treewide: refresh kmalloc_obj() conversionsgrafted

This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci

This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.

Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.

Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>

1 files changed, 1238 insertions, 0 deletions

diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
new file mode 100644
index 000000000..76e28d1e0
--- /dev/null
+++ b/fs/crypto/keyring.c
@@ -0,0 +1,1238 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Filesystem-level keyring for fscrypt
+ *
+ * Copyright 2019 Google LLC
+ */
+
+/*
+ * This file implements management of fscrypt master keys in the
+ * filesystem-level keyring, including the ioctls:
+ *
+ * - FS_IOC_ADD_ENCRYPTION_KEY
+ * - FS_IOC_REMOVE_ENCRYPTION_KEY
+ * - FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS
+ * - FS_IOC_GET_ENCRYPTION_KEY_STATUS
+ *
+ * See the "User API" section of Documentation/filesystems/fscrypt.rst for more
+ * information about these ioctls.
+ */
+
+#include <crypto/skcipher.h>
+#include <linux/export.h>
+#include <linux/key-type.h>
+#include <linux/once.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+#include <linux/unaligned.h>
+
+#include "fscrypt_private.h"
+
+/* The master encryption keys for a filesystem (->s_master_keys) */
+struct fscrypt_keyring {
+	/*
+	 * Lock that protects ->key_hashtable.  It does *not* protect the
+	 * fscrypt_master_key structs themselves.
+	 */
+	spinlock_t lock;
+
+	/* Hash table that maps fscrypt_key_specifier to fscrypt_master_key */
+	struct hlist_head key_hashtable[128];
+};
+
+static void wipe_master_key_secret(struct fscrypt_master_key_secret *secret)
+{
+	memzero_explicit(secret, sizeof(*secret));
+}
+
+static void move_master_key_secret(struct fscrypt_master_key_secret *dst,
+				   struct fscrypt_master_key_secret *src)
+{
+	memcpy(dst, src, sizeof(*dst));
+	memzero_explicit(src, sizeof(*src));
+}
+
+static void fscrypt_free_master_key(struct rcu_head *head)
+{
+	struct fscrypt_master_key *mk =
+		container_of(head, struct fscrypt_master_key, mk_rcu_head);
+	/*
+	 * The master key secret and any embedded subkeys should have already
+	 * been wiped when the last active reference to the fscrypt_master_key
+	 * struct was dropped; doing it here would be unnecessarily late.
+	 * Nevertheless, use kfree_sensitive() in case anything was missed.
+	 */
+	kfree_sensitive(mk);
+}
+
+static void clear_mk_users(struct fscrypt_master_key *mk);
+
+void fscrypt_put_master_key(struct fscrypt_master_key *mk)
+{
+	if (!refcount_dec_and_test(&mk->mk_struct_refs))
+		return;
+	/*
+	 * No structural references left, so clear ->mk_users, and also free the
+	 * fscrypt_master_key struct itself after an RCU grace period ensures
+	 * that concurrent keyring lookups can no longer find it.
+	 */
+	WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 0);
+	clear_mk_users(mk);
+	call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key);
+}
+
+void fscrypt_put_master_key_activeref(struct super_block *sb,
+				      struct fscrypt_master_key *mk)
+{
+	struct fscrypt_mode_key *node, *tmp;
+
+	if (!refcount_dec_and_test(&mk->mk_active_refs))
+		return;
+	/*
+	 * No active references left, so complete the full removal of this
+	 * fscrypt_master_key struct by removing it from the keyring and
+	 * destroying any non-file-scoped subkeys.
+	 */
+
+	if (WARN_ON_ONCE(!sb->s_master_keys))
+		return;
+	spin_lock(&sb->s_master_keys->lock);
+	hlist_del_rcu(&mk->mk_node);
+	spin_unlock(&sb->s_master_keys->lock);
+
+	/*
+	 * ->mk_active_refs == 0 implies that ->mk_present is false and
+	 * ->mk_decrypted_inodes is empty.
+	 */
+	WARN_ON_ONCE(mk->mk_present);
+	WARN_ON_ONCE(!list_empty(&mk->mk_decrypted_inodes));
+
+	/*
+	 * Destroy any non-file-scoped subkeys.  Since ->mk_active_refs == 0,
+	 * they're no longer referenced by any inodes.  Nor can key setup run
+	 * and use them again.  So they're no longer needed.  (This implies no
+	 * concurrent readers, so we don't need list_del_rcu() for example.)
+	 */
+	list_for_each_entry_safe(node, tmp, &mk->mk_mode_keys, link) {
+		fscrypt_destroy_prepared_key(sb, &node->key);
+		list_del(&node->link);
+		kfree(node);
+	}
+	memzero_explicit(&mk->mk_ino_hash_key,
+			 sizeof(mk->mk_ino_hash_key));
+	mk->mk_ino_hash_key_initialized = false;
+
+	/* Drop the structural ref associated with the active refs. */
+	fscrypt_put_master_key(mk);
+}
+
+/*
+ * This transitions the key state from present to incompletely removed, and then
+ * potentially to absent (depending on whether inodes remain).
+ */
+static void fscrypt_initiate_key_removal(struct super_block *sb,
+					 struct fscrypt_master_key *mk)
+{
+	WRITE_ONCE(mk->mk_present, false);
+	wipe_master_key_secret(&mk->mk_secret);
+	fscrypt_put_master_key_activeref(sb, mk);
+}
+
+static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec)
+{
+	if (spec->__reserved)
+		return false;
+	return master_key_spec_len(spec) != 0;
+}
+
+static int fscrypt_user_key_instantiate(struct key *key,
+					struct key_preparsed_payload *prep)
+{
+	/*
+	 * We just charge FSCRYPT_MAX_RAW_KEY_SIZE bytes to the user's key quota
+	 * for each key, regardless of the exact key size.  The amount of memory
+	 * actually used is greater than the size of the raw key anyway.
+	 */
+	return key_payload_reserve(key, FSCRYPT_MAX_RAW_KEY_SIZE);
+}
+
+static void fscrypt_user_key_describe(const struct key *key, struct seq_file *m)
+{
+	seq_puts(m, key->description);
+}
+
+/*
+ * Type of fscrypt_master_key_user::quota_key.  This contains no secret; it
+ * exists solely to charge a user's key quota.
+ *
+ * Note that the name of this key type really should be something like
+ * ".fscrypt-user" instead of simply ".fscrypt".  But the shorter name is chosen
+ * mainly for simplicity of presentation in /proc/keys when read by a non-root
+ * user.  And it is expected to be rare that a key is actually added by multiple
+ * users, since users should keep their encryption keys confidential.
+ */
+static struct key_type key_type_fscrypt_user = {
+	.name			= ".fscrypt",
+	.instantiate		= fscrypt_user_key_instantiate,
+	.describe		= fscrypt_user_key_describe,
+};
+
+#define FSCRYPT_MK_USER_DESCRIPTION_SIZE	\
+	(2 * FSCRYPT_KEY_IDENTIFIER_SIZE + CONST_STRLEN(".uid.") + 10 + 1)
+
+/* Create ->s_master_keys if needed.  Synchronized by fscrypt_add_key_mutex. */
+static int allocate_filesystem_keyring(struct super_block *sb)
+{
+	struct fscrypt_keyring *keyring;
+
+	if (sb->s_master_keys)
+		return 0;
+
+	keyring = kzalloc_obj(*keyring);
+	if (!keyring)
+		return -ENOMEM;
+	spin_lock_init(&keyring->lock);
+	/*
+	 * Pairs with the smp_load_acquire() in fscrypt_find_master_key().
+	 * I.e., here we publish ->s_master_keys with a RELEASE barrier so that
+	 * concurrent tasks can ACQUIRE it.
+	 */
+	smp_store_release(&sb->s_master_keys, keyring);
+	return 0;
+}
+
+/*
+ * Release all encryption keys that have been added to the filesystem, along
+ * with the keyring that contains them.
+ *
+ * This is called at unmount time, after all potentially-encrypted inodes have
+ * been evicted.  The filesystem's underlying block device(s) are still
+ * available at this time; this is important because after user file accesses
+ * have been allowed, this function may need to evict keys from the keyslots of
+ * an inline crypto engine, which requires the block device(s).
+ */
+void fscrypt_destroy_keyring(struct super_block *sb)
+{
+	struct fscrypt_keyring *keyring = sb->s_master_keys;
+	size_t i;
+
+	if (!keyring)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(keyring->key_hashtable); i++) {
+		struct hlist_head *bucket = &keyring->key_hashtable[i];
+		struct fscrypt_master_key *mk;
+		struct hlist_node *tmp;
+
+		hlist_for_each_entry_safe(mk, tmp, bucket, mk_node) {
+			/*
+			 * Since all potentially-encrypted inodes were already
+			 * evicted, every key remaining in the keyring should
+			 * have an empty inode list, and should only still be in
+			 * the keyring due to the single active ref associated
+			 * with ->mk_present.  There should be no structural
+			 * refs beyond the one associated with the active ref.
+			 */
+			WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 1);
+			WARN_ON_ONCE(refcount_read(&mk->mk_struct_refs) != 1);
+			WARN_ON_ONCE(!mk->mk_present);
+			fscrypt_initiate_key_removal(sb, mk);
+		}
+	}
+	kfree_sensitive(keyring);
+	sb->s_master_keys = NULL;
+}
+
+static struct hlist_head *
+fscrypt_mk_hash_bucket(struct fscrypt_keyring *keyring,
+		       const struct fscrypt_key_specifier *mk_spec)
+{
+	/*
+	 * Since key specifiers should be "random" values, it is sufficient to
+	 * use a trivial hash function that just takes the first several bits of
+	 * the key specifier.
+	 */
+	unsigned long i = get_unaligned((unsigned long *)&mk_spec->u);
+
+	return &keyring->key_hashtable[i % ARRAY_SIZE(keyring->key_hashtable)];
+}
+
+/*
+ * Find the specified master key struct in ->s_master_keys and take a structural
+ * ref to it.  The structural ref guarantees that the key struct continues to
+ * exist, but it does *not* guarantee that ->s_master_keys continues to contain
+ * the key struct.  The structural ref needs to be dropped by
+ * fscrypt_put_master_key().  Returns NULL if the key struct is not found.
+ */
+struct fscrypt_master_key *
+fscrypt_find_master_key(struct super_block *sb,
+			const struct fscrypt_key_specifier *mk_spec)
+{
+	struct fscrypt_keyring *keyring;
+	struct hlist_head *bucket;
+	struct fscrypt_master_key *mk;
+
+	/*
+	 * Pairs with the smp_store_release() in allocate_filesystem_keyring().
+	 * I.e., another task can publish ->s_master_keys concurrently,
+	 * executing a RELEASE barrier.  We need to use smp_load_acquire() here
+	 * to safely ACQUIRE the memory the other task published.
+	 */
+	keyring = smp_load_acquire(&sb->s_master_keys);
+	if (keyring == NULL)
+		return NULL; /* No keyring yet, so no keys yet. */
+
+	bucket = fscrypt_mk_hash_bucket(keyring, mk_spec);
+	rcu_read_lock();
+	switch (mk_spec->type) {
+	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
+		hlist_for_each_entry_rcu(mk, bucket, mk_node) {
+			if (mk->mk_spec.type ==
+				FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+			    memcmp(mk->mk_spec.u.descriptor,
+				   mk_spec->u.descriptor,
+				   FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
+			    refcount_inc_not_zero(&mk->mk_struct_refs))
+				goto out;
+		}
+		break;
+	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
+		hlist_for_each_entry_rcu(mk, bucket, mk_node) {
+			if (mk->mk_spec.type ==
+				FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
+			    memcmp(mk->mk_spec.u.identifier,
+				   mk_spec->u.identifier,
+				   FSCRYPT_KEY_IDENTIFIER_SIZE) == 0 &&
+			    refcount_inc_not_zero(&mk->mk_struct_refs))
+				goto out;
+		}
+		break;
+	}
+	mk = NULL;
+out:
+	rcu_read_unlock();
+	return mk;
+}
+
+/* Find the current user's claim in ->mk_users.  ->mk_sem must be held. */
+static struct fscrypt_master_key_user *
+find_master_key_user(struct fscrypt_master_key *mk)
+{
+	struct fscrypt_master_key_user *mk_user;
+	kuid_t uid = current_fsuid();
+
+	list_for_each_entry(mk_user, &mk->mk_users, link) {
+		if (uid_eq(mk_user->uid, uid))
+			return mk_user;
+	}
+	return NULL;
+}
+
+/*
+ * Give the current user a claim in ->mk_users.  This charges the user's quota
+ * and marks the master key as added by the current user, so that it cannot be
+ * removed by another user with the key.  Either ->mk_sem must be held for
+ * write, or the master key must be still undergoing initialization.
+ */
+static int add_master_key_user(struct fscrypt_master_key *mk)
+{
+	kuid_t uid = current_fsuid();
+	char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE];
+	struct key *quota_key;
+	struct fscrypt_master_key_user *mk_user;
+	int err;
+
+	snprintf(description, sizeof(description), "%*phN.uid.%u",
+		 FSCRYPT_KEY_IDENTIFIER_SIZE, mk->mk_spec.u.identifier,
+		 __kuid_val(uid));
+	quota_key = key_alloc(&key_type_fscrypt_user, description, uid,
+			      current_gid(), current_cred(),
+			      KEY_POS_SEARCH | KEY_USR_VIEW, 0, NULL);
+	if (IS_ERR(quota_key))
+		return PTR_ERR(quota_key);
+
+	err = key_instantiate_and_link(quota_key, NULL, 0, NULL, NULL);
+	if (err) {
+		key_put(quota_key);
+		return err;
+	}
+
+	mk_user = kzalloc_obj(*mk_user);
+	if (!mk_user) {
+		key_put(quota_key);
+		return -ENOMEM;
+	}
+	mk_user->uid = uid;
+	mk_user->quota_key = quota_key;
+	list_add(&mk_user->link, &mk->mk_users);
+	return 0;
+}
+
+static void unlink_and_free_mk_user(struct fscrypt_master_key_user *mk_user)
+{
+	list_del(&mk_user->link);
+	key_put(mk_user->quota_key);
+	kfree(mk_user);
+}
+
+/*
+ * Remove the current user's claim from ->mk_users.
+ * ->mk_sem must be held for write.
+ *
+ * Returns 0 if removed or -ENOKEY if not found.
+ */
+static int remove_master_key_user(struct fscrypt_master_key *mk)
+{
+	struct fscrypt_master_key_user *mk_user;
+
+	mk_user = find_master_key_user(mk);
+	if (!mk_user)
+		return -ENOKEY;
+	unlink_and_free_mk_user(mk_user);
+	return 0;
+}
+
+/*
+ * Clear ->mk_users.  Either ->mk_sem must be held for write, or 'mk' must have
+ * no structural references left.
+ */
+static void clear_mk_users(struct fscrypt_master_key *mk)
+{
+	struct fscrypt_master_key_user *mk_user, *tmp;
+
+	list_for_each_entry_safe(mk_user, tmp, &mk->mk_users, link)
+		unlink_and_free_mk_user(mk_user);
+}
+
+/*
+ * Allocate a new fscrypt_master_key, transfer the given secret over to it, and
+ * insert it into sb->s_master_keys.
+ */
+static int add_new_master_key(struct super_block *sb,
+			      struct fscrypt_master_key_secret *secret,
+			      const struct fscrypt_key_specifier *mk_spec)
+{
+	struct fscrypt_keyring *keyring = sb->s_master_keys;
+	struct fscrypt_master_key *mk;
+	int err;
+
+	mk = kzalloc_obj(*mk);
+	if (!mk)
+		return -ENOMEM;
+
+	init_rwsem(&mk->mk_sem);
+	refcount_set(&mk->mk_struct_refs, 1);
+	mk->mk_spec = *mk_spec;
+
+	INIT_LIST_HEAD(&mk->mk_users);
+
+	INIT_LIST_HEAD(&mk->mk_decrypted_inodes);
+	spin_lock_init(&mk->mk_decrypted_inodes_lock);
+
+	INIT_LIST_HEAD(&mk->mk_mode_keys);
+
+	if (mk_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
+		err = add_master_key_user(mk);
+		if (err)
+			goto out_put;
+	}
+
+	move_master_key_secret(&mk->mk_secret, secret);
+	mk->mk_present = true;
+	refcount_set(&mk->mk_active_refs, 1); /* ->mk_present is true */
+
+	spin_lock(&keyring->lock);
+	hlist_add_head_rcu(&mk->mk_node,
+			   fscrypt_mk_hash_bucket(keyring, mk_spec));
+	spin_unlock(&keyring->lock);
+	return 0;
+
+out_put:
+	fscrypt_put_master_key(mk);
+	return err;
+}
+
+#define KEY_DEAD	1
+
+static int add_existing_master_key(struct fscrypt_master_key *mk,
+				   struct fscrypt_master_key_secret *secret)
+{
+	int err;
+
+	/*
+	 * For v2 policy keys (FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER): If the current
+	 * user is already in ->mk_users, then there's nothing to do.
+	 * Otherwise, add the user to ->mk_users.
+	 */
+	if (mk->mk_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
+		if (find_master_key_user(mk) != NULL)
+			return 0;
+		err = add_master_key_user(mk);
+		if (err)
+			return err;
+	}
+
+	/* If the key is incompletely removed, make it present again. */
+	if (!mk->mk_present) {
+		if (!refcount_inc_not_zero(&mk->mk_active_refs)) {
+			/*
+			 * Raced with the last active ref being dropped, so the
+			 * key has become, or is about to become, "absent".
+			 * Therefore, we need to allocate a new key struct.
+			 */
+			return KEY_DEAD;
+		}
+		move_master_key_secret(&mk->mk_secret, secret);
+		WRITE_ONCE(mk->mk_present, true);
+	}
+
+	return 0;
+}
+
+static int do_add_master_key(struct super_block *sb,
+			     struct fscrypt_master_key_secret *secret,
+			     const struct fscrypt_key_specifier *mk_spec)
+{
+	static DEFINE_MUTEX(fscrypt_add_key_mutex);
+	struct fscrypt_master_key *mk;
+	int err;
+
+	guard(mutex)(&fscrypt_add_key_mutex); /* serialize find + link */
+
+	mk = fscrypt_find_master_key(sb, mk_spec);
+	if (!mk) {
+		/* Didn't find the key in ->s_master_keys.  Add it. */
+		err = allocate_filesystem_keyring(sb);
+		if (!err)
+			err = add_new_master_key(sb, secret, mk_spec);
+	} else {
+		/*
+		 * Found the key in ->s_master_keys.  Add the user to ->mk_users
+		 * if needed, and make the key "present" again if possible.
+		 */
+		down_write(&mk->mk_sem);
+		err = add_existing_master_key(mk, secret);
+		up_write(&mk->mk_sem);
+		if (err == KEY_DEAD) {
+			/*
+			 * We found a key struct, but it's already been fully
+			 * removed.  Ignore the old struct and add a new one.
+			 * fscrypt_add_key_mutex means we don't need to worry
+			 * about concurrent adds.
+			 */
+			err = add_new_master_key(sb, secret, mk_spec);
+		}
+		fscrypt_put_master_key(mk);
+	}
+	return err;
+}
+
+static int add_master_key(struct super_block *sb,
+			  struct fscrypt_master_key_secret *secret,
+			  struct fscrypt_key_specifier *key_spec)
+{
+	int err;
+
+	if (key_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
+		u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE];
+		u8 *kdf_key = secret->bytes;
+		unsigned int kdf_key_size = secret->size;
+		u8 keyid_kdf_ctx = HKDF_CONTEXT_KEY_IDENTIFIER_FOR_RAW_KEY;
+
+		/*
+		 * For raw keys, the fscrypt master key is used directly as the
+		 * fscrypt KDF key.  For hardware-wrapped keys, we have to pass
+		 * the master key to the hardware to derive the KDF key, which
+		 * is then only used to derive non-file-contents subkeys.
+		 */
+		if (secret->is_hw_wrapped) {
+			err = fscrypt_derive_sw_secret(sb, secret->bytes,
+						       secret->size, sw_secret);
+			if (err)
+				return err;
+			kdf_key = sw_secret;
+			kdf_key_size = sizeof(sw_secret);
+			/*
+			 * To avoid weird behavior if someone manages to
+			 * determine sw_secret and add it as a raw key, ensure
+			 * that hardware-wrapped keys and raw keys will have
+			 * different key identifiers by deriving their key
+			 * identifiers using different KDF contexts.
+			 */
+			keyid_kdf_ctx =
+				HKDF_CONTEXT_KEY_IDENTIFIER_FOR_HW_WRAPPED_KEY;
+		}
+		fscrypt_init_hkdf(&secret->hkdf, kdf_key, kdf_key_size);
+		/*
+		 * Now that the KDF context is initialized, the raw KDF key is
+		 * no longer needed.
+		 */
+		memzero_explicit(kdf_key, kdf_key_size);
+
+		/* Calculate the key identifier */
+		fscrypt_hkdf_expand(&secret->hkdf, keyid_kdf_ctx, NULL, 0,
+				    key_spec->u.identifier,
+				    FSCRYPT_KEY_IDENTIFIER_SIZE);
+	}
+	return do_add_master_key(sb, secret, key_spec);
+}
+
+/*
+ * Validate the size of an fscrypt master key being added.  Note that this is
+ * just an initial check, as we don't know which ciphers will be used yet.
+ * There is a stricter size check later when the key is actually used by a file.
+ */
+static inline bool fscrypt_valid_key_size(size_t size, u32 add_key_flags)
+{
+	u32 max_size = (add_key_flags & FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED) ?
+		       FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE :
+		       FSCRYPT_MAX_RAW_KEY_SIZE;
+
+	return size >= FSCRYPT_MIN_KEY_SIZE && size <= max_size;
+}
+
+static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep)
+{
+	const struct fscrypt_provisioning_key_payload *payload = prep->data;
+
+	if (prep->datalen < sizeof(*payload))
+		return -EINVAL;
+
+	if (!fscrypt_valid_key_size(prep->datalen - sizeof(*payload),
+				    payload->flags))
+		return -EINVAL;
+
+	if (payload->type != FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+	    payload->type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
+		return -EINVAL;
+
+	if (payload->flags & ~FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED)
+		return -EINVAL;
+
+	prep->payload.data[0] = kmemdup(payload, prep->datalen, GFP_KERNEL);
+	if (!prep->payload.data[0])
+		return -ENOMEM;
+
+	prep->quotalen = prep->datalen;
+	return 0;
+}
+
+static void fscrypt_provisioning_key_free_preparse(
+					struct key_preparsed_payload *prep)
+{
+	kfree_sensitive(prep->payload.data[0]);
+}
+
+static void fscrypt_provisioning_key_describe(const struct key *key,
+					      struct seq_file *m)
+{
+	seq_puts(m, key->description);
+	if (key_is_positive(key)) {
+		const struct fscrypt_provisioning_key_payload *payload =
+			key->payload.data[0];
+
+		seq_printf(m, ": %u [%u]", key->datalen, payload->type);
+	}
+}
+
+static void fscrypt_provisioning_key_destroy(struct key *key)
+{
+	kfree_sensitive(key->payload.data[0]);
+}
+
+static struct key_type key_type_fscrypt_provisioning = {
+	.name			= "fscrypt-provisioning",
+	.preparse		= fscrypt_provisioning_key_preparse,
+	.free_preparse		= fscrypt_provisioning_key_free_preparse,
+	.instantiate		= generic_key_instantiate,
+	.describe		= fscrypt_provisioning_key_describe,
+	.destroy		= fscrypt_provisioning_key_destroy,
+};
+
+/*
+ * Retrieve the key from the Linux keyring key specified by 'key_id', and store
+ * it into 'secret'.
+ *
+ * The key must be of type "fscrypt-provisioning" and must have the 'type' and
+ * 'flags' field of the payload set to the given values, indicating that the key
+ * is intended for use for the specified purpose.  We don't use the "logon" key
+ * type because there's no way to completely restrict the use of such keys; they
+ * can be used by any kernel API that accepts "logon" keys and doesn't require a
+ * specific service prefix.
+ *
+ * The ability to specify the key via Linux keyring key is intended for cases
+ * where userspace needs to re-add keys after the filesystem is unmounted and
+ * re-mounted.  Most users should just provide the key directly instead.
+ */
+static int get_keyring_key(u32 key_id, u32 type, u32 flags,
+			   struct fscrypt_master_key_secret *secret)
+{
+	key_ref_t ref;
+	struct key *key;
+	const struct fscrypt_provisioning_key_payload *payload;
+	int err;
+
+	ref = lookup_user_key(key_id, 0, KEY_NEED_SEARCH);
+	if (IS_ERR(ref))
+		return PTR_ERR(ref);
+	key = key_ref_to_ptr(ref);
+
+	if (key->type != &key_type_fscrypt_provisioning)
+		goto bad_key;
+	payload = key->payload.data[0];
+
+	/*
+	 * Don't allow fscrypt v1 keys to be used as v2 keys and vice versa.
+	 * Similarly, don't allow hardware-wrapped keys to be used as
+	 * non-hardware-wrapped keys and vice versa.
+	 */
+	if (payload->type != type || payload->flags != flags)
+		goto bad_key;
+
+	secret->size = key->datalen - sizeof(*payload);
+	memcpy(secret->bytes, payload->raw, secret->size);
+	err = 0;
+	goto out_put;
+
+bad_key:
+	err = -EKEYREJECTED;
+out_put:
+	key_ref_put(ref);
+	return err;
+}
+
+/*
+ * Add a master encryption key to the filesystem, causing all files which were
+ * encrypted with it to appear "unlocked" (decrypted) when accessed.
+ *
+ * When adding a key for use by v1 encryption policies, this ioctl is
+ * privileged, and userspace must provide the 'key_descriptor'.
+ *
+ * When adding a key for use by v2+ encryption policies, this ioctl is
+ * unprivileged.  This is needed, in general, to allow non-root users to use
+ * encryption without encountering the visibility problems of process-subscribed
+ * keyrings and the inability to properly remove keys.  This works by having
+ * each key identified by its cryptographically secure hash --- the
+ * 'key_identifier'.  The cryptographic hash ensures that a malicious user
+ * cannot add the wrong key for a given identifier.  Furthermore, each added key
+ * is charged to the appropriate user's quota for the keyrings service, which
+ * prevents a malicious user from adding too many keys.  Finally, we forbid a
+ * user from removing a key while other users have added it too, which prevents
+ * a user who knows another user's key from causing a denial-of-service by
+ * removing it at an inopportune time.  (We tolerate that a user who knows a key
+ * can prevent other users from removing it.)
+ *
+ * For more details, see the "FS_IOC_ADD_ENCRYPTION_KEY" section of
+ * Documentation/filesystems/fscrypt.rst.
+ */
+int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg)
+{
+	struct super_block *sb = file_inode(filp)->i_sb;
+	struct fscrypt_add_key_arg __user *uarg = _uarg;
+	struct fscrypt_add_key_arg arg;
+	struct fscrypt_master_key_secret secret;
+	int err;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	if (!valid_key_spec(&arg.key_spec))
+		return -EINVAL;
+
+	if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
+		return -EINVAL;
+
+	/*
+	 * Only root can add keys that are identified by an arbitrary descriptor
+	 * rather than by a cryptographic hash --- since otherwise a malicious
+	 * user could add the wrong key.
+	 */
+	if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	memset(&secret, 0, sizeof(secret));
+
+	if (arg.flags) {
+		if (arg.flags & ~FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED)
+			return -EINVAL;
+		if (arg.key_spec.type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
+			return -EINVAL;
+		secret.is_hw_wrapped = true;
+	}
+
+	if (arg.key_id) {
+		if (arg.raw_size != 0)
+			return -EINVAL;
+		err = get_keyring_key(arg.key_id, arg.key_spec.type, arg.flags,
+				      &secret);
+		if (err)
+			goto out_wipe_secret;
+	} else {
+		if (!fscrypt_valid_key_size(arg.raw_size, arg.flags))
+			return -EINVAL;
+		secret.size = arg.raw_size;
+		err = -EFAULT;
+		if (copy_from_user(secret.bytes, uarg->raw, secret.size))
+			goto out_wipe_secret;
+	}
+
+	err = add_master_key(sb, &secret, &arg.key_spec);
+	if (err)
+		goto out_wipe_secret;
+
+	/* Return the key identifier to userspace, if applicable */
+	err = -EFAULT;
+	if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
+	    copy_to_user(uarg->key_spec.u.identifier, arg.key_spec.u.identifier,
+			 FSCRYPT_KEY_IDENTIFIER_SIZE))
+		goto out_wipe_secret;
+	err = 0;
+out_wipe_secret:
+	wipe_master_key_secret(&secret);
+	return err;
+}
+EXPORT_SYMBOL_GPL(fscrypt_ioctl_add_key);
+
+static void
+fscrypt_get_test_dummy_secret(struct fscrypt_master_key_secret *secret)
+{
+	static u8 test_key[FSCRYPT_MAX_RAW_KEY_SIZE];
+
+	get_random_once(test_key, sizeof(test_key));
+
+	memset(secret, 0, sizeof(*secret));
+	secret->size = sizeof(test_key);
+	memcpy(secret->bytes, test_key, sizeof(test_key));
+}
+
+void fscrypt_get_test_dummy_key_identifier(
+				u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
+{
+	struct fscrypt_master_key_secret secret;
+
+	fscrypt_get_test_dummy_secret(&secret);
+	fscrypt_init_hkdf(&secret.hkdf, secret.bytes, secret.size);
+	fscrypt_hkdf_expand(&secret.hkdf,
+			    HKDF_CONTEXT_KEY_IDENTIFIER_FOR_RAW_KEY, NULL, 0,
+			    key_identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
+	wipe_master_key_secret(&secret);
+}
+
+/**
+ * fscrypt_add_test_dummy_key() - add the test dummy encryption key
+ * @sb: the filesystem instance to add the key to
+ * @key_spec: the key specifier of the test dummy encryption key
+ *
+ * Add the key for the test_dummy_encryption mount option to the filesystem.  To
+ * prevent misuse of this mount option, a per-boot random key is used instead of
+ * a hardcoded one.  This makes it so that any encrypted files created using
+ * this option won't be accessible after a reboot.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fscrypt_add_test_dummy_key(struct super_block *sb,
+			       struct fscrypt_key_specifier *key_spec)
+{
+	struct fscrypt_master_key_secret secret;
+	int err;
+
+	fscrypt_get_test_dummy_secret(&secret);
+	err = add_master_key(sb, &secret, key_spec);
+	wipe_master_key_secret(&secret);
+	return err;
+}
+
+/*
+ * Verify that the current user has added a master key with the given identifier
+ * (returns -ENOKEY if not).  This is needed to prevent a user from encrypting
+ * their files using some other user's key which they don't actually know.
+ * Cryptographically this isn't much of a problem, but the semantics of this
+ * would be a bit weird, so it's best to just forbid it.
+ *
+ * The system administrator (CAP_FOWNER) can override this, which should be
+ * enough for any use cases where encryption policies are being set using keys
+ * that were chosen ahead of time but aren't available at the moment.
+ *
+ * Note that the key may have already removed by the time this returns, but
+ * that's okay; we just care whether the key was there at some point.
+ *
+ * Return: 0 if the key is added, -ENOKEY if it isn't, or another -errno code
+ */
+int fscrypt_verify_key_added(struct super_block *sb,
+			     const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
+{
+	struct fscrypt_key_specifier mk_spec;
+	struct fscrypt_master_key *mk;
+	int err;
+
+	mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
+	memcpy(mk_spec.u.identifier, identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
+
+	mk = fscrypt_find_master_key(sb, &mk_spec);
+	if (!mk) {
+		err = -ENOKEY;
+		goto out;
+	}
+	down_read(&mk->mk_sem);
+	if (find_master_key_user(mk) != NULL)
+		err = 0;
+	else
+		err = -ENOKEY;
+	up_read(&mk->mk_sem);
+	fscrypt_put_master_key(mk);
+out:
+	if (err == -ENOKEY && capable(CAP_FOWNER))
+		err = 0;
+	return err;
+}
+
+/*
+ * Try to evict the inode's dentries from the dentry cache.  If the inode is a
+ * directory, then it can have at most one dentry; however, that dentry may be
+ * pinned by child dentries, so first try to evict the children too.
+ */
+static void shrink_dcache_inode(struct inode *inode)
+{
+	struct dentry *dentry;
+
+	if (S_ISDIR(inode->i_mode)) {
+		dentry = d_find_any_alias(inode);
+		if (dentry) {
+			shrink_dcache_parent(dentry);
+			dput(dentry);
+		}
+	}
+	d_prune_aliases(inode);
+}
+
+static void evict_dentries_for_decrypted_inodes(struct fscrypt_master_key *mk)
+{
+	struct fscrypt_inode_info *ci;
+	struct inode *inode;
+	struct inode *toput_inode = NULL;
+
+	spin_lock(&mk->mk_decrypted_inodes_lock);
+
+	list_for_each_entry(ci, &mk->mk_decrypted_inodes, ci_master_key_link) {
+		inode = ci->ci_inode;
+		spin_lock(&inode->i_lock);
+		if (inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&mk->mk_decrypted_inodes_lock);
+
+		shrink_dcache_inode(inode);
+		iput(toput_inode);
+		toput_inode = inode;
+
+		spin_lock(&mk->mk_decrypted_inodes_lock);
+	}
+
+	spin_unlock(&mk->mk_decrypted_inodes_lock);
+	iput(toput_inode);
+}
+
+static int check_for_busy_inodes(struct super_block *sb,
+				 struct fscrypt_master_key *mk)
+{
+	struct list_head *pos;
+	size_t busy_count = 0;
+	char ino_str[50] = "";
+	u64 ino;
+
+	spin_lock(&mk->mk_decrypted_inodes_lock);
+
+	list_for_each(pos, &mk->mk_decrypted_inodes)
+		busy_count++;
+
+	if (busy_count == 0) {
+		spin_unlock(&mk->mk_decrypted_inodes_lock);
+		return 0;
+	}
+
+	{
+		/* select an example file to show for debugging purposes */
+		struct inode *inode =
+			list_first_entry(&mk->mk_decrypted_inodes,
+					 struct fscrypt_inode_info,
+					 ci_master_key_link)->ci_inode;
+		ino = inode->i_ino;
+	}
+	spin_unlock(&mk->mk_decrypted_inodes_lock);
+
+	/* If the inode is currently being created, ino may still be 0. */
+	if (ino)
+		snprintf(ino_str, sizeof(ino_str), ", including ino %llu", ino);
+
+	fscrypt_warn(NULL,
+		     "%s: %zu inode(s) still busy after removing key with %s %*phN%s",
+		     sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec),
+		     master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u,
+		     ino_str);
+	return -EBUSY;
+}
+
+static int try_to_lock_encrypted_files(struct super_block *sb,
+				       struct fscrypt_master_key *mk)
+{
+	int err1;
+	int err2;
+
+	/*
+	 * An inode can't be evicted while it is dirty or has dirty pages.
+	 * Thus, we first have to clean the inodes in ->mk_decrypted_inodes.
+	 *
+	 * Just do it the easy way: call sync_filesystem().  It's overkill, but
+	 * it works, and it's more important to minimize the amount of caches we
+	 * drop than the amount of data we sync.  Also, unprivileged users can
+	 * already call sync_filesystem() via sys_syncfs() or sys_sync().
+	 */
+	down_read(&sb->s_umount);
+	err1 = sync_filesystem(sb);
+	up_read(&sb->s_umount);
+	/* If a sync error occurs, still try to evict as much as possible. */
+
+	/*
+	 * Inodes are pinned by their dentries, so we have to evict their
+	 * dentries.  shrink_dcache_sb() would suffice, but would be overkill
+	 * and inappropriate for use by unprivileged users.  So instead go
+	 * through the inodes' alias lists and try to evict each dentry.
+	 */
+	evict_dentries_for_decrypted_inodes(mk);
+
+	/*
+	 * evict_dentries_for_decrypted_inodes() already iput() each inode in
+	 * the list; any inodes for which that dropped the last reference will
+	 * have been evicted due to fscrypt_drop_inode() detecting the key
+	 * removal and telling the VFS to evict the inode.  So to finish, we
+	 * just need to check whether any inodes couldn't be evicted.
+	 */
+	err2 = check_for_busy_inodes(sb, mk);
+
+	return err1 ?: err2;
+}
+
+/*
+ * Try to remove an fscrypt master encryption key.
+ *
+ * FS_IOC_REMOVE_ENCRYPTION_KEY (all_users=false) removes the current user's
+ * claim to the key, then removes the key itself if no other users have claims.
+ * FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS (all_users=true) always removes the
+ * key itself.
+ *
+ * To "remove the key itself", first we transition the key to the "incompletely
+ * removed" state, so that no more inodes can be unlocked with it.  Then we try
+ * to evict all cached inodes that had been unlocked with the key.
+ *
+ * If all inodes were evicted, then we unlink the fscrypt_master_key from the
+ * keyring.  Otherwise it remains in the keyring in the "incompletely removed"
+ * state where it tracks the list of remaining inodes.  Userspace can execute
+ * the ioctl again later to retry eviction, or alternatively can re-add the key.
+ *
+ * For more details, see the "Removing keys" section of
+ * Documentation/filesystems/fscrypt.rst.
+ */
+static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users)
+{
+	struct super_block *sb = file_inode(filp)->i_sb;
+	struct fscrypt_remove_key_arg __user *uarg = _uarg;
+	struct fscrypt_remove_key_arg arg;
+	struct fscrypt_master_key *mk;
+	u32 status_flags = 0;
+	int err;
+	bool inodes_remain;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	if (!valid_key_spec(&arg.key_spec))
+		return -EINVAL;
+
+	if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
+		return -EINVAL;
+
+	/*
+	 * Only root can add and remove keys that are identified by an arbitrary
+	 * descriptor rather than by a cryptographic hash.
+	 */
+	if (arg.key_spec.type == FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	/* Find the key being removed. */
+	mk = fscrypt_find_master_key(sb, &arg.key_spec);
+	if (!mk)
+		return -ENOKEY;
+	down_write(&mk->mk_sem);
+
+	/* If relevant, remove current user's (or all users) claim to the key */
+	if (!list_empty(&mk->mk_users)) {
+		if (all_users) {
+			clear_mk_users(mk);
+			err = 0;
+		} else {
+			err = remove_master_key_user(mk);
+		}
+		if (err) {
+			up_write(&mk->mk_sem);
+			goto out_put_key;
+		}
+		if (!list_empty(&mk->mk_users)) {
+			/*
+			 * Other users have still added the key too.  We removed
+			 * the current user's claim to the key, but we still
+			 * can't remove the key itself.
+			 */
+			status_flags |=
+				FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS;
+			err = 0;
+			up_write(&mk->mk_sem);
+			goto out_put_key;
+		}
+	}
+
+	/* No user claims remaining.  Initiate removal of the key. */
+	err = -ENOKEY;
+	if (mk->mk_present) {
+		fscrypt_initiate_key_removal(sb, mk);
+		err = 0;
+	}
+	inodes_remain = refcount_read(&mk->mk_active_refs) > 0;
+	up_write(&mk->mk_sem);
+
+	if (inodes_remain) {
+		/* Some inodes still reference this key; try to evict them. */
+		err = try_to_lock_encrypted_files(sb, mk);
+		if (err == -EBUSY) {
+			status_flags |=
+				FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY;
+			err = 0;
+		}
+	}
+	/*
+	 * We return 0 if we successfully did something: removed a claim to the
+	 * key, initiated removal of the key, or tried locking the files again.
+	 * Users need to check the informational status flags if they care
+	 * whether the key has been fully removed including all files locked.
+	 */
+out_put_key:
+	fscrypt_put_master_key(mk);
+	if (err == 0)
+		err = put_user(status_flags, &uarg->removal_status_flags);
+	return err;
+}
+
+int fscrypt_ioctl_remove_key(struct file *filp, void __user *uarg)
+{
+	return do_remove_key(filp, uarg, false);
+}
+EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key);
+
+int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *uarg)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+	return do_remove_key(filp, uarg, true);
+}
+EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key_all_users);
+
+/*
+ * Retrieve the status of an fscrypt master encryption key.
+ *
+ * We set ->status to indicate whether the key is absent, present, or
+ * incompletely removed.  (For an explanation of what these statuses mean and
+ * how they are represented internally, see struct fscrypt_master_key.)  This
+ * field allows applications to easily determine the status of an encrypted
+ * directory without using a hack such as trying to open a regular file in it
+ * (which can confuse the "incompletely removed" status with absent or present).
+ *
+ * In addition, for v2 policy keys we allow applications to determine, via
+ * ->status_flags and ->user_count, whether the key has been added by the
+ * current user, by other users, or by both.  Most applications should not need
+ * this, since ordinarily only one user should know a given key.  However, if a
+ * secret key is shared by multiple users, applications may wish to add an
+ * already-present key to prevent other users from removing it.  This ioctl can
+ * be used to check whether that really is the case before the work is done to
+ * add the key --- which might e.g. require prompting the user for a passphrase.
+ *
+ * For more details, see the "FS_IOC_GET_ENCRYPTION_KEY_STATUS" section of
+ * Documentation/filesystems/fscrypt.rst.
+ */
+int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg)
+{
+	struct super_block *sb = file_inode(filp)->i_sb;
+	struct fscrypt_get_key_status_arg arg;
+	struct fscrypt_master_key *mk;
+	kuid_t uid;
+	const struct fscrypt_master_key_user *mk_user;
+	int err;
+
+	if (copy_from_user(&arg, uarg, sizeof(arg)))
+		return -EFAULT;
+
+	if (!valid_key_spec(&arg.key_spec))
+		return -EINVAL;
+
+	if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
+		return -EINVAL;
+
+	arg.status_flags = 0;
+	arg.user_count = 0;
+	memset(arg.__out_reserved, 0, sizeof(arg.__out_reserved));
+
+	mk = fscrypt_find_master_key(sb, &arg.key_spec);
+	if (!mk) {
+		arg.status = FSCRYPT_KEY_STATUS_ABSENT;
+		err = 0;
+		goto out;
+	}
+	down_read(&mk->mk_sem);
+
+	if (!mk->mk_present) {
+		arg.status = refcount_read(&mk->mk_active_refs) > 0 ?
+			FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED :
+			FSCRYPT_KEY_STATUS_ABSENT /* raced with full removal */;
+		err = 0;
+		goto out_release_key;
+	}
+
+	arg.status = FSCRYPT_KEY_STATUS_PRESENT;
+
+	uid = current_fsuid();
+	list_for_each_entry(mk_user, &mk->mk_users, link) {
+		arg.user_count++;
+		if (uid_eq(mk_user->uid, uid))
+			arg.status_flags |=
+				FSCRYPT_KEY_STATUS_FLAG_ADDED_BY_SELF;
+	}
+	err = 0;
+out_release_key:
+	up_read(&mk->mk_sem);
+	fscrypt_put_master_key(mk);
+out:
+	if (!err && copy_to_user(uarg, &arg, sizeof(arg)))
+		err = -EFAULT;
+	return err;
+}
+EXPORT_SYMBOL_GPL(fscrypt_ioctl_get_key_status);
+
+void __init fscrypt_init_keyring(void)
+{
+	int err;
+
+	/*
+	 * Note that register_key_type() fails only if a key type with the same
+	 * name already exists, which should never happen here.
+	 */
+	err = register_key_type(&key_type_fscrypt_user);
+	if (err)
+		panic("failed to register .fscrypt key type (%d)", err);
+	err = register_key_type(&key_type_fscrypt_provisioning);
+	if (err)
+		panic("failed to register fscrypt-provisioning key type (%d)",
+		      err);
+}