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Diffstat (limited to 'include/linux/cred.h')
| -rw-r--r-- | include/linux/cred.h | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h new file mode 100644 index 000000000..09c1ed924 --- /dev/null +++ b/include/linux/cred.h @@ -0,0 +1,428 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Credentials management - see Documentation/security/credentials.rst + * + * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#ifndef _LINUX_CRED_H +#define _LINUX_CRED_H + +#include <linux/capability.h> +#include <linux/init.h> +#include <linux/key.h> +#include <linux/atomic.h> +#include <linux/uidgid.h> +#include <linux/sched.h> +#include <linux/sched/user.h> + +struct cred; +struct inode; + +/* + * COW Supplementary groups list + */ +struct group_info { + atomic_t usage; + int ngroups; + kgid_t gid[]; +} __randomize_layout; + +/** + * 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) + +#ifdef CONFIG_MULTIUSER +extern struct group_info *groups_alloc(int); +extern void groups_free(struct group_info *); + +extern int in_group_p(kgid_t); +extern int in_egroup_p(kgid_t); +extern int groups_search(const struct group_info *, kgid_t); + +extern int set_current_groups(struct group_info *); +extern void set_groups(struct cred *, struct group_info *); +extern bool may_setgroups(void); +extern void groups_sort(struct group_info *); +#else +static inline void groups_free(struct group_info *group_info) +{ +} + +static inline int in_group_p(kgid_t grp) +{ + return 1; +} +static inline int in_egroup_p(kgid_t grp) +{ + return 1; +} +static inline int groups_search(const struct group_info *group_info, kgid_t grp) +{ + return 1; +} +#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_long_t usage; +#ifdef CONFIG_DEBUG_CREDENTIALS + atomic_t subscribers; /* number of processes subscribed */ + void *put_addr; + unsigned magic; +#define CRED_MAGIC 0x43736564 +#define CRED_MAGIC_DEAD 0x44656144 +#endif + kuid_t uid; /* real UID of the task */ + kgid_t gid; /* real GID of the task */ + kuid_t suid; /* saved UID of the task */ + kgid_t sgid; /* saved GID of the task */ + kuid_t euid; /* effective UID of the task */ + kgid_t egid; /* effective GID of the task */ + kuid_t fsuid; /* UID for VFS ops */ + kgid_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 */ + kernel_cap_t cap_ambient; /* Ambient capability set */ +#ifdef CONFIG_KEYS + unsigned char jit_keyring; /* default keyring to attach requested + * keys to */ + struct key *session_keyring; /* keyring inherited over fork */ + struct key *process_keyring; /* keyring private to this process */ + struct key *thread_keyring; /* keyring private to this thread */ + struct key *request_key_auth; /* assumed request_key authority */ +#endif +#ifdef CONFIG_SECURITY + void *security; /* LSM security */ +#endif + struct user_struct *user; /* real user ID subscription */ + struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */ + struct ucounts *ucounts; + struct group_info *group_info; /* supplementary groups for euid/fsgid */ + /* RCU deletion */ + union { + int non_rcu; /* Can we skip RCU deletion? */ + struct rcu_head rcu; /* RCU deletion hook */ + }; +} __randomize_layout; + +extern void __put_cred(struct cred *); +extern void exit_creds(struct task_struct *); +extern int copy_creds(struct task_struct *, unsigned long); +extern const struct cred *get_task_cred(struct task_struct *); +extern struct cred *cred_alloc_blank(void); +extern struct cred *prepare_creds(void); +extern struct cred *prepare_exec_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 int cred_fscmp(const struct cred *, const struct cred *); +extern void __init cred_init(void); +extern int set_cred_ucounts(struct cred *); + +/* + * check for validity of credentials + */ +#ifdef CONFIG_DEBUG_CREDENTIALS +extern void __noreturn __invalid_creds(const struct cred *, const char *, unsigned); +extern void __validate_process_creds(struct task_struct *, + const char *, unsigned); + +extern bool creds_are_invalid(const struct cred *cred); + +static inline void __validate_creds(const struct cred *cred, + const char *file, unsigned line) +{ + if (unlikely(creds_are_invalid(cred))) + __invalid_creds(cred, file, line); +} + +#define validate_creds(cred) \ +do { \ + __validate_creds((cred), __FILE__, __LINE__); \ +} while(0) + +#define validate_process_creds() \ +do { \ + __validate_process_creds(current, __FILE__, __LINE__); \ +} while(0) + +extern void validate_creds_for_do_exit(struct task_struct *); +#else +static inline void validate_creds(const struct cred *cred) +{ +} +static inline void validate_creds_for_do_exit(struct task_struct *tsk) +{ +} +static inline void validate_process_creds(void) +{ +} +#endif + +static inline bool cap_ambient_invariant_ok(const struct cred *cred) +{ + return cap_issubset(cred->cap_ambient, + cap_intersect(cred->cap_permitted, + cred->cap_inheritable)); +} + +/** + * 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_long_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. If %NULL is passed, it is returned with no action. + * + * 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) +{ + struct cred *nonconst_cred = (struct cred *) cred; + if (!cred) + return cred; + validate_creds(cred); + nonconst_cred->non_rcu = 0; + return get_new_cred(nonconst_cred); +} + +static inline const struct cred *get_cred_rcu(const struct cred *cred) +{ + struct cred *nonconst_cred = (struct cred *) cred; + if (!cred) + return NULL; + if (!atomic_long_inc_not_zero(&nonconst_cred->usage)) + return NULL; + validate_creds(cred); + nonconst_cred->non_rcu = 0; + return 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. If %NULL is passed, nothing is done. + * + * 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; + + if (cred) { + validate_creds(cred); + if (atomic_long_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. RCU-safe, + * since nobody else can modify it. + */ +#define current_cred() \ + rcu_dereference_protected(current->cred, 1) + +/** + * current_real_cred - Access the current task's objective credentials + * + * Access the objective credentials of the current task. RCU-safe, + * since nobody else can modify it. + */ +#define current_real_cred() \ + rcu_dereference_protected(current->real_cred, 1) + +/** + * __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 result of this function should not be passed directly to get_cred(); + * rather get_task_cred() should be used instead. + */ +#define __task_cred(task) \ + rcu_dereference((task)->real_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; \ + const struct cred *__cred; \ + __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; \ + const struct cred *__cred; \ + __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 task_ucounts(task) (task_cred_xxx((task), ucounts)) + +#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_ucounts() (current_cred_xxx(ucounts)) + +extern struct user_namespace init_user_ns; +#ifdef CONFIG_USER_NS +#define current_user_ns() (current_cred_xxx(user_ns)) +#else +static inline struct user_namespace *current_user_ns(void) +{ + return &init_user_ns; +} +#endif + + +#define current_uid_gid(_uid, _gid) \ +do { \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_uid) = __cred->uid; \ + *(_gid) = __cred->gid; \ +} while(0) + +#define current_euid_egid(_euid, _egid) \ +do { \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_euid) = __cred->euid; \ + *(_egid) = __cred->egid; \ +} while(0) + +#define current_fsuid_fsgid(_fsuid, _fsgid) \ +do { \ + const struct cred *__cred; \ + __cred = current_cred(); \ + *(_fsuid) = __cred->fsuid; \ + *(_fsgid) = __cred->fsgid; \ +} while(0) + +#endif /* _LINUX_CRED_H */ |