Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 821 insertions, 0 deletions

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
new file mode 100644
index 000000000..fa2bb9f2f
--- /dev/null
+++ b/security/keys/request_key.c
@@ -0,0 +1,821 @@
+// 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;
+
+	/* Do not cache key if it is a kernel thread */
+	if (!(t->flags & PF_KTHREAD)) {
+		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;
+				}
+			}
+
+			fallthrough;
+		case KEY_REQKEY_DEFL_THREAD_KEYRING:
+			dest_keyring = key_get(cred->thread_keyring);
+			if (dest_keyring)
+				break;
+
+			fallthrough;
+		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
+			dest_keyring = key_get(cred->process_keyring);
+			if (dest_keyring)
+				break;
+
+			fallthrough;
+		case KEY_REQKEY_DEFL_SESSION_KEYRING:
+			dest_keyring = key_get(cred->session_keyring);
+
+			if (dest_keyring)
+				break;
+
+			fallthrough;
+		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:
+			return -EINVAL;
+		}
+
+		/*
+		 * 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, &key->index_key);
+		if (ret < 0)
+			goto link_lock_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.
+	 *
+	 * The caller might specify a comparison function which looks for keys
+	 * that do not exactly match but are still equivalent from the caller's
+	 * perspective. The __key_link_begin() operation must be done only after
+	 * an actual key is determined.
+	 */
+	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) {
+		ret = __key_link_begin(dest_keyring, &key->index_key, &edit);
+		if (ret < 0)
+			goto link_alloc_failed;
+		__key_link(dest_keyring, key, &edit);
+	}
+
+	mutex_unlock(&key_construction_mutex);
+	if (dest_keyring)
+		__key_link_end(dest_keyring, &key->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_begin(dest_keyring, &key->index_key, &edit);
+		if (ret < 0)
+			goto link_alloc_failed_unlocked;
+		ret = __key_link_check_live_key(dest_keyring, key);
+		if (ret == 0)
+			__key_link(dest_keyring, key, &edit);
+		__key_link_end(dest_keyring, &key->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_alloc_failed:
+	mutex_unlock(&key_construction_mutex);
+link_alloc_failed_unlocked:
+	__key_link_end(dest_keyring, &key->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)
+		goto error_free;
+
+	/* 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);