linux_dsm_epyc7002/security/keys/request_key.c
Linus Torvalds 028db3e290 Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"
This reverts merge 0f75ef6a9c (and thus
effectively commits

   7a1ade8475 ("keys: Provide KEYCTL_GRANT_PERMISSION")
   2e12256b9a ("keys: Replace uid/gid/perm permissions checking with an ACL")

that the merge brought in).

It turns out that it breaks booting with an encrypted volume, and Eric
biggers reports that it also breaks the fscrypt tests [1] and loading of
in-kernel X.509 certificates [2].

The root cause of all the breakage is likely the same, but David Howells
is off email so rather than try to work it out it's getting reverted in
order to not impact the rest of the merge window.

 [1] https://lore.kernel.org/lkml/20190710011559.GA7973@sol.localdomain/
 [2] https://lore.kernel.org/lkml/20190710013225.GB7973@sol.localdomain/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-10 18:43:43 -07:00

806 lines
21 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* Request a key from userspace
*
* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* See Documentation/security/keys/request-key.rst
*/
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/err.h>
#include <linux/keyctl.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include "internal.h"
#include <keys/request_key_auth-type.h>
#define key_negative_timeout 60 /* default timeout on a negative key's existence */
static struct key *check_cached_key(struct keyring_search_context *ctx)
{
#ifdef CONFIG_KEYS_REQUEST_CACHE
struct key *key = current->cached_requested_key;
if (key &&
ctx->match_data.cmp(key, &ctx->match_data) &&
!(key->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED))))
return key_get(key);
#endif
return NULL;
}
static void cache_requested_key(struct key *key)
{
#ifdef CONFIG_KEYS_REQUEST_CACHE
struct task_struct *t = current;
key_put(t->cached_requested_key);
t->cached_requested_key = key_get(key);
set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
#endif
}
/**
* complete_request_key - Complete the construction of a key.
* @authkey: The authorisation key.
* @error: The success or failute of the construction.
*
* Complete the attempt to construct a key. The key will be negated
* if an error is indicated. The authorisation key will be revoked
* unconditionally.
*/
void complete_request_key(struct key *authkey, int error)
{
struct request_key_auth *rka = get_request_key_auth(authkey);
struct key *key = rka->target_key;
kenter("%d{%d},%d", authkey->serial, key->serial, error);
if (error < 0)
key_negate_and_link(key, key_negative_timeout, NULL, authkey);
else
key_revoke(authkey);
}
EXPORT_SYMBOL(complete_request_key);
/*
* Initialise a usermode helper that is going to have a specific session
* keyring.
*
* This is called in context of freshly forked kthread before kernel_execve(),
* so we can simply install the desired session_keyring at this point.
*/
static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
{
struct key *keyring = info->data;
return install_session_keyring_to_cred(cred, keyring);
}
/*
* Clean up a usermode helper with session keyring.
*/
static void umh_keys_cleanup(struct subprocess_info *info)
{
struct key *keyring = info->data;
key_put(keyring);
}
/*
* Call a usermode helper with a specific session keyring.
*/
static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
struct key *session_keyring, int wait)
{
struct subprocess_info *info;
info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
umh_keys_init, umh_keys_cleanup,
session_keyring);
if (!info)
return -ENOMEM;
key_get(session_keyring);
return call_usermodehelper_exec(info, wait);
}
/*
* 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 *authkey, void *aux)
{
static char const request_key[] = "/sbin/request-key";
struct request_key_auth *rka = get_request_key_auth(authkey);
const struct cred *cred = current_cred();
key_serial_t prkey, sskey;
struct key *key = rka->target_key, *keyring, *session, *user_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, rka->op);
ret = look_up_user_keyrings(NULL, &user_session);
if (ret < 0)
goto error_us;
/* 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);
session = cred->session_keyring;
if (!session)
session = user_session;
sskey = session->serial;
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++] = (char *)request_key;
argv[i++] = (char *)rka->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(request_key, 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:
key_put(keyring);
error_alloc:
key_put(user_session);
error_us:
complete_request_key(authkey, ret);
kleave(" = %d", ret);
return ret;
}
/*
* Call out to userspace for key construction.
*
* Program failure is ignored in favour of key status.
*/
static int construct_key(struct key *key, const void *callout_info,
size_t callout_len, void *aux,
struct key *dest_keyring)
{
request_key_actor_t actor;
struct key *authkey;
int ret;
kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
/* allocate an authorisation key */
authkey = request_key_auth_new(key, "create", callout_info, callout_len,
dest_keyring);
if (IS_ERR(authkey))
return PTR_ERR(authkey);
/* Make the call */
actor = call_sbin_request_key;
if (key->type->request_key)
actor = key->type->request_key;
ret = actor(authkey, aux);
/* check that the actor called complete_request_key() prior to
* returning an error */
WARN_ON(ret < 0 &&
!test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
key_put(authkey);
kleave(" = %d", ret);
return ret;
}
/*
* Get the appropriate destination keyring for the request.
*
* The keyring selected is returned with an extra reference upon it which the
* caller must release.
*/
static int construct_get_dest_keyring(struct key **_dest_keyring)
{
struct request_key_auth *rka;
const struct cred *cred = current_cred();
struct key *dest_keyring = *_dest_keyring, *authkey;
int ret;
kenter("%p", dest_keyring);
/* find the appropriate keyring */
if (dest_keyring) {
/* the caller supplied one */
key_get(dest_keyring);
} else {
bool do_perm_check = true;
/* use a default keyring; falling through the cases until we
* find one that we actually have */
switch (cred->jit_keyring) {
case KEY_REQKEY_DEFL_DEFAULT:
case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
if (cred->request_key_auth) {
authkey = cred->request_key_auth;
down_read(&authkey->sem);
rka = get_request_key_auth(authkey);
if (!test_bit(KEY_FLAG_REVOKED,
&authkey->flags))
dest_keyring =
key_get(rka->dest_keyring);
up_read(&authkey->sem);
if (dest_keyring) {
do_perm_check = false;
break;
}
}
/* fall through */
case KEY_REQKEY_DEFL_THREAD_KEYRING:
dest_keyring = key_get(cred->thread_keyring);
if (dest_keyring)
break;
/* fall through */
case KEY_REQKEY_DEFL_PROCESS_KEYRING:
dest_keyring = key_get(cred->process_keyring);
if (dest_keyring)
break;
/* fall through */
case KEY_REQKEY_DEFL_SESSION_KEYRING:
dest_keyring = key_get(cred->session_keyring);
if (dest_keyring)
break;
/* fall through */
case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
ret = look_up_user_keyrings(NULL, &dest_keyring);
if (ret < 0)
return ret;
break;
case KEY_REQKEY_DEFL_USER_KEYRING:
ret = look_up_user_keyrings(&dest_keyring, NULL);
if (ret < 0)
return ret;
break;
case KEY_REQKEY_DEFL_GROUP_KEYRING:
default:
BUG();
}
/*
* Require Write permission on the keyring. This is essential
* because the default keyring may be the session keyring, and
* joining a keyring only requires Search permission.
*
* However, this check is skipped for the "requestor keyring" so
* that /sbin/request-key can itself use request_key() to add
* keys to the original requestor's destination keyring.
*/
if (dest_keyring && do_perm_check) {
ret = key_permission(make_key_ref(dest_keyring, 1),
KEY_NEED_WRITE);
if (ret) {
key_put(dest_keyring);
return ret;
}
}
}
*_dest_keyring = dest_keyring;
kleave(" [dk %d]", key_serial(dest_keyring));
return 0;
}
/*
* Allocate a new key in under-construction state and attempt to link it in to
* the requested keyring.
*
* May return a key that's already under construction instead if there was a
* race between two thread calling request_key().
*/
static int construct_alloc_key(struct keyring_search_context *ctx,
struct key *dest_keyring,
unsigned long flags,
struct key_user *user,
struct key **_key)
{
struct assoc_array_edit *edit = NULL;
struct key *key;
key_perm_t perm;
key_ref_t key_ref;
int ret;
kenter("%s,%s,,,",
ctx->index_key.type->name, ctx->index_key.description);
*_key = NULL;
mutex_lock(&user->cons_lock);
perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
perm |= KEY_USR_VIEW;
if (ctx->index_key.type->read)
perm |= KEY_POS_READ;
if (ctx->index_key.type == &key_type_keyring ||
ctx->index_key.type->update)
perm |= KEY_POS_WRITE;
key = key_alloc(ctx->index_key.type, ctx->index_key.description,
ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
perm, flags, NULL);
if (IS_ERR(key))
goto alloc_failed;
set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
if (dest_keyring) {
ret = __key_link_lock(dest_keyring, &ctx->index_key);
if (ret < 0)
goto link_lock_failed;
ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
if (ret < 0)
goto link_prealloc_failed;
}
/* attach the key to the destination keyring under lock, but we do need
* to do another check just in case someone beat us to it whilst we
* waited for locks */
mutex_lock(&key_construction_mutex);
rcu_read_lock();
key_ref = search_process_keyrings_rcu(ctx);
rcu_read_unlock();
if (!IS_ERR(key_ref))
goto key_already_present;
if (dest_keyring)
__key_link(key, &edit);
mutex_unlock(&key_construction_mutex);
if (dest_keyring)
__key_link_end(dest_keyring, &ctx->index_key, edit);
mutex_unlock(&user->cons_lock);
*_key = key;
kleave(" = 0 [%d]", key_serial(key));
return 0;
/* the key is now present - we tell the caller that we found it by
* returning -EINPROGRESS */
key_already_present:
key_put(key);
mutex_unlock(&key_construction_mutex);
key = key_ref_to_ptr(key_ref);
if (dest_keyring) {
ret = __key_link_check_live_key(dest_keyring, key);
if (ret == 0)
__key_link(key, &edit);
__key_link_end(dest_keyring, &ctx->index_key, edit);
if (ret < 0)
goto link_check_failed;
}
mutex_unlock(&user->cons_lock);
*_key = key;
kleave(" = -EINPROGRESS [%d]", key_serial(key));
return -EINPROGRESS;
link_check_failed:
mutex_unlock(&user->cons_lock);
key_put(key);
kleave(" = %d [linkcheck]", ret);
return ret;
link_prealloc_failed:
__key_link_end(dest_keyring, &ctx->index_key, edit);
link_lock_failed:
mutex_unlock(&user->cons_lock);
key_put(key);
kleave(" = %d [prelink]", ret);
return ret;
alloc_failed:
mutex_unlock(&user->cons_lock);
kleave(" = %ld", PTR_ERR(key));
return PTR_ERR(key);
}
/*
* Commence key construction.
*/
static struct key *construct_key_and_link(struct keyring_search_context *ctx,
const char *callout_info,
size_t callout_len,
void *aux,
struct key *dest_keyring,
unsigned long flags)
{
struct key_user *user;
struct key *key;
int ret;
kenter("");
if (ctx->index_key.type == &key_type_keyring)
return ERR_PTR(-EPERM);
ret = construct_get_dest_keyring(&dest_keyring);
if (ret)
goto error;
user = key_user_lookup(current_fsuid());
if (!user) {
ret = -ENOMEM;
goto error_put_dest_keyring;
}
ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
key_user_put(user);
if (ret == 0) {
ret = construct_key(key, callout_info, callout_len, aux,
dest_keyring);
if (ret < 0) {
kdebug("cons failed");
goto construction_failed;
}
} else if (ret == -EINPROGRESS) {
ret = 0;
} else {
goto error_put_dest_keyring;
}
key_put(dest_keyring);
kleave(" = key %d", key_serial(key));
return key;
construction_failed:
key_negate_and_link(key, key_negative_timeout, NULL, NULL);
key_put(key);
error_put_dest_keyring:
key_put(dest_keyring);
error:
kleave(" = %d", ret);
return ERR_PTR(ret);
}
/**
* request_key_and_link - Request a key and cache it in a keyring.
* @type: The type of key we want.
* @description: The searchable description of the key.
* @domain_tag: The domain in which the key operates.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
* @aux: Auxiliary data for the upcall.
* @dest_keyring: Where to cache the key.
* @flags: Flags to key_alloc().
*
* A key matching the specified criteria (type, description, domain_tag) is
* searched for in the process's keyrings and returned with its usage count
* incremented if found. Otherwise, if callout_info is not NULL, a key will be
* allocated and some service (probably in userspace) will be asked to
* instantiate it.
*
* If successfully found or created, the key will be linked to the destination
* keyring if one is provided.
*
* Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
* or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
* found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
* if insufficient key quota was available to create a new key; or -ENOMEM if
* insufficient memory was available.
*
* If the returned key was created, then it may still be under construction,
* and wait_for_key_construction() should be used to wait for that to complete.
*/
struct key *request_key_and_link(struct key_type *type,
const char *description,
struct key_tag *domain_tag,
const void *callout_info,
size_t callout_len,
void *aux,
struct key *dest_keyring,
unsigned long flags)
{
struct keyring_search_context ctx = {
.index_key.type = type,
.index_key.domain_tag = domain_tag,
.index_key.description = description,
.index_key.desc_len = strlen(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 |
KEYRING_SEARCH_SKIP_EXPIRED |
KEYRING_SEARCH_RECURSE),
};
struct key *key;
key_ref_t key_ref;
int ret;
kenter("%s,%s,%p,%zu,%p,%p,%lx",
ctx.index_key.type->name, ctx.index_key.description,
callout_info, callout_len, aux, dest_keyring, flags);
if (type->match_preparse) {
ret = type->match_preparse(&ctx.match_data);
if (ret < 0) {
key = ERR_PTR(ret);
goto error;
}
}
key = check_cached_key(&ctx);
if (key)
return key;
/* search all the process keyrings for a key */
rcu_read_lock();
key_ref = search_process_keyrings_rcu(&ctx);
rcu_read_unlock();
if (!IS_ERR(key_ref)) {
if (dest_keyring) {
ret = key_task_permission(key_ref, current_cred(),
KEY_NEED_LINK);
if (ret < 0) {
key_ref_put(key_ref);
key = ERR_PTR(ret);
goto error_free;
}
}
key = key_ref_to_ptr(key_ref);
if (dest_keyring) {
ret = key_link(dest_keyring, key);
if (ret < 0) {
key_put(key);
key = ERR_PTR(ret);
goto error_free;
}
}
/* Only cache the key on immediate success */
cache_requested_key(key);
} else if (PTR_ERR(key_ref) != -EAGAIN) {
key = ERR_CAST(key_ref);
} else {
/* the search failed, but the keyrings were searchable, so we
* should consult userspace if we can */
key = ERR_PTR(-ENOKEY);
if (!callout_info)
goto error_free;
key = construct_key_and_link(&ctx, callout_info, callout_len,
aux, dest_keyring, flags);
}
error_free:
if (type->match_free)
type->match_free(&ctx.match_data);
error:
kleave(" = %p", key);
return key;
}
/**
* wait_for_key_construction - Wait for construction of a key to complete
* @key: The key being waited for.
* @intr: Whether to wait interruptibly.
*
* Wait for a key to finish being constructed.
*
* Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
* if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
* revoked or expired.
*/
int wait_for_key_construction(struct key *key, bool intr)
{
int ret;
ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
if (ret)
return -ERESTARTSYS;
ret = key_read_state(key);
if (ret < 0)
return ret;
return key_validate(key);
}
EXPORT_SYMBOL(wait_for_key_construction);
/**
* request_key_tag - Request a key and wait for construction
* @type: Type of key.
* @description: The searchable description of the key.
* @domain_tag: The domain in which the key operates.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found, new keys are always allocated in the user's quota,
* the callout_info must be a NUL-terminated string and no auxiliary data can
* be passed.
*
* Furthermore, it then works as wait_for_key_construction() to wait for the
* completion of keys undergoing construction with a non-interruptible wait.
*/
struct key *request_key_tag(struct key_type *type,
const char *description,
struct key_tag *domain_tag,
const char *callout_info)
{
struct key *key;
size_t callout_len = 0;
int ret;
if (callout_info)
callout_len = strlen(callout_info);
key = request_key_and_link(type, description, domain_tag,
callout_info, callout_len,
NULL, NULL, KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key)) {
ret = wait_for_key_construction(key, false);
if (ret < 0) {
key_put(key);
return ERR_PTR(ret);
}
}
return key;
}
EXPORT_SYMBOL(request_key_tag);
/**
* request_key_with_auxdata - Request a key with auxiliary data for the upcaller
* @type: The type of key we want.
* @description: The searchable description of the key.
* @domain_tag: The domain in which the key operates.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
* @aux: Auxiliary data for the upcall.
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found and new keys are always allocated in the user's quota.
*
* Furthermore, it then works as wait_for_key_construction() to wait for the
* completion of keys undergoing construction with a non-interruptible wait.
*/
struct key *request_key_with_auxdata(struct key_type *type,
const char *description,
struct key_tag *domain_tag,
const void *callout_info,
size_t callout_len,
void *aux)
{
struct key *key;
int ret;
key = request_key_and_link(type, description, domain_tag,
callout_info, callout_len,
aux, NULL, KEY_ALLOC_IN_QUOTA);
if (!IS_ERR(key)) {
ret = wait_for_key_construction(key, false);
if (ret < 0) {
key_put(key);
return ERR_PTR(ret);
}
}
return key;
}
EXPORT_SYMBOL(request_key_with_auxdata);
/**
* request_key_rcu - Request key from RCU-read-locked context
* @type: The type of key we want.
* @description: The name of the key we want.
* @domain_tag: The domain in which the key operates.
*
* Request a key from a context that we may not sleep in (such as RCU-mode
* pathwalk). Keys under construction are ignored.
*
* Return a pointer to the found key if successful, -ENOKEY if we couldn't find
* a key or some other error if the key found was unsuitable or inaccessible.
*/
struct key *request_key_rcu(struct key_type *type,
const char *description,
struct key_tag *domain_tag)
{
struct keyring_search_context ctx = {
.index_key.type = type,
.index_key.domain_tag = domain_tag,
.index_key.description = description,
.index_key.desc_len = strlen(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 |
KEYRING_SEARCH_SKIP_EXPIRED),
};
struct key *key;
key_ref_t key_ref;
kenter("%s,%s", type->name, description);
key = check_cached_key(&ctx);
if (key)
return key;
/* search all the process keyrings for a key */
key_ref = search_process_keyrings_rcu(&ctx);
if (IS_ERR(key_ref)) {
key = ERR_CAST(key_ref);
if (PTR_ERR(key_ref) == -EAGAIN)
key = ERR_PTR(-ENOKEY);
} else {
key = key_ref_to_ptr(key_ref);
cache_requested_key(key);
}
kleave(" = %p", key);
return key;
}
EXPORT_SYMBOL(request_key_rcu);