred_init(void); + +/** + * get_new_cred - Get a reference on a new set of credentials + * @cred: The new credentials to reference + * + * Get a reference on the specified set of new credentials. The caller must + * release the reference. + */ +static inline struct cred *get_new_cred(struct cred *cred) +{ + atomic_inc(&cred->usage); + return cred; +} + +/** + * get_cred - Get a reference on a set of credentials + * @cred: The credentials to reference + * + * Get a reference on the specified set of credentials. The caller must + * release the reference. + * + * This is used to deal with a committed set of credentials. Although the + * pointer is const, this will temporarily discard the const and increment the + * usage count. The purpose of this is to attempt to catch at compile time the + * accidental alteration of a set of credentials that should be considered + * immutable. + */ +static inline const struct cred *get_cred(const struct cred *cred) +{ + return get_new_cred((struct cred *) cred); +} + +/** + * put_cred - Release a reference to a set of credentials + * @cred: The credentials to release + * + * Release a reference to a set of credentials, deleting them when the last ref + * is released. + * + * This takes a const pointer to a set of credentials because the credentials + * on task_struct are attached by const pointers to prevent accidental + * alteration of otherwise immutable credential sets. + */ +static inline void put_cred(const struct cred *_cred) +{ + struct cred *cred = (struct cred *) _cred; + + BUG_ON(atomic_read(&(cred)->usage) <= 0); + if (atomic_dec_and_test(&(cred)->usage)) + __put_cred(cred); +} + +/** + * current_cred - Access the current task's subjective credentials + * + * Access the subjective credentials of the current task. + */ +#define current_cred() \ + (current->cred) + +/** + * __task_cred - Access a task's objective credentials + * @task: The task to query + * + * Access the objective credentials of a task. The caller must hold the RCU + * readlock. + * + * The caller must make sure task doesn't go away, either by holding a ref on + * task or by holding tasklist_lock to prevent it from being unlinked. + */ +#define __task_cred(task) \ + ((const struct cred *)(rcu_dereference((task)->real_cred))) + +/** + * get_task_cred - Get another task's objective credentials + * @task: The task to query + * + * Get the objective credentials of a task, pinning them so that they can't go + * away. Accessing a task's credentials directly is not permitted. + * + * The caller must make sure task doesn't go away, either by holding a ref on + * task or by holding tasklist_lock to prevent it from being unlinked. + */ +#define get_task_cred(task) \ +({ \ + struct cred *__cred; \ + rcu_read_lock(); \ + __cred = (struct cred *) __task_cred((task)); \ + get_cred(__cred); \ + rcu_read_unlock(); \ + __cred; \ +}) + +/** + * get_current_cred - Get the current task's subjective credentials + * + * Get the subjective credentials of the current task, pinning them so that + * they can't go away. Accessing the current task's credentials directly is + * not permitted. + */ +#define get_current_cred() \ + (get_cred(current_cred())) + +/** + * get_current_user - Get the current task's user_struct + * + * Get the user record of the current task, pinning it so that it can't go + * away. + */ +#define get_current_user() \ +({ \ + struct user_struct *__u; \ + struct cred *__cred; \ + __cred = (struct cred *) current_cred(); \ + __u = get_uid(__cred->user); \ + __u; \ +}) + +/** + * get_current_groups - Get the current task's supplementary group list + * + * Get the supplementary group list of the current task, pinning it so that it + * can't go away. + */ +#define get_current_groups() \ +({ \ + struct group_info *__groups; \ + struct cred *__cred; \ + __cred = (struct cred *) current_cred(); \ + __groups = get_group_info(__cred->group_info); \ + __groups; \ +}) + +#define task_cred_xxx(task, xxx) \ +({ \ + __typeof__(((struct cred *)NULL)->xxx) ___val; \ + rcu_read_lock(); \ + ___val = __task_cred((task))->xxx; \ + rcu_read_unlock(); \ + ___val; \ +}) + +#define task_uid(task) (task_cred_xxx((task), uid)) +#define task_euid(task) (task_cred_xxx((task), euid)) + +#define current_cred_xxx(xxx) \ +({ \ + current->cred->xxx; \ +}) + +#define current_uid() (current_cred_xxx(uid)) +#define current_gid() (current_cred_xxx(gid)) +#define current_euid() (current_cred_xxx(euid)) +#define current_egid() (current_cred_xxx(egid)) +#define current_suid() (current_cred_xxx(suid)) +#define current_sgid() (current_cred_xxx(sgid)) +#define current_fsuid() (current_cred_xxx(fsuid)) +#define current_fsgid() (current_cred_xxx(fsgid)) +#define current_cap() (current_cred_xxx(cap_effective)) +#define current_user() (current_cred_xxx(user)) +#define current_user_ns() (current_cred_xxx(user)->user_ns) +#define current_security() (current_cred_xxx(security)) #define current_uid_gid(_uid, _gid) \ do { \ - *(_uid) = current->uid; \ - *(_gid) = current->gid; \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_uid) = __cred->uid; \ + *(_gid) = __cred->gid; \ } while(0) -#define current_euid_egid(_uid, _gid) \ +#define current_euid_egid(_euid, _egid) \ do { \ - *(_uid) = current->euid; \ - *(_gid) = current->egid; \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_euid) = __cred->euid; \ + *(_egid) = __cred->egid; \ } while(0) -#define current_fsuid_fsgid(_uid, _gid) \ +#define current_fsuid_fsgid(_fsuid, _fsgid) \ do { \ - *(_uid) = current->fsuid; \ - *(_gid) = current->fsgid; \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_fsuid) = __cred->fsuid; \ + *(_fsgid) = __cred->fsgid; \ } while(0) #endif /* _LINUX_CRED_H */ |