-/* Credentials management
+/* Credentials management - see Documentation/credentials.txt
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
struct user_struct;
struct cred;
+struct inode;
/*
* COW Supplementary groups list
* get_group_info - Get a reference to a group info structure
* @group_info: The group info to reference
*
- * This must be called with the owning task locked (via task_lock()) when task
- * != current. The reason being that the vast majority of callers are looking
- * at current->group_info, which can not be changed except by the current task.
- * Changing current->group_info requires the task lock, too.
+ * 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.
*/
-#define get_group_info(group_info) \
-do { \
- atomic_inc(&(group_info)->usage); \
-} while (0)
+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
} 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(struct group_info *, gid_t);
+extern int groups_search(const struct group_info *, gid_t);
/* access the groups "array" with this macro */
#define GROUP_AT(gi, i) \
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:
* 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 */
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 */
- spinlock_t lock; /* lock for pointer changes */
};
-#define get_current_user() (get_uid(current->cred->user))
-
-#define task_uid(task) ((task)->cred->uid)
-#define task_gid(task) ((task)->cred->gid)
-#define task_euid(task) ((task)->cred->euid)
-#define task_egid(task) ((task)->cred->egid)
-
-#define current_uid() (current->cred->uid)
-#define current_gid() (current->cred->gid)
-#define current_euid() (current->cred->euid)
-#define current_egid() (current->cred->egid)
-#define current_suid() (current->cred->suid)
-#define current_sgid() (current->cred->sgid)
-#define current_fsuid() (current->cred->fsuid)
-#define current_fsgid() (current->cred->fsgid)
-#define current_cap() (current->cred->cap_effective)
-
-#define current_uid_gid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->uid; \
- *(_gid) = current->cred->gid; \
-} while(0)
-
-#define current_euid_egid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->euid; \
- *(_gid) = current->cred->egid; \
-} while(0)
-
-#define current_fsuid_fsgid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->fsuid; \
- *(_gid) = current->cred->fsgid; \
-} while(0)
-
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
*
* 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 struct cred *get_cred(struct cred *cred)
+static inline const struct cred *get_cred(const struct cred *cred)
{
- atomic_inc(&cred->usage);
- return cred;
+ return get_new_cred((struct cred *) cred);
}
/**
*
* 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(struct cred *cred)
+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 { \
+ 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 */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff