-/* Credentials management
+/* Credentials management - see Documentation/credentials.txt
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
#ifndef _LINUX_CRED_H
#define _LINUX_CRED_H
-#define get_current_user() (get_uid(current->user))
+#include <linux/capability.h>
+#include <linux/init.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 */
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