C++ put_cred函数代码示例

int vboxPciOsDevReattachHostDriver(PVBOXRAWPCIINS pIns)
{
    struct pci_dev *pPciDev = pIns->pPciDev;

    if (!pPciDev)
        return VINF_SUCCESS;

    if (pIns->szPrevDriver[0])
    {
        char*              szCmdBuf;
        char*              szFileBuf;
        struct file*       pFile;
        int                iCmdLen;
        const int          cMaxBuf = 128;
        const struct cred *pOldCreds;
        struct cred       *pNewCreds;
        uint8_t            uBus =   (pIns->HostPciAddress) >> 8;
        uint8_t            uDevFn = (pIns->HostPciAddress) & 0xff;

        printk(KERN_DEBUG "vboxpci: reattaching old host driver %s\n", pIns->szPrevDriver);
        /*
         * Now perform kernel analog of:
         *
         * echo -n 0000:03:00.0 > /sys/bus/pci/drivers/pci-stub/unbind
         * echo -n 0000:03:00.0 > /sys/bus/pci/drivers/nvidia/bind
         */
        szCmdBuf  = kmalloc(cMaxBuf, GFP_KERNEL);
        szFileBuf = kmalloc(cMaxBuf, GFP_KERNEL);

        if (!szCmdBuf || !szFileBuf)
            goto done;

        iCmdLen = RTStrPrintf(szCmdBuf, cMaxBuf,
                              "0000:%02x:%02x.%d",
                              uBus, uDevFn>>3, uDevFn&7);

        /* Somewhat ugly hack - override current credentials */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 29)
        pNewCreds = prepare_creds();
        if (!pNewCreds)
            goto done;

        pNewCreds->fsuid = 0;
        pOldCreds = override_creds(pNewCreds);
#endif
        RTStrPrintf(szFileBuf, cMaxBuf,
                    "/sys/bus/pci/drivers/%s/unbind",
                    PCI_STUB_MODULE);
        pFile = vboxPciFileOpen(szFileBuf, O_WRONLY);
        if (pFile)
        {

            /* Don't write trailing \0 */
            vboxPciFileWrite(pFile, 0, szCmdBuf, iCmdLen);
            vboxPciFileClose(pFile);
        }
        else
            printk(KERN_DEBUG "vboxpci: cannot open %s\n", szFileBuf);

        RTStrPrintf(szFileBuf, cMaxBuf,
                    "/sys/bus/pci/drivers/%s/bind",
                    pIns->szPrevDriver);
        pFile = vboxPciFileOpen(szFileBuf, O_WRONLY);
        if (pFile)
        {

            /* Don't write trailing \0 */
            vboxPciFileWrite(pFile, 0, szCmdBuf, iCmdLen);
            vboxPciFileClose(pFile);
            pIns->szPrevDriver[0] = '\0';
        }
        else
            printk(KERN_DEBUG "vboxpci: cannot open %s\n", szFileBuf);

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 29)
        revert_creds(pOldCreds);
        put_cred(pNewCreds);
#endif

      done:
        kfree(szCmdBuf);
        kfree(szFileBuf);
    }

static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
				struct pid *pid, struct task_struct *p)
{
	struct user_namespace *user_ns = seq_user_ns(m);
	struct group_info *group_info;
	int g, umask = -1;
	struct task_struct *tracer;
	const struct cred *cred;
	pid_t ppid, tpid = 0, tgid, ngid;
	unsigned int max_fds = 0;

	rcu_read_lock();
	ppid = pid_alive(p) ?
		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;

	tracer = ptrace_parent(p);
	if (tracer)
		tpid = task_pid_nr_ns(tracer, ns);

	tgid = task_tgid_nr_ns(p, ns);
	ngid = task_numa_group_id(p);
	cred = get_task_cred(p);

	task_lock(p);
	if (p->fs)
		umask = p->fs->umask;
	if (p->files)
		max_fds = files_fdtable(p->files)->max_fds;
	task_unlock(p);
	rcu_read_unlock();

	if (umask >= 0)
		seq_printf(m, "Umask:\t%#04o\n", umask);
	seq_puts(m, "State:\t");
	seq_puts(m, get_task_state(p));

	seq_put_decimal_ull(m, "\nTgid:\t", tgid);
	seq_put_decimal_ull(m, "\nNgid:\t", ngid);
	seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns));
	seq_put_decimal_ull(m, "\nPPid:\t", ppid);
	seq_put_decimal_ull(m, "\nTracerPid:\t", tpid);
	seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid));
	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid));
	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid));
	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid));
	seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid));
	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid));
	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid));
	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid));
	seq_put_decimal_ull(m, "\nFDSize:\t", max_fds);

	seq_puts(m, "\nGroups:\t");
	group_info = cred->group_info;
	for (g = 0; g < group_info->ngroups; g++)
		seq_put_decimal_ull(m, g ? " " : "",
				from_kgid_munged(user_ns, group_info->gid[g]));
	put_cred(cred);
	/* Trailing space shouldn't have been added in the first place. */
	seq_putc(m, ' ');

#ifdef CONFIG_PID_NS
	seq_puts(m, "\nNStgid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSpid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_put_decimal_ull(m, "\t", task_pid_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSpgid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSsid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
#endif
	seq_putc(m, '\n');
}

int
init_cifs_idmap(void)
{
	struct cred *cred;
	struct key *keyring;
	int ret;

	cFYI(1, "Registering the %s key type", cifs_idmap_key_type.name);

	/* create an override credential set with a special thread keyring in
	 * which requests are cached
	 *
	 * this is used to prevent malicious redirections from being installed
	 * with add_key().
	 */
	cred = prepare_kernel_cred(NULL);
	if (!cred)
		return -ENOMEM;

	keyring = key_alloc(&key_type_keyring, ".cifs_idmap", 0, 0, cred,
			    (KEY_POS_ALL & ~KEY_POS_SETATTR) |
			    KEY_USR_VIEW | KEY_USR_READ,
			    KEY_ALLOC_NOT_IN_QUOTA);
	if (IS_ERR(keyring)) {
		ret = PTR_ERR(keyring);
		goto failed_put_cred;
	}

	ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
	if (ret < 0)
		goto failed_put_key;

	ret = register_key_type(&cifs_idmap_key_type);
	if (ret < 0)
		goto failed_put_key;

	/* instruct request_key() to use this special keyring as a cache for
	 * the results it looks up */
	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
	cred->thread_keyring = keyring;
	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
	root_cred = cred;

	spin_lock_init(&siduidlock);
	uidtree = RB_ROOT;
	spin_lock_init(&sidgidlock);
	gidtree = RB_ROOT;

	spin_lock_init(&uidsidlock);
	siduidtree = RB_ROOT;
	spin_lock_init(&gidsidlock);
	sidgidtree = RB_ROOT;
	register_shrinker(&cifs_shrinker);

	cFYI(1, "cifs idmap keyring: %d", key_serial(keyring));
	return 0;

failed_put_key:
	key_put(keyring);
failed_put_cred:
	put_cred(cred);
	return ret;
}

/*
 * Request userspace finish the construction of a key
 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
 */
static int call_sbin_request_key(struct key_construction *cons,
				 const char *op,
				 void *aux)
{
	const struct cred *cred = current_cred();
	key_serial_t prkey, sskey;
	struct key *key = cons->key, *authkey = cons->authkey, *keyring,
		*session;
	char *argv[9], *envp[3], uid_str[12], gid_str[12];
	char key_str[12], keyring_str[3][12];
	char desc[20];
	int ret, i;

	kenter("{%d},{%d},%s", key->serial, authkey->serial, op);

	ret = install_user_keyrings();
	if (ret < 0)
		goto error_alloc;

	/* allocate a new session keyring */
	sprintf(desc, "_req.%u", key->serial);

	cred = get_current_cred();
	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
				KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
				KEY_ALLOC_QUOTA_OVERRUN, NULL, NULL);
	put_cred(cred);
	if (IS_ERR(keyring)) {
		ret = PTR_ERR(keyring);
		goto error_alloc;
	}

	/* attach the auth key to the session keyring */
	ret = key_link(keyring, authkey);
	if (ret < 0)
		goto error_link;

	/* record the UID and GID */
	sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
	sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));

	/* we say which key is under construction */
	sprintf(key_str, "%d", key->serial);

	/* we specify the process's default keyrings */
	sprintf(keyring_str[0], "%d",
		cred->thread_keyring ? cred->thread_keyring->serial : 0);

	prkey = 0;
	if (cred->process_keyring)
		prkey = cred->process_keyring->serial;
	sprintf(keyring_str[1], "%d", prkey);

	rcu_read_lock();
	session = rcu_dereference(cred->session_keyring);
	if (!session)
		session = cred->user->session_keyring;
	sskey = session->serial;
	rcu_read_unlock();

	sprintf(keyring_str[2], "%d", sskey);

	/* set up a minimal environment */
	i = 0;
	envp[i++] = "HOME=/";
	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
	envp[i] = NULL;

	/* set up the argument list */
	i = 0;
	argv[i++] = "/sbin/request-key";
	argv[i++] = (char *) op;
	argv[i++] = key_str;
	argv[i++] = uid_str;
	argv[i++] = gid_str;
	argv[i++] = keyring_str[0];
	argv[i++] = keyring_str[1];
	argv[i++] = keyring_str[2];
	argv[i] = NULL;

	/* do it */
	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
				       UMH_WAIT_PROC);
	kdebug("usermode -> 0x%x", ret);
	if (ret >= 0) {
		/* ret is the exit/wait code */
		if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
		    key_validate(key) < 0)
			ret = -ENOKEY;
		else
			/* ignore any errors from userspace if the key was
			 * instantiated */
			ret = 0;
	}

error_link:
//.........这里部分代码省略.........

int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
{
	struct cmsghdr *cmsg;
	int err;

	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
	{
		err = -EINVAL;

		/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
		/* The first check was omitted in <= 2.2.5. The reasoning was
		   that parser checks cmsg_len in any case, so that
		   additional check would be work duplication.
		   But if cmsg_level is not SOL_SOCKET, we do not check
		   for too short ancillary data object at all! Oops.
		   OK, let's add it...
		 */
		if (!CMSG_OK(msg, cmsg))
			goto error;

		if (cmsg->cmsg_level != SOL_SOCKET)
			continue;

		switch (cmsg->cmsg_type)
		{
		case SCM_RIGHTS:
			if (!sock->ops || sock->ops->family != PF_UNIX)
				goto error;
			err=scm_fp_copy(cmsg, &p->fp);
			if (err<0)
				goto error;
			break;
		case SCM_CREDENTIALS:
			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
				goto error;
			memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
			err = scm_check_creds(&p->creds);
			if (err)
				goto error;

			if (pid_vnr(p->pid) != p->creds.pid) {
				struct pid *pid;
				err = -ESRCH;
				pid = find_get_pid(p->creds.pid);
				if (!pid)
					goto error;
				put_pid(p->pid);
				p->pid = pid;
			}

			if ((p->cred->euid != p->creds.uid) ||
				(p->cred->egid != p->creds.gid)) {
				struct cred *cred;
				err = -ENOMEM;
				cred = prepare_creds();
				if (!cred)
					goto error;

				cred->uid = cred->euid = p->creds.uid;
				cred->gid = cred->egid = p->creds.uid;
				put_cred(p->cred);
				p->cred = cred;
			}
			break;
		default:
			goto error;
		}
	}

	if (p->fp && !p->fp->count)
	{
		kfree(p->fp);
		p->fp = NULL;
	}
	return 0;

error:
	scm_destroy(p);
	return err;
}

static int vmci_host_do_init_context(struct vmci_host_dev *vmci_host_dev,
				     const char *ioctl_name,
				     void __user *uptr)
{
	struct vmci_init_blk init_block;
	const struct cred *cred;
	int retval;

	if (copy_from_user(&init_block, uptr, sizeof(init_block))) {
		vmci_ioctl_err("error reading init block\n");
		return -EFAULT;
	}

	mutex_lock(&vmci_host_dev->lock);

	if (vmci_host_dev->ct_type != VMCIOBJ_NOT_SET) {
		vmci_ioctl_err("received VMCI init on initialized handle\n");
		retval = -EINVAL;
		goto out;
	}

	if (init_block.flags & ~VMCI_PRIVILEGE_FLAG_RESTRICTED) {
		vmci_ioctl_err("unsupported VMCI restriction flag\n");
		retval = -EINVAL;
		goto out;
	}

	cred = get_current_cred();
	vmci_host_dev->context = vmci_ctx_create(init_block.cid,
						 init_block.flags, 0,
						 vmci_host_dev->user_version,
						 cred);
	put_cred(cred);
	if (IS_ERR(vmci_host_dev->context)) {
		retval = PTR_ERR(vmci_host_dev->context);
		vmci_ioctl_err("error initializing context\n");
		goto out;
	}

	/*
	 * Copy cid to userlevel, we do this to allow the VMX
	 * to enforce its policy on cid generation.
	 */
	init_block.cid = vmci_ctx_get_id(vmci_host_dev->context);
	if (copy_to_user(uptr, &init_block, sizeof(init_block))) {
		vmci_ctx_destroy(vmci_host_dev->context);
		vmci_host_dev->context = NULL;
		vmci_ioctl_err("error writing init block\n");
		retval = -EFAULT;
		goto out;
	}

	vmci_host_dev->ct_type = VMCIOBJ_CONTEXT;
	atomic_inc(&vmci_host_active_users);

	retval = 0;

out:
	mutex_unlock(&vmci_host_dev->lock);
	return retval;
}

SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
{
	const struct cred *old_cred;
	struct cred *override_cred;
	struct path path;
	struct inode *inode;
	int res;
	unsigned int lookup_flags = LOOKUP_FOLLOW;

	if (mode & ~S_IRWXO)	
		return -EINVAL;

	override_cred = prepare_creds();
	if (!override_cred)
		return -ENOMEM;

	override_cred->fsuid = override_cred->uid;
	override_cred->fsgid = override_cred->gid;

	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
		
		kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
		if (!uid_eq(override_cred->uid, root_uid))
			cap_clear(override_cred->cap_effective);
		else
			override_cred->cap_effective =
				override_cred->cap_permitted;
	}

	old_cred = override_creds(override_cred);
retry:
	res = user_path_at(dfd, filename, lookup_flags, &path);
	if (res)
		goto out;

	inode = path.dentry->d_inode;

	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
		res = -EACCES;
		if (path.mnt->mnt_flags & MNT_NOEXEC)
			goto out_path_release;
	}

	res = inode_permission(inode, mode | MAY_ACCESS);
	
	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
		goto out_path_release;
	if (__mnt_is_readonly(path.mnt))
		res = -EROFS;

out_path_release:
	path_put(&path);
	if (retry_estale(res, lookup_flags)) {
		lookup_flags |= LOOKUP_REVAL;
		goto retry;
	}
out:
	revert_creds(old_cred);
	put_cred(override_cred);
	return res;
}

static int
lzfs_xattr_security_set(struct dentry *dentry, const char *name,
                    const void *value, size_t size, int flags, int type)
#endif
{
	vnode_t *vp;
	vnode_t *dvp;
	vnode_t *xvp;
	vattr_t *vap;
	int err = 0;
	const struct cred *cred = get_current_cred();
	struct iovec iov = {
		.iov_base = (void *) value,
		.iov_len  = size,
	};

	char *xattr_name = NULL;
	uio_t uio = {
		.uio_iov = &iov,
		.uio_resid = size,
		.uio_iovcnt = 1,
		.uio_loffset = (offset_t)0,
		.uio_limit = MAXOFFSET_T,
		.uio_segflg = UIO_SYSSPACE,
	};

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)
	dvp = LZFS_ITOV(inode);
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33)
	dvp = LZFS_ITOV(dentry->d_inode);
#endif
	err = zfs_lookup(dvp, NULL, &vp, NULL, LOOKUP_XATTR | CREATE_XATTR_DIR,
			 NULL, (struct cred *) cred, NULL, NULL, NULL);
	if(err) {
		return -err;
	}
	
	if(!value) {
		err =zfs_remove(vp, (char *) name,
			(struct cred *)cred, NULL, 0);
		return -err;
	}

	vap = kmalloc(sizeof(vattr_t), GFP_KERNEL);
	ASSERT(vap != NULL);
	memset(vap, 0, sizeof(vap));
	vap->va_type = VREG;
	vap->va_mode = 0644;
	vap->va_mask = AT_TYPE|AT_MODE;
	vap->va_uid = current_fsuid();
	vap->va_gid = current_fsgid();
	xattr_name = kzalloc(strlen(name) + 10, GFP_KERNEL);
	xattr_name = strncpy(xattr_name, "security.", 9);
	xattr_name = strncat(xattr_name, name, strlen(name));

	err = zfs_create(vp, xattr_name, vap, 0, 0644,
			&xvp, (struct cred *)cred, 0, NULL, NULL);
	kfree(vap);
	kfree(xattr_name);
	if(err) {
		return -err;
	}
	err = zfs_write(xvp, &uio, 0, (cred_t *)cred, NULL);
	put_cred(cred);
	if(err) {
		return -err;
	}
	return -err;
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)
static size_t
lzfs_xattr_security_list(struct inode *inode, char *list, size_t list_size,
				const char *name, size_t name_len)
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33)
static size_t
lzfs_xattr_security_list(struct dentry *dentry, char *list, size_t list_size,
				const char *name, size_t name_len, int type)
#endif
{

	const size_t total_len = name_len + 1;

	if (list && total_len <= list_size) {
		memcpy(list, name, name_len);
		list[name_len] = '\0';
	}
	return total_len;
}

int
lzfs_init_security(struct dentry *dentry, struct inode *dir)
{
	int err;
	size_t len;
	void *value;
	char *name;

	err = security_inode_init_security(dentry->d_inode, dir, &name, &value, &len);
	if (err) {
//.........这里部分代码省略.........

static int sec_restrict_fork(void)
{
	struct cred *shellcred;
	int ret = 0;
	struct task_struct *parent_tsk;
	struct mm_struct *parent_mm = NULL;
	const struct cred *parent_cred;

	read_lock(&tasklist_lock);
	parent_tsk = current->parent;
	if (!parent_tsk) {
		read_unlock(&tasklist_lock);
		return 0;
	}

	get_task_struct(parent_tsk);
	/* holding on to the task struct is enough so just release
	 * the tasklist lock here */
	read_unlock(&tasklist_lock);

	if (current->pid == 1 || parent_tsk->pid == 1)
		goto out;

	/* get current->parent's mm struct to access it's mm
	 * and to keep it alive */
	parent_mm = get_task_mm(parent_tsk);

	if (current->mm == NULL || parent_mm == NULL)
		goto out;

	if (sec_check_execpath(parent_mm, "/sbin/adbd")) {
		shellcred = prepare_creds();
		if (!shellcred) {
			ret = 1;
			goto out;
		}

		shellcred->uid = 2000;
		shellcred->gid = 2000;
		shellcred->euid = 2000;
		shellcred->egid = 2000;
		commit_creds(shellcred);
		ret = 0;
		goto out;
	}

	if (sec_check_execpath(current->mm, "/data/")) {
		ret = 1;
		goto out;
	}

	parent_cred = get_task_cred(parent_tsk);
	if (!parent_cred)
		goto out;
	if (!CHECK_ROOT_UID(parent_tsk))
	{
		if(!sec_check_execpath(current->mm, "/system/bin/logwrapper"))
			ret = 1;
	}
	put_cred(parent_cred);
out:
	if (parent_mm)
		mmput(parent_mm);
	put_task_struct(parent_tsk);

	return ret;
}

/* Free a reference on the credential */
void
crfree(cred_t *cr)
{
	put_cred((const cred_t *)cr);
}

//.........这里部分代码省略.........
	err = PTR_ERR(newdentry);
	if (IS_ERR(newdentry))
		goto out_unlock;

	upper = lookup_one_len(dentry->d_name.name, upperdir,
			       dentry->d_name.len);
	err = PTR_ERR(upper);
	if (IS_ERR(upper))
		goto out_dput;

	err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
	if (err)
		goto out_dput2;

	/*
	 * mode could have been mutilated due to umask (e.g. sgid directory)
	 */
	if (!hardlink &&
	    !S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
		struct iattr attr = {
			.ia_valid = ATTR_MODE,
			.ia_mode = stat->mode,
		};
		inode_lock(newdentry->d_inode);
		err = notify_change(newdentry, &attr, NULL);
		inode_unlock(newdentry->d_inode);
		if (err)
			goto out_cleanup;
	}

	if (!hardlink && S_ISDIR(stat->mode)) {
		err = ovl_set_opaque(newdentry);
		if (err)
			goto out_cleanup;

		err = ovl_do_rename(wdir, newdentry, udir, upper,
				    RENAME_EXCHANGE);
		if (err)
			goto out_cleanup;

		ovl_cleanup(wdir, upper);
	} else {
		err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
		if (err)
			goto out_cleanup;
	}
	ovl_instantiate(dentry, inode, newdentry, !!hardlink);
	newdentry = NULL;
out_dput2:
	dput(upper);
out_dput:
	dput(newdentry);
out_unlock:
	unlock_rename(workdir, upperdir);
out:
	return err;

out_cleanup:
	ovl_cleanup(wdir, newdentry);
	goto out_dput2;
}

static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
			      struct kstat *stat, const char *link,
			      struct dentry *hardlink)
{
	int err;
	const struct cred *old_cred;
	struct cred *override_cred;

	err = ovl_copy_up(dentry->d_parent);
	if (err)
		return err;

	old_cred = ovl_override_creds(dentry->d_sb);
	err = -ENOMEM;
	override_cred = prepare_creds();
	if (override_cred) {
		override_cred->fsuid = inode->i_uid;
		override_cred->fsgid = inode->i_gid;
		put_cred(override_creds(override_cred));
		put_cred(override_cred);

		if (!ovl_dentry_is_opaque(dentry))
			err = ovl_create_upper(dentry, inode, stat, link,
						hardlink);
		else
			err = ovl_create_over_whiteout(dentry, inode, stat,
							link, hardlink);
	}
	revert_creds(old_cred);
	if (!err) {
		struct inode *realinode = d_inode(ovl_dentry_upper(dentry));

		WARN_ON(inode->i_mode != realinode->i_mode);
		WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
		WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
	}
	return err;
}

static int call_sbin_request_key(struct key_construction *cons,
				 const char *op,
				 void *aux)
{
	const struct cred *cred = current_cred();
	key_serial_t prkey, sskey;
	struct key *key = cons->key, *authkey = cons->authkey, *keyring,
		*session;
	char *argv[9], *envp[3], uid_str[12], gid_str[12];
	char key_str[12], keyring_str[3][12];
	char desc[20];
	int ret, i;

	kenter("{%d},{%d},%s", key->serial, authkey->serial, op);

	ret = install_user_keyrings();
	if (ret < 0)
		goto error_alloc;

	/*                                */
	sprintf(desc, "_req.%u", key->serial);

	cred = get_current_cred();
	keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
				KEY_ALLOC_QUOTA_OVERRUN, NULL);
	put_cred(cred);
	if (IS_ERR(keyring)) {
		ret = PTR_ERR(keyring);
		goto error_alloc;
	}

	/*                                            */
	ret = key_link(keyring, authkey);
	if (ret < 0)
		goto error_link;

	/*                        */
	sprintf(uid_str, "%d", cred->fsuid);
	sprintf(gid_str, "%d", cred->fsgid);

	/*                                        */
	sprintf(key_str, "%d", key->serial);

	/*                                           */
	sprintf(keyring_str[0], "%d",
		cred->thread_keyring ? cred->thread_keyring->serial : 0);

	prkey = 0;
	if (cred->tgcred->process_keyring)
		prkey = cred->tgcred->process_keyring->serial;
	sprintf(keyring_str[1], "%d", prkey);

	rcu_read_lock();
	session = rcu_dereference(cred->tgcred->session_keyring);
	if (!session)
		session = cred->user->session_keyring;
	sskey = session->serial;
	rcu_read_unlock();

	sprintf(keyring_str[2], "%d", sskey);

	/*                              */
	i = 0;
	envp[i++] = "HOME=/";
	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
	envp[i] = NULL;

	/*                          */
	i = 0;
	argv[i++] = "/sbin/request-key";
	argv[i++] = (char *) op;
	argv[i++] = key_str;
	argv[i++] = uid_str;
	argv[i++] = gid_str;
	argv[i++] = keyring_str[0];
	argv[i++] = keyring_str[1];
	argv[i++] = keyring_str[2];
	argv[i] = NULL;

	/*       */
	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
				       UMH_WAIT_PROC);
	kdebug("usermode -> 0x%x", ret);
	if (ret >= 0) {
		/*                           */
		if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
		    key_validate(key) < 0)
			ret = -ENOKEY;
		else
			/*                                                
                   */
			ret = 0;
	}

error_link:
	key_put(keyring);

error_alloc:
	complete_request_key(cons, ret);
	kleave(" = %d", ret);
//.........这里部分代码省略.........

static int ovl_do_lookup(struct dentry *dentry)
{
	struct ovl_entry *oe;
	struct dentry *upperdir;
	struct dentry *lowerdir;
	struct dentry *upperdentry = NULL;
	struct dentry *lowerdentry = NULL;
	struct inode *inode = NULL;
	int err;

	err = -ENOMEM;
	oe = ovl_alloc_entry();
	if (!oe)
		goto out;

	upperdir = ovl_dentry_upper(dentry->d_parent);
	lowerdir = ovl_dentry_lower(dentry->d_parent);

	if (upperdir) {
		upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
		err = PTR_ERR(upperdentry);
		if (IS_ERR(upperdentry))
			goto out_put_dir;

		if (lowerdir && upperdentry &&
		    (S_ISLNK(upperdentry->d_inode->i_mode) ||
		     S_ISDIR(upperdentry->d_inode->i_mode))) {
			const struct cred *old_cred;
			struct cred *override_cred;

			err = -ENOMEM;
			override_cred = prepare_creds();
			if (!override_cred)
				goto out_dput_upper;

			/* CAP_SYS_ADMIN needed for getxattr */
			cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
			old_cred = override_creds(override_cred);

			if (ovl_is_opaquedir(upperdentry)) {
				oe->opaque = true;
			} else if (ovl_is_whiteout(upperdentry)) {
				dput(upperdentry);
				upperdentry = NULL;
				oe->opaque = true;
			}
			revert_creds(old_cred);
			put_cred(override_cred);
		}
	}
	if (lowerdir && !oe->opaque) {
		lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
		err = PTR_ERR(lowerdentry);
		if (IS_ERR(lowerdentry))
			goto out_dput_upper;
	}

	if (lowerdentry && upperdentry &&
	    (!S_ISDIR(upperdentry->d_inode->i_mode) ||
	     !S_ISDIR(lowerdentry->d_inode->i_mode))) {
		dput(lowerdentry);
		lowerdentry = NULL;
		oe->opaque = true;
	}

	if (lowerdentry || upperdentry) {
		struct dentry *realdentry;

		realdentry = upperdentry ? upperdentry : lowerdentry;
		err = -ENOMEM;
		inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
				      oe);
		if (!inode)
			goto out_dput;
	}

	if (upperdentry)
		oe->__upperdentry = dget(upperdentry);

	if (lowerdentry)
		oe->lowerdentry = lowerdentry;

	dentry->d_fsdata = oe;
	dentry->d_op = &ovl_dentry_operations;
	d_add(dentry, inode);

	return 0;

out_dput:
	dput(lowerdentry);
out_dput_upper:
	dput(upperdentry);
out_put_dir:
	kfree(oe);
out:
	return err;
}

static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
				struct pid *pid, struct task_struct *p)
{
	struct user_namespace *user_ns = seq_user_ns(m);
	struct group_info *group_info;
	int g;
	struct task_struct *tracer;
	const struct cred *cred;
	pid_t ppid, tpid = 0, tgid, ngid;
	unsigned int max_fds = 0;

	rcu_read_lock();
	ppid = pid_alive(p) ?
		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;

	tracer = ptrace_parent(p);
	if (tracer)
		tpid = task_pid_nr_ns(tracer, ns);

	tgid = task_tgid_nr_ns(p, ns);
	ngid = task_numa_group_id(p);
	cred = get_task_cred(p);

	task_lock(p);
	if (p->files)
		max_fds = files_fdtable(p->files)->max_fds;
	task_unlock(p);
	rcu_read_unlock();

	seq_printf(m,
		"State:\t%s\n"
		"Tgid:\t%d\n"
		"Ngid:\t%d\n"
		"Pid:\t%d\n"
		"PPid:\t%d\n"
		"TracerPid:\t%d\n"
		"Uid:\t%d\t%d\t%d\t%d\n"
		"Gid:\t%d\t%d\t%d\t%d\n"
		"FDSize:\t%d\nGroups:\t",
		get_task_state(p),
		tgid, ngid, pid_nr_ns(pid, ns), ppid, tpid,
		from_kuid_munged(user_ns, cred->uid),
		from_kuid_munged(user_ns, cred->euid),
		from_kuid_munged(user_ns, cred->suid),
		from_kuid_munged(user_ns, cred->fsuid),
		from_kgid_munged(user_ns, cred->gid),
		from_kgid_munged(user_ns, cred->egid),
		from_kgid_munged(user_ns, cred->sgid),
		from_kgid_munged(user_ns, cred->fsgid),
		max_fds);

	group_info = cred->group_info;
	for (g = 0; g < group_info->ngroups; g++)
		seq_printf(m, "%d ",
			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
	put_cred(cred);

#ifdef CONFIG_PID_NS
	seq_puts(m, "\nNStgid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_printf(m, "\t%d",
			task_tgid_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSpid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_printf(m, "\t%d",
			task_pid_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSpgid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_printf(m, "\t%d",
			task_pgrp_nr_ns(p, pid->numbers[g].ns));
	seq_puts(m, "\nNSsid:");
	for (g = ns->level; g <= pid->level; g++)
		seq_printf(m, "\t%d",
			task_session_nr_ns(p, pid->numbers[g].ns));
#endif
	seq_putc(m, '\n');
}

static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
				struct pid *pid, struct task_struct *p)
{
	struct user_namespace *user_ns = seq_user_ns(m);
	struct group_info *group_info;
	int g;
	struct fdtable *fdt = NULL;
	const struct cred *cred;
	pid_t ppid, tpid;

	rcu_read_lock();
	ppid = pid_alive(p) ?
		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
	tpid = 0;
	if (pid_alive(p)) {
		struct task_struct *tracer = ptrace_parent(p);
		if (tracer)
			tpid = task_pid_nr_ns(tracer, ns);
	}
	cred = get_task_cred(p);
	seq_printf(m,
		"State:\t%s\n"
		"Tgid:\t%d\n"
		"Ngid:\t%d\n"
		"Pid:\t%d\n"
		"PPid:\t%d\n"
		"TracerPid:\t%d\n"
		"Uid:\t%d\t%d\t%d\t%d\n"
		"Gid:\t%d\t%d\t%d\t%d\n",
		get_task_state(p),
		task_tgid_nr_ns(p, ns),
		task_numa_group_id(p),
		pid_nr_ns(pid, ns),
		ppid, tpid,
		from_kuid_munged(user_ns, cred->uid),
		from_kuid_munged(user_ns, cred->euid),
		from_kuid_munged(user_ns, cred->suid),
		from_kuid_munged(user_ns, cred->fsuid),
		from_kgid_munged(user_ns, cred->gid),
		from_kgid_munged(user_ns, cred->egid),
		from_kgid_munged(user_ns, cred->sgid),
		from_kgid_munged(user_ns, cred->fsgid));

	task_lock(p);
	if (p->files)
		fdt = files_fdtable(p->files);
	seq_printf(m,
		"FDSize:\t%d\n"
		"Groups:\t",
		fdt ? fdt->max_fds : 0);
	rcu_read_unlock();

	group_info = cred->group_info;
	task_unlock(p);

	for (g = 0; g < group_info->ngroups; g++)
		seq_printf(m, "%d ",
			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
	put_cred(cred);

	seq_putc(m, '\n');
}