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Add per-file file system encryption support

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This commit is contained in:
James Christopher Adduono 2016-04-03 21:22:45 -04:00 committed by HackerOO7
parent 9019c15774
commit 59334583dc
12 changed files with 1974 additions and 0 deletions
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2
fs/Kconfig
View file

@ -62,6 +62,8 @@ config FILE_LOCKING
for filesystems like NFS and for the flock() system
call. Disabling this option saves about 11k.
source "fs/crypto/Kconfig"
source "fs/notify/Kconfig"
source "fs/quota/Kconfig"

1
fs/Makefile
View file

@ -28,6 +28,7 @@ obj-$(CONFIG_SIGNALFD) += signalfd.o
obj-$(CONFIG_TIMERFD) += timerfd.o
obj-$(CONFIG_EVENTFD) += eventfd.o
obj-$(CONFIG_AIO) += aio.o
obj-$(CONFIG_FS_ENCRYPTION) += crypto/
obj-$(CONFIG_FILE_LOCKING) += locks.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
obj-$(CONFIG_BINFMT_AOUT) += binfmt_aout.o

18
fs/crypto/Kconfig Normal file
View file

@ -0,0 +1,18 @@
config FS_ENCRYPTION
tristate "FS Encryption (Per-file encryption)"
depends on BLOCK
select CRYPTO
select CRYPTO_AES
select CRYPTO_CBC
select CRYPTO_ECB
select CRYPTO_XTS
select CRYPTO_CTS
select CRYPTO_CTR
select CRYPTO_SHA256
select KEYS
select ENCRYPTED_KEYS
help
Enable encryption of files and directories. This
feature is similar to ecryptfs, but it is more memory
efficient since it avoids caching the encrypted and
decrypted pages in the page cache.

3
fs/crypto/Makefile Normal file
View file

@ -0,0 +1,3 @@
obj-$(CONFIG_FS_ENCRYPTION) += fscrypto.o
fscrypto-y := crypto.o fname.o policy.o keyinfo.o

554
fs/crypto/crypto.c Normal file
View file

@ -0,0 +1,554 @@
/*
* This contains encryption functions for per-file encryption.
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility
*
* Written by Michael Halcrow, 2014.
*
* Filename encryption additions
* Uday Savagaonkar, 2014
* Encryption policy handling additions
* Ildar Muslukhov, 2014
* Add fscrypt_pullback_bio_page()
* Jaegeuk Kim, 2015.
*
* This has not yet undergone a rigorous security audit.
*
* The usage of AES-XTS should conform to recommendations in NIST
* Special Publication 800-38E and IEEE P1619/D16.
*/
#include <linux/crypto.h>
#include <linux/ecryptfs.h>
#include <linux/pagemap.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/ratelimit.h>
#include <linux/bio.h>
#include <linux/dcache.h>
#include <linux/fscrypto.h>
static unsigned int num_prealloc_crypto_pages = 32;
static unsigned int num_prealloc_crypto_ctxs = 128;
module_param(num_prealloc_crypto_pages, uint, 0444);
MODULE_PARM_DESC(num_prealloc_crypto_pages,
"Number of crypto pages to preallocate");
module_param(num_prealloc_crypto_ctxs, uint, 0444);
MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
"Number of crypto contexts to preallocate");
static mempool_t *fscrypt_bounce_page_pool = NULL;
static LIST_HEAD(fscrypt_free_ctxs);
static DEFINE_SPINLOCK(fscrypt_ctx_lock);
static struct workqueue_struct *fscrypt_read_workqueue;
static DEFINE_MUTEX(fscrypt_init_mutex);
static struct kmem_cache *fscrypt_ctx_cachep;
struct kmem_cache *fscrypt_info_cachep;
/**
* fscrypt_release_ctx() - Releases an encryption context
* @ctx: The encryption context to release.
*
* If the encryption context was allocated from the pre-allocated pool, returns
* it to that pool. Else, frees it.
*
* If there's a bounce page in the context, this frees that.
*/
void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
{
unsigned long flags;
if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) {
mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
ctx->w.bounce_page = NULL;
}
ctx->w.control_page = NULL;
if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
kmem_cache_free(fscrypt_ctx_cachep, ctx);
} else {
spin_lock_irqsave(&fscrypt_ctx_lock, flags);
list_add(&ctx->free_list, &fscrypt_free_ctxs);
spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
}
}
EXPORT_SYMBOL(fscrypt_release_ctx);
/**
* fscrypt_get_ctx() - Gets an encryption context
* @inode: The inode for which we are doing the crypto
*
* Allocates and initializes an encryption context.
*
* Return: An allocated and initialized encryption context on success; error
* value or NULL otherwise.
*/
struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode)
{
struct fscrypt_ctx *ctx = NULL;
struct fscrypt_info *ci = inode->i_crypt_info;
unsigned long flags;
if (ci == NULL)
return ERR_PTR(-ENOKEY);
/*
* We first try getting the ctx from a free list because in
* the common case the ctx will have an allocated and
* initialized crypto tfm, so it's probably a worthwhile
* optimization. For the bounce page, we first try getting it
* from the kernel allocator because that's just about as fast
* as getting it from a list and because a cache of free pages
* should generally be a "last resort" option for a filesystem
* to be able to do its job.
*/
spin_lock_irqsave(&fscrypt_ctx_lock, flags);
ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
struct fscrypt_ctx, free_list);
if (ctx)
list_del(&ctx->free_list);
spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
if (!ctx) {
ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
if (!ctx)
return ERR_PTR(-ENOMEM);
ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->flags &= ~FS_WRITE_PATH_FL;
return ctx;
}
EXPORT_SYMBOL(fscrypt_get_ctx);
/**
* fscrypt_complete() - The completion callback for page encryption
* @req: The asynchronous encryption request context
* @res: The result of the encryption operation
*/
static void fscrypt_complete(struct crypto_async_request *req, int res)
{
struct fscrypt_completion_result *ecr = req->data;
if (res == -EINPROGRESS)
return;
ecr->res = res;
complete(&ecr->completion);
}
typedef enum {
FS_DECRYPT = 0,
FS_ENCRYPT,
} fscrypt_direction_t;
static int do_page_crypto(struct inode *inode,
fscrypt_direction_t rw, pgoff_t index,
struct page *src_page, struct page *dest_page)
{
u8 xts_tweak[FS_XTS_TWEAK_SIZE];
struct ablkcipher_request *req = NULL;
DECLARE_FS_COMPLETION_RESULT(ecr);
struct scatterlist dst, src;
struct fscrypt_info *ci = inode->i_crypt_info;
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n",
__func__);
return -ENOMEM;
}
ablkcipher_request_set_callback(
req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
fscrypt_complete, &ecr);
BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index));
memcpy(xts_tweak, &inode->i_ino, sizeof(index));
memset(&xts_tweak[sizeof(index)], 0,
FS_XTS_TWEAK_SIZE - sizeof(index));
sg_init_table(&dst, 1);
sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0);
sg_init_table(&src, 1);
sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
xts_tweak);
if (rw == FS_DECRYPT)
res = crypto_ablkcipher_decrypt(req);
else
res = crypto_ablkcipher_encrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
BUG_ON(req->base.data != &ecr);
wait_for_completion(&ecr.completion);
res = ecr.res;
}
ablkcipher_request_free(req);
if (res) {
printk_ratelimited(KERN_ERR
"%s: crypto_ablkcipher_encrypt() returned %d\n",
__func__, res);
return res;
}
return 0;
}
static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
{
ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool,
GFP_NOWAIT);
if (ctx->w.bounce_page == NULL)
return ERR_PTR(-ENOMEM);
ctx->flags |= FS_WRITE_PATH_FL;
return ctx->w.bounce_page;
}
/**
* fscypt_encrypt_page() - Encrypts a page
* @inode: The inode for which the encryption should take place
* @plaintext_page: The page to encrypt. Must be locked.
*
* Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
* encryption context.
*
* Called on the page write path. The caller must call
* fscrypt_restore_control_page() on the returned ciphertext page to
* release the bounce buffer and the encryption context.
*
* Return: An allocated page with the encrypted content on success. Else, an
* error value or NULL.
*/
struct page *fscrypt_encrypt_page(struct inode *inode,
struct page *plaintext_page)
{
struct fscrypt_ctx *ctx;
struct page *ciphertext_page = NULL;
int err;
BUG_ON(!PageLocked(plaintext_page));
ctx = fscrypt_get_ctx(inode);
if (IS_ERR(ctx))
return (struct page *)ctx;
/* The encryption operation will require a bounce page. */
ciphertext_page = alloc_bounce_page(ctx);
if (IS_ERR(ciphertext_page))
goto errout;
ctx->w.control_page = plaintext_page;
err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
plaintext_page, ciphertext_page);
if (err) {
ciphertext_page = ERR_PTR(err);
goto errout;
}
SetPagePrivate(ciphertext_page);
set_page_private(ciphertext_page, (unsigned long)ctx);
lock_page(ciphertext_page);
return ciphertext_page;
errout:
fscrypt_release_ctx(ctx);
return ciphertext_page;
}
EXPORT_SYMBOL(fscrypt_encrypt_page);
/**
* f2crypt_decrypt_page() - Decrypts a page in-place
* @page: The page to decrypt. Must be locked.
*
* Decrypts page in-place using the ctx encryption context.
*
* Called from the read completion callback.
*
* Return: Zero on success, non-zero otherwise.
*/
int fscrypt_decrypt_page(struct page *page)
{
BUG_ON(!PageLocked(page));
return do_page_crypto(page->mapping->host,
FS_DECRYPT, page->index, page, page);
}
EXPORT_SYMBOL(fscrypt_decrypt_page);
int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
sector_t pblk, unsigned int len)
{
struct fscrypt_ctx *ctx;
struct page *ciphertext_page = NULL;
struct bio *bio;
int ret, err = 0;
BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
ctx = fscrypt_get_ctx(inode);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
ciphertext_page = alloc_bounce_page(ctx);
if (IS_ERR(ciphertext_page)) {
err = PTR_ERR(ciphertext_page);
goto errout;
}
while (len--) {
err = do_page_crypto(inode, FS_ENCRYPT, lblk,
ZERO_PAGE(0), ciphertext_page);
if (err)
goto errout;
bio = bio_alloc(GFP_KERNEL, 1);
if (!bio) {
err = -ENOMEM;
goto errout;
}
bio->bi_bdev = inode->i_sb->s_bdev;
bio->bi_iter.bi_sector =
pblk << (inode->i_sb->s_blocksize_bits - 9);
ret = bio_add_page(bio, ciphertext_page,
inode->i_sb->s_blocksize, 0);
if (ret != inode->i_sb->s_blocksize) {
/* should never happen! */
WARN_ON(1);
bio_put(bio);
err = -EIO;
goto errout;
}
err = submit_bio_wait(WRITE, bio);
bio_put(bio);
if (err)
goto errout;
lblk++;
pblk++;
}
err = 0;
errout:
fscrypt_release_ctx(ctx);
return err;
}
EXPORT_SYMBOL(fscrypt_zeroout_range);
/*
* Validate dentries for encrypted directories to make sure we aren't
* potentially caching stale data after a key has been added or
* removed.
*/
static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
{
struct inode *dir = d_inode(dentry->d_parent);
struct fscrypt_info *ci = dir->i_crypt_info;
int dir_has_key, cached_with_key;
if (!dir->i_sb->s_cop->is_encrypted(dir))
return 0;
if (ci && ci->ci_keyring_key &&
(ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED) |
(1 << KEY_FLAG_DEAD))))
ci = NULL;
/* this should eventually be an flag in d_flags */
spin_lock(&dentry->d_lock);
cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
spin_unlock(&dentry->d_lock);
dir_has_key = (ci != NULL);
/*
* If the dentry was cached without the key, and it is a
* negative dentry, it might be a valid name. We can't check
* if the key has since been made available due to locking
* reasons, so we fail the validation so ext4_lookup() can do
* this check.
*
* We also fail the validation if the dentry was created with
* the key present, but we no longer have the key, or vice versa.
*/
if ((!cached_with_key && d_is_negative(dentry)) ||
(!cached_with_key && dir_has_key) ||
(cached_with_key && !dir_has_key))
return 0;
return 1;
}
const struct dentry_operations fscrypt_d_ops = {
.d_revalidate = fscrypt_d_revalidate,
};
EXPORT_SYMBOL(fscrypt_d_ops);
/*
* Call fscrypt_decrypt_page on every single page, reusing the encryption
* context.
*/
static void completion_pages(struct work_struct *work)
{
struct fscrypt_ctx *ctx =
container_of(work, struct fscrypt_ctx, r.work);
struct bio *bio = ctx->r.bio;
struct bio_vec *bv;
int i;
bio_for_each_segment_all(bv, bio, i) {
struct page *page = bv->bv_page;
int ret = fscrypt_decrypt_page(page);
if (ret) {
WARN_ON_ONCE(1);
SetPageError(page);
} else {
SetPageUptodate(page);
}
unlock_page(page);
}
fscrypt_release_ctx(ctx);
bio_put(bio);
}
void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
{
INIT_WORK(&ctx->r.work, completion_pages);
ctx->r.bio = bio;
queue_work(fscrypt_read_workqueue, &ctx->r.work);
}
EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
void fscrypt_pullback_bio_page(struct page **page, bool restore)
{
struct fscrypt_ctx *ctx;
struct page *bounce_page;
/* The bounce data pages are unmapped. */
if ((*page)->mapping)
return;
/* The bounce data page is unmapped. */
bounce_page = *page;
ctx = (struct fscrypt_ctx *)page_private(bounce_page);
/* restore control page */
*page = ctx->w.control_page;
if (restore)
fscrypt_restore_control_page(bounce_page);
}
EXPORT_SYMBOL(fscrypt_pullback_bio_page);
void fscrypt_restore_control_page(struct page *page)
{
struct fscrypt_ctx *ctx;
ctx = (struct fscrypt_ctx *)page_private(page);
set_page_private(page, (unsigned long)NULL);
ClearPagePrivate(page);
unlock_page(page);
fscrypt_release_ctx(ctx);
}
EXPORT_SYMBOL(fscrypt_restore_control_page);
static void fscrypt_destroy(void)
{
struct fscrypt_ctx *pos, *n;
list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
kmem_cache_free(fscrypt_ctx_cachep, pos);
INIT_LIST_HEAD(&fscrypt_free_ctxs);
mempool_destroy(fscrypt_bounce_page_pool);
fscrypt_bounce_page_pool = NULL;
}
/**
* fscrypt_initialize() - allocate major buffers for fs encryption.
*
* We only call this when we start accessing encrypted files, since it
* results in memory getting allocated that wouldn't otherwise be used.
*
* Return: Zero on success, non-zero otherwise.
*/
int fscrypt_initialize(void)
{
int i, res = -ENOMEM;
if (fscrypt_bounce_page_pool)
return 0;
mutex_lock(&fscrypt_init_mutex);
if (fscrypt_bounce_page_pool)
goto already_initialized;
for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
struct fscrypt_ctx *ctx;
ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
if (!ctx)
goto fail;
list_add(&ctx->free_list, &fscrypt_free_ctxs);
}
fscrypt_bounce_page_pool =
mempool_create_page_pool(num_prealloc_crypto_pages, 0);
if (!fscrypt_bounce_page_pool)
goto fail;
already_initialized:
mutex_unlock(&fscrypt_init_mutex);
return 0;
fail:
fscrypt_destroy();
mutex_unlock(&fscrypt_init_mutex);
return res;
}
EXPORT_SYMBOL(fscrypt_initialize);
/**
* fscrypt_init() - Set up for fs encryption.
*/
static int __init fscrypt_init(void)
{
fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
WQ_HIGHPRI, 0);
if (!fscrypt_read_workqueue)
goto fail;
fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
if (!fscrypt_ctx_cachep)
goto fail_free_queue;
fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
if (!fscrypt_info_cachep)
goto fail_free_ctx;
return 0;
fail_free_ctx:
kmem_cache_destroy(fscrypt_ctx_cachep);
fail_free_queue:
destroy_workqueue(fscrypt_read_workqueue);
fail:
return -ENOMEM;
}
module_init(fscrypt_init)
/**
* fscrypt_exit() - Shutdown the fs encryption system
*/
static void __exit fscrypt_exit(void)
{
fscrypt_destroy();
if (fscrypt_read_workqueue)
destroy_workqueue(fscrypt_read_workqueue);
kmem_cache_destroy(fscrypt_ctx_cachep);
kmem_cache_destroy(fscrypt_info_cachep);
}
module_exit(fscrypt_exit);
MODULE_LICENSE("GPL");

427
fs/crypto/fname.c Normal file
View file

@ -0,0 +1,427 @@
/*
* This contains functions for filename crypto management
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility
*
* Written by Uday Savagaonkar, 2014.
* Modified by Jaegeuk Kim, 2015.
*
* This has not yet undergone a rigorous security audit.
*/
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <keys/encrypted-type.h>
#include <keys/user-type.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <linux/ratelimit.h>
#include <linux/fscrypto.h>
static u32 size_round_up(size_t size, size_t blksize)
{
return ((size + blksize - 1) / blksize) * blksize;
}
/**
* dir_crypt_complete() -
*/
static void dir_crypt_complete(struct crypto_async_request *req, int res)
{
struct fscrypt_completion_result *ecr = req->data;
if (res == -EINPROGRESS)
return;
ecr->res = res;
complete(&ecr->completion);
}
/**
* fname_encrypt() -
*
* This function encrypts the input filename, and returns the length of the
* ciphertext. Errors are returned as negative numbers. We trust the caller to
* allocate sufficient memory to oname string.
*/
static int fname_encrypt(struct inode *inode,
const struct qstr *iname, struct fscrypt_str *oname)
{
u32 ciphertext_len;
struct ablkcipher_request *req = NULL;
DECLARE_FS_COMPLETION_RESULT(ecr);
struct fscrypt_info *ci = inode->i_crypt_info;
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
char iv[FS_CRYPTO_BLOCK_SIZE];
struct scatterlist src_sg, dst_sg;
int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
char *workbuf, buf[32], *alloc_buf = NULL;
unsigned lim;
lim = inode->i_sb->s_cop->max_namelen(inode);
if (iname->len <= 0 || iname->len > lim)
return -EIO;
ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ?
FS_CRYPTO_BLOCK_SIZE : iname->len;
ciphertext_len = size_round_up(ciphertext_len, padding);
ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
if (ciphertext_len <= sizeof(buf)) {
workbuf = buf;
} else {
alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
if (!alloc_buf)
return -ENOMEM;
workbuf = alloc_buf;
}
/* Allocate request */
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n", __func__);
kfree(alloc_buf);
return -ENOMEM;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
dir_crypt_complete, &ecr);
/* Copy the input */
memcpy(workbuf, iname->name, iname->len);
if (iname->len < ciphertext_len)
memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
/* Initialize IV */
memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
/* Create encryption request */
sg_init_one(&src_sg, workbuf, ciphertext_len);
sg_init_one(&dst_sg, oname->name, ciphertext_len);
ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
res = crypto_ablkcipher_encrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
wait_for_completion(&ecr.completion);
res = ecr.res;
}
kfree(alloc_buf);
ablkcipher_request_free(req);
if (res < 0)
printk_ratelimited(KERN_ERR
"%s: Error (error code %d)\n", __func__, res);
oname->len = ciphertext_len;
return res;
}
/*
* fname_decrypt()
* This function decrypts the input filename, and returns
* the length of the plaintext.
* Errors are returned as negative numbers.
* We trust the caller to allocate sufficient memory to oname string.
*/
static int fname_decrypt(struct inode *inode,
const struct fscrypt_str *iname,
struct fscrypt_str *oname)
{
struct ablkcipher_request *req = NULL;
DECLARE_FS_COMPLETION_RESULT(ecr);
struct scatterlist src_sg, dst_sg;
struct fscrypt_info *ci = inode->i_crypt_info;
struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
char iv[FS_CRYPTO_BLOCK_SIZE];
unsigned lim;
lim = inode->i_sb->s_cop->max_namelen(inode);
if (iname->len <= 0 || iname->len > lim)
return -EIO;
/* Allocate request */
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n", __func__);
return -ENOMEM;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
dir_crypt_complete, &ecr);
/* Initialize IV */
memset(iv, 0, FS_CRYPTO_BLOCK_SIZE);
/* Create decryption request */
sg_init_one(&src_sg, iname->name, iname->len);
sg_init_one(&dst_sg, oname->name, oname->len);
ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
res = crypto_ablkcipher_decrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
wait_for_completion(&ecr.completion);
res = ecr.res;
}
ablkcipher_request_free(req);
if (res < 0) {
printk_ratelimited(KERN_ERR
"%s: Error (error code %d)\n", __func__, res);
return res;
}
oname->len = strnlen(oname->name, iname->len);
return oname->len;
}
static const char *lookup_table =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
/**
* digest_encode() -
*
* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
* The encoded string is roughly 4/3 times the size of the input string.
*/
static int digest_encode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
char *cp = dst;
while (i < len) {
ac += (((unsigned char) src[i]) << bits);
bits += 8;
do {
*cp++ = lookup_table[ac & 0x3f];
ac >>= 6;
bits -= 6;
} while (bits >= 6);
i++;
}
if (bits)
*cp++ = lookup_table[ac & 0x3f];
return cp - dst;
}
static int digest_decode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
const char *p;
char *cp = dst;
while (i < len) {
p = strchr(lookup_table, src[i]);
if (p == NULL || src[i] == 0)
return -2;
ac += (p - lookup_table) << bits;
bits += 6;
if (bits >= 8) {
*cp++ = ac & 0xff;
ac >>= 8;
bits -= 8;
}
i++;
}
if (ac)
return -1;
return cp - dst;
}
u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen)
{
int padding = 32;
struct fscrypt_info *ci = inode->i_crypt_info;
if (ci)
padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
if (ilen < FS_CRYPTO_BLOCK_SIZE)
ilen = FS_CRYPTO_BLOCK_SIZE;
return size_round_up(ilen, padding);
}
EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
/**
* fscrypt_fname_crypto_alloc_obuff() -
*
* Allocates an output buffer that is sufficient for the crypto operation
* specified by the context and the direction.
*/
int fscrypt_fname_alloc_buffer(struct inode *inode,
u32 ilen, struct fscrypt_str *crypto_str)
{
unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen);
crypto_str->len = olen;
if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
/*
* Allocated buffer can hold one more character to null-terminate the
* string
*/
crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
if (!(crypto_str->name))
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
/**
* fscrypt_fname_crypto_free_buffer() -
*
* Frees the buffer allocated for crypto operation.
*/
void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
{
if (!crypto_str)
return;
kfree(crypto_str->name);
crypto_str->name = NULL;
}
EXPORT_SYMBOL(fscrypt_fname_free_buffer);
/**
* fscrypt_fname_disk_to_usr() - converts a filename from disk space to user
* space
*/
int fscrypt_fname_disk_to_usr(struct inode *inode,
u32 hash, u32 minor_hash,
const struct fscrypt_str *iname,
struct fscrypt_str *oname)
{
const struct qstr qname = FSTR_TO_QSTR(iname);
char buf[24];
int ret;
if (fscrypt_is_dot_dotdot(&qname)) {
oname->name[0] = '.';
oname->name[iname->len - 1] = '.';
oname->len = iname->len;
return oname->len;
}
if (iname->len < FS_CRYPTO_BLOCK_SIZE)
return -EUCLEAN;
if (inode->i_crypt_info)
return fname_decrypt(inode, iname, oname);
if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) {
ret = digest_encode(iname->name, iname->len, oname->name);
oname->len = ret;
return ret;
}
if (hash) {
memcpy(buf, &hash, 4);
memcpy(buf + 4, &minor_hash, 4);
} else {
memset(buf, 0, 8);
}
memcpy(buf + 8, iname->name + iname->len - 16, 16);
oname->name[0] = '_';
ret = digest_encode(buf, 24, oname->name + 1);
oname->len = ret + 1;
return ret + 1;
}
EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
/**
* fscrypt_fname_usr_to_disk() - converts a filename from user space to disk
* space
*/
int fscrypt_fname_usr_to_disk(struct inode *inode,
const struct qstr *iname,
struct fscrypt_str *oname)
{
if (fscrypt_is_dot_dotdot(iname)) {
oname->name[0] = '.';
oname->name[iname->len - 1] = '.';
oname->len = iname->len;
return oname->len;
}
if (inode->i_crypt_info)
return fname_encrypt(inode, iname, oname);
/*
* Without a proper key, a user is not allowed to modify the filenames
* in a directory. Consequently, a user space name cannot be mapped to
* a disk-space name
*/
return -EACCES;
}
EXPORT_SYMBOL(fscrypt_fname_usr_to_disk);
int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
int lookup, struct fscrypt_name *fname)
{
int ret = 0, bigname = 0;
memset(fname, 0, sizeof(struct fscrypt_name));
fname->usr_fname = iname;
if (!dir->i_sb->s_cop->is_encrypted(dir) ||
fscrypt_is_dot_dotdot(iname)) {
fname->disk_name.name = (unsigned char *)iname->name;
fname->disk_name.len = iname->len;
return 0;
}
ret = get_crypt_info(dir);
if (ret && ret != -EOPNOTSUPP)
return ret;
if (dir->i_crypt_info) {
ret = fscrypt_fname_alloc_buffer(dir, iname->len,
&fname->crypto_buf);
if (ret < 0)
return ret;
ret = fname_encrypt(dir, iname, &fname->crypto_buf);
if (ret < 0)
goto errout;
fname->disk_name.name = fname->crypto_buf.name;
fname->disk_name.len = fname->crypto_buf.len;
return 0;
}
if (!lookup)
return -EACCES;
/*
* We don't have the key and we are doing a lookup; decode the
* user-supplied name
*/
if (iname->name[0] == '_')
bigname = 1;
if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43)))
return -ENOENT;
fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
if (fname->crypto_buf.name == NULL)
return -ENOMEM;
ret = digest_decode(iname->name + bigname, iname->len - bigname,
fname->crypto_buf.name);
if (ret < 0) {
ret = -ENOENT;
goto errout;
}
fname->crypto_buf.len = ret;
if (bigname) {
memcpy(&fname->hash, fname->crypto_buf.name, 4);
memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4);
} else {
fname->disk_name.name = fname->crypto_buf.name;
fname->disk_name.len = fname->crypto_buf.len;
}
return 0;
errout:
fscrypt_fname_free_buffer(&fname->crypto_buf);
return ret;
}
EXPORT_SYMBOL(fscrypt_setup_filename);
void fscrypt_free_filename(struct fscrypt_name *fname)
{
kfree(fname->crypto_buf.name);
fname->crypto_buf.name = NULL;
fname->usr_fname = NULL;
fname->disk_name.name = NULL;
}
EXPORT_SYMBOL(fscrypt_free_filename);

278
fs/crypto/keyinfo.c Normal file
View file

@ -0,0 +1,278 @@
/*
* key management facility for FS encryption support.
*
* Copyright (C) 2015, Google, Inc.
*
* This contains encryption key functions.
*
* Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
*/
#include <keys/encrypted-type.h>
#include <keys/user-type.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <uapi/linux/keyctl.h>
#include <crypto/hash.h>
#include <linux/fscrypto.h>
static void derive_crypt_complete(struct crypto_async_request *req, int rc)
{
struct fscrypt_completion_result *ecr = req->data;
if (rc == -EINPROGRESS)
return;
ecr->res = rc;
complete(&ecr->completion);
}
/**
* derive_key_aes() - Derive a key using AES-128-ECB
* @deriving_key: Encryption key used for derivation.
* @source_key: Source key to which to apply derivation.
* @derived_key: Derived key.
*
* Return: Zero on success; non-zero otherwise.
*/
static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE],
u8 source_key[FS_AES_256_XTS_KEY_SIZE],
u8 derived_key[FS_AES_256_XTS_KEY_SIZE])
{
int res = 0;
struct ablkcipher_request *req = NULL;
DECLARE_FS_COMPLETION_RESULT(ecr);
struct scatterlist src_sg, dst_sg;
struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
0);
if (IS_ERR(tfm)) {
res = PTR_ERR(tfm);
tfm = NULL;
goto out;
}
crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
res = -ENOMEM;
goto out;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
derive_crypt_complete, &ecr);
res = crypto_ablkcipher_setkey(tfm, deriving_key,
FS_AES_128_ECB_KEY_SIZE);
if (res < 0)
goto out;
sg_init_one(&src_sg, source_key, FS_AES_256_XTS_KEY_SIZE);
sg_init_one(&dst_sg, derived_key, FS_AES_256_XTS_KEY_SIZE);
ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
FS_AES_256_XTS_KEY_SIZE, NULL);
res = crypto_ablkcipher_encrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
wait_for_completion(&ecr.completion);
res = ecr.res;
}
out:
if (req)
ablkcipher_request_free(req);
if (tfm)
crypto_free_ablkcipher(tfm);
return res;
}
static void put_crypt_info(struct fscrypt_info *ci)
{
if (!ci)
return;
if (ci->ci_keyring_key)
key_put(ci->ci_keyring_key);
crypto_free_ablkcipher(ci->ci_ctfm);
kmem_cache_free(fscrypt_info_cachep, ci);
}
int get_crypt_info(struct inode *inode)
{
struct fscrypt_info *crypt_info;
u8 full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE +
(FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
struct key *keyring_key = NULL;
struct fscrypt_key *master_key;
struct fscrypt_context ctx;
struct user_key_payload *ukp;
struct crypto_ablkcipher *ctfm;
const char *cipher_str;
u8 raw_key[FS_MAX_KEY_SIZE];
u8 mode;
int res;
res = fscrypt_initialize();
if (res)
return res;
if (!inode->i_sb->s_cop->get_context)
return -EOPNOTSUPP;
retry:
crypt_info = ACCESS_ONCE(inode->i_crypt_info);
if (crypt_info) {
if (!crypt_info->ci_keyring_key ||
key_validate(crypt_info->ci_keyring_key) == 0)
return 0;
fscrypt_put_encryption_info(inode, crypt_info);
goto retry;
}
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (res < 0) {
if (!fscrypt_dummy_context_enabled(inode))
return res;
ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
ctx.flags = 0;
} else if (res != sizeof(ctx)) {
return -EINVAL;
}
res = 0;
crypt_info = kmem_cache_alloc(fscrypt_info_cachep, GFP_NOFS);
if (!crypt_info)
return -ENOMEM;
crypt_info->ci_flags = ctx.flags;
crypt_info->ci_data_mode = ctx.contents_encryption_mode;
crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
crypt_info->ci_ctfm = NULL;
crypt_info->ci_keyring_key = NULL;
memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
sizeof(crypt_info->ci_master_key));
if (S_ISREG(inode->i_mode))
mode = crypt_info->ci_data_mode;
else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
mode = crypt_info->ci_filename_mode;
else
BUG();
switch (mode) {
case FS_ENCRYPTION_MODE_AES_256_XTS:
cipher_str = "xts(aes)";
break;
case FS_ENCRYPTION_MODE_AES_256_CTS:
cipher_str = "cts(cbc(aes))";
break;
default:
printk_once(KERN_WARNING
"%s: unsupported key mode %d (ino %u)\n",
__func__, mode, (unsigned) inode->i_ino);
res = -ENOKEY;
goto out;
}
if (fscrypt_dummy_context_enabled(inode)) {
memset(raw_key, 0x42, FS_AES_256_XTS_KEY_SIZE);
goto got_key;
}
memcpy(full_key_descriptor, FS_KEY_DESC_PREFIX,
FS_KEY_DESC_PREFIX_SIZE);
sprintf(full_key_descriptor + FS_KEY_DESC_PREFIX_SIZE,
"%*phN", FS_KEY_DESCRIPTOR_SIZE,
ctx.master_key_descriptor);
full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE +
(2 * FS_KEY_DESCRIPTOR_SIZE)] = '\0';
keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
if (IS_ERR(keyring_key)) {
res = PTR_ERR(keyring_key);
keyring_key = NULL;
goto out;
}
crypt_info->ci_keyring_key = keyring_key;
if (keyring_key->type != &key_type_logon) {
printk_once(KERN_WARNING
"%s: key type must be logon\n", __func__);
res = -ENOKEY;
goto out;
}
down_read(&keyring_key->sem);
ukp = ((struct user_key_payload *)keyring_key->payload.data);
if (ukp->datalen != sizeof(struct fscrypt_key)) {
res = -EINVAL;
up_read(&keyring_key->sem);
goto out;
}
master_key = (struct fscrypt_key *)ukp->data;
BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE);
if (master_key->size != FS_AES_256_XTS_KEY_SIZE) {
printk_once(KERN_WARNING
"%s: key size incorrect: %d\n",
__func__, master_key->size);
res = -ENOKEY;
up_read(&keyring_key->sem);
goto out;
}
res = derive_key_aes(ctx.nonce, master_key->raw, raw_key);
up_read(&keyring_key->sem);
if (res)
goto out;
got_key:
ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
if (!ctfm || IS_ERR(ctfm)) {
res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
printk(KERN_DEBUG
"%s: error %d (inode %u) allocating crypto tfm\n",
__func__, res, (unsigned) inode->i_ino);
goto out;
}
crypt_info->ci_ctfm = ctfm;
crypto_ablkcipher_clear_flags(ctfm, ~0);
crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
CRYPTO_TFM_REQ_WEAK_KEY);
res = crypto_ablkcipher_setkey(ctfm, raw_key, fscrypt_key_size(mode));
if (res)
goto out;
memzero_explicit(raw_key, sizeof(raw_key));
if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) != NULL) {
put_crypt_info(crypt_info);
goto retry;
}
return 0;
out:
if (res == -ENOKEY)
res = 0;
put_crypt_info(crypt_info);
memzero_explicit(raw_key, sizeof(raw_key));
return res;
}
void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci)
{
struct fscrypt_info *prev;
if (ci == NULL)
ci = ACCESS_ONCE(inode->i_crypt_info);
if (ci == NULL)
return;
prev = cmpxchg(&inode->i_crypt_info, ci, NULL);
if (prev != ci)
return;
put_crypt_info(ci);
}
EXPORT_SYMBOL(fscrypt_put_encryption_info);
int fscrypt_get_encryption_info(struct inode *inode)
{
struct fscrypt_info *ci = inode->i_crypt_info;
if (!ci ||
(ci->ci_keyring_key &&
(ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED) |
(1 << KEY_FLAG_DEAD)))))
return get_crypt_info(inode);
return 0;
}
EXPORT_SYMBOL(fscrypt_get_encryption_info);

229
fs/crypto/policy.c Normal file
View file

@ -0,0 +1,229 @@
/*
* Encryption policy functions for per-file encryption support.
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility.
*
* Written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
*/
#include <linux/random.h>
#include <linux/string.h>
#include <linux/fscrypto.h>
static int inode_has_encryption_context(struct inode *inode)
{
if (!inode->i_sb->s_cop->get_context)
return 0;
return (inode->i_sb->s_cop->get_context(inode, NULL, 0L) > 0);
}
/*
* check whether the policy is consistent with the encryption context
* for the inode
*/
static int is_encryption_context_consistent_with_policy(struct inode *inode,
const struct fscrypt_policy *policy)
{
struct fscrypt_context ctx;
int res;
if (!inode->i_sb->s_cop->get_context)
return 0;
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (res != sizeof(ctx))
return 0;
return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(ctx.flags == policy->flags) &&
(ctx.contents_encryption_mode ==
policy->contents_encryption_mode) &&
(ctx.filenames_encryption_mode ==
policy->filenames_encryption_mode));
}
static int create_encryption_context_from_policy(struct inode *inode,
const struct fscrypt_policy *policy)
{
struct fscrypt_context ctx;
int res;
if (!inode->i_sb->s_cop->set_context)
return -EOPNOTSUPP;
if (inode->i_sb->s_cop->prepare_context) {
res = inode->i_sb->s_cop->prepare_context(inode);
if (res)
return res;
}
ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE);
if (!fscrypt_valid_contents_enc_mode(
policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
return -EINVAL;
}
if (!fscrypt_valid_filenames_enc_mode(
policy->filenames_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid filenames encryption mode %d\n", __func__,
policy->filenames_encryption_mode);
return -EINVAL;
}
if (policy->flags & ~FS_POLICY_FLAGS_VALID)
return -EINVAL;
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
ctx.flags = policy->flags;
BUILD_BUG_ON(sizeof(ctx.nonce) != FS_KEY_DERIVATION_NONCE_SIZE);
get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL);
}
int fscrypt_process_policy(struct inode *inode,
const struct fscrypt_policy *policy)
{
if (policy->version != 0)
return -EINVAL;
if (!inode_has_encryption_context(inode)) {
if (!inode->i_sb->s_cop->empty_dir)
return -EOPNOTSUPP;
if (!inode->i_sb->s_cop->empty_dir(inode))
return -ENOTEMPTY;
return create_encryption_context_from_policy(inode, policy);
}
if (is_encryption_context_consistent_with_policy(inode, policy))
return 0;
printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n",
__func__);
return -EINVAL;
}
EXPORT_SYMBOL(fscrypt_process_policy);
int fscrypt_get_policy(struct inode *inode, struct fscrypt_policy *policy)
{
struct fscrypt_context ctx;
int res;
if (!inode->i_sb->s_cop->get_context ||
!inode->i_sb->s_cop->is_encrypted(inode))
return -ENODATA;
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
if (res != sizeof(ctx))
return -ENODATA;
if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
return -EINVAL;
policy->version = 0;
policy->contents_encryption_mode = ctx.contents_encryption_mode;
policy->filenames_encryption_mode = ctx.filenames_encryption_mode;
policy->flags = ctx.flags;
memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor,
FS_KEY_DESCRIPTOR_SIZE);
return 0;
}
EXPORT_SYMBOL(fscrypt_get_policy);
int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
{
struct fscrypt_info *parent_ci, *child_ci;
int res;
if ((parent == NULL) || (child == NULL)) {
printk(KERN_ERR "parent %p child %p\n", parent, child);
BUG_ON(1);
}
/* no restrictions if the parent directory is not encrypted */
if (!parent->i_sb->s_cop->is_encrypted(parent))
return 1;
/* if the child directory is not encrypted, this is always a problem */
if (!parent->i_sb->s_cop->is_encrypted(child))
return 0;
res = fscrypt_get_encryption_info(parent);
if (res)
return 0;
res = fscrypt_get_encryption_info(child);
if (res)
return 0;
parent_ci = parent->i_crypt_info;
child_ci = child->i_crypt_info;
if (!parent_ci && !child_ci)
return 1;
if (!parent_ci || !child_ci)
return 0;
return (memcmp(parent_ci->ci_master_key,
child_ci->ci_master_key,
FS_KEY_DESCRIPTOR_SIZE) == 0 &&
(parent_ci->ci_data_mode == child_ci->ci_data_mode) &&
(parent_ci->ci_filename_mode == child_ci->ci_filename_mode) &&
(parent_ci->ci_flags == child_ci->ci_flags));
}
EXPORT_SYMBOL(fscrypt_has_permitted_context);
/**
* fscrypt_inherit_context() - Sets a child context from its parent
* @parent: Parent inode from which the context is inherited.
* @child: Child inode that inherits the context from @parent.
* @fs_data: private data given by FS.
* @preload: preload child i_crypt_info
*
* Return: Zero on success, non-zero otherwise
*/
int fscrypt_inherit_context(struct inode *parent, struct inode *child,
void *fs_data, bool preload)
{
struct fscrypt_context ctx;
struct fscrypt_info *ci;
int res;
if (!parent->i_sb->s_cop->set_context)
return -EOPNOTSUPP;
res = fscrypt_get_encryption_info(parent);
if (res < 0)
return res;
ci = parent->i_crypt_info;
if (ci == NULL)
return -ENOKEY;
ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
if (fscrypt_dummy_context_enabled(parent)) {
ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
ctx.flags = 0;
memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
res = 0;
} else {
ctx.contents_encryption_mode = ci->ci_data_mode;
ctx.filenames_encryption_mode = ci->ci_filename_mode;
ctx.flags = ci->ci_flags;
memcpy(ctx.master_key_descriptor, ci->ci_master_key,
FS_KEY_DESCRIPTOR_SIZE);
}
get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
res = parent->i_sb->s_cop->set_context(child, &ctx,
sizeof(ctx), fs_data);
if (res)
return res;
return preload ? fscrypt_get_encryption_info(child): 0;
}
EXPORT_SYMBOL(fscrypt_inherit_context);

2
include/linux/dcache.h
View file

@ -223,6 +223,8 @@ struct dentry_operations {
#define DCACHE_MAY_FREE 0x00800000
#define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a valid key */
extern seqlock_t rename_lock;
/*

9
include/linux/fs.h
View file

@ -49,6 +49,8 @@ struct swap_info_struct;
struct seq_file;
struct workqueue_struct;
struct iov_iter;
struct fscrypt_info;
struct fscrypt_operations;
extern void __init inode_init(void);
extern void __init inode_init_early(void);
@ -641,6 +643,10 @@ struct inode {
struct hlist_head i_fsnotify_marks;
#endif
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
struct fscrypt_info *i_crypt_info;
#endif
void *i_private; /* fs or device private pointer */
};
@ -1236,6 +1242,9 @@ struct super_block {
const struct xattr_handler **s_xattr;
struct list_head s_inodes; /* all inodes */
const struct fscrypt_operations *s_cop;
struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */
struct list_head s_mounts; /* list of mounts; _not_ for fs use */
struct block_device *s_bdev;

433
include/linux/fscrypto.h Normal file
View file

@ -0,0 +1,433 @@
/*
* General per-file encryption definition
*
* Copyright (C) 2015, Google, Inc.
*
* Written by Michael Halcrow, 2015.
* Modified by Jaegeuk Kim, 2015.
*/
#ifndef _LINUX_FSCRYPTO_H
#define _LINUX_FSCRYPTO_H
#include <linux/key.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/bio.h>
#include <linux/dcache.h>
#include <uapi/linux/fs.h>
#define FS_KEY_DERIVATION_NONCE_SIZE 16
#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
#define FS_POLICY_FLAGS_PAD_4 0x00
#define FS_POLICY_FLAGS_PAD_8 0x01
#define FS_POLICY_FLAGS_PAD_16 0x02
#define FS_POLICY_FLAGS_PAD_32 0x03
#define FS_POLICY_FLAGS_PAD_MASK 0x03
#define FS_POLICY_FLAGS_VALID 0x03
/* Encryption algorithms */
#define FS_ENCRYPTION_MODE_INVALID 0
#define FS_ENCRYPTION_MODE_AES_256_XTS 1
#define FS_ENCRYPTION_MODE_AES_256_GCM 2
#define FS_ENCRYPTION_MODE_AES_256_CBC 3
#define FS_ENCRYPTION_MODE_AES_256_CTS 4
/**
* Encryption context for inode
*
* Protector format:
* 1 byte: Protector format (1 = this version)
* 1 byte: File contents encryption mode
* 1 byte: File names encryption mode
* 1 byte: Flags
* 8 bytes: Master Key descriptor
* 16 bytes: Encryption Key derivation nonce
*/
struct fscrypt_context {
u8 format;
u8 contents_encryption_mode;
u8 filenames_encryption_mode;
u8 flags;
u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
} __packed;
/* Encryption parameters */
#define FS_XTS_TWEAK_SIZE 16
#define FS_AES_128_ECB_KEY_SIZE 16
#define FS_AES_256_GCM_KEY_SIZE 32
#define FS_AES_256_CBC_KEY_SIZE 32
#define FS_AES_256_CTS_KEY_SIZE 32
#define FS_AES_256_XTS_KEY_SIZE 64
#define FS_MAX_KEY_SIZE 64
#define FS_KEY_DESC_PREFIX "fscrypt:"
#define FS_KEY_DESC_PREFIX_SIZE 8
/* This is passed in from userspace into the kernel keyring */
struct fscrypt_key {
u32 mode;
u8 raw[FS_MAX_KEY_SIZE];
u32 size;
} __packed;
struct fscrypt_info {
u8 ci_data_mode;
u8 ci_filename_mode;
u8 ci_flags;
struct crypto_ablkcipher *ci_ctfm;
struct key *ci_keyring_key;
u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
};
#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
#define FS_WRITE_PATH_FL 0x00000002
struct fscrypt_ctx {
union {
struct {
struct page *bounce_page; /* Ciphertext page */
struct page *control_page; /* Original page */
} w;
struct {
struct bio *bio;
struct work_struct work;
} r;
struct list_head free_list; /* Free list */
};
u8 flags; /* Flags */
u8 mode; /* Encryption mode for tfm */
};
struct fscrypt_completion_result {
struct completion completion;
int res;
};
#define DECLARE_FS_COMPLETION_RESULT(ecr) \
struct fscrypt_completion_result ecr = { \
COMPLETION_INITIALIZER((ecr).completion), 0 }
static inline int fscrypt_key_size(int mode)
{
switch (mode) {
case FS_ENCRYPTION_MODE_AES_256_XTS:
return FS_AES_256_XTS_KEY_SIZE;
case FS_ENCRYPTION_MODE_AES_256_GCM:
return FS_AES_256_GCM_KEY_SIZE;
case FS_ENCRYPTION_MODE_AES_256_CBC:
return FS_AES_256_CBC_KEY_SIZE;
case FS_ENCRYPTION_MODE_AES_256_CTS:
return FS_AES_256_CTS_KEY_SIZE;
default:
BUG();
}
return 0;
}
#define FS_FNAME_NUM_SCATTER_ENTRIES 4
#define FS_CRYPTO_BLOCK_SIZE 16
#define FS_FNAME_CRYPTO_DIGEST_SIZE 32
/**
* For encrypted symlinks, the ciphertext length is stored at the beginning
* of the string in little-endian format.
*/
struct fscrypt_symlink_data {
__le16 len;
char encrypted_path[1];
} __packed;
/**
* This function is used to calculate the disk space required to
* store a filename of length l in encrypted symlink format.
*/
static inline u32 fscrypt_symlink_data_len(u32 l)
{
if (l < FS_CRYPTO_BLOCK_SIZE)
l = FS_CRYPTO_BLOCK_SIZE;
return (l + sizeof(struct fscrypt_symlink_data) - 1);
}
struct fscrypt_str {
unsigned char *name;
u32 len;
};
struct fscrypt_name {
const struct qstr *usr_fname;
struct fscrypt_str disk_name;
u32 hash;
u32 minor_hash;
struct fscrypt_str crypto_buf;
};
#define FSTR_INIT(n, l) { .name = n, .len = l }
#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
#define fname_name(p) ((p)->disk_name.name)
#define fname_len(p) ((p)->disk_name.len)
/*
* crypto opertions for filesystems
*/
struct fscrypt_operations {
int (*get_context)(struct inode *, void *, size_t);
int (*prepare_context)(struct inode *);
int (*set_context)(struct inode *, const void *, size_t, void *);
int (*dummy_context)(struct inode *);
bool (*is_encrypted)(struct inode *);
bool (*empty_dir)(struct inode *);
unsigned (*max_namelen)(struct inode *);
};
static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
{
if (inode->i_sb->s_cop->dummy_context &&
inode->i_sb->s_cop->dummy_context(inode))
return true;
return false;
}
static inline bool fscrypt_valid_contents_enc_mode(u32 mode)
{
return (mode == FS_ENCRYPTION_MODE_AES_256_XTS);
}
static inline bool fscrypt_valid_filenames_enc_mode(u32 mode)
{
return (mode == FS_ENCRYPTION_MODE_AES_256_CTS);
}
static inline u32 fscrypt_validate_encryption_key_size(u32 mode, u32 size)
{
if (size == fscrypt_key_size(mode))
return size;
return 0;
}
static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
{
if (str->len == 1 && str->name[0] == '.')
return true;
if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
return true;
return false;
}
static inline struct page *fscrypt_control_page(struct page *page)
{
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
#else
WARN_ON_ONCE(1);
return ERR_PTR(-EINVAL);
#endif
}
static inline int fscrypt_has_encryption_key(struct inode *inode)
{
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
return (inode->i_crypt_info != NULL);
#else
return 0;
#endif
}
static inline void fscrypt_set_encrypted_dentry(struct dentry *dentry)
{
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
spin_lock(&dentry->d_lock);
dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
spin_unlock(&dentry->d_lock);
#endif
}
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
extern const struct dentry_operations fscrypt_d_ops;
#endif
static inline void fscrypt_set_d_op(struct dentry *dentry)
{
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
d_set_d_op(dentry, &fscrypt_d_ops);
#endif
}
#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
/* crypto.c */
extern struct kmem_cache *fscrypt_info_cachep;
int fscrypt_initialize(void);
extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
extern struct page *fscrypt_encrypt_page(struct inode *, struct page *);
extern int fscrypt_decrypt_page(struct page *);
extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
extern void fscrypt_pullback_bio_page(struct page **, bool);
extern void fscrypt_restore_control_page(struct page *);
extern int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t,
unsigned int);
/* policy.c */
extern int fscrypt_process_policy(struct inode *,
const struct fscrypt_policy *);
extern int fscrypt_get_policy(struct inode *, struct fscrypt_policy *);
extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
extern int fscrypt_inherit_context(struct inode *, struct inode *,
void *, bool);
/* keyinfo.c */
extern int get_crypt_info(struct inode *);
extern int fscrypt_get_encryption_info(struct inode *);
extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
/* fname.c */
extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
int lookup, struct fscrypt_name *);
extern void fscrypt_free_filename(struct fscrypt_name *);
extern u32 fscrypt_fname_encrypted_size(struct inode *, u32);
extern int fscrypt_fname_alloc_buffer(struct inode *, u32,
struct fscrypt_str *);
extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
const struct fscrypt_str *, struct fscrypt_str *);
extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
struct fscrypt_str *);
#endif
/* crypto.c */
static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
{
return;
}
static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
struct page *p)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline int fscrypt_notsupp_decrypt_page(struct page *p)
{
return -EOPNOTSUPP;
}
static inline void fscrypt_notsupp_decrypt_bio_pages(struct fscrypt_ctx *c,
struct bio *b)
{
return;
}
static inline void fscrypt_notsupp_pullback_bio_page(struct page **p, bool b)
{
return;
}
static inline void fscrypt_notsupp_restore_control_page(struct page *p)
{
return;
}
static inline int fscrypt_notsupp_zeroout_range(struct inode *i, pgoff_t p,
sector_t s, unsigned int f)
{
return -EOPNOTSUPP;
}
/* policy.c */
static inline int fscrypt_notsupp_process_policy(struct inode *i,
const struct fscrypt_policy *p)
{
return -EOPNOTSUPP;
}
static inline int fscrypt_notsupp_get_policy(struct inode *i,
struct fscrypt_policy *p)
{
return -EOPNOTSUPP;
}
static inline int fscrypt_notsupp_has_permitted_context(struct inode *p,
struct inode *i)
{
return 0;
}
static inline int fscrypt_notsupp_inherit_context(struct inode *p,
struct inode *i, void *v, bool b)
{
return -EOPNOTSUPP;
}
/* keyinfo.c */
static inline int fscrypt_notsupp_get_encryption_info(struct inode *i)
{
return -EOPNOTSUPP;
}
static inline void fscrypt_notsupp_put_encryption_info(struct inode *i,
struct fscrypt_info *f)
{
return;
}
/* fname.c */
static inline int fscrypt_notsupp_setup_filename(struct inode *dir,
const struct qstr *iname,
int lookup, struct fscrypt_name *fname)
{
if (dir->i_sb->s_cop->is_encrypted(dir))
return -EOPNOTSUPP;
memset(fname, 0, sizeof(struct fscrypt_name));
fname->usr_fname = iname;
fname->disk_name.name = (unsigned char *)iname->name;
fname->disk_name.len = iname->len;
return 0;
}
static inline void fscrypt_notsupp_free_filename(struct fscrypt_name *fname)
{
return;
}
static inline u32 fscrypt_notsupp_fname_encrypted_size(struct inode *i, u32 s)
{
/* never happens */
WARN_ON(1);
return 0;
}
static inline int fscrypt_notsupp_fname_alloc_buffer(struct inode *inode,
u32 ilen, struct fscrypt_str *crypto_str)
{
return -EOPNOTSUPP;
}
static inline void fscrypt_notsupp_fname_free_buffer(struct fscrypt_str *c)
{
return;
}
static inline int fscrypt_notsupp_fname_disk_to_usr(struct inode *inode,
u32 hash, u32 minor_hash,
const struct fscrypt_str *iname,
struct fscrypt_str *oname)
{
return -EOPNOTSUPP;
}
static inline int fscrypt_notsupp_fname_usr_to_disk(struct inode *inode,
const struct qstr *iname,
struct fscrypt_str *oname)
{
return -EOPNOTSUPP;
}
#endif /* _LINUX_FSCRYPTO_H */

18
include/uapi/linux/fs.h
View file

@ -172,6 +172,24 @@ struct inodes_stat_t {
#define FS_IOC_INVAL_MAPPING _IO('f', 13)
/*
* File system encryption support
*/
/* Policy provided via an ioctl on the topmost directory */
#define FS_KEY_DESCRIPTOR_SIZE 8
struct fscrypt_policy {
__u8 version;
__u8 contents_encryption_mode;
__u8 filenames_encryption_mode;
__u8 flags;
__u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
} __packed;
#define FS_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct fscrypt_policy)
#define FS_IOC_GET_ENCRYPTION_PWSALT _IOW('f', 20, __u8[16])
#define FS_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct fscrypt_policy)
/*
* Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
*/