diff options
Diffstat (limited to 'security/keys')
-rw-r--r-- | security/keys/Kconfig | 4 | ||||
-rw-r--r-- | security/keys/big_key.c | 240 |
2 files changed, 35 insertions, 209 deletions
diff --git a/security/keys/Kconfig b/security/keys/Kconfig index 47c041563d41..8153ea01d7bb 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -60,9 +60,7 @@ config BIG_KEYS bool "Large payload keys" depends on KEYS depends on TMPFS - select CRYPTO - select CRYPTO_AES - select CRYPTO_GCM + depends on CRYPTO_LIB_CHACHA20POLY1305 = y help This option provides support for holding large keys within the kernel (for example Kerberos ticket caches). The data may be stored out to diff --git a/security/keys/big_key.c b/security/keys/big_key.c index 82008f900930..d43f3daab2b8 100644 --- a/security/keys/big_key.c +++ b/security/keys/big_key.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0-or-later /* Large capacity key type * - * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. + * Copyright (C) 2017-2020 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) */ @@ -12,20 +12,10 @@ #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[]; -}; +#include <crypto/chacha20poly1305.h> /* * Layout of key payload words. @@ -38,14 +28,6 @@ enum { }; /* - * 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. @@ -53,16 +35,6 @@ enum big_key_op { #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 */ @@ -75,136 +47,20 @@ struct key_type key_type_big_key = { .destroy = big_key_destroy, .describe = big_key_describe, .read = big_key_read, - /* no ->update(); don't add it without changing big_key_crypt() nonce */ + /* no ->update(); don't add it without changing chacha20poly1305's 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; + u8 *buf, *enckey; ssize_t written; - size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE; + size_t datalen = prep->datalen; + size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE; int ret; if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data) @@ -220,28 +76,28 @@ int big_key_preparse(struct key_preparsed_payload *prep) * to be swapped out if needed. * * File content is stored encrypted with randomly generated key. + * Since the key is random for each file, we can set the nonce + * to zero, provided we never define a ->update() call. */ loff_t pos = 0; - buf = big_key_alloc_buffer(enclen); + buf = kvmalloc(enclen, GFP_KERNEL); if (!buf) return -ENOMEM; - memcpy(buf->virt, prep->data, datalen); /* generate random key */ - enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL); + enckey = kmalloc(CHACHA20POLY1305_KEY_SIZE, GFP_KERNEL); if (!enckey) { ret = -ENOMEM; goto error; } - ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE); + ret = get_random_bytes_wait(enckey, CHACHA20POLY1305_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; + /* encrypt data */ + chacha20poly1305_encrypt(buf, prep->data, datalen, NULL, 0, + 0, enckey); /* save aligned data to file */ file = shmem_kernel_file_setup("", enclen, 0); @@ -250,11 +106,11 @@ int big_key_preparse(struct key_preparsed_payload *prep) goto err_enckey; } - written = kernel_write(file, buf->virt, enclen, &pos); + written = kernel_write(file, buf, enclen, &pos); if (written != enclen) { ret = written; if (written >= 0) - ret = -ENOMEM; + ret = -EIO; goto err_fput; } @@ -265,7 +121,8 @@ int big_key_preparse(struct key_preparsed_payload *prep) *path = file->f_path; path_get(path); fput(file); - big_key_free_buffer(buf); + memzero_explicit(buf, enclen); + kvfree(buf); } else { /* Just store the data in a buffer */ void *data = kmalloc(datalen, GFP_KERNEL); @@ -283,7 +140,8 @@ err_fput: err_enckey: kzfree(enckey); error: - big_key_free_buffer(buf); + memzero_explicit(buf, enclen); + kvfree(buf); return ret; } @@ -361,14 +219,13 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen) 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; + u8 *buf, *enckey = (u8 *)key->payload.data[big_key_data]; + size_t enclen = datalen + CHACHA20POLY1305_AUTHTAG_SIZE; loff_t pos = 0; - buf = big_key_alloc_buffer(enclen); + buf = kvmalloc(enclen, GFP_KERNEL); if (!buf) return -ENOMEM; @@ -379,25 +236,28 @@ long big_key_read(const struct key *key, char *buffer, size_t buflen) } /* read file to kernel and decrypt */ - ret = kernel_read(file, buf->virt, enclen, &pos); - if (ret >= 0 && ret != enclen) { - ret = -EIO; + ret = kernel_read(file, buf, enclen, &pos); + if (ret != enclen) { + if (ret >= 0) + ret = -EIO; goto err_fput; } - ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey); - if (ret) + ret = chacha20poly1305_decrypt(buf, buf, enclen, NULL, 0, 0, + enckey) ? 0 : -EBADMSG; + if (unlikely(ret)) goto err_fput; ret = datalen; /* copy out decrypted data */ - memcpy(buffer, buf->virt, datalen); + memcpy(buffer, buf, datalen); err_fput: fput(file); error: - big_key_free_buffer(buf); + memzero_explicit(buf, enclen); + kvfree(buf); } else { ret = datalen; memcpy(buffer, key->payload.data[big_key_data], datalen); @@ -411,39 +271,7 @@ error: */ 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; + return register_key_type(&key_type_big_key); } late_initcall(big_key_init); |