CRED: Wrap task credential accesses in the filesystem subsystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <[e-mail]>
Reviewed-by: James Morris <[e-mail]>
Acked-by: Serge Hallyn <[e-mail]>
Cc: Al Viro <[e-mail]>
Signed-off-by: James Morris <[e-mail]>

fs/anon_inodes.c

···
 	 */
 	inode->i_state = I_DIRTY;
 	inode->i_mode = S_IRUSR | S_IWUSR;
-	inode->i_uid = current->fsuid;
-	inode->i_gid = current->fsgid;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 	return inode;
 }

fs/attr.c

···
 
 	/* Make sure a caller can chown. */
 	if ((ia_valid & ATTR_UID) &&
-	    (current->fsuid != inode->i_uid ||
+	    (current_fsuid() != inode->i_uid ||
 	     attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
 		goto error;
 
 	/* Make sure caller can chgrp. */
 	if ((ia_valid & ATTR_GID) &&
-	    (current->fsuid != inode->i_uid ||
+	    (current_fsuid() != inode->i_uid ||
 	    (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
 	    !capable(CAP_CHOWN))
 		goto error;

fs/binfmt_elf_fdpic.c

···
 	NEW_AUX_ENT(AT_BASE,	interp_params->elfhdr_addr);
 	NEW_AUX_ENT(AT_FLAGS,	0);
 	NEW_AUX_ENT(AT_ENTRY,	exec_params->entry_addr);
-	NEW_AUX_ENT(AT_UID,	(elf_addr_t) current->uid);
-	NEW_AUX_ENT(AT_EUID,	(elf_addr_t) current->euid);
-	NEW_AUX_ENT(AT_GID,	(elf_addr_t) current->gid);
-	NEW_AUX_ENT(AT_EGID,	(elf_addr_t) current->egid);
+	NEW_AUX_ENT(AT_UID,	(elf_addr_t) current_uid());
+	NEW_AUX_ENT(AT_EUID,	(elf_addr_t) current_euid());
+	NEW_AUX_ENT(AT_GID,	(elf_addr_t) current_gid());
+	NEW_AUX_ENT(AT_EGID,	(elf_addr_t) current_egid());
 	NEW_AUX_ENT(AT_SECURE,	security_bprm_secureexec(bprm));
 	NEW_AUX_ENT(AT_EXECFN,	bprm->exec);
 

fs/dquot.c

···
 
 	switch (dquot->dq_type) {
 		case USRQUOTA:
-			return current->fsuid == dquot->dq_id;
+			return current_fsuid() == dquot->dq_id;
 		case GRPQUOTA:
 			return in_group_p(dquot->dq_id);
 	}
···
 		MINOR(dquot->dq_sb->s_dev));
 	if (ret)
 		goto attr_err_out;
-	ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current->user->uid);
+	ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
 	if (ret)
 		goto attr_err_out;
 	genlmsg_end(skb, msg_head);

fs/exec.c

···
 	/* This is the point of no return */
 	current->sas_ss_sp = current->sas_ss_size = 0;
 
-	if (current->euid == current->uid && current->egid == current->gid)
+	if (current_euid() == current_uid() && current_egid() == current_gid())
 		set_dumpable(current->mm, 1);
 	else
 		set_dumpable(current->mm, suid_dumpable);
···
 	 */
 	current->mm->task_size = TASK_SIZE;
 
-	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
+	if (bprm->e_uid != current_euid() || bprm->e_gid != current_egid()) {
 		suid_keys(current);
 		set_dumpable(current->mm, suid_dumpable);
 		current->pdeath_signal = 0;
···
 	if (bprm->file->f_op == NULL)
 		return -EACCES;
 
-	bprm->e_uid = current->euid;
-	bprm->e_gid = current->egid;
+	bprm->e_uid = current_euid();
+	bprm->e_gid = current_egid();
 
 	if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
 		/* Set-uid? */
···
 {
 	int unsafe;
 
-	if (bprm->e_uid != current->uid) {
+	if (bprm->e_uid != current_uid()) {
 		suid_keys(current);
 		current->pdeath_signal = 0;
 	}
···
 			/* uid */
 			case 'u':
 				rc = snprintf(out_ptr, out_end - out_ptr,
-					      "%d", current->uid);
+					      "%d", current_uid());
 				if (rc > out_end - out_ptr)
 					goto out;
 				out_ptr += rc;
···
 			/* gid */
 			case 'g':
 				rc = snprintf(out_ptr, out_end - out_ptr,
-					      "%d", current->gid);
+					      "%d", current_gid());
 				if (rc > out_end - out_ptr)
 					goto out;
 				out_ptr += rc;
···
 	struct inode * inode;
 	struct file * file;
 	int retval = 0;
-	int fsuid = current->fsuid;
+	int fsuid = current_fsuid();
 	int flag = 0;
 	int ispipe = 0;
 	unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
···
 	 * Dont allow local users get cute and trick others to coredump
 	 * into their pre-created files:
 	 */
-	if (inode->i_uid != current->fsuid)
+	if (inode->i_uid != current_fsuid())
 		goto close_fail;
 	if (!file->f_op)
 		goto close_fail;

fs/fcntl.c

···
 	if (err)
 		return err;
 
-	f_modown(filp, pid, type, current->uid, current->euid, force);
+	f_modown(filp, pid, type, current_uid(), current_euid(), force);
 	return 0;
 }
 EXPORT_SYMBOL(__f_setown);

fs/inotify_user.c

···
 		goto out_put_fd;
 	}
 
-	user = get_uid(current->user);
+	user = get_current_user();
 	if (unlikely(atomic_read(&user->inotify_devs) >=
 			inotify_max_user_instances)) {
 		ret = -EMFILE;

fs/ioprio.c

···
 	int err;
 	struct io_context *ioc;
 
-	if (task->uid != current->euid &&
-	    task->uid != current->uid && !capable(CAP_SYS_NICE))
+	if (task->uid != current_euid() &&
+	    task->uid != current_uid() && !capable(CAP_SYS_NICE))
 		return -EPERM;
 
 	err = security_task_setioprio(task, ioprio);

fs/locks.c

···
 	struct inode *inode = dentry->d_inode;
 	int error, rdlease_count = 0, wrlease_count = 0;
 
-	if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE))
+	if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
 		return -EACCES;
 	if (!S_ISREG(inode->i_mode))
 		return -EINVAL;

fs/namei.c

···
 
 	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 
-	if (current->fsuid == inode->i_uid)
+	if (current_fsuid() == inode->i_uid)
 		mode >>= 6;
 	else {
 		if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
···
 	if (inode->i_op && inode->i_op->permission)
 		return -EAGAIN;
 
-	if (current->fsuid == inode->i_uid)
+	if (current_fsuid() == inode->i_uid)
 		mode >>= 6;
 	else if (in_group_p(inode->i_gid))
 		mode >>= 3;
···
  */
 static inline int check_sticky(struct inode *dir, struct inode *inode)
 {
+	uid_t fsuid = current_fsuid();
+
 	if (!(dir->i_mode & S_ISVTX))
 		return 0;
-	if (inode->i_uid == current->fsuid)
+	if (inode->i_uid == fsuid)
 		return 0;
-	if (dir->i_uid == current->fsuid)
+	if (dir->i_uid == fsuid)
 		return 0;
 	return !capable(CAP_FOWNER);
 }

fs/namespace.c

···
 	if (S_ISLNK(path->dentry->d_inode->i_mode))
 		return -EPERM;
 	if (path->dentry->d_inode->i_mode & S_ISVTX) {
-		if (current->uid != path->dentry->d_inode->i_uid)
+		if (current_uid() != path->dentry->d_inode->i_uid)
 			return -EPERM;
 	}
 	if (inode_permission(path->dentry->d_inode, MAY_WRITE))

fs/pipe.c

···
 	 */
 	inode->i_state = I_DIRTY;
 	inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
-	inode->i_uid = current->fsuid;
-	inode->i_gid = current->fsgid;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 
 	return inode;

fs/posix_acl.c

···
                 switch(pa->e_tag) {
                         case ACL_USER_OBJ:
 				/* (May have been checked already) */
-                                if (inode->i_uid == current->fsuid)
+				if (inode->i_uid == current_fsuid())
                                         goto check_perm;
                                 break;
                         case ACL_USER:
-                                if (pa->e_id == current->fsuid)
+				if (pa->e_id == current_fsuid())
                                         goto mask;
 				break;
                         case ACL_GROUP_OBJ:

fs/quota.c

···
 
 	/* Check privileges */
 	if (cmd == Q_GETQUOTA) {
-		if (((type == USRQUOTA && current->euid != id) ||
+		if (((type == USRQUOTA && current_euid() != id) ||
 		     (type == GRPQUOTA && !in_egroup_p(id))) &&
 		    !capable(CAP_SYS_ADMIN))
 			return -EPERM;
···
 
 	/* Check privileges */
 	if (cmd == Q_XGETQUOTA) {
-		if (((type == XQM_USRQUOTA && current->euid != id) ||
+		if (((type == XQM_USRQUOTA && current_euid() != id) ||
 		     (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
 		     !capable(CAP_SYS_ADMIN))
 			return -EPERM;

include/linux/fs.h

···
 #define has_fs_excl() atomic_read(&current->fs_excl)
 
 #define is_owner_or_cap(inode)	\
-	((current->fsuid == (inode)->i_uid) || capable(CAP_FOWNER))
+	((current_fsuid() == (inode)->i_uid) || capable(CAP_FOWNER))
 
 /* not quite ready to be deprecated, but... */
 extern void lock_super(struct super_block *);