CRED: Inaugurate COW credentials

Inaugurate copy-on-write credentials management.  This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.

A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().

With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:

	struct cred *new = prepare_creds();
	int ret = blah(new);
	if (ret < 0) {
		abort_creds(new);
		return ret;
	}
	return commit_creds(new);

There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.

To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const.  The purpose of this is compile-time
discouragement of altering credentials through those pointers.  Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:

  (1) Its reference count may incremented and decremented.

  (2) The keyrings to which it points may be modified, but not replaced.

The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     This now prepares and commits credentials in various places in the
     security code rather than altering the current creds directly.

 (2) Temporary credential overrides.

     do_coredump() and sys_faccessat() now prepare their own credentials and
     temporarily override the ones currently on the acting thread, whilst
     preventing interference from other threads by holding cred_replace_mutex
     on the thread being dumped.

     This will be replaced in a future patch by something that hands down the
     credentials directly to the functions being called, rather than altering
     the task's objective credentials.

 (3) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_capset_check(), ->capset_check()
     (*) security_capset_set(), ->capset_set()

     	 Removed in favour of security_capset().

     (*) security_capset(), ->capset()

     	 New.  This is passed a pointer to the new creds, a pointer to the old
     	 creds and the proposed capability sets.  It should fill in the new
     	 creds or return an error.  All pointers, barring the pointer to the
     	 new creds, are now const.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()

     	 Changed; now returns a value, which will cause the process to be
     	 killed if it's an error.

     (*) security_task_alloc(), ->task_alloc_security()

     	 Removed in favour of security_prepare_creds().

     (*) security_cred_free(), ->cred_free()

     	 New.  Free security data attached to cred->security.

     (*) security_prepare_creds(), ->cred_prepare()

     	 New. Duplicate any security data attached to cred->security.

     (*) security_commit_creds(), ->cred_commit()

     	 New. Apply any security effects for the upcoming installation of new
     	 security by commit_creds().

     (*) security_task_post_setuid(), ->task_post_setuid()

     	 Removed in favour of security_task_fix_setuid().

     (*) security_task_fix_setuid(), ->task_fix_setuid()

     	 Fix up the proposed new credentials for setuid().  This is used by
     	 cap_set_fix_setuid() to implicitly adjust capabilities in line with
     	 setuid() changes.  Changes are made to the new credentials, rather
     	 than the task itself as in security_task_post_setuid().

     (*) security_task_reparent_to_init(), ->task_reparent_to_init()

     	 Removed.  Instead the task being reparented to init is referred
     	 directly to init's credentials.

	 NOTE!  This results in the loss of some state: SELinux's osid no
	 longer records the sid of the thread that forked it.

     (*) security_key_alloc(), ->key_alloc()
     (*) security_key_permission(), ->key_permission()

     	 Changed.  These now take cred pointers rather than task pointers to
     	 refer to the security context.

 (4) sys_capset().

     This has been simplified and uses less locking.  The LSM functions it
     calls have been merged.

 (5) reparent_to_kthreadd().

     This gives the current thread the same credentials as init by simply using
     commit_thread() to point that way.

 (6) __sigqueue_alloc() and switch_uid()

     __sigqueue_alloc() can't stop the target task from changing its creds
     beneath it, so this function gets a reference to the currently applicable
     user_struct which it then passes into the sigqueue struct it returns if
     successful.

     switch_uid() is now called from commit_creds(), and possibly should be
     folded into that.  commit_creds() should take care of protecting
     __sigqueue_alloc().

 (7) [sg]et[ug]id() and co and [sg]et_current_groups.

     The set functions now all use prepare_creds(), commit_creds() and
     abort_creds() to build and check a new set of credentials before applying
     it.

     security_task_set[ug]id() is called inside the prepared section.  This
     guarantees that nothing else will affect the creds until we've finished.

     The calling of set_dumpable() has been moved into commit_creds().

     Much of the functionality of set_user() has been moved into
     commit_creds().

     The get functions all simply access the data directly.

 (8) security_task_prctl() and cap_task_prctl().

     security_task_prctl() has been modified to return -ENOSYS if it doesn't
     want to handle a function, or otherwise return the return value directly
     rather than through an argument.

     Additionally, cap_task_prctl() now prepares a new set of credentials, even
     if it doesn't end up using it.

 (9) Keyrings.

     A number of changes have been made to the keyrings code:

     (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
     	 all been dropped and built in to the credentials functions directly.
     	 They may want separating out again later.

     (b) key_alloc() and search_process_keyrings() now take a cred pointer
     	 rather than a task pointer to specify the security context.

     (c) copy_creds() gives a new thread within the same thread group a new
     	 thread keyring if its parent had one, otherwise it discards the thread
     	 keyring.

     (d) The authorisation key now points directly to the credentials to extend
     	 the search into rather pointing to the task that carries them.

     (e) Installing thread, process or session keyrings causes a new set of
     	 credentials to be created, even though it's not strictly necessary for
     	 process or session keyrings (they're shared).

(10) Usermode helper.

     The usermode helper code now carries a cred struct pointer in its
     subprocess_info struct instead of a new session keyring pointer.  This set
     of credentials is derived from init_cred and installed on the new process
     after it has been cloned.

     call_usermodehelper_setup() allocates the new credentials and
     call_usermodehelper_freeinfo() discards them if they haven't been used.  A
     special cred function (prepare_usermodeinfo_creds()) is provided
     specifically for call_usermodehelper_setup() to call.

     call_usermodehelper_setkeys() adjusts the credentials to sport the
     supplied keyring as the new session keyring.

(11) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) selinux_setprocattr() no longer does its check for whether the
     	 current ptracer can access processes with the new SID inside the lock
     	 that covers getting the ptracer's SID.  Whilst this lock ensures that
     	 the check is done with the ptracer pinned, the result is only valid
     	 until the lock is released, so there's no point doing it inside the
     	 lock.

(12) is_single_threaded().

     This function has been extracted from selinux_setprocattr() and put into
     a file of its own in the lib/ directory as join_session_keyring() now
     wants to use it too.

     The code in SELinux just checked to see whether a task shared mm_structs
     with other tasks (CLONE_VM), but that isn't good enough.  We really want
     to know if they're part of the same thread group (CLONE_THREAD).

(13) nfsd.

     The NFS server daemon now has to use the COW credentials to set the
     credentials it is going to use.  It really needs to pass the credentials
     down to the functions it calls, but it can't do that until other patches
     in this series have been applied.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>

7 files changed, 139 insertions, 137 deletions

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 6fbebac7b1b..0b2fcb698a6 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -454,8 +454,10 @@ extern int __audit_mq_timedsend(mqd_t mqdes, size_t msg_len, unsigned int msg_pr
 extern int __audit_mq_timedreceive(mqd_t mqdes, size_t msg_len, unsigned int __user *u_msg_prio, const struct timespec __user *u_abs_timeout);
 extern int __audit_mq_notify(mqd_t mqdes, const struct sigevent __user *u_notification);
 extern int __audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat);
-extern void __audit_log_bprm_fcaps(struct linux_binprm *bprm, kernel_cap_t *pP, kernel_cap_t *pE);
-extern int __audit_log_capset(pid_t pid, kernel_cap_t *eff, kernel_cap_t *inh, kernel_cap_t *perm);
+extern int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
+				  const struct cred *new,
+				  const struct cred *old);
+extern int __audit_log_capset(pid_t pid, const struct cred *new, const struct cred *old);
 
 static inline int audit_ipc_obj(struct kern_ipc_perm *ipcp)
 {
@@ -522,16 +524,20 @@ static inline int audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat)
  *
  * -Eric
  */
-static inline void audit_log_bprm_fcaps(struct linux_binprm *bprm, kernel_cap_t *pP, kernel_cap_t *pE)
+static inline int audit_log_bprm_fcaps(struct linux_binprm *bprm,
+				       const struct cred *new,
+				       const struct cred *old)
 {
 	if (unlikely(!audit_dummy_context()))
-		__audit_log_bprm_fcaps(bprm, pP, pE);
+		return __audit_log_bprm_fcaps(bprm, new, old);
+	return 0;
 }
 
-static inline int audit_log_capset(pid_t pid, kernel_cap_t *eff, kernel_cap_t *inh, kernel_cap_t *perm)
+static inline int audit_log_capset(pid_t pid, const struct cred *new,
+				   const struct cred *old)
 {
 	if (unlikely(!audit_dummy_context()))
-		return __audit_log_capset(pid, eff, inh, perm);
+		return __audit_log_capset(pid, new, old);
 	return 0;
 }
 
@@ -566,8 +572,8 @@ extern int audit_signals;
 #define audit_mq_timedreceive(d,l,p,t) ({ 0; })
 #define audit_mq_notify(d,n) ({ 0; })
 #define audit_mq_getsetattr(d,s) ({ 0; })
-#define audit_log_bprm_fcaps(b, p, e) do { ; } while (0)
-#define audit_log_capset(pid, e, i, p) ({ 0; })
+#define audit_log_bprm_fcaps(b, ncr, ocr) ({ 0; })
+#define audit_log_capset(pid, ncr, ocr) ({ 0; })
 #define audit_ptrace(t) ((void)0)
 #define audit_n_rules 0
 #define audit_signals 0
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 7f26580a5a4..e22f48c2a46 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -519,8 +519,6 @@ extern const kernel_cap_t __cap_empty_set;
 extern const kernel_cap_t __cap_full_set;
 extern const kernel_cap_t __cap_init_eff_set;
 
-kernel_cap_t cap_set_effective(const kernel_cap_t pE_new);
-
 /**
  * has_capability - Determine if a task has a superior capability available
  * @t: The task in question
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 62b9e532422..eaf6fa695a0 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -84,6 +84,8 @@ struct thread_group_cred {
 	struct key	*process_keyring;	/* keyring private to this process */
 	struct rcu_head	rcu;			/* RCU deletion hook */
 };
+
+extern void release_tgcred(struct cred *cred);
 #endif
 
 /*
@@ -137,11 +139,30 @@ struct cred {
 	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 */
 };
 
 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_usermodehelper_creds(void);
+extern int commit_creds(struct cred *);
+extern void abort_creds(struct cred *);
+extern const struct cred *override_creds(const struct cred *) __deprecated;
+extern void revert_creds(const struct cred *) __deprecated;
+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
@@ -150,10 +171,9 @@ extern int copy_creds(struct task_struct *, unsigned long);
  * Get a reference on the specified set of credentials.  The caller must
  * release the reference.
  */
-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);
 }
 
 /**
@@ -166,6 +186,8 @@ static inline struct cred *get_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);
 }
@@ -250,13 +272,13 @@ static inline void put_cred(const struct cred *_cred)
 	__groups;					\
 })
 
-#define task_cred_xxx(task, xxx)		\
-({						\
-	__typeof__(task->cred->xxx) ___val;	\
-	rcu_read_lock();			\
-	___val = __task_cred((task))->xxx;	\
-	rcu_read_unlock();			\
-	___val;					\
+#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))
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 5e24c54b6df..08c3b24ad9a 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -150,6 +150,8 @@ extern struct cred init_cred;
 	.sibling	= LIST_HEAD_INIT(tsk.sibling),			\
 	.group_leader	= &tsk,						\
 	.cred		= &init_cred,					\
+	.cred_exec_mutex =						\
+		 __MUTEX_INITIALIZER(tsk.cred_exec_mutex),		\
 	.comm		= "swapper",					\
 	.thread		= INIT_THREAD,					\
 	.fs		= &init_fs,					\
diff --git a/include/linux/key.h b/include/linux/key.h
index 0836cc838b0..69ecf0934b0 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -73,6 +73,7 @@ struct key;
 struct seq_file;
 struct user_struct;
 struct signal_struct;
+struct cred;
 
 struct key_type;
 struct key_owner;
@@ -181,7 +182,7 @@ struct key {
 extern struct key *key_alloc(struct key_type *type,
 			     const char *desc,
 			     uid_t uid, gid_t gid,
-			     struct task_struct *ctx,
+			     const struct cred *cred,
 			     key_perm_t perm,
 			     unsigned long flags);
 
@@ -249,7 +250,7 @@ extern int key_unlink(struct key *keyring,
 		      struct key *key);
 
 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
-				 struct task_struct *ctx,
+				 const struct cred *cred,
 				 unsigned long flags,
 				 struct key *dest);
 
@@ -276,22 +277,12 @@ extern ctl_table key_sysctls[];
 /*
  * the userspace interface
  */
-extern void switch_uid_keyring(struct user_struct *new_user);
-extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
-extern void exit_keys(struct task_struct *tsk);
-extern int suid_keys(struct task_struct *tsk);
+extern int install_thread_keyring_to_cred(struct cred *cred);
 extern int exec_keys(struct task_struct *tsk);
 extern void key_fsuid_changed(struct task_struct *tsk);
 extern void key_fsgid_changed(struct task_struct *tsk);
 extern void key_init(void);
 
-#define __install_session_keyring(keyring)				\
-({									\
-	struct key *old_session = current->cred->tgcred->session_keyring; \
-	current->cred->tgcred->session_keyring = keyring;		\
-	old_session;							\
-})
-
 #else /* CONFIG_KEYS */
 
 #define key_validate(k)			0
@@ -303,11 +294,6 @@ extern void key_init(void);
 #define make_key_ref(k, p)		NULL
 #define key_ref_to_ptr(k)		NULL
 #define is_key_possessed(k)		0
-#define switch_uid_keyring(u)		do { } while(0)
-#define __install_session_keyring(k)	({ NULL; })
-#define copy_keys(f,t)			0
-#define exit_keys(t)			do { } while(0)
-#define suid_keys(t)			do { } while(0)
 #define exec_keys(t)			do { } while(0)
 #define key_fsuid_changed(t)		do { } while(0)
 #define key_fsgid_changed(t)		do { } while(0)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2913252989b..121d655e460 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1145,7 +1145,8 @@ struct task_struct {
 	struct list_head cpu_timers[3];
 
 /* process credentials */
-	struct cred *cred;	/* actual/objective task credentials */
+	const struct cred *cred;	/* actual/objective task credentials (COW) */
+	struct mutex cred_exec_mutex;	/* execve vs ptrace cred calculation mutex */
 
 	char comm[TASK_COMM_LEN]; /* executable name excluding path
 				     - access with [gs]et_task_comm (which lock
@@ -1720,7 +1721,6 @@ static inline struct user_struct *get_uid(struct user_struct *u)
 	return u;
 }
 extern void free_uid(struct user_struct *);
-extern void switch_uid(struct user_struct *);
 extern void release_uids(struct user_namespace *ns);
 
 #include <asm/current.h>
@@ -1870,6 +1870,8 @@ static inline unsigned long wait_task_inactive(struct task_struct *p,
 #define for_each_process(p) \
 	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
 
+extern bool is_single_threaded(struct task_struct *);
+
 /*
  * Careful: do_each_thread/while_each_thread is a double loop so
  *          'break' will not work as expected - use goto instead.
diff --git a/include/linux/security.h b/include/linux/security.h
index 7e9fe046a0d..68be1125144 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -53,24 +53,21 @@ extern int cap_settime(struct timespec *ts, struct timezone *tz);
 extern int cap_ptrace_may_access(struct task_struct *child, unsigned int mode);
 extern int cap_ptrace_traceme(struct task_struct *parent);
 extern int cap_capget(struct task_struct *target, kernel_cap_t *effective, kernel_cap_t *inheritable, kernel_cap_t *permitted);
-extern int cap_capset_check(const kernel_cap_t *effective,
-			    const kernel_cap_t *inheritable,
-			    const kernel_cap_t *permitted);
-extern void cap_capset_set(const kernel_cap_t *effective,
-			   const kernel_cap_t *inheritable,
-			   const kernel_cap_t *permitted);
+extern int cap_capset(struct cred *new, const struct cred *old,
+		      const kernel_cap_t *effective,
+		      const kernel_cap_t *inheritable,
+		      const kernel_cap_t *permitted);
 extern int cap_bprm_set_security(struct linux_binprm *bprm);
-extern void cap_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
+extern int cap_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
 extern int cap_bprm_secureexec(struct linux_binprm *bprm);
 extern int cap_inode_setxattr(struct dentry *dentry, const char *name,
 			      const void *value, size_t size, int flags);
 extern int cap_inode_removexattr(struct dentry *dentry, const char *name);
 extern int cap_inode_need_killpriv(struct dentry *dentry);
 extern int cap_inode_killpriv(struct dentry *dentry);
-extern int cap_task_post_setuid(uid_t old_ruid, uid_t old_euid, uid_t old_suid, int flags);
-extern void cap_task_reparent_to_init(struct task_struct *p);
+extern int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags);
 extern int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
-			  unsigned long arg4, unsigned long arg5, long *rc_p);
+			  unsigned long arg4, unsigned long arg5);
 extern int cap_task_setscheduler(struct task_struct *p, int policy, struct sched_param *lp);
 extern int cap_task_setioprio(struct task_struct *p, int ioprio);
 extern int cap_task_setnice(struct task_struct *p, int nice);
@@ -170,8 +167,8 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	Compute and set the security attributes of a process being transformed
  *	by an execve operation based on the old attributes (current->security)
  *	and the information saved in @bprm->security by the set_security hook.
- *	Since this hook function (and its caller) are void, this hook can not
- *	return an error.  However, it can leave the security attributes of the
+ *	Since this function may return an error, in which case the process will
+ *      be killed.  However, it can leave the security attributes of the
  *	process unchanged if an access failure occurs at this point.
  *	bprm_apply_creds is called under task_lock.  @unsafe indicates various
  *	reasons why it may be unsafe to change security state.
@@ -593,15 +590,18 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	manual page for definitions of the @clone_flags.
  *	@clone_flags contains the flags indicating what should be shared.
  *	Return 0 if permission is granted.
- * @cred_alloc_security:
- *	@cred contains the cred struct for child process.
- *	Allocate and attach a security structure to the cred->security field.
- *	The security field is initialized to NULL when the task structure is
- *	allocated.
- *	Return 0 if operation was successful.
  * @cred_free:
  *	@cred points to the credentials.
  *	Deallocate and clear the cred->security field in a set of credentials.
+ * @cred_prepare:
+ *	@new points to the new credentials.
+ *	@old points to the original credentials.
+ *	@gfp indicates the atomicity of any memory allocations.
+ *	Prepare a new set of credentials by copying the data from the old set.
+ * @cred_commit:
+ *	@new points to the new credentials.
+ *	@old points to the original credentials.
+ *	Install a new set of credentials.
  * @task_setuid:
  *	Check permission before setting one or more of the user identity
  *	attributes of the current process.  The @flags parameter indicates
@@ -614,15 +614,13 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	@id2 contains a uid.
  *	@flags contains one of the LSM_SETID_* values.
  *	Return 0 if permission is granted.
- * @task_post_setuid:
+ * @task_fix_setuid:
  *	Update the module's state after setting one or more of the user
  *	identity attributes of the current process.  The @flags parameter
  *	indicates which of the set*uid system calls invoked this hook.  If
- *	@flags is LSM_SETID_FS, then @old_ruid is the old fs uid and the other
- *	parameters are not used.
- *	@old_ruid contains the old real uid (or fs uid if LSM_SETID_FS).
- *	@old_euid contains the old effective uid (or -1 if LSM_SETID_FS).
- *	@old_suid contains the old saved uid (or -1 if LSM_SETID_FS).
+ *	@new is the set of credentials that will be installed.  Modifications
+ *	should be made to this rather than to @current->cred.
+ *	@old is the set of credentials that are being replaces
  *	@flags contains one of the LSM_SETID_* values.
  *	Return 0 on success.
  * @task_setgid:
@@ -725,13 +723,8 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	@arg3 contains a argument.
  *	@arg4 contains a argument.
  *	@arg5 contains a argument.
- *      @rc_p contains a pointer to communicate back the forced return code
- *	Return 0 if permission is granted, and non-zero if the security module
- *      has taken responsibility (setting *rc_p) for the prctl call.
- * @task_reparent_to_init:
- *	Set the security attributes in @p->security for a kernel thread that
- *	is being reparented to the init task.
- *	@p contains the task_struct for the kernel thread.
+ *	Return -ENOSYS if no-one wanted to handle this op, any other value to
+ *	cause prctl() to return immediately with that value.
  * @task_to_inode:
  *	Set the security attributes for an inode based on an associated task's
  *	security attributes, e.g. for /proc/pid inodes.
@@ -1008,7 +1001,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	See whether a specific operational right is granted to a process on a
  *	key.
  *	@key_ref refers to the key (key pointer + possession attribute bit).
- *	@context points to the process to provide the context against which to
+ *	@cred points to the credentials to provide the context against which to
  *	evaluate the security data on the key.
  *	@perm describes the combination of permissions required of this key.
  *	Return 1 if permission granted, 0 if permission denied and -ve it the
@@ -1170,6 +1163,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	@child process.
  *	Security modules may also want to perform a process tracing check
  *	during an execve in the set_security or apply_creds hooks of
+ *	tracing check during an execve in the bprm_set_creds hook of
  *	binprm_security_ops if the process is being traced and its security
  *	attributes would be changed by the execve.
  *	@child contains the task_struct structure for the target process.
@@ -1193,19 +1187,15 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *	@inheritable contains the inheritable capability set.
  *	@permitted contains the permitted capability set.
  *	Return 0 if the capability sets were successfully obtained.
- * @capset_check:
- *	Check permission before setting the @effective, @inheritable, and
- *	@permitted capability sets for the current process.
- *	@effective contains the effective capability set.
- *	@inheritable contains the inheritable capability set.
- *	@permitted contains the permitted capability set.
- *	Return 0 if permission is granted.
- * @capset_set:
+ * @capset:
  *	Set the @effective, @inheritable, and @permitted capability sets for
  *	the current process.
+ *	@new contains the new credentials structure for target process.
+ *	@old contains the current credentials structure for target process.
  *	@effective contains the effective capability set.
  *	@inheritable contains the inheritable capability set.
  *	@permitted contains the permitted capability set.
+ *	Return 0 and update @new if permission is granted.
  * @capable:
  *	Check whether the @tsk process has the @cap capability.
  *	@tsk contains the task_struct for the process.
@@ -1297,12 +1287,11 @@ struct security_operations {
 	int (*capget) (struct task_struct *target,
 		       kernel_cap_t *effective,
 		       kernel_cap_t *inheritable, kernel_cap_t *permitted);
-	int (*capset_check) (const kernel_cap_t *effective,
-			     const kernel_cap_t *inheritable,
-			     const kernel_cap_t *permitted);
-	void (*capset_set) (const kernel_cap_t *effective,
-			    const kernel_cap_t *inheritable,
-			    const kernel_cap_t *permitted);
+	int (*capset) (struct cred *new,
+		       const struct cred *old,
+		       const kernel_cap_t *effective,
+		       const kernel_cap_t *inheritable,
+		       const kernel_cap_t *permitted);
 	int (*capable) (struct task_struct *tsk, int cap, int audit);
 	int (*acct) (struct file *file);
 	int (*sysctl) (struct ctl_table *table, int op);
@@ -1314,7 +1303,7 @@ struct security_operations {
 
 	int (*bprm_alloc_security) (struct linux_binprm *bprm);
 	void (*bprm_free_security) (struct linux_binprm *bprm);
-	void (*bprm_apply_creds) (struct linux_binprm *bprm, int unsafe);
+	int (*bprm_apply_creds) (struct linux_binprm *bprm, int unsafe);
 	void (*bprm_post_apply_creds) (struct linux_binprm *bprm);
 	int (*bprm_set_security) (struct linux_binprm *bprm);
 	int (*bprm_check_security) (struct linux_binprm *bprm);
@@ -1405,11 +1394,13 @@ struct security_operations {
 	int (*dentry_open) (struct file *file, const struct cred *cred);
 
 	int (*task_create) (unsigned long clone_flags);
-	int (*cred_alloc_security) (struct cred *cred);
 	void (*cred_free) (struct cred *cred);
+	int (*cred_prepare)(struct cred *new, const struct cred *old,
+			    gfp_t gfp);
+	void (*cred_commit)(struct cred *new, const struct cred *old);
 	int (*task_setuid) (uid_t id0, uid_t id1, uid_t id2, int flags);
-	int (*task_post_setuid) (uid_t old_ruid /* or fsuid */ ,
-				 uid_t old_euid, uid_t old_suid, int flags);
+	int (*task_fix_setuid) (struct cred *new, const struct cred *old,
+				int flags);
 	int (*task_setgid) (gid_t id0, gid_t id1, gid_t id2, int flags);
 	int (*task_setpgid) (struct task_struct *p, pid_t pgid);
 	int (*task_getpgid) (struct task_struct *p);
@@ -1429,8 +1420,7 @@ struct security_operations {
 	int (*task_wait) (struct task_struct *p);
 	int (*task_prctl) (int option, unsigned long arg2,
 			   unsigned long arg3, unsigned long arg4,
-			   unsigned long arg5, long *rc_p);
-	void (*task_reparent_to_init) (struct task_struct *p);
+			   unsigned long arg5);
 	void (*task_to_inode) (struct task_struct *p, struct inode *inode);
 
 	int (*ipc_permission) (struct kern_ipc_perm *ipcp, short flag);
@@ -1535,10 +1525,10 @@ struct security_operations {
 
 	/* key management security hooks */
 #ifdef CONFIG_KEYS
-	int (*key_alloc) (struct key *key, struct task_struct *tsk, unsigned long flags);
+	int (*key_alloc) (struct key *key, const struct cred *cred, unsigned long flags);
 	void (*key_free) (struct key *key);
 	int (*key_permission) (key_ref_t key_ref,
-			       struct task_struct *context,
+			       const struct cred *cred,
 			       key_perm_t perm);
 	int (*key_getsecurity)(struct key *key, char **_buffer);
 #endif	/* CONFIG_KEYS */
@@ -1564,12 +1554,10 @@ int security_capget(struct task_struct *target,
 		    kernel_cap_t *effective,
 		    kernel_cap_t *inheritable,
 		    kernel_cap_t *permitted);
-int security_capset_check(const kernel_cap_t *effective,
-			  const kernel_cap_t *inheritable,
-			  const kernel_cap_t *permitted);
-void security_capset_set(const kernel_cap_t *effective,
-			 const kernel_cap_t *inheritable,
-			 const kernel_cap_t *permitted);
+int security_capset(struct cred *new, const struct cred *old,
+		    const kernel_cap_t *effective,
+		    const kernel_cap_t *inheritable,
+		    const kernel_cap_t *permitted);
 int security_capable(struct task_struct *tsk, int cap);
 int security_capable_noaudit(struct task_struct *tsk, int cap);
 int security_acct(struct file *file);
@@ -1583,7 +1571,7 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
 int security_vm_enough_memory_kern(long pages);
 int security_bprm_alloc(struct linux_binprm *bprm);
 void security_bprm_free(struct linux_binprm *bprm);
-void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
+int security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe);
 void security_bprm_post_apply_creds(struct linux_binprm *bprm);
 int security_bprm_set(struct linux_binprm *bprm);
 int security_bprm_check(struct linux_binprm *bprm);
@@ -1660,11 +1648,12 @@ int security_file_send_sigiotask(struct task_struct *tsk,
 int security_file_receive(struct file *file);
 int security_dentry_open(struct file *file, const struct cred *cred);
 int security_task_create(unsigned long clone_flags);
-int security_cred_alloc(struct cred *cred);
 void security_cred_free(struct cred *cred);
+int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
+void security_commit_creds(struct cred *new, const struct cred *old);
 int security_task_setuid(uid_t id0, uid_t id1, uid_t id2, int flags);
-int security_task_post_setuid(uid_t old_ruid, uid_t old_euid,
-			      uid_t old_suid, int flags);
+int security_task_fix_setuid(struct cred *new, const struct cred *old,
+			     int flags);
 int security_task_setgid(gid_t id0, gid_t id1, gid_t id2, int flags);
 int security_task_setpgid(struct task_struct *p, pid_t pgid);
 int security_task_getpgid(struct task_struct *p);
@@ -1683,8 +1672,7 @@ int security_task_kill(struct task_struct *p, struct siginfo *info,
 			int sig, u32 secid);
 int security_task_wait(struct task_struct *p);
 int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
-			 unsigned long arg4, unsigned long arg5, long *rc_p);
-void security_task_reparent_to_init(struct task_struct *p);
+			unsigned long arg4, unsigned long arg5);
 void security_task_to_inode(struct task_struct *p, struct inode *inode);
 int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag);
 void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid);
@@ -1759,18 +1747,13 @@ static inline int security_capget(struct task_struct *target,
 	return cap_capget(target, effective, inheritable, permitted);
 }
 
-static inline int security_capset_check(const kernel_cap_t *effective,
-					const kernel_cap_t *inheritable,
-					const kernel_cap_t *permitted)
+static inline int security_capset(struct cred *new,
+				   const struct cred *old,
+				   const kernel_cap_t *effective,
+				   const kernel_cap_t *inheritable,
+				   const kernel_cap_t *permitted)
 {
-	return cap_capset_check(effective, inheritable, permitted);
-}
-
-static inline void security_capset_set(const kernel_cap_t *effective,
-				       const kernel_cap_t *inheritable,
-				       const kernel_cap_t *permitted)
-{
-	cap_capset_set(effective, inheritable, permitted);
+	return cap_capset(new, old, effective, inheritable, permitted);
 }
 
 static inline int security_capable(struct task_struct *tsk, int cap)
@@ -1837,9 +1820,9 @@ static inline int security_bprm_alloc(struct linux_binprm *bprm)
 static inline void security_bprm_free(struct linux_binprm *bprm)
 { }
 
-static inline void security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe)
+static inline int security_bprm_apply_creds(struct linux_binprm *bprm, int unsafe)
 {
-	cap_bprm_apply_creds(bprm, unsafe);
+	return cap_bprm_apply_creds(bprm, unsafe);
 }
 
 static inline void security_bprm_post_apply_creds(struct linux_binprm *bprm)
@@ -2182,13 +2165,20 @@ static inline int security_task_create(unsigned long clone_flags)
 	return 0;
 }
 
-static inline int security_cred_alloc(struct cred *cred)
+static inline void security_cred_free(struct cred *cred)
+{ }
+
+static inline int security_prepare_creds(struct cred *new,
+					 const struct cred *old,
+					 gfp_t gfp)
 {
 	return 0;
 }
 
-static inline void security_cred_free(struct cred *cred)
-{ }
+static inline void security_commit_creds(struct cred *new,
+					 const struct cred *old)
+{
+}
 
 static inline int security_task_setuid(uid_t id0, uid_t id1, uid_t id2,
 				       int flags)
@@ -2196,10 +2186,11 @@ static inline int security_task_setuid(uid_t id0, uid_t id1, uid_t id2,
 	return 0;
 }
 
-static inline int security_task_post_setuid(uid_t old_ruid, uid_t old_euid,
-					    uid_t old_suid, int flags)
+static inline int security_task_fix_setuid(struct cred *new,
+					   const struct cred *old,
+					   int flags)
 {
-	return cap_task_post_setuid(old_ruid, old_euid, old_suid, flags);
+	return cap_task_fix_setuid(new, old, flags);
 }
 
 static inline int security_task_setgid(gid_t id0, gid_t id1, gid_t id2,
@@ -2286,14 +2277,9 @@ static inline int security_task_wait(struct task_struct *p)
 static inline int security_task_prctl(int option, unsigned long arg2,
 				      unsigned long arg3,
 				      unsigned long arg4,
-				      unsigned long arg5, long *rc_p)
-{
-	return cap_task_prctl(option, arg2, arg3, arg3, arg5, rc_p);
-}
-
-static inline void security_task_reparent_to_init(struct task_struct *p)
+				      unsigned long arg5)
 {
-	cap_task_reparent_to_init(p);
+	return cap_task_prctl(option, arg2, arg3, arg3, arg5);
 }
 
 static inline void security_task_to_inode(struct task_struct *p, struct inode *inode)
@@ -2719,16 +2705,16 @@ static inline void security_skb_classify_flow(struct sk_buff *skb, struct flowi
 #ifdef CONFIG_KEYS
 #ifdef CONFIG_SECURITY
 
-int security_key_alloc(struct key *key, struct task_struct *tsk, unsigned long flags);
+int security_key_alloc(struct key *key, const struct cred *cred, unsigned long flags);
 void security_key_free(struct key *key);
 int security_key_permission(key_ref_t key_ref,
-			    struct task_struct *context, key_perm_t perm);
+			    const struct cred *cred, key_perm_t perm);
 int security_key_getsecurity(struct key *key, char **_buffer);
 
 #else
 
 static inline int security_key_alloc(struct key *key,
-				     struct task_struct *tsk,
+				     const struct cred *cred,
 				     unsigned long flags)
 {
 	return 0;
@@ -2739,7 +2725,7 @@ static inline void security_key_free(struct key *key)
 }
 
 static inline int security_key_permission(key_ref_t key_ref,
-					  struct task_struct *context,
+					  const struct cred *cred,
 					  key_perm_t perm)
 {
 	return 0;