Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index d5b25e5..09541de 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -1,15 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
/* Manage a process's keyrings
*
* Copyright (C) 2004-2005, 2008 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.
*/
-#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/user.h>
@@ -20,14 +15,13 @@
#include <linux/security.h>
#include <linux/user_namespace.h>
#include <linux/uaccess.h>
+#include <linux/init_task.h>
+#include <keys/request_key_auth-type.h>
#include "internal.h"
/* Session keyring create vs join semaphore */
static DEFINE_MUTEX(key_session_mutex);
-/* User keyring creation semaphore */
-static DEFINE_MUTEX(key_user_keyring_mutex);
-
/* The root user's tracking struct */
struct key_user root_key_user = {
.usage = REFCOUNT_INIT(3),
@@ -39,97 +33,186 @@
};
/*
- * Install the user and user session keyrings for the current process's UID.
+ * Get or create a user register keyring.
*/
-int install_user_keyrings(void)
+static struct key *get_user_register(struct user_namespace *user_ns)
{
- struct user_struct *user;
- const struct cred *cred;
- struct key *uid_keyring, *session_keyring;
+ struct key *reg_keyring = READ_ONCE(user_ns->user_keyring_register);
+
+ if (reg_keyring)
+ return reg_keyring;
+
+ down_write(&user_ns->keyring_sem);
+
+ /* Make sure there's a register keyring. It gets owned by the
+ * user_namespace's owner.
+ */
+ reg_keyring = user_ns->user_keyring_register;
+ if (!reg_keyring) {
+ reg_keyring = keyring_alloc(".user_reg",
+ user_ns->owner, INVALID_GID,
+ &init_cred,
+ KEY_POS_WRITE | KEY_POS_SEARCH |
+ KEY_USR_VIEW | KEY_USR_READ,
+ 0,
+ NULL, NULL);
+ if (!IS_ERR(reg_keyring))
+ smp_store_release(&user_ns->user_keyring_register,
+ reg_keyring);
+ }
+
+ up_write(&user_ns->keyring_sem);
+
+ /* We don't return a ref since the keyring is pinned by the user_ns */
+ return reg_keyring;
+}
+
+/*
+ * Look up the user and user session keyrings for the current process's UID,
+ * creating them if they don't exist.
+ */
+int look_up_user_keyrings(struct key **_user_keyring,
+ struct key **_user_session_keyring)
+{
+ const struct cred *cred = current_cred();
+ struct user_namespace *user_ns = current_user_ns();
+ struct key *reg_keyring, *uid_keyring, *session_keyring;
key_perm_t user_keyring_perm;
+ key_ref_t uid_keyring_r, session_keyring_r;
+ uid_t uid = from_kuid(user_ns, cred->user->uid);
char buf[20];
int ret;
- uid_t uid;
user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL;
- cred = current_cred();
- user = cred->user;
- uid = from_kuid(cred->user_ns, user->uid);
- kenter("%p{%u}", user, uid);
+ kenter("%u", uid);
- if (user->uid_keyring && user->session_keyring) {
- kleave(" = 0 [exist]");
- return 0;
- }
+ reg_keyring = get_user_register(user_ns);
+ if (IS_ERR(reg_keyring))
+ return PTR_ERR(reg_keyring);
- mutex_lock(&key_user_keyring_mutex);
+ down_write(&user_ns->keyring_sem);
ret = 0;
- if (!user->uid_keyring) {
- /* get the UID-specific keyring
- * - there may be one in existence already as it may have been
- * pinned by a session, but the user_struct pointing to it
- * may have been destroyed by setuid */
- sprintf(buf, "_uid.%u", uid);
-
- uid_keyring = find_keyring_by_name(buf, true);
+ /* Get the user keyring. Note that there may be one in existence
+ * already as it may have been pinned by a session, but the user_struct
+ * pointing to it may have been destroyed by setuid.
+ */
+ snprintf(buf, sizeof(buf), "_uid.%u", uid);
+ uid_keyring_r = keyring_search(make_key_ref(reg_keyring, true),
+ &key_type_keyring, buf, false);
+ kdebug("_uid %p", uid_keyring_r);
+ if (uid_keyring_r == ERR_PTR(-EAGAIN)) {
+ uid_keyring = keyring_alloc(buf, cred->user->uid, INVALID_GID,
+ cred, user_keyring_perm,
+ KEY_ALLOC_UID_KEYRING |
+ KEY_ALLOC_IN_QUOTA,
+ NULL, reg_keyring);
if (IS_ERR(uid_keyring)) {
- uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID,
- cred, user_keyring_perm,
- KEY_ALLOC_UID_KEYRING |
- KEY_ALLOC_IN_QUOTA,
- NULL, NULL);
- if (IS_ERR(uid_keyring)) {
- ret = PTR_ERR(uid_keyring);
- goto error;
- }
+ ret = PTR_ERR(uid_keyring);
+ goto error;
}
-
- /* get a default session keyring (which might also exist
- * already) */
- sprintf(buf, "_uid_ses.%u", uid);
-
- session_keyring = find_keyring_by_name(buf, true);
- if (IS_ERR(session_keyring)) {
- session_keyring =
- keyring_alloc(buf, user->uid, INVALID_GID,
- cred, user_keyring_perm,
- KEY_ALLOC_UID_KEYRING |
- KEY_ALLOC_IN_QUOTA,
- NULL, NULL);
- if (IS_ERR(session_keyring)) {
- ret = PTR_ERR(session_keyring);
- goto error_release;
- }
-
- /* we install a link from the user session keyring to
- * the user keyring */
- ret = key_link(session_keyring, uid_keyring);
- if (ret < 0)
- goto error_release_both;
- }
-
- /* install the keyrings */
- user->uid_keyring = uid_keyring;
- user->session_keyring = session_keyring;
+ } else if (IS_ERR(uid_keyring_r)) {
+ ret = PTR_ERR(uid_keyring_r);
+ goto error;
+ } else {
+ uid_keyring = key_ref_to_ptr(uid_keyring_r);
}
- mutex_unlock(&key_user_keyring_mutex);
+ /* Get a default session keyring (which might also exist already) */
+ snprintf(buf, sizeof(buf), "_uid_ses.%u", uid);
+ session_keyring_r = keyring_search(make_key_ref(reg_keyring, true),
+ &key_type_keyring, buf, false);
+ kdebug("_uid_ses %p", session_keyring_r);
+ if (session_keyring_r == ERR_PTR(-EAGAIN)) {
+ session_keyring = keyring_alloc(buf, cred->user->uid, INVALID_GID,
+ cred, user_keyring_perm,
+ KEY_ALLOC_UID_KEYRING |
+ KEY_ALLOC_IN_QUOTA,
+ NULL, NULL);
+ if (IS_ERR(session_keyring)) {
+ ret = PTR_ERR(session_keyring);
+ goto error_release;
+ }
+
+ /* We install a link from the user session keyring to
+ * the user keyring.
+ */
+ ret = key_link(session_keyring, uid_keyring);
+ if (ret < 0)
+ goto error_release_session;
+
+ /* And only then link the user-session keyring to the
+ * register.
+ */
+ ret = key_link(reg_keyring, session_keyring);
+ if (ret < 0)
+ goto error_release_session;
+ } else if (IS_ERR(session_keyring_r)) {
+ ret = PTR_ERR(session_keyring_r);
+ goto error_release;
+ } else {
+ session_keyring = key_ref_to_ptr(session_keyring_r);
+ }
+
+ up_write(&user_ns->keyring_sem);
+
+ if (_user_session_keyring)
+ *_user_session_keyring = session_keyring;
+ else
+ key_put(session_keyring);
+ if (_user_keyring)
+ *_user_keyring = uid_keyring;
+ else
+ key_put(uid_keyring);
kleave(" = 0");
return 0;
-error_release_both:
+error_release_session:
key_put(session_keyring);
error_release:
key_put(uid_keyring);
error:
- mutex_unlock(&key_user_keyring_mutex);
+ up_write(&user_ns->keyring_sem);
kleave(" = %d", ret);
return ret;
}
/*
+ * Get the user session keyring if it exists, but don't create it if it
+ * doesn't.
+ */
+struct key *get_user_session_keyring_rcu(const struct cred *cred)
+{
+ struct key *reg_keyring = READ_ONCE(cred->user_ns->user_keyring_register);
+ key_ref_t session_keyring_r;
+ char buf[20];
+
+ struct keyring_search_context ctx = {
+ .index_key.type = &key_type_keyring,
+ .index_key.description = buf,
+ .cred = cred,
+ .match_data.cmp = key_default_cmp,
+ .match_data.raw_data = buf,
+ .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
+ .flags = KEYRING_SEARCH_DO_STATE_CHECK,
+ };
+
+ if (!reg_keyring)
+ return NULL;
+
+ ctx.index_key.desc_len = snprintf(buf, sizeof(buf), "_uid_ses.%u",
+ from_kuid(cred->user_ns,
+ cred->user->uid));
+
+ session_keyring_r = keyring_search_rcu(make_key_ref(reg_keyring, true),
+ &ctx);
+ if (IS_ERR(session_keyring_r))
+ return NULL;
+ return key_ref_to_ptr(session_keyring_r);
+}
+
+/*
* Install a thread keyring to the given credentials struct if it didn't have
* one already. This is allowed to overrun the quota.
*
@@ -227,6 +310,7 @@
* Install the given keyring as the session keyring of the given credentials
* struct, replacing the existing one if any. If the given keyring is NULL,
* then install a new anonymous session keyring.
+ * @cred can not be in use by any task yet.
*
* Return: 0 on success; -errno on failure.
*/
@@ -254,7 +338,7 @@
/* install the keyring */
old = cred->session_keyring;
- rcu_assign_pointer(cred->session_keyring, keyring);
+ cred->session_keyring = keyring;
if (old)
key_put(old);
@@ -290,34 +374,33 @@
/*
* Handle the fsuid changing.
*/
-void key_fsuid_changed(struct task_struct *tsk)
+void key_fsuid_changed(struct cred *new_cred)
{
/* update the ownership of the thread keyring */
- BUG_ON(!tsk->cred);
- if (tsk->cred->thread_keyring) {
- down_write(&tsk->cred->thread_keyring->sem);
- tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
- up_write(&tsk->cred->thread_keyring->sem);
+ if (new_cred->thread_keyring) {
+ down_write(&new_cred->thread_keyring->sem);
+ new_cred->thread_keyring->uid = new_cred->fsuid;
+ up_write(&new_cred->thread_keyring->sem);
}
}
/*
* Handle the fsgid changing.
*/
-void key_fsgid_changed(struct task_struct *tsk)
+void key_fsgid_changed(struct cred *new_cred)
{
/* update the ownership of the thread keyring */
- BUG_ON(!tsk->cred);
- if (tsk->cred->thread_keyring) {
- down_write(&tsk->cred->thread_keyring->sem);
- tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
- up_write(&tsk->cred->thread_keyring->sem);
+ if (new_cred->thread_keyring) {
+ down_write(&new_cred->thread_keyring->sem);
+ new_cred->thread_keyring->gid = new_cred->fsgid;
+ up_write(&new_cred->thread_keyring->sem);
}
}
/*
* Search the process keyrings attached to the supplied cred for the first
- * matching key.
+ * matching key under RCU conditions (the caller must be holding the RCU read
+ * lock).
*
* The search criteria are the type and the match function. The description is
* given to the match function as a parameter, but doesn't otherwise influence
@@ -336,9 +419,11 @@
* In the case of a successful return, the possession attribute is set on the
* returned key reference.
*/
-key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx)
+key_ref_t search_cred_keyrings_rcu(struct keyring_search_context *ctx)
{
+ struct key *user_session;
key_ref_t key_ref, ret, err;
+ const struct cred *cred = ctx->cred;
/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
* searchable, but we failed to find a key or we found a negative key;
@@ -352,9 +437,9 @@
err = ERR_PTR(-EAGAIN);
/* search the thread keyring first */
- if (ctx->cred->thread_keyring) {
- key_ref = keyring_search_aux(
- make_key_ref(ctx->cred->thread_keyring, 1), ctx);
+ if (cred->thread_keyring) {
+ key_ref = keyring_search_rcu(
+ make_key_ref(cred->thread_keyring, 1), ctx);
if (!IS_ERR(key_ref))
goto found;
@@ -370,9 +455,9 @@
}
/* search the process keyring second */
- if (ctx->cred->process_keyring) {
- key_ref = keyring_search_aux(
- make_key_ref(ctx->cred->process_keyring, 1), ctx);
+ if (cred->process_keyring) {
+ key_ref = keyring_search_rcu(
+ make_key_ref(cred->process_keyring, 1), ctx);
if (!IS_ERR(key_ref))
goto found;
@@ -380,6 +465,7 @@
case -EAGAIN: /* no key */
if (ret)
break;
+ /* fall through */
case -ENOKEY: /* negative key */
ret = key_ref;
break;
@@ -390,12 +476,9 @@
}
/* search the session keyring */
- if (ctx->cred->session_keyring) {
- rcu_read_lock();
- key_ref = keyring_search_aux(
- make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1),
- ctx);
- rcu_read_unlock();
+ if (cred->session_keyring) {
+ key_ref = keyring_search_rcu(
+ make_key_ref(cred->session_keyring, 1), ctx);
if (!IS_ERR(key_ref))
goto found;
@@ -404,6 +487,7 @@
case -EAGAIN: /* no key */
if (ret)
break;
+ /* fall through */
case -ENOKEY: /* negative key */
ret = key_ref;
break;
@@ -413,10 +497,11 @@
}
}
/* or search the user-session keyring */
- else if (ctx->cred->user->session_keyring) {
- key_ref = keyring_search_aux(
- make_key_ref(ctx->cred->user->session_keyring, 1),
- ctx);
+ else if ((user_session = get_user_session_keyring_rcu(cred))) {
+ key_ref = keyring_search_rcu(make_key_ref(user_session, 1),
+ ctx);
+ key_put(user_session);
+
if (!IS_ERR(key_ref))
goto found;
@@ -424,6 +509,7 @@
case -EAGAIN: /* no key */
if (ret)
break;
+ /* fall through */
case -ENOKEY: /* negative key */
ret = key_ref;
break;
@@ -446,16 +532,16 @@
* the keys attached to the assumed authorisation key using its credentials if
* one is available.
*
- * Return same as search_my_process_keyrings().
+ * The caller must be holding the RCU read lock.
+ *
+ * Return same as search_cred_keyrings_rcu().
*/
-key_ref_t search_process_keyrings(struct keyring_search_context *ctx)
+key_ref_t search_process_keyrings_rcu(struct keyring_search_context *ctx)
{
struct request_key_auth *rka;
key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
- might_sleep();
-
- key_ref = search_my_process_keyrings(ctx);
+ key_ref = search_cred_keyrings_rcu(ctx);
if (!IS_ERR(key_ref))
goto found;
err = key_ref;
@@ -470,24 +556,17 @@
) {
const struct cred *cred = ctx->cred;
- /* defend against the auth key being revoked */
- down_read(&cred->request_key_auth->sem);
-
- if (key_validate(ctx->cred->request_key_auth) == 0) {
+ if (key_validate(cred->request_key_auth) == 0) {
rka = ctx->cred->request_key_auth->payload.data[0];
+ //// was search_process_keyrings() [ie. recursive]
ctx->cred = rka->cred;
- key_ref = search_process_keyrings(ctx);
+ key_ref = search_cred_keyrings_rcu(ctx);
ctx->cred = cred;
- up_read(&cred->request_key_auth->sem);
-
if (!IS_ERR(key_ref))
goto found;
-
ret = key_ref;
- } else {
- up_read(&cred->request_key_auth->sem);
}
}
@@ -502,7 +581,6 @@
found:
return key_ref;
}
-
/*
* See if the key we're looking at is the target key.
*/
@@ -536,10 +614,11 @@
struct keyring_search_context ctx = {
.match_data.cmp = lookup_user_key_possessed,
.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
- .flags = KEYRING_SEARCH_NO_STATE_CHECK,
+ .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
+ KEYRING_SEARCH_RECURSE),
};
struct request_key_auth *rka;
- struct key *key;
+ struct key *key, *user_session;
key_ref_t key_ref, skey_ref;
int ret;
@@ -588,20 +667,20 @@
if (!ctx.cred->session_keyring) {
/* always install a session keyring upon access if one
* doesn't exist yet */
- ret = install_user_keyrings();
+ ret = look_up_user_keyrings(NULL, &user_session);
if (ret < 0)
goto error;
if (lflags & KEY_LOOKUP_CREATE)
ret = join_session_keyring(NULL);
else
- ret = install_session_keyring(
- ctx.cred->user->session_keyring);
+ ret = install_session_keyring(user_session);
+ key_put(user_session);
if (ret < 0)
goto error;
goto reget_creds;
- } else if (ctx.cred->session_keyring ==
- ctx.cred->user->session_keyring &&
+ } else if (test_bit(KEY_FLAG_UID_KEYRING,
+ &ctx.cred->session_keyring->flags) &&
lflags & KEY_LOOKUP_CREATE) {
ret = join_session_keyring(NULL);
if (ret < 0)
@@ -609,34 +688,22 @@
goto reget_creds;
}
- rcu_read_lock();
- key = rcu_dereference(ctx.cred->session_keyring);
+ key = ctx.cred->session_keyring;
__key_get(key);
- rcu_read_unlock();
key_ref = make_key_ref(key, 1);
break;
case KEY_SPEC_USER_KEYRING:
- if (!ctx.cred->user->uid_keyring) {
- ret = install_user_keyrings();
- if (ret < 0)
- goto error;
- }
-
- key = ctx.cred->user->uid_keyring;
- __key_get(key);
+ ret = look_up_user_keyrings(&key, NULL);
+ if (ret < 0)
+ goto error;
key_ref = make_key_ref(key, 1);
break;
case KEY_SPEC_USER_SESSION_KEYRING:
- if (!ctx.cred->user->session_keyring) {
- ret = install_user_keyrings();
- if (ret < 0)
- goto error;
- }
-
- key = ctx.cred->user->session_keyring;
- __key_get(key);
+ ret = look_up_user_keyrings(NULL, &key);
+ if (ret < 0)
+ goto error;
key_ref = make_key_ref(key, 1);
break;
@@ -688,12 +755,12 @@
key_ref = make_key_ref(key, 0);
/* check to see if we possess the key */
- ctx.index_key.type = key->type;
- ctx.index_key.description = key->description;
- ctx.index_key.desc_len = strlen(key->description);
+ ctx.index_key = key->index_key;
ctx.match_data.raw_data = key;
kdebug("check possessed");
- skey_ref = search_process_keyrings(&ctx);
+ rcu_read_lock();
+ skey_ref = search_process_keyrings_rcu(&ctx);
+ rcu_read_unlock();
kdebug("possessed=%p", skey_ref);
if (!IS_ERR(skey_ref)) {
@@ -755,6 +822,7 @@
put_cred(ctx.cred);
goto try_again;
}
+EXPORT_SYMBOL(lookup_user_key);
/*
* Join the named keyring as the session keyring if possible else attempt to
@@ -884,7 +952,7 @@
*/
static int __init init_root_keyring(void)
{
- return install_user_keyrings();
+ return look_up_user_keyrings(NULL, NULL);
}
late_initcall(init_root_keyring);