[deliverable/linux.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/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) {
		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) {
		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 (iname->len < EXT4_CRYPTO_BLOCK_SIZE) {
		EXT4_ERROR_INODE(inode, "encrypted inode too small");
		return -EUCLEAN;
	}
	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>
d5d0e8c7 MH	22	#include <linux/list.h>
	23	#include <linux/mempool.h>
	24	#include <linux/random.h>
	25	#include <linux/scatterlist.h>
	26	#include <linux/spinlock_types.h>
	27
	28	#include "ext4.h"
	29	#include "ext4_crypto.h"
	30	#include "xattr.h"
	31
	32	/**
	33	* ext4_dir_crypt_complete() -
	34	*/
	35	static void ext4_dir_crypt_complete(struct crypto_async_request *req, int res)
	36	{
	37	struct ext4_completion_result *ecr = req->data;
	38
	39	if (res == -EINPROGRESS)
	40	return;
	41	ecr->res = res;
	42	complete(&ecr->completion);
	43	}
	44
	45	bool ext4_valid_filenames_enc_mode(uint32_t mode)
	46	{
	47	return (mode == EXT4_ENCRYPTION_MODE_AES_256_CTS);
	48	}
	49
b7236e21 TT	50	static unsigned max_name_len(struct inode *inode)
	51	{
	52	return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
	53	EXT4_NAME_LEN;
	54	}
	55
d5d0e8c7 MH	56	/**
	57	* ext4_fname_encrypt() -
	58	*
	59	* This function encrypts the input filename, and returns the length of the
	60	* ciphertext. Errors are returned as negative numbers. We trust the caller to
	61	* allocate sufficient memory to oname string.
	62	*/
b7236e21	63	static int ext4_fname_encrypt(struct inode *inode,
d5d0e8c7 MH	64	const struct qstr *iname,
	65	struct ext4_str *oname)
	66	{
	67	u32 ciphertext_len;
	68	struct ablkcipher_request *req = NULL;
	69	DECLARE_EXT4_COMPLETION_RESULT(ecr);
b7236e21 TT	70	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
b7236e21 TT	71	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
d5d0e8c7 MH	72	int res = 0;
d5d0e8c7 MH	73	char iv[EXT4_CRYPTO_BLOCK_SIZE];
d2299590	74	struct scatterlist src_sg, dst_sg;
b7236e21	75	int padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
d2299590	76	char workbuf, buf[32], alloc_buf = NULL;
b7236e21	77	unsigned lim = max_name_len(inode);
d5d0e8c7	78
b7236e21	79	if (iname->len <= 0 \|\| iname->len > lim)
d5d0e8c7 MH	80	return -EIO;
	81
	82	ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
	83	EXT4_CRYPTO_BLOCK_SIZE : iname->len;
a44cd7a0	84	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
b7236e21 TT	85	ciphertext_len = (ciphertext_len > lim)
b7236e21 TT	86	? lim : ciphertext_len;
d5d0e8c7	87
d2299590 TT	88	if (ciphertext_len <= sizeof(buf)) {
	89	workbuf = buf;
	90	} else {
	91	alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
	92	if (!alloc_buf)
	93	return -ENOMEM;
	94	workbuf = alloc_buf;
	95	}
	96
d5d0e8c7 MH	97	/* Allocate request */
	98	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	99	if (!req) {
	100	printk_ratelimited(
	101	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
d2299590	102	kfree(alloc_buf);
d5d0e8c7 MH	103	return -ENOMEM;
	104	}
	105	ablkcipher_request_set_callback(req,
	106	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	107	ext4_dir_crypt_complete, &ecr);
	108
d5d0e8c7 MH	109	/* Copy the input */
	110	memcpy(workbuf, iname->name, iname->len);
	111	if (iname->len < ciphertext_len)
	112	memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
	113
	114	/* Initialize IV */
	115	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
	116
	117	/* Create encryption request */
d2299590 TT	118	sg_init_one(&src_sg, workbuf, ciphertext_len);
	119	sg_init_one(&dst_sg, oname->name, ciphertext_len);
	120	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
d5d0e8c7 MH	121	res = crypto_ablkcipher_encrypt(req);
d5d0e8c7 MH	122	if (res == -EINPROGRESS \|\| res == -EBUSY) {
d5d0e8c7 MH	123	wait_for_completion(&ecr.completion);
	124	res = ecr.res;
	125	}
d2299590	126	kfree(alloc_buf);
d5d0e8c7 MH	127	ablkcipher_request_free(req);
	128	if (res < 0) {
	129	printk_ratelimited(
	130	KERN_ERR "%s: Error (error code %d)\n", __func__, res);
	131	}
	132	oname->len = ciphertext_len;
	133	return res;
	134	}
	135
	136	/*
	137	* ext4_fname_decrypt()
	138	* This function decrypts the input filename, and returns
	139	* the length of the plaintext.
	140	* Errors are returned as negative numbers.
	141	* We trust the caller to allocate sufficient memory to oname string.
	142	*/
b7236e21	143	static int ext4_fname_decrypt(struct inode *inode,
d5d0e8c7 MH	144	const struct ext4_str *iname,
	145	struct ext4_str *oname)
	146	{
	147	struct ext4_str tmp_in[2], tmp_out[1];
	148	struct ablkcipher_request *req = NULL;
	149	DECLARE_EXT4_COMPLETION_RESULT(ecr);
d2299590	150	struct scatterlist src_sg, dst_sg;
b7236e21 TT	151	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
b7236e21 TT	152	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
d5d0e8c7 MH	153	int res = 0;
d5d0e8c7 MH	154	char iv[EXT4_CRYPTO_BLOCK_SIZE];
b7236e21	155	unsigned lim = max_name_len(inode);
d5d0e8c7	156
b7236e21	157	if (iname->len <= 0 \|\| iname->len > lim)
d5d0e8c7 MH	158	return -EIO;
	159
	160	tmp_in[0].name = iname->name;
	161	tmp_in[0].len = iname->len;
	162	tmp_out[0].name = oname->name;
	163
	164	/* Allocate request */
	165	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	166	if (!req) {
	167	printk_ratelimited(
	168	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
	169	return -ENOMEM;
	170	}
	171	ablkcipher_request_set_callback(req,
	172	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	173	ext4_dir_crypt_complete, &ecr);
	174
d5d0e8c7 MH	175	/* Initialize IV */
	176	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
	177
	178	/* Create encryption request */
d2299590 TT	179	sg_init_one(&src_sg, iname->name, iname->len);
	180	sg_init_one(&dst_sg, oname->name, oname->len);
	181	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
d5d0e8c7 MH	182	res = crypto_ablkcipher_decrypt(req);
d5d0e8c7 MH	183	if (res == -EINPROGRESS \|\| res == -EBUSY) {
d5d0e8c7 MH	184	wait_for_completion(&ecr.completion);
	185	res = ecr.res;
	186	}
d5d0e8c7 MH	187	ablkcipher_request_free(req);
	188	if (res < 0) {
	189	printk_ratelimited(
	190	KERN_ERR "%s: Error in ext4_fname_encrypt (error code %d)\n",
	191	__func__, res);
	192	return res;
	193	}
	194
	195	oname->len = strnlen(oname->name, iname->len);
	196	return oname->len;
	197	}
	198
5de0b4d0 TT	199	static const char *lookup_table =
	200	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
	201
d5d0e8c7 MH	202	/**
	203	* ext4_fname_encode_digest() -
	204	*
	205	* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
	206	* The encoded string is roughly 4/3 times the size of the input string.
	207	*/
5de0b4d0	208	static int digest_encode(const char src, int len, char dst)
d5d0e8c7	209	{
5de0b4d0 TT	210	int i = 0, bits = 0, ac = 0;
	211	char *cp = dst;
	212
	213	while (i < len) {
	214	ac += (((unsigned char) src[i]) << bits);
	215	bits += 8;
	216	do {
	217	*cp++ = lookup_table[ac & 0x3f];
	218	ac >>= 6;
	219	bits -= 6;
	220	} while (bits >= 6);
d5d0e8c7 MH	221	i++;
d5d0e8c7 MH	222	}
5de0b4d0 TT	223	if (bits)
	224	*cp++ = lookup_table[ac & 0x3f];
	225	return cp - dst;
d5d0e8c7 MH	226	}
d5d0e8c7 MH	227
5de0b4d0	228	static int digest_decode(const char src, int len, char dst)
d5d0e8c7	229	{
5de0b4d0 TT	230	int i = 0, bits = 0, ac = 0;
	231	const char *p;
	232	char *cp = dst;
	233
	234	while (i < len) {
	235	p = strchr(lookup_table, src[i]);
	236	if (p == NULL \|\| src[i] == 0)
	237	return -2;
	238	ac += (p - lookup_table) << bits;
	239	bits += 6;
	240	if (bits >= 8) {
	241	*cp++ = ac & 0xff;
	242	ac >>= 8;
	243	bits -= 8;
	244	}
	245	i++;
d5d0e8c7	246	}
5de0b4d0 TT	247	if (ac)
	248	return -1;
	249	return cp - dst;
d5d0e8c7 MH	250	}
d5d0e8c7 MH	251
d5d0e8c7 MH	252	/**
	253	* ext4_fname_crypto_round_up() -
	254	*
	255	* Return: The next multiple of block size
	256	*/
	257	u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
	258	{
	259	return ((size+blksize-1)/blksize)*blksize;
	260	}
	261
4d3c4e5b TT	262	unsigned ext4_fname_encrypted_size(struct inode *inode, u32 ilen)
	263	{
	264	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
	265	int padding = 32;
	266
	267	if (ci)
	268	padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
	269	if (ilen < EXT4_CRYPTO_BLOCK_SIZE)
	270	ilen = EXT4_CRYPTO_BLOCK_SIZE;
	271	return ext4_fname_crypto_round_up(ilen, padding);
	272	}
	273
	274	/*
	275	* ext4_fname_crypto_alloc_buffer() -
d5d0e8c7 MH	276	*
	277	* Allocates an output buffer that is sufficient for the crypto operation
	278	* specified by the context and the direction.
	279	*/
b7236e21	280	int ext4_fname_crypto_alloc_buffer(struct inode *inode,
d5d0e8c7 MH	281	u32 ilen, struct ext4_str *crypto_str)
d5d0e8c7 MH	282	{
4d3c4e5b	283	unsigned int olen = ext4_fname_encrypted_size(inode, ilen);
d5d0e8c7	284
d5d0e8c7 MH	285	crypto_str->len = olen;
	286	if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
	287	olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;
	288	/* Allocated buffer can hold one more character to null-terminate the
	289	* string */
	290	crypto_str->name = kmalloc(olen+1, GFP_NOFS);
	291	if (!(crypto_str->name))
	292	return -ENOMEM;
	293	return 0;
	294	}
	295
	296	/**
	297	* ext4_fname_crypto_free_buffer() -
	298	*
	299	* Frees the buffer allocated for crypto operation.
	300	*/
	301	void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
	302	{
	303	if (!crypto_str)
	304	return;
	305	kfree(crypto_str->name);
	306	crypto_str->name = NULL;
	307	}
	308
	309	/**
	310	* ext4_fname_disk_to_usr() - converts a filename from disk space to user space
	311	*/
b7236e21	312	int _ext4_fname_disk_to_usr(struct inode *inode,
5de0b4d0 TT	313	struct dx_hash_info *hinfo,
	314	const struct ext4_str *iname,
	315	struct ext4_str *oname)
d5d0e8c7	316	{
5de0b4d0 TT	317	char buf[24];
	318	int ret;
	319
d5d0e8c7 MH	320	if (iname->len < 3) {
	321	/Check for . and .. /
	322	if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
	323	oname->name[0] = '.';
	324	oname->name[iname->len-1] = '.';
	325	oname->len = iname->len;
	326	return oname->len;
	327	}
	328	}
27977b69 TT	329	if (iname->len < EXT4_CRYPTO_BLOCK_SIZE) {
	330	EXT4_ERROR_INODE(inode, "encrypted inode too small");
	331	return -EUCLEAN;
	332	}
b7236e21 TT	333	if (EXT4_I(inode)->i_crypt_info)
b7236e21 TT	334	return ext4_fname_decrypt(inode, iname, oname);
5de0b4d0 TT	335
	336	if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
	337	ret = digest_encode(iname->name, iname->len, oname->name);
	338	oname->len = ret;
	339	return ret;
	340	}
	341	if (hinfo) {
	342	memcpy(buf, &hinfo->hash, 4);
	343	memcpy(buf+4, &hinfo->minor_hash, 4);
	344	} else
	345	memset(buf, 0, 8);
	346	memcpy(buf + 8, iname->name + iname->len - 16, 16);
	347	oname->name[0] = '_';
	348	ret = digest_encode(buf, 24, oname->name+1);
	349	oname->len = ret + 1;
	350	return ret + 1;
d5d0e8c7 MH	351	}
d5d0e8c7 MH	352
b7236e21	353	int ext4_fname_disk_to_usr(struct inode *inode,
5de0b4d0	354	struct dx_hash_info *hinfo,
d5d0e8c7 MH	355	const struct ext4_dir_entry_2 *de,
	356	struct ext4_str *oname)
	357	{
	358	struct ext4_str iname = {.name = (unsigned char *) de->name,
	359	.len = de->name_len };
	360
b7236e21	361	return _ext4_fname_disk_to_usr(inode, hinfo, &iname, oname);
d5d0e8c7 MH	362	}
	363
	364
	365	/**
	366	* ext4_fname_usr_to_disk() - converts a filename from user space to disk space
	367	*/
b7236e21	368	int ext4_fname_usr_to_disk(struct inode *inode,
d5d0e8c7 MH	369	const struct qstr *iname,
	370	struct ext4_str *oname)
	371	{
	372	int res;
b7236e21	373	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
d5d0e8c7	374
d5d0e8c7 MH	375	if (iname->len < 3) {
	376	/Check for . and .. /
	377	if (iname->name[0] == '.' &&
	378	iname->name[iname->len-1] == '.') {
	379	oname->name[0] = '.';
	380	oname->name[iname->len-1] = '.';
	381	oname->len = iname->len;
	382	return oname->len;
	383	}
	384	}
b7236e21 TT	385	if (ci) {
b7236e21 TT	386	res = ext4_fname_encrypt(inode, iname, oname);
d5d0e8c7 MH	387	return res;
	388	}
	389	/* Without a proper key, a user is not allowed to modify the filenames
	390	* in a directory. Consequently, a user space name cannot be mapped to
	391	* a disk-space name */
	392	return -EACCES;
	393	}
	394
5b643f9c TT	395	int ext4_fname_setup_filename(struct inode dir, const struct qstr iname,
5b643f9c TT	396	int lookup, struct ext4_filename *fname)
d5d0e8c7	397	{
b7236e21	398	struct ext4_crypt_info *ci;
5b643f9c TT	399	int ret = 0, bigname = 0;
	400
	401	memset(fname, 0, sizeof(struct ext4_filename));
	402	fname->usr_fname = iname;
d5d0e8c7	403
b7236e21	404	if (!ext4_encrypted_inode(dir) \|\|
d5d0e8c7 MH	405	((iname->name[0] == '.') &&
	406	((iname->len == 1) \|\|
	407	((iname->name[1] == '.') && (iname->len == 2))))) {
5b643f9c TT	408	fname->disk_name.name = (unsigned char *) iname->name;
5b643f9c TT	409	fname->disk_name.len = iname->len;
82d0d3e7	410	return 0;
d5d0e8c7	411	}
c936e1ec	412	ret = ext4_get_encryption_info(dir);
b7236e21 TT	413	if (ret)
	414	return ret;
	415	ci = EXT4_I(dir)->i_crypt_info;
	416	if (ci) {
	417	ret = ext4_fname_crypto_alloc_buffer(dir, iname->len,
5b643f9c TT	418	&fname->crypto_buf);
5b643f9c TT	419	if (ret < 0)
82d0d3e7	420	return ret;
b7236e21	421	ret = ext4_fname_encrypt(dir, iname, &fname->crypto_buf);
5b643f9c	422	if (ret < 0)
82d0d3e7	423	goto errout;
5b643f9c TT	424	fname->disk_name.name = fname->crypto_buf.name;
5b643f9c TT	425	fname->disk_name.len = fname->crypto_buf.len;
82d0d3e7	426	return 0;
5de0b4d0	427	}
82d0d3e7 TT	428	if (!lookup)
82d0d3e7 TT	429	return -EACCES;
5de0b4d0	430
5b643f9c TT	431	/* We don't have the key and we are doing a lookup; decode the
	432	* user-supplied name
	433	*/
	434	if (iname->name[0] == '_')
	435	bigname = 1;
	436	if ((bigname && (iname->len != 33)) \|\|
82d0d3e7 TT	437	(!bigname && (iname->len > 43)))
	438	return -ENOENT;
	439
5b643f9c	440	fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
82d0d3e7 TT	441	if (fname->crypto_buf.name == NULL)
82d0d3e7 TT	442	return -ENOMEM;
5b643f9c TT	443	ret = digest_decode(iname->name + bigname, iname->len - bigname,
	444	fname->crypto_buf.name);
	445	if (ret < 0) {
	446	ret = -ENOENT;
82d0d3e7	447	goto errout;
5b643f9c TT	448	}
	449	fname->crypto_buf.len = ret;
	450	if (bigname) {
	451	memcpy(&fname->hinfo.hash, fname->crypto_buf.name, 4);
	452	memcpy(&fname->hinfo.minor_hash, fname->crypto_buf.name + 4, 4);
	453	} else {
	454	fname->disk_name.name = fname->crypto_buf.name;
	455	fname->disk_name.len = fname->crypto_buf.len;
	456	}
82d0d3e7 TT	457	return 0;
	458	errout:
	459	kfree(fname->crypto_buf.name);
	460	fname->crypto_buf.name = NULL;
d5d0e8c7 MH	461	return ret;
	462	}
	463
5b643f9c	464	void ext4_fname_free_filename(struct ext4_filename *fname)
d5d0e8c7	465	{
5b643f9c TT	466	kfree(fname->crypto_buf.name);
	467	fname->crypto_buf.name = NULL;
	468	fname->usr_fname = NULL;
	469	fname->disk_name.name = NULL;
d5d0e8c7	470	}