security/keys/request_key_auth.c - arm/linux - Git at Google

 /* Request key authorisation token key definition.
  *
  * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  *
  * See Documentation/security/keys/request-key.rst
  */

 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include "internal.h"
 #include <keys/user-type.h>

 static int request_key_auth_preparse(struct key_preparsed_payload *);
 static void request_key_auth_free_preparse(struct key_preparsed_payload *);
 static int request_key_auth_instantiate(struct key *,
 					struct key_preparsed_payload *);
 static void request_key_auth_describe(const struct key *, struct seq_file *);
 static void request_key_auth_revoke(struct key *);
 static void request_key_auth_destroy(struct key *);
 static long request_key_auth_read(const struct key *, char __user *, size_t);

 /*
  * The request-key authorisation key type definition.
  */
 struct key_type key_type_request_key_auth = {
 	.name		= ".request_key_auth",
 	.def_datalen	= sizeof(struct request_key_auth),
 	.preparse	= request_key_auth_preparse,
 	.free_preparse	= request_key_auth_free_preparse,
 	.instantiate	= request_key_auth_instantiate,
 	.describe	= request_key_auth_describe,
 	.revoke		= request_key_auth_revoke,
 	.destroy	= request_key_auth_destroy,
 	.read		= request_key_auth_read,
 };

 static int request_key_auth_preparse(struct key_preparsed_payload *prep)
 {
 	return 0;
 }

 static void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
 {
 }

 /*
  * Instantiate a request-key authorisation key.
  */
 static int request_key_auth_instantiate(struct key *key,
 					struct key_preparsed_payload *prep)
 {
 	key->payload.data[0] = (struct request_key_auth *)prep->data;
 	return 0;
 }

 /*
  * Describe an authorisation token.
  */
 static void request_key_auth_describe(const struct key *key,
 				      struct seq_file *m)
 {
 	struct request_key_auth *rka = key->payload.data[0];

 	seq_puts(m, "key:");
 	seq_puts(m, key->description);
 	if (key_is_instantiated(key))
 		seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
 }

 /*
  * Read the callout_info data (retrieves the callout information).
  * - the key's semaphore is read-locked
  */
 static long request_key_auth_read(const struct key *key,
 				  char __user *buffer, size_t buflen)
 {
 	struct request_key_auth *rka = key->payload.data[0];
 	size_t datalen;
 	long ret;

 	datalen = rka->callout_len;
 	ret = datalen;

 	/* we can return the data as is */
 	if (buffer && buflen > 0) {
 		if (buflen > datalen)
 			buflen = datalen;

 		if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
 			ret = -EFAULT;
 	}

 	return ret;
 }

 /*
  * Handle revocation of an authorisation token key.
  *
  * Called with the key sem write-locked.
  */
 static void request_key_auth_revoke(struct key *key)
 {
 	struct request_key_auth *rka = key->payload.data[0];

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

 	if (rka->cred) {
 		put_cred(rka->cred);
 		rka->cred = NULL;
 	}
 }

 static void free_request_key_auth(struct request_key_auth *rka)
 {
 	if (!rka)
 		return;
 	key_put(rka->target_key);
 	key_put(rka->dest_keyring);
 	if (rka->cred)
 		put_cred(rka->cred);
 	kfree(rka->callout_info);
 	kfree(rka);
 }

 /*
  * Destroy an instantiation authorisation token key.
  */
 static void request_key_auth_destroy(struct key *key)
 {
 	struct request_key_auth *rka = key->payload.data[0];

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

 	free_request_key_auth(rka);
 }

 /*
  * Create an authorisation token for /sbin/request-key or whoever to gain
  * access to the caller's security data.
  */
 struct key *request_key_auth_new(struct key *target, const void *callout_info,
 				 size_t callout_len, struct key *dest_keyring)
 {
 	struct request_key_auth *rka, *irka;
 	const struct cred *cred = current->cred;
 	struct key *authkey = NULL;
 	char desc[20];
 	int ret = -ENOMEM;

 	kenter("%d,", target->serial);

 	/* allocate a auth record */
 	rka = kzalloc(sizeof(*rka), GFP_KERNEL);
 	if (!rka)
 		goto error;
 	rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
 	if (!rka->callout_info)
 		goto error_free_rka;
 	rka->callout_len = callout_len;

 	/* see if the calling process is already servicing the key request of
 	 * another process */
 	if (cred->request_key_auth) {
 		/* it is - use that instantiation context here too */
 		down_read(&cred->request_key_auth->sem);

 		/* if the auth key has been revoked, then the key we're
 		 * servicing is already instantiated */
 		if (test_bit(KEY_FLAG_REVOKED,
 			     &cred->request_key_auth->flags)) {
 			up_read(&cred->request_key_auth->sem);
 			ret = -EKEYREVOKED;
 			goto error_free_rka;
 		}

 		irka = cred->request_key_auth->payload.data[0];
 		rka->cred = get_cred(irka->cred);
 		rka->pid = irka->pid;

 		up_read(&cred->request_key_auth->sem);
 	}
 	else {
 		/* it isn't - use this process as the context */
 		rka->cred = get_cred(cred);
 		rka->pid = current->pid;
 	}

 	rka->target_key = key_get(target);
 	rka->dest_keyring = key_get(dest_keyring);

 	/* allocate the auth key */
 	sprintf(desc, "%x", target->serial);

 	authkey = key_alloc(&key_type_request_key_auth, desc,
 			    cred->fsuid, cred->fsgid, cred,
 			    KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
 			    KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
 	if (IS_ERR(authkey)) {
 		ret = PTR_ERR(authkey);
 		goto error_free_rka;
 	}

 	/* construct the auth key */
 	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
 	if (ret < 0)
 		goto error_put_authkey;

 	kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
 	return authkey;

 error_put_authkey:
 	key_put(authkey);
 error_free_rka:
 	free_request_key_auth(rka);
 error:
 	kleave("= %d", ret);
 	return ERR_PTR(ret);
 }

 /*
  * Search the current process's keyrings for the authorisation key for
  * instantiation of a key.
  */
 struct key *key_get_instantiation_authkey(key_serial_t target_id)
 {
 	char description[16];
 	struct keyring_search_context ctx = {
 		.index_key.type		= &key_type_request_key_auth,
 		.index_key.description	= description,
 		.cred			= current_cred(),
 		.match_data.cmp		= key_default_cmp,
 		.match_data.raw_data	= description,
 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 		.flags			= KEYRING_SEARCH_DO_STATE_CHECK,
 	};
 	struct key *authkey;
 	key_ref_t authkey_ref;

 	sprintf(description, "%x", target_id);

 	authkey_ref = search_process_keyrings(&ctx);

 	if (IS_ERR(authkey_ref)) {
 		authkey = ERR_CAST(authkey_ref);
 		if (authkey == ERR_PTR(-EAGAIN))
 			authkey = ERR_PTR(-ENOKEY);
 		goto error;
 	}

 	authkey = key_ref_to_ptr(authkey_ref);
 	if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
 		key_put(authkey);
 		authkey = ERR_PTR(-EKEYREVOKED);
 	}

 error:
 	return authkey;
 }
	/* Request key authorisation token key definition.
	*
	* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	* See Documentation/security/keys/request-key.rst
	*/

	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/err.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/uaccess.h>
	#include "internal.h"
	#include <keys/user-type.h>

	static int request_key_auth_preparse(struct key_preparsed_payload *);
	static void request_key_auth_free_preparse(struct key_preparsed_payload *);
	static int request_key_auth_instantiate(struct key *,
	struct key_preparsed_payload *);
	static void request_key_auth_describe(const struct key , struct seq_file );
	static void request_key_auth_revoke(struct key *);
	static void request_key_auth_destroy(struct key *);
	static long request_key_auth_read(const struct key , char __user , size_t);

	/*
	* The request-key authorisation key type definition.
	*/
	struct key_type key_type_request_key_auth = {
	.name = ".request_key_auth",
	.def_datalen = sizeof(struct request_key_auth),
	.preparse = request_key_auth_preparse,
	.free_preparse = request_key_auth_free_preparse,
	.instantiate = request_key_auth_instantiate,
	.describe = request_key_auth_describe,
	.revoke = request_key_auth_revoke,
	.destroy = request_key_auth_destroy,
	.read = request_key_auth_read,
	};

	static int request_key_auth_preparse(struct key_preparsed_payload *prep)
	{
	return 0;
	}

	static void request_key_auth_free_preparse(struct key_preparsed_payload *prep)
	{
	}

	/*
	* Instantiate a request-key authorisation key.
	*/
	static int request_key_auth_instantiate(struct key *key,
	struct key_preparsed_payload *prep)
	{
	key->payload.data[0] = (struct request_key_auth *)prep->data;
	return 0;
	}

	/*
	* Describe an authorisation token.
	*/
	static void request_key_auth_describe(const struct key *key,
	struct seq_file *m)
	{
	struct request_key_auth *rka = key->payload.data[0];

	seq_puts(m, "key:");
	seq_puts(m, key->description);
	if (key_is_instantiated(key))
	seq_printf(m, " pid:%d ci:%zu", rka->pid, rka->callout_len);
	}

	/*
	* Read the callout_info data (retrieves the callout information).
	* - the key's semaphore is read-locked
	*/
	static long request_key_auth_read(const struct key *key,
	char __user *buffer, size_t buflen)
	{
	struct request_key_auth *rka = key->payload.data[0];
	size_t datalen;
	long ret;

	datalen = rka->callout_len;
	ret = datalen;

	/* we can return the data as is */
	if (buffer && buflen > 0) {
	if (buflen > datalen)
	buflen = datalen;

	if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
	ret = -EFAULT;
	}

	return ret;
	}

	/*
	* Handle revocation of an authorisation token key.
	*
	* Called with the key sem write-locked.
	*/
	static void request_key_auth_revoke(struct key *key)
	{
	struct request_key_auth *rka = key->payload.data[0];

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

	if (rka->cred) {
	put_cred(rka->cred);
	rka->cred = NULL;
	}
	}

	static void free_request_key_auth(struct request_key_auth *rka)
	{
	if (!rka)
	return;
	key_put(rka->target_key);
	key_put(rka->dest_keyring);
	if (rka->cred)
	put_cred(rka->cred);
	kfree(rka->callout_info);
	kfree(rka);
	}

	/*
	* Destroy an instantiation authorisation token key.
	*/
	static void request_key_auth_destroy(struct key *key)
	{
	struct request_key_auth *rka = key->payload.data[0];

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

	free_request_key_auth(rka);
	}

	/*
	* Create an authorisation token for /sbin/request-key or whoever to gain
	* access to the caller's security data.
	*/
	struct key request_key_auth_new(struct key target, const void *callout_info,
	size_t callout_len, struct key *dest_keyring)
	{
	struct request_key_auth rka, irka;
	const struct cred *cred = current->cred;
	struct key *authkey = NULL;
	char desc[20];
	int ret = -ENOMEM;

	kenter("%d,", target->serial);

	/* allocate a auth record */
	rka = kzalloc(sizeof(*rka), GFP_KERNEL);
	if (!rka)
	goto error;
	rka->callout_info = kmemdup(callout_info, callout_len, GFP_KERNEL);
	if (!rka->callout_info)
	goto error_free_rka;
	rka->callout_len = callout_len;

	/* see if the calling process is already servicing the key request of
	* another process */
	if (cred->request_key_auth) {
	/* it is - use that instantiation context here too */
	down_read(&cred->request_key_auth->sem);

	/* if the auth key has been revoked, then the key we're
	* servicing is already instantiated */
	if (test_bit(KEY_FLAG_REVOKED,
	&cred->request_key_auth->flags)) {
	up_read(&cred->request_key_auth->sem);
	ret = -EKEYREVOKED;
	goto error_free_rka;
	}

	irka = cred->request_key_auth->payload.data[0];
	rka->cred = get_cred(irka->cred);
	rka->pid = irka->pid;

	up_read(&cred->request_key_auth->sem);
	}
	else {
	/* it isn't - use this process as the context */
	rka->cred = get_cred(cred);
	rka->pid = current->pid;
	}

	rka->target_key = key_get(target);
	rka->dest_keyring = key_get(dest_keyring);

	/* allocate the auth key */
	sprintf(desc, "%x", target->serial);

	authkey = key_alloc(&key_type_request_key_auth, desc,
	cred->fsuid, cred->fsgid, cred,
	KEY_POS_VIEW \| KEY_POS_READ \| KEY_POS_SEARCH \|
	KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA, NULL);
	if (IS_ERR(authkey)) {
	ret = PTR_ERR(authkey);
	goto error_free_rka;
	}

	/* construct the auth key */
	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
	if (ret < 0)
	goto error_put_authkey;

	kleave(" = {%d,%d}", authkey->serial, refcount_read(&authkey->usage));
	return authkey;

	error_put_authkey:
	key_put(authkey);
	error_free_rka:
	free_request_key_auth(rka);
	error:
	kleave("= %d", ret);
	return ERR_PTR(ret);
	}

	/*
	* Search the current process's keyrings for the authorisation key for
	* instantiation of a key.
	*/
	struct key *key_get_instantiation_authkey(key_serial_t target_id)
	{
	char description[16];
	struct keyring_search_context ctx = {
	.index_key.type = &key_type_request_key_auth,
	.index_key.description = description,
	.cred = current_cred(),
	.match_data.cmp = key_default_cmp,
	.match_data.raw_data = description,
	.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
	.flags = KEYRING_SEARCH_DO_STATE_CHECK,
	};
	struct key *authkey;
	key_ref_t authkey_ref;

	sprintf(description, "%x", target_id);

	authkey_ref = search_process_keyrings(&ctx);

	if (IS_ERR(authkey_ref)) {
	authkey = ERR_CAST(authkey_ref);
	if (authkey == ERR_PTR(-EAGAIN))
	authkey = ERR_PTR(-ENOKEY);
	goto error;
	}

	authkey = key_ref_to_ptr(authkey_ref);
	if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
	key_put(authkey);
	authkey = ERR_PTR(-EKEYREVOKED);
	}

	error:
	return authkey;
	}