[linux-2.6-block.git] / fs / ext4 / crypto_fname.c

/*
 * 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);
}

static unsigned max_name_len(struct inode *inode)
{
	return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
		EXT4_NAME_LEN;
}

/**
 * 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 inode *inode,
			      const struct qstr *iname,
			      struct ext4_str *oname)
{
	u32 ciphertext_len;
	struct ablkcipher_request *req = NULL;
	DECLARE_EXT4_COMPLETION_RESULT(ecr);
	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
	int res = 0;
	char iv[EXT4_CRYPTO_BLOCK_SIZE];
	struct scatterlist src_sg, dst_sg;
	int padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
	char *workbuf, buf[32], *alloc_buf = NULL;
	unsigned lim = max_name_len(inode);

	if (iname->len <= 0 || iname->len > lim)
		return -EIO;

	ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
		EXT4_CRYPTO_BLOCK_SIZE : iname->len;
	ciphertext_len = ext4_fname_crypto_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,
		ext4_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, EXT4_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) {
		BUG_ON(req->base.data != &ecr);
		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;
}

/*
 * 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 inode *inode,
			      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 src_sg, dst_sg;
	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
	int res = 0;
	char iv[EXT4_CRYPTO_BLOCK_SIZE];
	unsigned lim = max_name_len(inode);

	if (iname->len <= 0 || iname->len > 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);

	/* Initialize IV */
	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);

	/* Create encryption 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) {
		BUG_ON(req->base.data != &ecr);
		wait_for_completion(&ecr.completion);
		res = ecr.res;
	}
	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;
}

static const char *lookup_table =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";

/**
 * 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.
 */
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;
}

/**
 * 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;
}

unsigned ext4_fname_encrypted_size(struct inode *inode, u32 ilen)
{
	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
	int padding = 32;

	if (ci)
		padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
	if (ilen < EXT4_CRYPTO_BLOCK_SIZE)
		ilen = EXT4_CRYPTO_BLOCK_SIZE;
	return ext4_fname_crypto_round_up(ilen, padding);
}

/*
 * ext4_fname_crypto_alloc_buffer() -
 *
 * 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 inode *inode,
				   u32 ilen, struct ext4_str *crypto_str)
{
	unsigned int olen = ext4_fname_encrypted_size(inode, ilen);

	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+1, 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 inode *inode,
			    struct dx_hash_info *hinfo,
			    const struct ext4_str *iname,
			    struct ext4_str *oname)
{
	char buf[24];
	int ret;

	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 (EXT4_I(inode)->i_crypt_info)
		return ext4_fname_decrypt(inode, iname, oname);

	if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
		ret = digest_encode(iname->name, iname->len, oname->name);
		oname->len = ret;
		return ret;
	}
	if (hinfo) {
		memcpy(buf, &hinfo->hash, 4);
		memcpy(buf+4, &hinfo->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;
}

int ext4_fname_disk_to_usr(struct inode *inode,
			   struct dx_hash_info *hinfo,
			   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(inode, hinfo, &iname, oname);
}


/**
 * ext4_fname_usr_to_disk() - converts a filename from user space to disk space
 */
int ext4_fname_usr_to_disk(struct inode *inode,
			   const struct qstr *iname,
			   struct ext4_str *oname)
{
	int res;
	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;

	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 (ci) {
		res = ext4_fname_encrypt(inode, 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;
}

int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
			      int lookup, struct ext4_filename *fname)
{
	struct ext4_crypt_info *ci;
	int ret = 0, bigname = 0;

	memset(fname, 0, sizeof(struct ext4_filename));
	fname->usr_fname = iname;

	if (!ext4_encrypted_inode(dir) ||
	    ((iname->name[0] == '.') &&
	     ((iname->len == 1) ||
	      ((iname->name[1] == '.') && (iname->len == 2))))) {
		fname->disk_name.name = (unsigned char *) iname->name;
		fname->disk_name.len = iname->len;
		return 0;
	}
	ret = ext4_get_encryption_info(dir);
	if (ret)
		return ret;
	ci = EXT4_I(dir)->i_crypt_info;
	if (ci) {
		ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
						     &fname->crypto_buf);
		if (ret < 0)
			return ret;
		ret = ext4_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->hinfo.hash, fname->crypto_buf.name, 4);
		memcpy(&fname->hinfo.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:
	kfree(fname->crypto_buf.name);
	fname->crypto_buf.name = NULL;
	return ret;
}

void ext4_fname_free_filename(struct ext4_filename *fname)
{
	kfree(fname->crypto_buf.name);
	fname->crypto_buf.name = NULL;
	fname->usr_fname = NULL;
	fname->disk_name.name = NULL;
}
Commit	Line	Data
d5d0e8c7 MH	1	/*
	2	* linux/fs/ext4/crypto_fname.c
	3	*
	4	* Copyright (C) 2015, Google, Inc.
	5	*
	6	* This contains functions for filename crypto management in ext4
	7	*
	8	* Written by Uday Savagaonkar, 2014.
	9	*
	10	* This has not yet undergone a rigorous security audit.
	11	*
	12	*/
	13
	14	#include <crypto/hash.h>
	15	#include <crypto/sha.h>
	16	#include <keys/encrypted-type.h>
	17	#include <keys/user-type.h>
	18	#include <linux/crypto.h>
	19	#include <linux/gfp.h>
	20	#include <linux/kernel.h>
	21	#include <linux/key.h>
	22	#include <linux/key.h>
	23	#include <linux/list.h>
	24	#include <linux/mempool.h>
	25	#include <linux/random.h>
	26	#include <linux/scatterlist.h>
	27	#include <linux/spinlock_types.h>
	28
	29	#include "ext4.h"
	30	#include "ext4_crypto.h"
	31	#include "xattr.h"
	32
	33	/**
	34	* ext4_dir_crypt_complete() -
	35	*/
	36	static void ext4_dir_crypt_complete(struct crypto_async_request *req, int res)
	37	{
	38	struct ext4_completion_result *ecr = req->data;
	39
	40	if (res == -EINPROGRESS)
	41	return;
	42	ecr->res = res;
	43	complete(&ecr->completion);
	44	}
	45
	46	bool ext4_valid_filenames_enc_mode(uint32_t mode)
	47	{
	48	return (mode == EXT4_ENCRYPTION_MODE_AES_256_CTS);
	49	}
	50
b7236e21 TT	51	static unsigned max_name_len(struct inode *inode)
	52	{
	53	return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
	54	EXT4_NAME_LEN;
	55	}
	56
d5d0e8c7 MH	57	/**
	58	* ext4_fname_encrypt() -
	59	*
	60	* This function encrypts the input filename, and returns the length of the
	61	* ciphertext. Errors are returned as negative numbers. We trust the caller to
	62	* allocate sufficient memory to oname string.
	63	*/
b7236e21	64	static int ext4_fname_encrypt(struct inode *inode,
d5d0e8c7 MH	65	const struct qstr *iname,
	66	struct ext4_str *oname)
	67	{
	68	u32 ciphertext_len;
	69	struct ablkcipher_request *req = NULL;
	70	DECLARE_EXT4_COMPLETION_RESULT(ecr);
b7236e21 TT	71	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
b7236e21 TT	72	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
d5d0e8c7 MH	73	int res = 0;
d5d0e8c7 MH	74	char iv[EXT4_CRYPTO_BLOCK_SIZE];
d2299590	75	struct scatterlist src_sg, dst_sg;
b7236e21	76	int padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
d2299590	77	char workbuf, buf[32], alloc_buf = NULL;
b7236e21	78	unsigned lim = max_name_len(inode);
d5d0e8c7	79
b7236e21	80	if (iname->len <= 0 \|\| iname->len > lim)
d5d0e8c7 MH	81	return -EIO;
	82
	83	ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
	84	EXT4_CRYPTO_BLOCK_SIZE : iname->len;
a44cd7a0	85	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
b7236e21 TT	86	ciphertext_len = (ciphertext_len > lim)
b7236e21 TT	87	? lim : ciphertext_len;
d5d0e8c7	88
d2299590 TT	89	if (ciphertext_len <= sizeof(buf)) {
	90	workbuf = buf;
	91	} else {
	92	alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
	93	if (!alloc_buf)
	94	return -ENOMEM;
	95	workbuf = alloc_buf;
	96	}
	97
d5d0e8c7 MH	98	/* Allocate request */
	99	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	100	if (!req) {
	101	printk_ratelimited(
	102	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
d2299590	103	kfree(alloc_buf);
d5d0e8c7 MH	104	return -ENOMEM;
	105	}
	106	ablkcipher_request_set_callback(req,
	107	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	108	ext4_dir_crypt_complete, &ecr);
	109
d5d0e8c7 MH	110	/* Copy the input */
	111	memcpy(workbuf, iname->name, iname->len);
	112	if (iname->len < ciphertext_len)
	113	memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
	114
	115	/* Initialize IV */
	116	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
	117
	118	/* Create encryption request */
d2299590 TT	119	sg_init_one(&src_sg, workbuf, ciphertext_len);
	120	sg_init_one(&dst_sg, oname->name, ciphertext_len);
	121	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
d5d0e8c7 MH	122	res = crypto_ablkcipher_encrypt(req);
	123	if (res == -EINPROGRESS \|\| res == -EBUSY) {
	124	BUG_ON(req->base.data != &ecr);
	125	wait_for_completion(&ecr.completion);
	126	res = ecr.res;
	127	}
d2299590	128	kfree(alloc_buf);
d5d0e8c7 MH	129	ablkcipher_request_free(req);
	130	if (res < 0) {
	131	printk_ratelimited(
	132	KERN_ERR "%s: Error (error code %d)\n", __func__, res);
	133	}
	134	oname->len = ciphertext_len;
	135	return res;
	136	}
	137
	138	/*
	139	* ext4_fname_decrypt()
	140	* This function decrypts the input filename, and returns
	141	* the length of the plaintext.
	142	* Errors are returned as negative numbers.
	143	* We trust the caller to allocate sufficient memory to oname string.
	144	*/
b7236e21	145	static int ext4_fname_decrypt(struct inode *inode,
d5d0e8c7 MH	146	const struct ext4_str *iname,
	147	struct ext4_str *oname)
	148	{
	149	struct ext4_str tmp_in[2], tmp_out[1];
	150	struct ablkcipher_request *req = NULL;
	151	DECLARE_EXT4_COMPLETION_RESULT(ecr);
d2299590	152	struct scatterlist src_sg, dst_sg;
b7236e21 TT	153	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
b7236e21 TT	154	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
d5d0e8c7 MH	155	int res = 0;
d5d0e8c7 MH	156	char iv[EXT4_CRYPTO_BLOCK_SIZE];
b7236e21	157	unsigned lim = max_name_len(inode);
d5d0e8c7	158
b7236e21	159	if (iname->len <= 0 \|\| iname->len > lim)
d5d0e8c7 MH	160	return -EIO;
	161
	162	tmp_in[0].name = iname->name;
	163	tmp_in[0].len = iname->len;
	164	tmp_out[0].name = oname->name;
	165
	166	/* Allocate request */
	167	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	168	if (!req) {
	169	printk_ratelimited(
	170	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
	171	return -ENOMEM;
	172	}
	173	ablkcipher_request_set_callback(req,
	174	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	175	ext4_dir_crypt_complete, &ecr);
	176
d5d0e8c7 MH	177	/* Initialize IV */
	178	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
	179
	180	/* Create encryption request */
d2299590 TT	181	sg_init_one(&src_sg, iname->name, iname->len);
	182	sg_init_one(&dst_sg, oname->name, oname->len);
	183	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
d5d0e8c7 MH	184	res = crypto_ablkcipher_decrypt(req);
	185	if (res == -EINPROGRESS \|\| res == -EBUSY) {
	186	BUG_ON(req->base.data != &ecr);
	187	wait_for_completion(&ecr.completion);
	188	res = ecr.res;
	189	}
d5d0e8c7 MH	190	ablkcipher_request_free(req);
	191	if (res < 0) {
	192	printk_ratelimited(
	193	KERN_ERR "%s: Error in ext4_fname_encrypt (error code %d)\n",
	194	__func__, res);
	195	return res;
	196	}
	197
	198	oname->len = strnlen(oname->name, iname->len);
	199	return oname->len;
	200	}
	201
5de0b4d0 TT	202	static const char *lookup_table =
	203	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
	204
d5d0e8c7 MH	205	/**
	206	* ext4_fname_encode_digest() -
	207	*
	208	* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
	209	* The encoded string is roughly 4/3 times the size of the input string.
	210	*/
5de0b4d0	211	static int digest_encode(const char src, int len, char dst)
d5d0e8c7	212	{
5de0b4d0 TT	213	int i = 0, bits = 0, ac = 0;
	214	char *cp = dst;
	215
	216	while (i < len) {
	217	ac += (((unsigned char) src[i]) << bits);
	218	bits += 8;
	219	do {
	220	*cp++ = lookup_table[ac & 0x3f];
	221	ac >>= 6;
	222	bits -= 6;
	223	} while (bits >= 6);
d5d0e8c7 MH	224	i++;
d5d0e8c7 MH	225	}
5de0b4d0 TT	226	if (bits)
	227	*cp++ = lookup_table[ac & 0x3f];
	228	return cp - dst;
d5d0e8c7 MH	229	}
d5d0e8c7 MH	230
5de0b4d0	231	static int digest_decode(const char src, int len, char dst)
d5d0e8c7	232	{
5de0b4d0 TT	233	int i = 0, bits = 0, ac = 0;
	234	const char *p;
	235	char *cp = dst;
	236
	237	while (i < len) {
	238	p = strchr(lookup_table, src[i]);
	239	if (p == NULL \|\| src[i] == 0)
	240	return -2;
	241	ac += (p - lookup_table) << bits;
	242	bits += 6;
	243	if (bits >= 8) {
	244	*cp++ = ac & 0xff;
	245	ac >>= 8;
	246	bits -= 8;
	247	}
	248	i++;
d5d0e8c7	249	}
5de0b4d0 TT	250	if (ac)
	251	return -1;
	252	return cp - dst;
d5d0e8c7 MH	253	}
d5d0e8c7 MH	254
d5d0e8c7 MH	255	/**
	256	* ext4_fname_crypto_round_up() -
	257	*
	258	* Return: The next multiple of block size
	259	*/
	260	u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
	261	{
	262	return ((size+blksize-1)/blksize)*blksize;
	263	}
	264
4d3c4e5b TT	265	unsigned ext4_fname_encrypted_size(struct inode *inode, u32 ilen)
	266	{
	267	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
	268	int padding = 32;
	269
	270	if (ci)
	271	padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
	272	if (ilen < EXT4_CRYPTO_BLOCK_SIZE)
	273	ilen = EXT4_CRYPTO_BLOCK_SIZE;
	274	return ext4_fname_crypto_round_up(ilen, padding);
	275	}
	276
	277	/*
	278	* ext4_fname_crypto_alloc_buffer() -
d5d0e8c7 MH	279	*
	280	* Allocates an output buffer that is sufficient for the crypto operation
	281	* specified by the context and the direction.
	282	*/
b7236e21	283	int ext4_fname_crypto_alloc_buffer(struct inode *inode,
d5d0e8c7 MH	284	u32 ilen, struct ext4_str *crypto_str)
d5d0e8c7 MH	285	{
4d3c4e5b	286	unsigned int olen = ext4_fname_encrypted_size(inode, ilen);
d5d0e8c7	287
d5d0e8c7 MH	288	crypto_str->len = olen;
	289	if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
	290	olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;
	291	/* Allocated buffer can hold one more character to null-terminate the
	292	* string */
	293	crypto_str->name = kmalloc(olen+1, GFP_NOFS);
	294	if (!(crypto_str->name))
	295	return -ENOMEM;
	296	return 0;
	297	}
	298
	299	/**
	300	* ext4_fname_crypto_free_buffer() -
	301	*
	302	* Frees the buffer allocated for crypto operation.
	303	*/
	304	void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
	305	{
	306	if (!crypto_str)
	307	return;
	308	kfree(crypto_str->name);
	309	crypto_str->name = NULL;
	310	}
	311
	312	/**
	313	* ext4_fname_disk_to_usr() - converts a filename from disk space to user space
	314	*/
b7236e21	315	int _ext4_fname_disk_to_usr(struct inode *inode,
5de0b4d0 TT	316	struct dx_hash_info *hinfo,
	317	const struct ext4_str *iname,
	318	struct ext4_str *oname)
d5d0e8c7	319	{
5de0b4d0 TT	320	char buf[24];
	321	int ret;
	322
d5d0e8c7 MH	323	if (iname->len < 3) {
	324	/Check for . and .. /
	325	if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
	326	oname->name[0] = '.';
	327	oname->name[iname->len-1] = '.';
	328	oname->len = iname->len;
	329	return oname->len;
	330	}
	331	}
b7236e21 TT	332	if (EXT4_I(inode)->i_crypt_info)
b7236e21 TT	333	return ext4_fname_decrypt(inode, iname, oname);
5de0b4d0 TT	334
	335	if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
	336	ret = digest_encode(iname->name, iname->len, oname->name);
	337	oname->len = ret;
	338	return ret;
	339	}
	340	if (hinfo) {
	341	memcpy(buf, &hinfo->hash, 4);
	342	memcpy(buf+4, &hinfo->minor_hash, 4);
	343	} else
	344	memset(buf, 0, 8);
	345	memcpy(buf + 8, iname->name + iname->len - 16, 16);
	346	oname->name[0] = '_';
	347	ret = digest_encode(buf, 24, oname->name+1);
	348	oname->len = ret + 1;
	349	return ret + 1;
d5d0e8c7 MH	350	}
d5d0e8c7 MH	351
b7236e21	352	int ext4_fname_disk_to_usr(struct inode *inode,
5de0b4d0	353	struct dx_hash_info *hinfo,
d5d0e8c7 MH	354	const struct ext4_dir_entry_2 *de,
	355	struct ext4_str *oname)
	356	{
	357	struct ext4_str iname = {.name = (unsigned char *) de->name,
	358	.len = de->name_len };
	359
b7236e21	360	return _ext4_fname_disk_to_usr(inode, hinfo, &iname, oname);
d5d0e8c7 MH	361	}
	362
	363
	364	/**
	365	* ext4_fname_usr_to_disk() - converts a filename from user space to disk space
	366	*/
b7236e21	367	int ext4_fname_usr_to_disk(struct inode *inode,
d5d0e8c7 MH	368	const struct qstr *iname,
	369	struct ext4_str *oname)
	370	{
	371	int res;
b7236e21	372	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
d5d0e8c7	373
d5d0e8c7 MH	374	if (iname->len < 3) {
	375	/Check for . and .. /
	376	if (iname->name[0] == '.' &&
	377	iname->name[iname->len-1] == '.') {
	378	oname->name[0] = '.';
	379	oname->name[iname->len-1] = '.';
	380	oname->len = iname->len;
	381	return oname->len;
	382	}
	383	}
b7236e21 TT	384	if (ci) {
b7236e21 TT	385	res = ext4_fname_encrypt(inode, iname, oname);
d5d0e8c7 MH	386	return res;
	387	}
	388	/* Without a proper key, a user is not allowed to modify the filenames
	389	* in a directory. Consequently, a user space name cannot be mapped to
	390	* a disk-space name */
	391	return -EACCES;
	392	}
	393
5b643f9c TT	394	int ext4_fname_setup_filename(struct inode dir, const struct qstr iname,
5b643f9c TT	395	int lookup, struct ext4_filename *fname)
d5d0e8c7	396	{
b7236e21	397	struct ext4_crypt_info *ci;
5b643f9c TT	398	int ret = 0, bigname = 0;
	399
	400	memset(fname, 0, sizeof(struct ext4_filename));
	401	fname->usr_fname = iname;
d5d0e8c7	402
b7236e21	403	if (!ext4_encrypted_inode(dir) \|\|
d5d0e8c7 MH	404	((iname->name[0] == '.') &&
	405	((iname->len == 1) \|\|
	406	((iname->name[1] == '.') && (iname->len == 2))))) {
5b643f9c TT	407	fname->disk_name.name = (unsigned char *) iname->name;
5b643f9c TT	408	fname->disk_name.len = iname->len;
82d0d3e7	409	return 0;
d5d0e8c7	410	}
c936e1ec	411	ret = ext4_get_encryption_info(dir);
b7236e21 TT	412	if (ret)
	413	return ret;
	414	ci = EXT4_I(dir)->i_crypt_info;
	415	if (ci) {
	416	ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
5b643f9c TT	417	&fname->crypto_buf);
5b643f9c TT	418	if (ret < 0)
82d0d3e7	419	return ret;
b7236e21	420	ret = ext4_fname_encrypt(dir, iname, &fname->crypto_buf);
5b643f9c	421	if (ret < 0)
82d0d3e7	422	goto errout;
5b643f9c TT	423	fname->disk_name.name = fname->crypto_buf.name;
5b643f9c TT	424	fname->disk_name.len = fname->crypto_buf.len;
82d0d3e7	425	return 0;
5de0b4d0	426	}
82d0d3e7 TT	427	if (!lookup)
82d0d3e7 TT	428	return -EACCES;
5de0b4d0	429
5b643f9c TT	430	/* We don't have the key and we are doing a lookup; decode the
	431	* user-supplied name
	432	*/
	433	if (iname->name[0] == '_')
	434	bigname = 1;
	435	if ((bigname && (iname->len != 33)) \|\|
82d0d3e7 TT	436	(!bigname && (iname->len > 43)))
	437	return -ENOENT;
	438
5b643f9c	439	fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
82d0d3e7 TT	440	if (fname->crypto_buf.name == NULL)
82d0d3e7 TT	441	return -ENOMEM;
5b643f9c TT	442	ret = digest_decode(iname->name + bigname, iname->len - bigname,
	443	fname->crypto_buf.name);
	444	if (ret < 0) {
	445	ret = -ENOENT;
82d0d3e7	446	goto errout;
5b643f9c TT	447	}
	448	fname->crypto_buf.len = ret;
	449	if (bigname) {
	450	memcpy(&fname->hinfo.hash, fname->crypto_buf.name, 4);
	451	memcpy(&fname->hinfo.minor_hash, fname->crypto_buf.name + 4, 4);
	452	} else {
	453	fname->disk_name.name = fname->crypto_buf.name;
	454	fname->disk_name.len = fname->crypto_buf.len;
	455	}
82d0d3e7 TT	456	return 0;
	457	errout:
	458	kfree(fname->crypto_buf.name);
	459	fname->crypto_buf.name = NULL;
d5d0e8c7 MH	460	return ret;
	461	}
	462
5b643f9c	463	void ext4_fname_free_filename(struct ext4_filename *fname)
d5d0e8c7	464	{
5b643f9c TT	465	kfree(fname->crypto_buf.name);
	466	fname->crypto_buf.name = NULL;
	467	fname->usr_fname = NULL;
	468	fname->disk_name.name = NULL;
d5d0e8c7	469	}