mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-13 10:06:47 +07:00
687c3c36e7
Buggy (or hostile) userspace should not be able to cause the kernel to crash. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
471 lines
12 KiB
C
471 lines
12 KiB
C
/*
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* linux/fs/ext4/crypto_fname.c
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*
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* Copyright (C) 2015, Google, Inc.
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*
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* This contains functions for filename crypto management in ext4
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*
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* Written by Uday Savagaonkar, 2014.
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*
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* This has not yet undergone a rigorous security audit.
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*
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*/
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#include <crypto/hash.h>
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#include <crypto/sha.h>
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#include <keys/encrypted-type.h>
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#include <keys/user-type.h>
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#include <linux/crypto.h>
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include <linux/key.h>
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#include <linux/list.h>
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#include <linux/mempool.h>
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#include <linux/random.h>
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#include <linux/scatterlist.h>
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#include <linux/spinlock_types.h>
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#include "ext4.h"
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#include "ext4_crypto.h"
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#include "xattr.h"
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/**
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* ext4_dir_crypt_complete() -
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*/
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static void ext4_dir_crypt_complete(struct crypto_async_request *req, int res)
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{
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struct ext4_completion_result *ecr = req->data;
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if (res == -EINPROGRESS)
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return;
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ecr->res = res;
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complete(&ecr->completion);
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}
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bool ext4_valid_filenames_enc_mode(uint32_t mode)
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{
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return (mode == EXT4_ENCRYPTION_MODE_AES_256_CTS);
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}
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static unsigned max_name_len(struct inode *inode)
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{
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return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
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EXT4_NAME_LEN;
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}
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/**
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* ext4_fname_encrypt() -
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*
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* This function encrypts the input filename, and returns the length of the
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* ciphertext. Errors are returned as negative numbers. We trust the caller to
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* allocate sufficient memory to oname string.
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*/
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static int ext4_fname_encrypt(struct inode *inode,
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const struct qstr *iname,
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struct ext4_str *oname)
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{
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u32 ciphertext_len;
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struct ablkcipher_request *req = NULL;
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DECLARE_EXT4_COMPLETION_RESULT(ecr);
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struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
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struct crypto_ablkcipher *tfm = ci->ci_ctfm;
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int res = 0;
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char iv[EXT4_CRYPTO_BLOCK_SIZE];
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struct scatterlist src_sg, dst_sg;
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int padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
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char *workbuf, buf[32], *alloc_buf = NULL;
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unsigned lim = max_name_len(inode);
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if (iname->len <= 0 || iname->len > lim)
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return -EIO;
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ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
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EXT4_CRYPTO_BLOCK_SIZE : iname->len;
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ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
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ciphertext_len = (ciphertext_len > lim)
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? lim : ciphertext_len;
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if (ciphertext_len <= sizeof(buf)) {
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workbuf = buf;
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} else {
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alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
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if (!alloc_buf)
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return -ENOMEM;
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workbuf = alloc_buf;
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}
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/* Allocate request */
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req = ablkcipher_request_alloc(tfm, GFP_NOFS);
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if (!req) {
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printk_ratelimited(
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KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
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kfree(alloc_buf);
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return -ENOMEM;
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}
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ablkcipher_request_set_callback(req,
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CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
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ext4_dir_crypt_complete, &ecr);
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/* Copy the input */
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memcpy(workbuf, iname->name, iname->len);
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if (iname->len < ciphertext_len)
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memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
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/* Initialize IV */
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memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
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/* Create encryption request */
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sg_init_one(&src_sg, workbuf, ciphertext_len);
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sg_init_one(&dst_sg, oname->name, ciphertext_len);
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ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
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res = crypto_ablkcipher_encrypt(req);
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if (res == -EINPROGRESS || res == -EBUSY) {
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wait_for_completion(&ecr.completion);
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res = ecr.res;
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}
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kfree(alloc_buf);
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ablkcipher_request_free(req);
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if (res < 0) {
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printk_ratelimited(
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KERN_ERR "%s: Error (error code %d)\n", __func__, res);
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}
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oname->len = ciphertext_len;
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return res;
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}
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/*
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* ext4_fname_decrypt()
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* This function decrypts the input filename, and returns
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* the length of the plaintext.
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* Errors are returned as negative numbers.
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* We trust the caller to allocate sufficient memory to oname string.
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*/
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static int ext4_fname_decrypt(struct inode *inode,
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const struct ext4_str *iname,
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struct ext4_str *oname)
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{
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struct ext4_str tmp_in[2], tmp_out[1];
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struct ablkcipher_request *req = NULL;
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DECLARE_EXT4_COMPLETION_RESULT(ecr);
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struct scatterlist src_sg, dst_sg;
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struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
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struct crypto_ablkcipher *tfm = ci->ci_ctfm;
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int res = 0;
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char iv[EXT4_CRYPTO_BLOCK_SIZE];
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unsigned lim = max_name_len(inode);
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if (iname->len <= 0 || iname->len > lim)
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return -EIO;
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tmp_in[0].name = iname->name;
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tmp_in[0].len = iname->len;
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tmp_out[0].name = oname->name;
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/* Allocate request */
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req = ablkcipher_request_alloc(tfm, GFP_NOFS);
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if (!req) {
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printk_ratelimited(
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KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
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return -ENOMEM;
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}
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ablkcipher_request_set_callback(req,
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CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
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ext4_dir_crypt_complete, &ecr);
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/* Initialize IV */
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memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
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/* Create encryption request */
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sg_init_one(&src_sg, iname->name, iname->len);
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sg_init_one(&dst_sg, oname->name, oname->len);
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ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
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res = crypto_ablkcipher_decrypt(req);
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if (res == -EINPROGRESS || res == -EBUSY) {
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wait_for_completion(&ecr.completion);
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res = ecr.res;
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}
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ablkcipher_request_free(req);
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if (res < 0) {
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printk_ratelimited(
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KERN_ERR "%s: Error in ext4_fname_encrypt (error code %d)\n",
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__func__, res);
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return res;
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}
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oname->len = strnlen(oname->name, iname->len);
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return oname->len;
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}
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static const char *lookup_table =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
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/**
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* ext4_fname_encode_digest() -
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*
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* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
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* The encoded string is roughly 4/3 times the size of the input string.
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*/
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static int digest_encode(const char *src, int len, char *dst)
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{
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int i = 0, bits = 0, ac = 0;
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char *cp = dst;
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while (i < len) {
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ac += (((unsigned char) src[i]) << bits);
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bits += 8;
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do {
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*cp++ = lookup_table[ac & 0x3f];
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ac >>= 6;
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bits -= 6;
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} while (bits >= 6);
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i++;
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}
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if (bits)
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*cp++ = lookup_table[ac & 0x3f];
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return cp - dst;
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}
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static int digest_decode(const char *src, int len, char *dst)
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{
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int i = 0, bits = 0, ac = 0;
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const char *p;
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char *cp = dst;
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while (i < len) {
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p = strchr(lookup_table, src[i]);
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if (p == NULL || src[i] == 0)
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return -2;
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ac += (p - lookup_table) << bits;
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bits += 6;
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if (bits >= 8) {
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*cp++ = ac & 0xff;
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ac >>= 8;
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bits -= 8;
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}
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i++;
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}
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if (ac)
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return -1;
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return cp - dst;
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}
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/**
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* ext4_fname_crypto_round_up() -
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*
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* Return: The next multiple of block size
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*/
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u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
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{
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return ((size+blksize-1)/blksize)*blksize;
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}
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unsigned ext4_fname_encrypted_size(struct inode *inode, u32 ilen)
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{
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struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
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int padding = 32;
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if (ci)
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padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
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if (ilen < EXT4_CRYPTO_BLOCK_SIZE)
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ilen = EXT4_CRYPTO_BLOCK_SIZE;
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return ext4_fname_crypto_round_up(ilen, padding);
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}
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/*
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* ext4_fname_crypto_alloc_buffer() -
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*
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* Allocates an output buffer that is sufficient for the crypto operation
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* specified by the context and the direction.
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*/
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int ext4_fname_crypto_alloc_buffer(struct inode *inode,
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u32 ilen, struct ext4_str *crypto_str)
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{
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unsigned int olen = ext4_fname_encrypted_size(inode, ilen);
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crypto_str->len = olen;
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if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
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olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;
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/* Allocated buffer can hold one more character to null-terminate the
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* string */
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crypto_str->name = kmalloc(olen+1, GFP_NOFS);
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if (!(crypto_str->name))
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return -ENOMEM;
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return 0;
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}
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/**
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* ext4_fname_crypto_free_buffer() -
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*
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* Frees the buffer allocated for crypto operation.
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*/
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void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
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{
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if (!crypto_str)
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return;
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kfree(crypto_str->name);
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crypto_str->name = NULL;
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}
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/**
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* ext4_fname_disk_to_usr() - converts a filename from disk space to user space
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*/
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int _ext4_fname_disk_to_usr(struct inode *inode,
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struct dx_hash_info *hinfo,
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const struct ext4_str *iname,
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struct ext4_str *oname)
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{
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char buf[24];
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int ret;
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if (iname->len < 3) {
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/*Check for . and .. */
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if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
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oname->name[0] = '.';
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oname->name[iname->len-1] = '.';
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oname->len = iname->len;
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return oname->len;
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}
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}
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if (iname->len < EXT4_CRYPTO_BLOCK_SIZE) {
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EXT4_ERROR_INODE(inode, "encrypted inode too small");
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return -EUCLEAN;
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}
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if (EXT4_I(inode)->i_crypt_info)
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return ext4_fname_decrypt(inode, iname, oname);
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if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
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ret = digest_encode(iname->name, iname->len, oname->name);
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oname->len = ret;
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return ret;
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}
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if (hinfo) {
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memcpy(buf, &hinfo->hash, 4);
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memcpy(buf+4, &hinfo->minor_hash, 4);
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} else
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memset(buf, 0, 8);
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memcpy(buf + 8, iname->name + iname->len - 16, 16);
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oname->name[0] = '_';
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ret = digest_encode(buf, 24, oname->name+1);
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oname->len = ret + 1;
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return ret + 1;
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}
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int ext4_fname_disk_to_usr(struct inode *inode,
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struct dx_hash_info *hinfo,
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const struct ext4_dir_entry_2 *de,
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struct ext4_str *oname)
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{
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struct ext4_str iname = {.name = (unsigned char *) de->name,
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.len = de->name_len };
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return _ext4_fname_disk_to_usr(inode, hinfo, &iname, oname);
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}
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/**
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* ext4_fname_usr_to_disk() - converts a filename from user space to disk space
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*/
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int ext4_fname_usr_to_disk(struct inode *inode,
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const struct qstr *iname,
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struct ext4_str *oname)
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{
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int res;
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struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
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if (iname->len < 3) {
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/*Check for . and .. */
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if (iname->name[0] == '.' &&
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iname->name[iname->len-1] == '.') {
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oname->name[0] = '.';
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oname->name[iname->len-1] = '.';
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oname->len = iname->len;
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return oname->len;
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}
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}
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if (ci) {
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res = ext4_fname_encrypt(inode, iname, oname);
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return res;
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}
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/* Without a proper key, a user is not allowed to modify the filenames
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* in a directory. Consequently, a user space name cannot be mapped to
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* a disk-space name */
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return -EACCES;
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}
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int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
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int lookup, struct ext4_filename *fname)
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{
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struct ext4_crypt_info *ci;
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int ret = 0, bigname = 0;
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memset(fname, 0, sizeof(struct ext4_filename));
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fname->usr_fname = iname;
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if (!ext4_encrypted_inode(dir) ||
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((iname->name[0] == '.') &&
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((iname->len == 1) ||
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((iname->name[1] == '.') && (iname->len == 2))))) {
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fname->disk_name.name = (unsigned char *) iname->name;
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fname->disk_name.len = iname->len;
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return 0;
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}
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ret = ext4_get_encryption_info(dir);
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if (ret)
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return ret;
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ci = EXT4_I(dir)->i_crypt_info;
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if (ci) {
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ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
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&fname->crypto_buf);
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if (ret < 0)
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return ret;
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ret = ext4_fname_encrypt(dir, iname, &fname->crypto_buf);
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if (ret < 0)
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goto errout;
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fname->disk_name.name = fname->crypto_buf.name;
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fname->disk_name.len = fname->crypto_buf.len;
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return 0;
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}
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if (!lookup)
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return -EACCES;
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/* We don't have the key and we are doing a lookup; decode the
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* user-supplied name
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*/
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if (iname->name[0] == '_')
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bigname = 1;
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if ((bigname && (iname->len != 33)) ||
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(!bigname && (iname->len > 43)))
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return -ENOENT;
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fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
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if (fname->crypto_buf.name == NULL)
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return -ENOMEM;
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ret = digest_decode(iname->name + bigname, iname->len - bigname,
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fname->crypto_buf.name);
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if (ret < 0) {
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ret = -ENOENT;
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goto errout;
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}
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fname->crypto_buf.len = ret;
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if (bigname) {
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memcpy(&fname->hinfo.hash, fname->crypto_buf.name, 4);
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memcpy(&fname->hinfo.minor_hash, fname->crypto_buf.name + 4, 4);
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} else {
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fname->disk_name.name = fname->crypto_buf.name;
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fname->disk_name.len = fname->crypto_buf.len;
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}
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return 0;
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errout:
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kfree(fname->crypto_buf.name);
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fname->crypto_buf.name = NULL;
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return ret;
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}
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void ext4_fname_free_filename(struct ext4_filename *fname)
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{
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kfree(fname->crypto_buf.name);
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fname->crypto_buf.name = NULL;
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fname->usr_fname = NULL;
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fname->disk_name.name = NULL;
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}
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