415 lines
12 KiB
C
415 lines
12 KiB
C
/* Credentials management - see Documentation/security/credentials.rst
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _LINUX_CRED_H
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#define _LINUX_CRED_H
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/key.h>
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#include <linux/selinux.h>
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#include <linux/atomic.h>
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#include <linux/uidgid.h>
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#include <linux/sched.h>
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#include <linux/sched/user.h>
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struct cred;
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struct inode;
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/*
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* COW Supplementary groups list
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*/
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struct group_info {
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atomic_t usage;
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int ngroups;
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kgid_t gid[0];
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} __randomize_layout;
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/**
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* get_group_info - Get a reference to a group info structure
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* @group_info: The group info to reference
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*
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* This gets a reference to a set of supplementary groups.
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*
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* If the caller is accessing a task's credentials, they must hold the RCU read
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* lock when reading.
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*/
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static inline struct group_info *get_group_info(struct group_info *gi)
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{
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atomic_inc(&gi->usage);
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return gi;
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}
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/**
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* put_group_info - Release a reference to a group info structure
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* @group_info: The group info to release
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*/
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#define put_group_info(group_info) \
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do { \
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if (atomic_dec_and_test(&(group_info)->usage)) \
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groups_free(group_info); \
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} while (0)
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extern struct group_info init_groups;
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#ifdef CONFIG_MULTIUSER
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extern struct group_info *groups_alloc(int);
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extern void groups_free(struct group_info *);
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extern int in_group_p(kgid_t);
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extern int in_egroup_p(kgid_t);
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extern int groups_search(const struct group_info *, kgid_t);
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extern int set_current_groups(struct group_info *);
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extern void set_groups(struct cred *, struct group_info *);
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extern bool may_setgroups(void);
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extern void groups_sort(struct group_info *);
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#else
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static inline void groups_free(struct group_info *group_info)
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{
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}
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static inline int in_group_p(kgid_t grp)
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{
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return 1;
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}
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static inline int in_egroup_p(kgid_t grp)
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{
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return 1;
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}
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static inline int groups_search(const struct group_info *group_info, kgid_t grp)
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{
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return 1;
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}
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#endif
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/*
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* The security context of a task
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*
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* The parts of the context break down into two categories:
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*
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* (1) The objective context of a task. These parts are used when some other
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* task is attempting to affect this one.
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*
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* (2) The subjective context. These details are used when the task is acting
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* upon another object, be that a file, a task, a key or whatever.
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*
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* Note that some members of this structure belong to both categories - the
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* LSM security pointer for instance.
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*
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* A task has two security pointers. task->real_cred points to the objective
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* context that defines that task's actual details. The objective part of this
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* context is used whenever that task is acted upon.
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*
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* task->cred points to the subjective context that defines the details of how
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* that task is going to act upon another object. This may be overridden
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* temporarily to point to another security context, but normally points to the
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* same context as task->real_cred.
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*/
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struct cred {
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atomic_t usage;
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#ifdef CONFIG_DEBUG_CREDENTIALS
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atomic_t subscribers; /* number of processes subscribed */
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void *put_addr;
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unsigned magic;
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#define CRED_MAGIC 0x43736564
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#define CRED_MAGIC_DEAD 0x44656144
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#endif
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kuid_t uid; /* real UID of the task */
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kgid_t gid; /* real GID of the task */
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kuid_t suid; /* saved UID of the task */
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kgid_t sgid; /* saved GID of the task */
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kuid_t euid; /* effective UID of the task */
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kgid_t egid; /* effective GID of the task */
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kuid_t fsuid; /* UID for VFS ops */
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kgid_t fsgid; /* GID for VFS ops */
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unsigned securebits; /* SUID-less security management */
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kernel_cap_t cap_inheritable; /* caps our children can inherit */
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kernel_cap_t cap_permitted; /* caps we're permitted */
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kernel_cap_t cap_effective; /* caps we can actually use */
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kernel_cap_t cap_bset; /* capability bounding set */
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kernel_cap_t cap_ambient; /* Ambient capability set */
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#ifdef CONFIG_KEYS
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unsigned char jit_keyring; /* default keyring to attach requested
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* keys to */
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struct key __rcu *session_keyring; /* keyring inherited over fork */
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struct key *process_keyring; /* keyring private to this process */
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struct key *thread_keyring; /* keyring private to this thread */
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struct key *request_key_auth; /* assumed request_key authority */
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#endif
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#ifdef CONFIG_SECURITY
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void *security; /* subjective LSM security */
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#endif
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struct user_struct *user; /* real user ID subscription */
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struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
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struct group_info *group_info; /* supplementary groups for euid/fsgid */
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/* RCU deletion */
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union {
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int non_rcu; /* Can we skip RCU deletion? */
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struct rcu_head rcu; /* RCU deletion hook */
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};
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} __randomize_layout;
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extern void __put_cred(struct cred *);
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extern void exit_creds(struct task_struct *);
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extern int copy_creds(struct task_struct *, unsigned long);
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extern const struct cred *get_task_cred(struct task_struct *);
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extern struct cred *cred_alloc_blank(void);
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extern struct cred *prepare_creds(void);
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extern struct cred *prepare_exec_creds(void);
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extern int commit_creds(struct cred *);
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extern void abort_creds(struct cred *);
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extern const struct cred *override_creds(const struct cred *);
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extern void revert_creds(const struct cred *);
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extern struct cred *prepare_kernel_cred(struct task_struct *);
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extern int change_create_files_as(struct cred *, struct inode *);
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extern int set_security_override(struct cred *, u32);
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extern int set_security_override_from_ctx(struct cred *, const char *);
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extern int set_create_files_as(struct cred *, struct inode *);
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extern void __init cred_init(void);
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/*
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* check for validity of credentials
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*/
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#ifdef CONFIG_DEBUG_CREDENTIALS
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extern void __invalid_creds(const struct cred *, const char *, unsigned);
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extern void __validate_process_creds(struct task_struct *,
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const char *, unsigned);
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extern bool creds_are_invalid(const struct cred *cred);
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static inline void __validate_creds(const struct cred *cred,
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const char *file, unsigned line)
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{
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if (unlikely(creds_are_invalid(cred)))
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__invalid_creds(cred, file, line);
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}
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#define validate_creds(cred) \
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do { \
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__validate_creds((cred), __FILE__, __LINE__); \
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} while(0)
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#define validate_process_creds() \
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do { \
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__validate_process_creds(current, __FILE__, __LINE__); \
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} while(0)
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extern void validate_creds_for_do_exit(struct task_struct *);
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#else
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static inline void validate_creds(const struct cred *cred)
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{
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}
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static inline void validate_creds_for_do_exit(struct task_struct *tsk)
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{
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}
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static inline void validate_process_creds(void)
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{
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}
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#endif
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static inline bool cap_ambient_invariant_ok(const struct cred *cred)
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{
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return cap_issubset(cred->cap_ambient,
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cap_intersect(cred->cap_permitted,
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cred->cap_inheritable));
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}
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/**
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* get_new_cred - Get a reference on a new set of credentials
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* @cred: The new credentials to reference
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*
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* Get a reference on the specified set of new credentials. The caller must
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* release the reference.
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*/
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static inline struct cred *get_new_cred(struct cred *cred)
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{
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atomic_inc(&cred->usage);
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return cred;
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}
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/**
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* get_cred - Get a reference on a set of credentials
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* @cred: The credentials to reference
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*
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* Get a reference on the specified set of credentials. The caller must
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* release the reference.
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*
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* This is used to deal with a committed set of credentials. Although the
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* pointer is const, this will temporarily discard the const and increment the
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* usage count. The purpose of this is to attempt to catch at compile time the
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* accidental alteration of a set of credentials that should be considered
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* immutable.
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*/
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static inline const struct cred *get_cred(const struct cred *cred)
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{
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struct cred *nonconst_cred = (struct cred *) cred;
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validate_creds(cred);
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nonconst_cred->non_rcu = 0;
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return get_new_cred(nonconst_cred);
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}
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/**
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* put_cred - Release a reference to a set of credentials
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* @cred: The credentials to release
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*
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* Release a reference to a set of credentials, deleting them when the last ref
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* is released.
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*
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* This takes a const pointer to a set of credentials because the credentials
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* on task_struct are attached by const pointers to prevent accidental
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* alteration of otherwise immutable credential sets.
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*/
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static inline void put_cred(const struct cred *_cred)
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{
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struct cred *cred = (struct cred *) _cred;
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validate_creds(cred);
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if (atomic_dec_and_test(&(cred)->usage))
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__put_cred(cred);
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}
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/**
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* current_cred - Access the current task's subjective credentials
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*
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* Access the subjective credentials of the current task. RCU-safe,
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* since nobody else can modify it.
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*/
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#define current_cred() \
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rcu_dereference_protected(current->cred, 1)
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/**
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* current_real_cred - Access the current task's objective credentials
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*
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* Access the objective credentials of the current task. RCU-safe,
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* since nobody else can modify it.
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*/
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#define current_real_cred() \
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rcu_dereference_protected(current->real_cred, 1)
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/**
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* __task_cred - Access a task's objective credentials
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* @task: The task to query
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*
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* Access the objective credentials of a task. The caller must hold the RCU
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* readlock.
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*
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* The result of this function should not be passed directly to get_cred();
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* rather get_task_cred() should be used instead.
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*/
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#define __task_cred(task) \
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rcu_dereference((task)->real_cred)
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/**
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* get_current_cred - Get the current task's subjective credentials
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*
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* Get the subjective credentials of the current task, pinning them so that
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* they can't go away. Accessing the current task's credentials directly is
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* not permitted.
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*/
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#define get_current_cred() \
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(get_cred(current_cred()))
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/**
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* get_current_user - Get the current task's user_struct
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*
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* Get the user record of the current task, pinning it so that it can't go
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* away.
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*/
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#define get_current_user() \
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({ \
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struct user_struct *__u; \
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const struct cred *__cred; \
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__cred = current_cred(); \
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__u = get_uid(__cred->user); \
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__u; \
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})
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/**
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* get_current_groups - Get the current task's supplementary group list
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*
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* Get the supplementary group list of the current task, pinning it so that it
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* can't go away.
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*/
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#define get_current_groups() \
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({ \
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struct group_info *__groups; \
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const struct cred *__cred; \
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__cred = current_cred(); \
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__groups = get_group_info(__cred->group_info); \
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__groups; \
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})
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#define task_cred_xxx(task, xxx) \
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({ \
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__typeof__(((struct cred *)NULL)->xxx) ___val; \
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rcu_read_lock(); \
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___val = __task_cred((task))->xxx; \
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rcu_read_unlock(); \
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___val; \
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})
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#define task_uid(task) (task_cred_xxx((task), uid))
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#define task_euid(task) (task_cred_xxx((task), euid))
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#define current_cred_xxx(xxx) \
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({ \
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current_cred()->xxx; \
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})
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#define current_uid() (current_cred_xxx(uid))
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#define current_gid() (current_cred_xxx(gid))
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#define current_euid() (current_cred_xxx(euid))
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#define current_egid() (current_cred_xxx(egid))
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#define current_suid() (current_cred_xxx(suid))
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#define current_sgid() (current_cred_xxx(sgid))
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#define current_fsuid() (current_cred_xxx(fsuid))
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#define current_fsgid() (current_cred_xxx(fsgid))
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#define current_cap() (current_cred_xxx(cap_effective))
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#define current_user() (current_cred_xxx(user))
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#define current_security() (current_cred_xxx(security))
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extern struct user_namespace init_user_ns;
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#ifdef CONFIG_USER_NS
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#define current_user_ns() (current_cred_xxx(user_ns))
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#else
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static inline struct user_namespace *current_user_ns(void)
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{
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return &init_user_ns;
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}
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#endif
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#define current_uid_gid(_uid, _gid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_uid) = __cred->uid; \
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*(_gid) = __cred->gid; \
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} while(0)
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#define current_euid_egid(_euid, _egid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_euid) = __cred->euid; \
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*(_egid) = __cred->egid; \
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} while(0)
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#define current_fsuid_fsgid(_fsuid, _fsgid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_fsuid) = __cred->fsuid; \
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*(_fsgid) = __cred->fsgid; \
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} while(0)
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#endif /* _LINUX_CRED_H */
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