v4.19.13 snapshot.
diff --git a/security/keys/big_key.c b/security/keys/big_key.c
new file mode 100644
index 0000000..2806e70
--- /dev/null
+++ b/security/keys/big_key.c
@@ -0,0 +1,456 @@
+/* Large capacity key type
+ *
+ * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * Copyright (C) 2013 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 Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "big_key: "fmt
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/file.h>
+#include <linux/shmem_fs.h>
+#include <linux/err.h>
+#include <linux/scatterlist.h>
+#include <linux/random.h>
+#include <linux/vmalloc.h>
+#include <keys/user-type.h>
+#include <keys/big_key-type.h>
+#include <crypto/aead.h>
+#include <crypto/gcm.h>
+
+struct big_key_buf {
+ unsigned int nr_pages;
+ void *virt;
+ struct scatterlist *sg;
+ struct page *pages[];
+};
+
+/*
+ * Layout of key payload words.
+ */
+enum {
+ big_key_data,
+ big_key_path,
+ big_key_path_2nd_part,
+ big_key_len,
+};
+
+/*
+ * Crypto operation with big_key data
+ */
+enum big_key_op {
+ BIG_KEY_ENC,
+ BIG_KEY_DEC,
+};
+
+/*
+ * If the data is under this limit, there's no point creating a shm file to
+ * hold it as the permanently resident metadata for the shmem fs will be at
+ * least as large as the data.
+ */
+#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
+
+/*
+ * Key size for big_key data encryption
+ */
+#define ENC_KEY_SIZE 32
+
+/*
+ * Authentication tag length
+ */
+#define ENC_AUTHTAG_SIZE 16
+
+/*
+ * big_key defined keys take an arbitrary string as the description and an
+ * arbitrary blob of data as the payload
+ */
+struct key_type key_type_big_key = {
+ .name = "big_key",
+ .preparse = big_key_preparse,
+ .free_preparse = big_key_free_preparse,
+ .instantiate = generic_key_instantiate,
+ .revoke = big_key_revoke,
+ .destroy = big_key_destroy,
+ .describe = big_key_describe,
+ .read = big_key_read,
+ /* no ->update(); don't add it without changing big_key_crypt() nonce */
+};
+
+/*
+ * Crypto names for big_key data authenticated encryption
+ */
+static const char big_key_alg_name[] = "gcm(aes)";
+#define BIG_KEY_IV_SIZE GCM_AES_IV_SIZE
+
+/*
+ * Crypto algorithms for big_key data authenticated encryption
+ */
+static struct crypto_aead *big_key_aead;
+
+/*
+ * Since changing the key affects the entire object, we need a mutex.
+ */
+static DEFINE_MUTEX(big_key_aead_lock);
+
+/*
+ * Encrypt/decrypt big_key data
+ */
+static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t datalen, u8 *key)
+{
+ int ret;
+ struct aead_request *aead_req;
+ /* We always use a zero nonce. The reason we can get away with this is
+ * because we're using a different randomly generated key for every
+ * different encryption. Notably, too, key_type_big_key doesn't define
+ * an .update function, so there's no chance we'll wind up reusing the
+ * key to encrypt updated data. Simply put: one key, one encryption.
+ */
+ u8 zero_nonce[BIG_KEY_IV_SIZE];
+
+ aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
+ if (!aead_req)
+ return -ENOMEM;
+
+ memset(zero_nonce, 0, sizeof(zero_nonce));
+ aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce);
+ aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
+ aead_request_set_ad(aead_req, 0);
+
+ mutex_lock(&big_key_aead_lock);
+ if (crypto_aead_setkey(big_key_aead, key, ENC_KEY_SIZE)) {
+ ret = -EAGAIN;
+ goto error;
+ }
+ if (op == BIG_KEY_ENC)
+ ret = crypto_aead_encrypt(aead_req);
+ else
+ ret = crypto_aead_decrypt(aead_req);
+error:
+ mutex_unlock(&big_key_aead_lock);
+ aead_request_free(aead_req);
+ return ret;
+}
+
+/*
+ * Free up the buffer.
+ */
+static void big_key_free_buffer(struct big_key_buf *buf)
+{
+ unsigned int i;
+
+ if (buf->virt) {
+ memset(buf->virt, 0, buf->nr_pages * PAGE_SIZE);
+ vunmap(buf->virt);
+ }
+
+ for (i = 0; i < buf->nr_pages; i++)
+ if (buf->pages[i])
+ __free_page(buf->pages[i]);
+
+ kfree(buf);
+}
+
+/*
+ * Allocate a buffer consisting of a set of pages with a virtual mapping
+ * applied over them.
+ */
+static void *big_key_alloc_buffer(size_t len)
+{
+ struct big_key_buf *buf;
+ unsigned int npg = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned int i, l;
+
+ buf = kzalloc(sizeof(struct big_key_buf) +
+ sizeof(struct page) * npg +
+ sizeof(struct scatterlist) * npg,
+ GFP_KERNEL);
+ if (!buf)
+ return NULL;
+
+ buf->nr_pages = npg;
+ buf->sg = (void *)(buf->pages + npg);
+ sg_init_table(buf->sg, npg);
+
+ for (i = 0; i < buf->nr_pages; i++) {
+ buf->pages[i] = alloc_page(GFP_KERNEL);
+ if (!buf->pages[i])
+ goto nomem;
+
+ l = min_t(size_t, len, PAGE_SIZE);
+ sg_set_page(&buf->sg[i], buf->pages[i], l, 0);
+ len -= l;
+ }
+
+ buf->virt = vmap(buf->pages, buf->nr_pages, VM_MAP, PAGE_KERNEL);
+ if (!buf->virt)
+ goto nomem;
+
+ return buf;
+
+nomem:
+ big_key_free_buffer(buf);
+ return NULL;
+}
+
+/*
+ * Preparse a big key
+ */
+int big_key_preparse(struct key_preparsed_payload *prep)
+{
+ struct big_key_buf *buf;
+ struct path *path = (struct path *)&prep->payload.data[big_key_path];
+ struct file *file;
+ u8 *enckey;
+ ssize_t written;
+ size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE;
+ int ret;
+
+ if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data)
+ return -EINVAL;
+
+ /* Set an arbitrary quota */
+ prep->quotalen = 16;
+
+ prep->payload.data[big_key_len] = (void *)(unsigned long)datalen;
+
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
+ /* Create a shmem file to store the data in. This will permit the data
+ * to be swapped out if needed.
+ *
+ * File content is stored encrypted with randomly generated key.
+ */
+ loff_t pos = 0;
+
+ buf = big_key_alloc_buffer(enclen);
+ if (!buf)
+ return -ENOMEM;
+ memcpy(buf->virt, prep->data, datalen);
+
+ /* generate random key */
+ enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
+ if (!enckey) {
+ ret = -ENOMEM;
+ goto error;
+ }
+ ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
+ if (unlikely(ret))
+ goto err_enckey;
+
+ /* encrypt aligned data */
+ ret = big_key_crypt(BIG_KEY_ENC, buf, datalen, enckey);
+ if (ret)
+ goto err_enckey;
+
+ /* save aligned data to file */
+ file = shmem_kernel_file_setup("", enclen, 0);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto err_enckey;
+ }
+
+ written = kernel_write(file, buf->virt, enclen, &pos);
+ if (written != enclen) {
+ ret = written;
+ if (written >= 0)
+ ret = -ENOMEM;
+ goto err_fput;
+ }
+
+ /* Pin the mount and dentry to the key so that we can open it again
+ * later
+ */
+ prep->payload.data[big_key_data] = enckey;
+ *path = file->f_path;
+ path_get(path);
+ fput(file);
+ big_key_free_buffer(buf);
+ } else {
+ /* Just store the data in a buffer */
+ void *data = kmalloc(datalen, GFP_KERNEL);
+
+ if (!data)
+ return -ENOMEM;
+
+ prep->payload.data[big_key_data] = data;
+ memcpy(data, prep->data, prep->datalen);
+ }
+ return 0;
+
+err_fput:
+ fput(file);
+err_enckey:
+ kzfree(enckey);
+error:
+ big_key_free_buffer(buf);
+ return ret;
+}
+
+/*
+ * Clear preparsement.
+ */
+void big_key_free_preparse(struct key_preparsed_payload *prep)
+{
+ if (prep->datalen > BIG_KEY_FILE_THRESHOLD) {
+ struct path *path = (struct path *)&prep->payload.data[big_key_path];
+
+ path_put(path);
+ }
+ kzfree(prep->payload.data[big_key_data]);
+}
+
+/*
+ * dispose of the links from a revoked keyring
+ * - called with the key sem write-locked
+ */
+void big_key_revoke(struct key *key)
+{
+ struct path *path = (struct path *)&key->payload.data[big_key_path];
+
+ /* clear the quota */
+ key_payload_reserve(key, 0);
+ if (key_is_positive(key) &&
+ (size_t)key->payload.data[big_key_len] > BIG_KEY_FILE_THRESHOLD)
+ vfs_truncate(path, 0);
+}
+
+/*
+ * dispose of the data dangling from the corpse of a big_key key
+ */
+void big_key_destroy(struct key *key)
+{
+ size_t datalen = (size_t)key->payload.data[big_key_len];
+
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
+ struct path *path = (struct path *)&key->payload.data[big_key_path];
+
+ path_put(path);
+ path->mnt = NULL;
+ path->dentry = NULL;
+ }
+ kzfree(key->payload.data[big_key_data]);
+ key->payload.data[big_key_data] = NULL;
+}
+
+/*
+ * describe the big_key key
+ */
+void big_key_describe(const struct key *key, struct seq_file *m)
+{
+ size_t datalen = (size_t)key->payload.data[big_key_len];
+
+ seq_puts(m, key->description);
+
+ if (key_is_positive(key))
+ seq_printf(m, ": %zu [%s]",
+ datalen,
+ datalen > BIG_KEY_FILE_THRESHOLD ? "file" : "buff");
+}
+
+/*
+ * read the key data
+ * - the key's semaphore is read-locked
+ */
+long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
+{
+ size_t datalen = (size_t)key->payload.data[big_key_len];
+ long ret;
+
+ if (!buffer || buflen < datalen)
+ return datalen;
+
+ if (datalen > BIG_KEY_FILE_THRESHOLD) {
+ struct big_key_buf *buf;
+ struct path *path = (struct path *)&key->payload.data[big_key_path];
+ struct file *file;
+ u8 *enckey = (u8 *)key->payload.data[big_key_data];
+ size_t enclen = datalen + ENC_AUTHTAG_SIZE;
+ loff_t pos = 0;
+
+ buf = big_key_alloc_buffer(enclen);
+ if (!buf)
+ return -ENOMEM;
+
+ file = dentry_open(path, O_RDONLY, current_cred());
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto error;
+ }
+
+ /* read file to kernel and decrypt */
+ ret = kernel_read(file, buf->virt, enclen, &pos);
+ if (ret >= 0 && ret != enclen) {
+ ret = -EIO;
+ goto err_fput;
+ }
+
+ ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey);
+ if (ret)
+ goto err_fput;
+
+ ret = datalen;
+
+ /* copy decrypted data to user */
+ if (copy_to_user(buffer, buf->virt, datalen) != 0)
+ ret = -EFAULT;
+
+err_fput:
+ fput(file);
+error:
+ big_key_free_buffer(buf);
+ } else {
+ ret = datalen;
+ if (copy_to_user(buffer, key->payload.data[big_key_data],
+ datalen) != 0)
+ ret = -EFAULT;
+ }
+
+ return ret;
+}
+
+/*
+ * Register key type
+ */
+static int __init big_key_init(void)
+{
+ int ret;
+
+ /* init block cipher */
+ big_key_aead = crypto_alloc_aead(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(big_key_aead)) {
+ ret = PTR_ERR(big_key_aead);
+ pr_err("Can't alloc crypto: %d\n", ret);
+ return ret;
+ }
+
+ if (unlikely(crypto_aead_ivsize(big_key_aead) != BIG_KEY_IV_SIZE)) {
+ WARN(1, "big key algorithm changed?");
+ ret = -EINVAL;
+ goto free_aead;
+ }
+
+ ret = crypto_aead_setauthsize(big_key_aead, ENC_AUTHTAG_SIZE);
+ if (ret < 0) {
+ pr_err("Can't set crypto auth tag len: %d\n", ret);
+ goto free_aead;
+ }
+
+ ret = register_key_type(&key_type_big_key);
+ if (ret < 0) {
+ pr_err("Can't register type: %d\n", ret);
+ goto free_aead;
+ }
+
+ return 0;
+
+free_aead:
+ crypto_free_aead(big_key_aead);
+ return ret;
+}
+
+late_initcall(big_key_init);