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Date: Sun, 12 Apr 2015 23:16:29 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: mhalcrow@...gle.com, Uday Savagaonkar <savagaon@...gle.com>,
Ildar Muslukhov <ildarm@...gle.com>,
Theodore Ts'o <tytso@....edu>
Subject: [PATCH-v2 13/20] ext4 crypto: filename encryption facilities
From: Michael Halcrow <mhalcrow@...gle.com>
Change-Id: Ia924500cc0395bc96b7099962041641eb336276b
Signed-off-by: Uday Savagaonkar <savagaon@...gle.com>
Signed-off-by: Ildar Muslukhov <ildarm@...gle.com>
Signed-off-by: Michael Halcrow <mhalcrow@...gle.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
fs/ext4/Makefile | 3 +-
fs/ext4/crypto_fname.c | 709 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/crypto_policy.c | 7 +
fs/ext4/ext4.h | 41 +++
fs/ext4/ext4_crypto.h | 20 ++
5 files changed, 779 insertions(+), 1 deletion(-)
create mode 100644 fs/ext4/crypto_fname.c
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 4e5af21..75285ea 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -12,4 +12,5 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
-ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o crypto_key.o
+ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o \
+ crypto_key.o crypto_fname.o
diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c
new file mode 100644
index 0000000..2283e39
--- /dev/null
+++ b/fs/ext4/crypto_fname.c
@@ -0,0 +1,709 @@
+/*
+ * linux/fs/ext4/crypto_fname.c
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This contains functions for filename crypto management in ext4
+ *
+ * Written by Uday Savagaonkar, 2014.
+ *
+ * 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/gfp.h>
+#include <linux/kernel.h>
+#include <linux/key.h>
+#include <linux/key.h>
+#include <linux/list.h>
+#include <linux/mempool.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <linux/spinlock_types.h>
+
+#include "ext4.h"
+#include "ext4_crypto.h"
+#include "xattr.h"
+
+/**
+ * ext4_dir_crypt_complete() -
+ */
+static void ext4_dir_crypt_complete(struct crypto_async_request *req, int res)
+{
+ struct ext4_completion_result *ecr = req->data;
+
+ if (res == -EINPROGRESS)
+ return;
+ ecr->res = res;
+ complete(&ecr->completion);
+}
+
+bool ext4_valid_filenames_enc_mode(uint32_t mode)
+{
+ return (mode == EXT4_ENCRYPTION_MODE_AES_256_CTS);
+}
+
+/**
+ * ext4_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 ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
+ const struct qstr *iname,
+ struct ext4_str *oname)
+{
+ u32 ciphertext_len;
+ struct ablkcipher_request *req = NULL;
+ DECLARE_EXT4_COMPLETION_RESULT(ecr);
+ struct crypto_ablkcipher *tfm = ctx->ctfm;
+ int res = 0;
+ char iv[EXT4_CRYPTO_BLOCK_SIZE];
+ struct scatterlist sg[1];
+ char *workbuf;
+
+ if (iname->len <= 0 || iname->len > ctx->lim)
+ return -EIO;
+
+ ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
+ EXT4_CRYPTO_BLOCK_SIZE : iname->len;
+ ciphertext_len = (ciphertext_len > ctx->lim)
+ ? ctx->lim : ciphertext_len;
+
+ /* 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,
+ ext4_dir_crypt_complete, &ecr);
+
+ /* Map the workpage */
+ workbuf = kmap(ctx->workpage);
+
+ /* 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, EXT4_CRYPTO_BLOCK_SIZE);
+
+ /* Create encryption request */
+ sg_init_table(sg, 1);
+ sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
+ ablkcipher_request_set_crypt(req, sg, sg, iname->len, iv);
+ res = crypto_ablkcipher_encrypt(req);
+ if (res == -EINPROGRESS || res == -EBUSY) {
+ BUG_ON(req->base.data != &ecr);
+ wait_for_completion(&ecr.completion);
+ res = ecr.res;
+ }
+ if (res >= 0) {
+ /* Copy the result to output */
+ memcpy(oname->name, workbuf, ciphertext_len);
+ res = ciphertext_len;
+ }
+ kunmap(ctx->workpage);
+ 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;
+}
+
+/*
+ * ext4_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 ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_str *iname,
+ struct ext4_str *oname)
+{
+ struct ext4_str tmp_in[2], tmp_out[1];
+ struct ablkcipher_request *req = NULL;
+ DECLARE_EXT4_COMPLETION_RESULT(ecr);
+ struct scatterlist sg[1];
+ struct crypto_ablkcipher *tfm = ctx->ctfm;
+ int res = 0;
+ char iv[EXT4_CRYPTO_BLOCK_SIZE];
+ char *workbuf;
+
+ if (iname->len <= 0 || iname->len > ctx->lim)
+ return -EIO;
+
+ tmp_in[0].name = iname->name;
+ tmp_in[0].len = iname->len;
+ tmp_out[0].name = oname->name;
+
+ /* 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,
+ ext4_dir_crypt_complete, &ecr);
+
+ /* Map the workpage */
+ workbuf = kmap(ctx->workpage);
+
+ /* Copy the input */
+ memcpy(workbuf, iname->name, iname->len);
+
+ /* Initialize IV */
+ memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
+
+ /* Create encryption request */
+ sg_init_table(sg, 1);
+ sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
+ ablkcipher_request_set_crypt(req, sg, sg, iname->len, iv);
+ res = crypto_ablkcipher_decrypt(req);
+ if (res == -EINPROGRESS || res == -EBUSY) {
+ BUG_ON(req->base.data != &ecr);
+ wait_for_completion(&ecr.completion);
+ res = ecr.res;
+ }
+ if (res >= 0) {
+ /* Copy the result to output */
+ memcpy(oname->name, workbuf, iname->len);
+ res = iname->len;
+ }
+ kunmap(ctx->workpage);
+ ablkcipher_request_free(req);
+ if (res < 0) {
+ printk_ratelimited(
+ KERN_ERR "%s: Error in ext4_fname_encrypt (error code %d)\n",
+ __func__, res);
+ return res;
+ }
+
+ oname->len = strnlen(oname->name, iname->len);
+ return oname->len;
+}
+
+/**
+ * ext4_fname_encode_digest() -
+ *
+ * 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.
+ */
+int ext4_fname_encode_digest(char *dst, char *src, u32 len)
+{
+ static const char *lookup_table =
+ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_+";
+ u32 current_chunk, num_chunks, i;
+ char tmp_buf[3];
+ u32 c0, c1, c2, c3;
+
+ current_chunk = 0;
+ num_chunks = len/3;
+ for (i = 0; i < num_chunks; i++) {
+ c0 = src[3*i] & 0x3f;
+ c1 = (((src[3*i]>>6)&0x3) | ((src[3*i+1] & 0xf)<<2)) & 0x3f;
+ c2 = (((src[3*i+1]>>4)&0xf) | ((src[3*i+2] & 0x3)<<4)) & 0x3f;
+ c3 = (src[3*i+2]>>2) & 0x3f;
+ dst[4*i] = lookup_table[c0];
+ dst[4*i+1] = lookup_table[c1];
+ dst[4*i+2] = lookup_table[c2];
+ dst[4*i+3] = lookup_table[c3];
+ }
+ if (i*3 < len) {
+ memset(tmp_buf, 0, 3);
+ memcpy(tmp_buf, &src[3*i], len-3*i);
+ c0 = tmp_buf[0] & 0x3f;
+ c1 = (((tmp_buf[0]>>6)&0x3) | ((tmp_buf[1] & 0xf)<<2)) & 0x3f;
+ c2 = (((tmp_buf[1]>>4)&0xf) | ((tmp_buf[2] & 0x3)<<4)) & 0x3f;
+ c3 = (tmp_buf[2]>>2) & 0x3f;
+ dst[4*i] = lookup_table[c0];
+ dst[4*i+1] = lookup_table[c1];
+ dst[4*i+2] = lookup_table[c2];
+ dst[4*i+3] = lookup_table[c3];
+ i++;
+ }
+ return (i * 4);
+}
+
+/**
+ * ext4_fname_hash() -
+ *
+ * This function computes the hash of the input filename, and sets the output
+ * buffer to the *encoded* digest. It returns the length of the digest as its
+ * return value. Errors are returned as negative numbers. We trust the caller
+ * to allocate sufficient memory to oname string.
+ */
+static int ext4_fname_hash(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_str *iname,
+ struct ext4_str *oname)
+{
+ struct scatterlist sg;
+ struct hash_desc desc = {
+ .tfm = (struct crypto_hash *)ctx->htfm,
+ .flags = CRYPTO_TFM_REQ_MAY_SLEEP
+ };
+ int res = 0;
+
+ if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
+ res = ext4_fname_encode_digest(oname->name, iname->name,
+ iname->len);
+ oname->len = res;
+ return res;
+ }
+
+ sg_init_one(&sg, iname->name, iname->len);
+ res = crypto_hash_init(&desc);
+ if (res) {
+ printk(KERN_ERR
+ "%s: Error initializing crypto hash; res = [%d]\n",
+ __func__, res);
+ goto out;
+ }
+ res = crypto_hash_update(&desc, &sg, iname->len);
+ if (res) {
+ printk(KERN_ERR
+ "%s: Error updating crypto hash; res = [%d]\n",
+ __func__, res);
+ goto out;
+ }
+ res = crypto_hash_final(&desc,
+ &oname->name[EXT4_FNAME_CRYPTO_DIGEST_SIZE]);
+ if (res) {
+ printk(KERN_ERR
+ "%s: Error finalizing crypto hash; res = [%d]\n",
+ __func__, res);
+ goto out;
+ }
+ /* Encode the digest as a printable string--this will increase the
+ * size of the digest */
+ oname->name[0] = 'I';
+ res = ext4_fname_encode_digest(oname->name+1,
+ &oname->name[EXT4_FNAME_CRYPTO_DIGEST_SIZE],
+ EXT4_FNAME_CRYPTO_DIGEST_SIZE) + 1;
+ oname->len = res;
+out:
+ return res;
+}
+
+/**
+ * ext4_free_fname_crypto_ctx() -
+ *
+ * Frees up a crypto context.
+ */
+void ext4_free_fname_crypto_ctx(struct ext4_fname_crypto_ctx *ctx)
+{
+ if (ctx == NULL || IS_ERR(ctx))
+ return;
+
+ if (ctx->ctfm && !IS_ERR(ctx->ctfm))
+ crypto_free_ablkcipher(ctx->ctfm);
+ if (ctx->htfm && !IS_ERR(ctx->htfm))
+ crypto_free_hash(ctx->htfm);
+ if (ctx->workpage && !IS_ERR(ctx->workpage))
+ __free_page(ctx->workpage);
+ kfree(ctx);
+}
+
+/**
+ * ext4_put_fname_crypto_ctx() -
+ *
+ * Return: The crypto context onto free list. If the free list is above a
+ * threshold, completely frees up the context, and returns the memory.
+ *
+ * TODO: Currently we directly free the crypto context. Eventually we should
+ * add code it to return to free list. Such an approach will increase
+ * efficiency of directory lookup.
+ */
+void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx)
+{
+ if (*ctx == NULL || IS_ERR(*ctx))
+ return;
+ ext4_free_fname_crypto_ctx(*ctx);
+ *ctx = NULL;
+}
+
+/**
+ * ext4_search_fname_crypto_ctx() -
+ */
+static struct ext4_fname_crypto_ctx *ext4_search_fname_crypto_ctx(
+ const struct ext4_encryption_key *key)
+{
+ return NULL;
+}
+
+/**
+ * ext4_alloc_fname_crypto_ctx() -
+ */
+struct ext4_fname_crypto_ctx *ext4_alloc_fname_crypto_ctx(
+ const struct ext4_encryption_key *key)
+{
+ struct ext4_fname_crypto_ctx *ctx;
+
+ ctx = kmalloc(sizeof(struct ext4_fname_crypto_ctx), GFP_NOFS);
+ if (ctx == NULL)
+ return ERR_PTR(-ENOMEM);
+ if (key->mode == EXT4_ENCRYPTION_MODE_INVALID) {
+ /* This will automatically set key mode to invalid
+ * As enum for ENCRYPTION_MODE_INVALID is zero */
+ memset(&ctx->key, 0, sizeof(ctx->key));
+ } else {
+ memcpy(&ctx->key, key, sizeof(struct ext4_encryption_key));
+ }
+ ctx->has_valid_key = (EXT4_ENCRYPTION_MODE_INVALID == key->mode)
+ ? 0 : 1;
+ ctx->ctfm_key_is_ready = 0;
+ ctx->ctfm = NULL;
+ ctx->htfm = NULL;
+ ctx->workpage = NULL;
+ return ctx;
+}
+
+/**
+ * ext4_get_fname_crypto_ctx() -
+ *
+ * Allocates a free crypto context and initializes it to hold
+ * the crypto material for the inode.
+ *
+ * Return: NULL if not encrypted. Error value on error. Valid pointer otherwise.
+ */
+struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(
+ struct inode *inode, u32 max_ciphertext_len)
+{
+ struct ext4_fname_crypto_ctx *ctx;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ int res;
+
+ /* Check if the crypto policy is set on the inode */
+ res = ext4_encrypted_inode(inode);
+ if (res == 0)
+ return NULL;
+
+ if (!ext4_has_encryption_key(inode))
+ ext4_generate_encryption_key(inode);
+
+ /* Get a crypto context based on the key.
+ * A new context is allocated if no context matches the requested key.
+ */
+ ctx = ext4_search_fname_crypto_ctx(&(ei->i_encryption_key));
+ if (ctx == NULL)
+ ctx = ext4_alloc_fname_crypto_ctx(&(ei->i_encryption_key));
+ if (IS_ERR(ctx))
+ return ctx;
+
+ if (ctx->has_valid_key) {
+ if (ctx->key.mode != EXT4_ENCRYPTION_MODE_AES_256_CTS) {
+ printk_once(KERN_WARNING
+ "ext4: unsupported key mode %d\n",
+ ctx->key.mode);
+ return ERR_PTR(-ENOKEY);
+ }
+
+ /* As a first cut, we will allocate new tfm in every call.
+ * later, we will keep the tfm around, in case the key gets
+ * re-used */
+ if (ctx->ctfm == NULL) {
+ ctx->ctfm = crypto_alloc_ablkcipher("cts(cbc(aes))",
+ 0, 0);
+ }
+ if (IS_ERR(ctx->ctfm)) {
+ res = PTR_ERR(ctx->ctfm);
+ printk(
+ KERN_DEBUG "%s: error (%d) allocating crypto tfm\n",
+ __func__, res);
+ ctx->ctfm = NULL;
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(res);
+ }
+ if (ctx->ctfm == NULL) {
+ printk(
+ KERN_DEBUG "%s: could not allocate crypto tfm\n",
+ __func__);
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(-ENOMEM);
+ }
+ if (ctx->workpage == NULL)
+ ctx->workpage = alloc_page(GFP_NOFS);
+ if (IS_ERR(ctx->workpage)) {
+ res = PTR_ERR(ctx->workpage);
+ printk(
+ KERN_DEBUG "%s: error (%d) allocating work page\n",
+ __func__, res);
+ ctx->workpage = NULL;
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(res);
+ }
+ if (ctx->workpage == NULL) {
+ printk(
+ KERN_DEBUG "%s: could not allocate work page\n",
+ __func__);
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(-ENOMEM);
+ }
+ ctx->lim = max_ciphertext_len;
+ crypto_ablkcipher_clear_flags(ctx->ctfm, ~0);
+ crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctx->ctfm),
+ CRYPTO_TFM_REQ_WEAK_KEY);
+
+ /* If we are lucky, we will get a context that is already
+ * set up with the right key. Else, we will have to
+ * set the key */
+ if (!ctx->ctfm_key_is_ready) {
+ /* Since our crypto objectives for filename encryption
+ * are pretty weak,
+ * we directly use the inode master key */
+ res = crypto_ablkcipher_setkey(ctx->ctfm,
+ ctx->key.raw, ctx->key.size);
+ if (res) {
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(-EIO);
+ }
+ ctx->ctfm_key_is_ready = 1;
+ } else {
+ /* In the current implementation, key should never be
+ * marked "ready" for a context that has just been
+ * allocated. So we should never reach here */
+ BUG();
+ }
+ }
+ if (ctx->htfm == NULL)
+ ctx->htfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(ctx->htfm)) {
+ res = PTR_ERR(ctx->htfm);
+ printk(KERN_DEBUG "%s: error (%d) allocating hash tfm\n",
+ __func__, res);
+ ctx->htfm = NULL;
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(res);
+ }
+ if (ctx->htfm == NULL) {
+ printk(KERN_DEBUG "%s: could not allocate hash tfm\n",
+ __func__);
+ ext4_put_fname_crypto_ctx(&ctx);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ return ctx;
+}
+
+/**
+ * ext4_fname_crypto_round_up() -
+ *
+ * Return: The next multiple of block size
+ */
+u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
+{
+ return ((size+blksize-1)/blksize)*blksize;
+}
+
+/**
+ * ext4_fname_crypto_namelen_on_disk() -
+ */
+int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
+ u32 namelen)
+{
+ u32 ciphertext_len;
+
+ if (ctx == NULL)
+ return -EIO;
+ if (!(ctx->has_valid_key))
+ return -EACCES;
+ ciphertext_len = (namelen < EXT4_CRYPTO_BLOCK_SIZE) ?
+ EXT4_CRYPTO_BLOCK_SIZE : namelen;
+ ciphertext_len = (ciphertext_len > ctx->lim)
+ ? ctx->lim : ciphertext_len;
+ return (int) ciphertext_len;
+}
+
+/**
+ * ext4_fname_crypto_alloc_obuff() -
+ *
+ * Allocates an output buffer that is sufficient for the crypto operation
+ * specified by the context and the direction.
+ */
+int ext4_fname_crypto_alloc_buffer(struct ext4_fname_crypto_ctx *ctx,
+ u32 ilen, struct ext4_str *crypto_str)
+{
+ unsigned int olen;
+
+ if (!ctx)
+ return -EIO;
+ olen = ext4_fname_crypto_round_up(ilen, EXT4_CRYPTO_BLOCK_SIZE);
+ crypto_str->len = olen;
+ if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
+ olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;
+ /* Allocated buffer can hold one more character to null-terminate the
+ * string */
+ crypto_str->name = kmalloc(olen, GFP_NOFS);
+ if (!(crypto_str->name))
+ return -ENOMEM;
+ return 0;
+}
+
+/**
+ * ext4_fname_crypto_free_buffer() -
+ *
+ * Frees the buffer allocated for crypto operation.
+ */
+void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
+{
+ if (!crypto_str)
+ return;
+ kfree(crypto_str->name);
+ crypto_str->name = NULL;
+}
+
+/**
+ * ext4_fname_disk_to_usr() - converts a filename from disk space to user space
+ */
+int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_str *iname,
+ struct ext4_str *oname)
+{
+ if (ctx == NULL)
+ return -EIO;
+ if (iname->len < 3) {
+ /*Check for . and .. */
+ if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
+ oname->name[0] = '.';
+ oname->name[iname->len-1] = '.';
+ oname->len = iname->len;
+ return oname->len;
+ }
+ }
+ if (ctx->has_valid_key)
+ return ext4_fname_decrypt(ctx, iname, oname);
+ else
+ return ext4_fname_hash(ctx, iname, oname);
+}
+
+int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_dir_entry_2 * de,
+ struct ext4_str *oname)
+{
+ struct ext4_str iname = {.name = (unsigned char *) de->name,
+ .len = de->name_len };
+
+ return _ext4_fname_disk_to_usr(ctx, &iname, oname);
+}
+
+
+/**
+ * ext4_fname_usr_to_disk() - converts a filename from user space to disk space
+ */
+int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
+ const struct qstr *iname,
+ struct ext4_str *oname)
+{
+ int res;
+
+ if (ctx == NULL)
+ return -EIO;
+ if (iname->len < 3) {
+ /*Check for . and .. */
+ if (iname->name[0] == '.' &&
+ iname->name[iname->len-1] == '.') {
+ oname->name[0] = '.';
+ oname->name[iname->len-1] = '.';
+ oname->len = iname->len;
+ return oname->len;
+ }
+ }
+ if (ctx->has_valid_key) {
+ res = ext4_fname_encrypt(ctx, iname, oname);
+ return res;
+ }
+ /* 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;
+}
+
+/*
+ * Calculate the htree hash from a filename from user space
+ */
+int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
+ const struct qstr *iname,
+ struct dx_hash_info *hinfo)
+{
+ struct ext4_str tmp, tmp2;
+ int ret = 0;
+
+ if (!ctx || !ctx->has_valid_key ||
+ ((iname->name[0] == '.') &&
+ ((iname->len == 1) ||
+ ((iname->name[1] == '.') && (iname->len == 2))))) {
+ ext4fs_dirhash(iname->name, iname->len, hinfo);
+ return 0;
+ }
+
+ /* First encrypt the plaintext name */
+ ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len, &tmp);
+ if (ret < 0)
+ return ret;
+
+ ret = ext4_fname_encrypt(ctx, iname, &tmp);
+ if (ret < 0)
+ goto out;
+
+ tmp2.len = (4 * ((EXT4_FNAME_CRYPTO_DIGEST_SIZE + 2) / 3)) + 1;
+ tmp2.name = kmalloc(tmp2.len + 1, GFP_KERNEL);
+ if (tmp2.name == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = ext4_fname_hash(ctx, &tmp, &tmp2);
+ if (ret > 0)
+ ext4fs_dirhash(tmp2.name, tmp2.len, hinfo);
+ ext4_fname_crypto_free_buffer(&tmp2);
+out:
+ ext4_fname_crypto_free_buffer(&tmp);
+ return ret;
+}
+
+/**
+ * ext4_fname_disk_to_htree() - converts a filename from disk space to htree-access string
+ */
+int ext4_fname_disk_to_hash(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_dir_entry_2 * de,
+ struct dx_hash_info *hinfo)
+{
+ struct ext4_str iname = {.name = (unsigned char *) de->name,
+ .len = de->name_len};
+ struct ext4_str tmp;
+ int ret;
+
+ if (!ctx ||
+ ((iname.name[0] == '.') &&
+ ((iname.len == 1) ||
+ ((iname.name[1] == '.') && (iname.len == 2))))) {
+ ext4fs_dirhash(iname.name, iname.len, hinfo);
+ return 0;
+ }
+
+ tmp.len = (4 * ((EXT4_FNAME_CRYPTO_DIGEST_SIZE + 2) / 3)) + 1;
+ tmp.name = kmalloc(tmp.len + 1, GFP_KERNEL);
+ if (tmp.name == NULL)
+ return -ENOMEM;
+
+ ret = ext4_fname_hash(ctx, &iname, &tmp);
+ if (ret > 0)
+ ext4fs_dirhash(tmp.name, tmp.len, hinfo);
+ ext4_fname_crypto_free_buffer(&tmp);
+ return ret;
+}
diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
index e08b28b..5b4fbb3 100644
--- a/fs/ext4/crypto_policy.c
+++ b/fs/ext4/crypto_policy.c
@@ -59,6 +59,13 @@ static int ext4_create_encryption_context_from_policy(
res = -EINVAL;
goto out;
}
+ if (!ext4_valid_filenames_enc_mode(policy->filenames_encryption_mode)) {
+ printk(KERN_WARNING
+ "%s: Invalid filenames encryption mode %d\n", __func__,
+ policy->filenames_encryption_mode);
+ res = -EINVAL;
+ goto out;
+ }
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 89b999f..e44436b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2065,6 +2065,47 @@ static inline int ext4_sb_has_crypto(struct super_block *sb)
}
#endif
+/* crypto_fname.c */
+bool ext4_valid_filenames_enc_mode(uint32_t mode);
+u32 ext4_fname_crypto_round_up(u32 size, u32 blksize);
+int ext4_fname_crypto_alloc_buffer(struct ext4_fname_crypto_ctx *ctx,
+ u32 ilen, struct ext4_str *crypto_str);
+int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_str *iname,
+ struct ext4_str *oname);
+int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_dir_entry_2 * de,
+ struct ext4_str *oname);
+int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
+ const struct qstr *iname,
+ struct ext4_str *oname);
+int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
+ const struct qstr *iname,
+ struct dx_hash_info *hinfo);
+int ext4_fname_disk_to_hash(struct ext4_fname_crypto_ctx *ctx,
+ const struct ext4_dir_entry_2 * de,
+ struct dx_hash_info *hinfo);
+int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
+ u32 namelen);
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx);
+struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
+ u32 max_len);
+void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str);
+#else
+static inline
+void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx) { }
+static inline
+struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(struct inode *inode,
+ u32 max_len)
+{
+ return NULL;
+}
+static inline void ext4_fname_crypto_free_buffer(struct ext4_str *p) { }
+#endif
+
+
/* crypto_key.c */
int ext4_generate_encryption_key(struct inode *inode);
diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
index 6a7c0c0..f7d46e8 100644
--- a/fs/ext4/ext4_crypto.h
+++ b/fs/ext4/ext4_crypto.h
@@ -104,4 +104,24 @@ static inline int ext4_encryption_key_size(int mode)
return 0;
}
+#define EXT4_FNAME_NUM_SCATTER_ENTRIES 4
+#define EXT4_CRYPTO_BLOCK_SIZE 16
+#define EXT4_FNAME_CRYPTO_DIGEST_SIZE 32
+
+struct ext4_str {
+ unsigned char *name;
+ u32 len;
+};
+
+struct ext4_fname_crypto_ctx {
+ u32 lim;
+ char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE];
+ struct crypto_ablkcipher *ctfm;
+ struct crypto_hash *htfm;
+ struct page *workpage;
+ struct ext4_encryption_key key;
+ unsigned has_valid_key : 1;
+ unsigned ctfm_key_is_ready : 1;
+};
+
#endif /* _EXT4_CRYPTO_H */
--
2.3.0
--
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