[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);
}

/**
 * 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];
	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
	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 = ext4_fname_crypto_round_up(ciphertext_len, padding);
	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, 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;
	}
	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;
}

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_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;

	ctx->flags = ei->i_crypt_policy_flags;
	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;
	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);

	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 = ext4_fname_crypto_round_up(ciphertext_len, padding);
	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;
	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);

	if (!ctx)
		return -EIO;
	if (padding < EXT4_CRYPTO_BLOCK_SIZE)
		padding = EXT4_CRYPTO_BLOCK_SIZE;
	olen = ext4_fname_crypto_round_up(ilen, padding);
	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 ext4_fname_crypto_ctx *ctx,
			    struct dx_hash_info *hinfo,
			    const struct ext4_str *iname,
			    struct ext4_str *oname)
{
	char buf[24];
	int ret;

	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);

	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 ext4_fname_crypto_ctx *ctx,
			   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(ctx, hinfo, &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;
	int ret = 0;
	char buf[EXT4_FNAME_CRYPTO_DIGEST_SIZE+1];

	if (!ctx ||
	    ((iname->name[0] == '.') &&
	     ((iname->len == 1) ||
	      ((iname->name[1] == '.') && (iname->len == 2))))) {
		ext4fs_dirhash(iname->name, iname->len, hinfo);
		return 0;
	}

	if (!ctx->has_valid_key && iname->name[0] == '_') {
		if (iname->len != 33)
			return -ENOENT;
		ret = digest_decode(iname->name+1, iname->len, buf);
		if (ret != 24)
			return -ENOENT;
		memcpy(&hinfo->hash, buf, 4);
		memcpy(&hinfo->minor_hash, buf + 4, 4);
		return 0;
	}

	if (!ctx->has_valid_key && iname->name[0] != '_') {
		if (iname->len > 43)
			return -ENOENT;
		ret = digest_decode(iname->name, iname->len, buf);
		ext4fs_dirhash(buf, ret, 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) {
		ext4fs_dirhash(tmp.name, tmp.len, hinfo);
		ret = 0;
	}

	ext4_fname_crypto_free_buffer(&tmp);
	return ret;
}

int ext4_fname_match(struct ext4_fname_crypto_ctx *ctx, struct ext4_str *cstr,
		     int len, const char * const name,
		     struct ext4_dir_entry_2 *de)
{
	int ret = -ENOENT;
	int bigname = (*name == '_');

	if (ctx->has_valid_key) {
		if (cstr->name == NULL) {
			struct qstr istr;

			ret = ext4_fname_crypto_alloc_buffer(ctx, len, cstr);
			if (ret < 0)
				goto errout;
			istr.name = name;
			istr.len = len;
			ret = ext4_fname_encrypt(ctx, &istr, cstr);
			if (ret < 0)
				goto errout;
		}
	} else {
		if (cstr->name == NULL) {
			cstr->name = kmalloc(32, GFP_KERNEL);
			if (cstr->name == NULL)
				return -ENOMEM;
			if ((bigname && (len != 33)) ||
			    (!bigname && (len > 43)))
				goto errout;
			ret = digest_decode(name+bigname, len-bigname,
					    cstr->name);
			if (ret < 0) {
				ret = -ENOENT;
				goto errout;
			}
			cstr->len = ret;
		}
		if (bigname) {
			if (de->name_len < 16)
				return 0;
			ret = memcmp(de->name + de->name_len - 16,
				     cstr->name + 8, 16);
			return (ret == 0) ? 1 : 0;
		}
	}
	if (de->name_len != cstr->len)
		return 0;
	ret = memcmp(de->name, cstr->name, cstr->len);
	return (ret == 0) ? 1 : 0;
errout:
	kfree(cstr->name);
	cstr->name = NULL;
	return ret;
}
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
	51	/**
	52	* ext4_fname_encrypt() -
	53	*
	54	* This function encrypts the input filename, and returns the length of the
	55	* ciphertext. Errors are returned as negative numbers. We trust the caller to
	56	* allocate sufficient memory to oname string.
	57	*/
	58	static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
	59	const struct qstr *iname,
	60	struct ext4_str *oname)
	61	{
	62	u32 ciphertext_len;
	63	struct ablkcipher_request *req = NULL;
	64	DECLARE_EXT4_COMPLETION_RESULT(ecr);
65	struct crypto_ablkcipher *tfm = ctx->ctfm;
66	int res = 0;
67	char iv[EXT4_CRYPTO_BLOCK_SIZE];
68	struct scatterlist sg[1];
a44cd7a0	69	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
d5d0e8c7 MH	70	char *workbuf;
	71
	72	if (iname->len <= 0 \|\| iname->len > ctx->lim)
	73	return -EIO;
	74
	75	ciphertext_len = (iname->len < EXT4_CRYPTO_BLOCK_SIZE) ?
	76	EXT4_CRYPTO_BLOCK_SIZE : iname->len;
a44cd7a0	77	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
d5d0e8c7 MH	78	ciphertext_len = (ciphertext_len > ctx->lim)
	79	? ctx->lim : ciphertext_len;
	80
	81	/* Allocate request */
	82	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	83	if (!req) {
	84	printk_ratelimited(
	85	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
	86	return -ENOMEM;
	87	}
	88	ablkcipher_request_set_callback(req,
	89	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	90	ext4_dir_crypt_complete, &ecr);
	91
	92	/* Map the workpage */
	93	workbuf = kmap(ctx->workpage);
	94
	95	/* Copy the input */
	96	memcpy(workbuf, iname->name, iname->len);
	97	if (iname->len < ciphertext_len)
	98	memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
	99
	100	/* Initialize IV */
	101	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
	102
	103	/* Create encryption request */
	104	sg_init_table(sg, 1);
	105	sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
a44cd7a0	106	ablkcipher_request_set_crypt(req, sg, sg, ciphertext_len, iv);
d5d0e8c7 MH	107	res = crypto_ablkcipher_encrypt(req);
	108	if (res == -EINPROGRESS \|\| res == -EBUSY) {
	109	BUG_ON(req->base.data != &ecr);
	110	wait_for_completion(&ecr.completion);
	111	res = ecr.res;
	112	}
	113	if (res >= 0) {
	114	/* Copy the result to output */
	115	memcpy(oname->name, workbuf, ciphertext_len);
	116	res = ciphertext_len;
	117	}
	118	kunmap(ctx->workpage);
	119	ablkcipher_request_free(req);
	120	if (res < 0) {
	121	printk_ratelimited(
	122	KERN_ERR "%s: Error (error code %d)\n", __func__, res);
	123	}
	124	oname->len = ciphertext_len;
	125	return res;
	126	}
	127
	128	/*
	129	* ext4_fname_decrypt()
	130	* This function decrypts the input filename, and returns
	131	* the length of the plaintext.
	132	* Errors are returned as negative numbers.
	133	* We trust the caller to allocate sufficient memory to oname string.
	134	*/
	135	static int ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
	136	const struct ext4_str *iname,
	137	struct ext4_str *oname)
	138	{
	139	struct ext4_str tmp_in[2], tmp_out[1];
	140	struct ablkcipher_request *req = NULL;
	141	DECLARE_EXT4_COMPLETION_RESULT(ecr);
	142	struct scatterlist sg[1];
	143	struct crypto_ablkcipher *tfm = ctx->ctfm;
	144	int res = 0;
	145	char iv[EXT4_CRYPTO_BLOCK_SIZE];
	146	char *workbuf;
	147
	148	if (iname->len <= 0 \|\| iname->len > ctx->lim)
	149	return -EIO;
	150
	151	tmp_in[0].name = iname->name;
	152	tmp_in[0].len = iname->len;
	153	tmp_out[0].name = oname->name;
	154
	155	/* Allocate request */
	156	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	157	if (!req) {
	158	printk_ratelimited(
	159	KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
	160	return -ENOMEM;
	161	}
	162	ablkcipher_request_set_callback(req,
	163	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	164	ext4_dir_crypt_complete, &ecr);
	165
	166	/* Map the workpage */
	167	workbuf = kmap(ctx->workpage);
	168
	169	/* Copy the input */
	170	memcpy(workbuf, iname->name, iname->len);
171
172	/* Initialize IV */
173	memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
174
175	/* Create encryption request */
176	sg_init_table(sg, 1);
177	sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
178	ablkcipher_request_set_crypt(req, sg, sg, iname->len, iv);
179	res = crypto_ablkcipher_decrypt(req);
180	if (res == -EINPROGRESS \|\| res == -EBUSY) {
181	BUG_ON(req->base.data != &ecr);
182	wait_for_completion(&ecr.completion);
183	res = ecr.res;
184	}
185	if (res >= 0) {
186	/* Copy the result to output */
187	memcpy(oname->name, workbuf, iname->len);
188	res = iname->len;
189	}
190	kunmap(ctx->workpage);
191	ablkcipher_request_free(req);
192	if (res < 0) {
193	printk_ratelimited(
194	KERN_ERR "%s: Error in ext4_fname_encrypt (error code %d)\n",
195	__func__, res);
196	return res;
197	}
198
199	oname->len = strnlen(oname->name, iname->len);
200	return oname->len;
201	}
202
5de0b4d0 TT	203	static const char *lookup_table =
	204	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
	205
d5d0e8c7 MH	206	/**
	207	* ext4_fname_encode_digest() -
	208	*
	209	* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
	210	* The encoded string is roughly 4/3 times the size of the input string.
	211	*/
5de0b4d0	212	static int digest_encode(const char src, int len, char dst)
d5d0e8c7	213	{
5de0b4d0 TT	214	int i = 0, bits = 0, ac = 0;
	215	char *cp = dst;
	216
	217	while (i < len) {
	218	ac += (((unsigned char) src[i]) << bits);
	219	bits += 8;
	220	do {
	221	*cp++ = lookup_table[ac & 0x3f];
	222	ac >>= 6;
	223	bits -= 6;
	224	} while (bits >= 6);
d5d0e8c7 MH	225	i++;
d5d0e8c7 MH	226	}
5de0b4d0 TT	227	if (bits)
	228	*cp++ = lookup_table[ac & 0x3f];
	229	return cp - dst;
d5d0e8c7 MH	230	}
d5d0e8c7 MH	231
5de0b4d0	232	static int digest_decode(const char src, int len, char dst)
d5d0e8c7	233	{
5de0b4d0 TT	234	int i = 0, bits = 0, ac = 0;
	235	const char *p;
	236	char *cp = dst;
	237
	238	while (i < len) {
	239	p = strchr(lookup_table, src[i]);
	240	if (p == NULL \|\| src[i] == 0)
	241	return -2;
	242	ac += (p - lookup_table) << bits;
	243	bits += 6;
	244	if (bits >= 8) {
	245	*cp++ = ac & 0xff;
	246	ac >>= 8;
	247	bits -= 8;
	248	}
	249	i++;
d5d0e8c7	250	}
5de0b4d0 TT	251	if (ac)
	252	return -1;
	253	return cp - dst;
d5d0e8c7 MH	254	}
	255
	256	/**
	257	* ext4_free_fname_crypto_ctx() -
	258	*
	259	* Frees up a crypto context.
	260	*/
	261	void ext4_free_fname_crypto_ctx(struct ext4_fname_crypto_ctx *ctx)
	262	{
	263	if (ctx == NULL \|\| IS_ERR(ctx))
	264	return;
	265
	266	if (ctx->ctfm && !IS_ERR(ctx->ctfm))
	267	crypto_free_ablkcipher(ctx->ctfm);
	268	if (ctx->htfm && !IS_ERR(ctx->htfm))
	269	crypto_free_hash(ctx->htfm);
	270	if (ctx->workpage && !IS_ERR(ctx->workpage))
	271	__free_page(ctx->workpage);
	272	kfree(ctx);
	273	}
	274
	275	/**
	276	* ext4_put_fname_crypto_ctx() -
	277	*
	278	* Return: The crypto context onto free list. If the free list is above a
	279	* threshold, completely frees up the context, and returns the memory.
	280	*
	281	* TODO: Currently we directly free the crypto context. Eventually we should
	282	* add code it to return to free list. Such an approach will increase
	283	* efficiency of directory lookup.
	284	*/
	285	void ext4_put_fname_crypto_ctx(struct ext4_fname_crypto_ctx **ctx)
	286	{
	287	if (ctx == NULL \|\| IS_ERR(ctx))
	288	return;
	289	ext4_free_fname_crypto_ctx(*ctx);
	290	*ctx = NULL;
	291	}
	292
	293	/**
	294	* ext4_search_fname_crypto_ctx() -
	295	*/
	296	static struct ext4_fname_crypto_ctx *ext4_search_fname_crypto_ctx(
	297	const struct ext4_encryption_key *key)
	298	{
	299	return NULL;
	300	}
	301
	302	/**
	303	* ext4_alloc_fname_crypto_ctx() -
	304	*/
	305	struct ext4_fname_crypto_ctx *ext4_alloc_fname_crypto_ctx(
	306	const struct ext4_encryption_key *key)
	307	{
	308	struct ext4_fname_crypto_ctx *ctx;
	309
	310	ctx = kmalloc(sizeof(struct ext4_fname_crypto_ctx), GFP_NOFS);
	311	if (ctx == NULL)
	312	return ERR_PTR(-ENOMEM);
	313	if (key->mode == EXT4_ENCRYPTION_MODE_INVALID) {
	314	/* This will automatically set key mode to invalid
	315	* As enum for ENCRYPTION_MODE_INVALID is zero */
	316	memset(&ctx->key, 0, sizeof(ctx->key));
	317	} else {
318	memcpy(&ctx->key, key, sizeof(struct ext4_encryption_key));
319	}
320	ctx->has_valid_key = (EXT4_ENCRYPTION_MODE_INVALID == key->mode)
321	? 0 : 1;
322	ctx->ctfm_key_is_ready = 0;
323	ctx->ctfm = NULL;
324	ctx->htfm = NULL;
325	ctx->workpage = NULL;
326	return ctx;
327	}
328
329	/**
330	* ext4_get_fname_crypto_ctx() -
331	*
332	* Allocates a free crypto context and initializes it to hold
333	* the crypto material for the inode.
334	*
335	* Return: NULL if not encrypted. Error value on error. Valid pointer otherwise.
336	*/
337	struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(
338	struct inode *inode, u32 max_ciphertext_len)
339	{
340	struct ext4_fname_crypto_ctx *ctx;
341	struct ext4_inode_info *ei = EXT4_I(inode);
342	int res;
343
344	/* Check if the crypto policy is set on the inode */
345	res = ext4_encrypted_inode(inode);
346	if (res == 0)
347	return NULL;
348
349	if (!ext4_has_encryption_key(inode))
350	ext4_generate_encryption_key(inode);
351
352	/* Get a crypto context based on the key.
353	* A new context is allocated if no context matches the requested key.
354	*/
355	ctx = ext4_search_fname_crypto_ctx(&(ei->i_encryption_key));
356	if (ctx == NULL)
357	ctx = ext4_alloc_fname_crypto_ctx(&(ei->i_encryption_key));
358	if (IS_ERR(ctx))
359	return ctx;
360
a44cd7a0	361	ctx->flags = ei->i_crypt_policy_flags;
d5d0e8c7 MH	362	if (ctx->has_valid_key) {
	363	if (ctx->key.mode != EXT4_ENCRYPTION_MODE_AES_256_CTS) {
	364	printk_once(KERN_WARNING
	365	"ext4: unsupported key mode %d\n",
	366	ctx->key.mode);
	367	return ERR_PTR(-ENOKEY);
	368	}
	369
	370	/* As a first cut, we will allocate new tfm in every call.
	371	* later, we will keep the tfm around, in case the key gets
	372	* re-used */
	373	if (ctx->ctfm == NULL) {
	374	ctx->ctfm = crypto_alloc_ablkcipher("cts(cbc(aes))",
	375	0, 0);
	376	}
	377	if (IS_ERR(ctx->ctfm)) {
	378	res = PTR_ERR(ctx->ctfm);
	379	printk(
	380	KERN_DEBUG "%s: error (%d) allocating crypto tfm\n",
	381	__func__, res);
	382	ctx->ctfm = NULL;
	383	ext4_put_fname_crypto_ctx(&ctx);
	384	return ERR_PTR(res);
	385	}
	386	if (ctx->ctfm == NULL) {
	387	printk(
	388	KERN_DEBUG "%s: could not allocate crypto tfm\n",
	389	__func__);
	390	ext4_put_fname_crypto_ctx(&ctx);
	391	return ERR_PTR(-ENOMEM);
	392	}
	393	if (ctx->workpage == NULL)
	394	ctx->workpage = alloc_page(GFP_NOFS);
	395	if (IS_ERR(ctx->workpage)) {
	396	res = PTR_ERR(ctx->workpage);
	397	printk(
	398	KERN_DEBUG "%s: error (%d) allocating work page\n",
	399	__func__, res);
	400	ctx->workpage = NULL;
	401	ext4_put_fname_crypto_ctx(&ctx);
	402	return ERR_PTR(res);
	403	}
	404	if (ctx->workpage == NULL) {
	405	printk(
	406	KERN_DEBUG "%s: could not allocate work page\n",
	407	__func__);
	408	ext4_put_fname_crypto_ctx(&ctx);
	409	return ERR_PTR(-ENOMEM);
	410	}
	411	ctx->lim = max_ciphertext_len;
	412	crypto_ablkcipher_clear_flags(ctx->ctfm, ~0);
	413	crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctx->ctfm),
	414	CRYPTO_TFM_REQ_WEAK_KEY);
	415
	416	/* If we are lucky, we will get a context that is already
	417	* set up with the right key. Else, we will have to
	418	* set the key */
	419	if (!ctx->ctfm_key_is_ready) {
	420	/* Since our crypto objectives for filename encryption
	421	* are pretty weak,
	422	* we directly use the inode master key */
	423	res = crypto_ablkcipher_setkey(ctx->ctfm,
	424	ctx->key.raw, ctx->key.size);
	425	if (res) {
426	ext4_put_fname_crypto_ctx(&ctx);
427	return ERR_PTR(-EIO);
428	}
429	ctx->ctfm_key_is_ready = 1;
430	} else {
431	/* In the current implementation, key should never be
432	* marked "ready" for a context that has just been
433	* allocated. So we should never reach here */
434	BUG();
435	}
436	}
437	if (ctx->htfm == NULL)
438	ctx->htfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
439	if (IS_ERR(ctx->htfm)) {
440	res = PTR_ERR(ctx->htfm);
441	printk(KERN_DEBUG "%s: error (%d) allocating hash tfm\n",
442	__func__, res);
443	ctx->htfm = NULL;
444	ext4_put_fname_crypto_ctx(&ctx);
445	return ERR_PTR(res);
446	}
447	if (ctx->htfm == NULL) {
448	printk(KERN_DEBUG "%s: could not allocate hash tfm\n",
449	__func__);
450	ext4_put_fname_crypto_ctx(&ctx);
451	return ERR_PTR(-ENOMEM);
452	}
453
454	return ctx;
455	}
456
457	/**
458	* ext4_fname_crypto_round_up() -
459	*
460	* Return: The next multiple of block size
461	*/
462	u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
463	{
464	return ((size+blksize-1)/blksize)*blksize;
465	}
466
467	/**
468	* ext4_fname_crypto_namelen_on_disk() -
469	*/
470	int ext4_fname_crypto_namelen_on_disk(struct ext4_fname_crypto_ctx *ctx,
471	u32 namelen)
472	{
473	u32 ciphertext_len;
a44cd7a0	474	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
d5d0e8c7 MH	475
	476	if (ctx == NULL)
	477	return -EIO;
	478	if (!(ctx->has_valid_key))
	479	return -EACCES;
	480	ciphertext_len = (namelen < EXT4_CRYPTO_BLOCK_SIZE) ?
	481	EXT4_CRYPTO_BLOCK_SIZE : namelen;
a44cd7a0	482	ciphertext_len = ext4_fname_crypto_round_up(ciphertext_len, padding);
d5d0e8c7 MH	483	ciphertext_len = (ciphertext_len > ctx->lim)
	484	? ctx->lim : ciphertext_len;
	485	return (int) ciphertext_len;
	486	}
	487
	488	/**
	489	* ext4_fname_crypto_alloc_obuff() -
	490	*
	491	* Allocates an output buffer that is sufficient for the crypto operation
	492	* specified by the context and the direction.
	493	*/
	494	int ext4_fname_crypto_alloc_buffer(struct ext4_fname_crypto_ctx *ctx,
	495	u32 ilen, struct ext4_str *crypto_str)
	496	{
	497	unsigned int olen;
a44cd7a0	498	int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
d5d0e8c7 MH	499
	500	if (!ctx)
	501	return -EIO;
a44cd7a0 TT	502	if (padding < EXT4_CRYPTO_BLOCK_SIZE)
	503	padding = EXT4_CRYPTO_BLOCK_SIZE;
	504	olen = ext4_fname_crypto_round_up(ilen, padding);
d5d0e8c7 MH	505	crypto_str->len = olen;
	506	if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
	507	olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;
	508	/* Allocated buffer can hold one more character to null-terminate the
	509	* string */
	510	crypto_str->name = kmalloc(olen+1, GFP_NOFS);
	511	if (!(crypto_str->name))
	512	return -ENOMEM;
	513	return 0;
	514	}
	515
	516	/**
	517	* ext4_fname_crypto_free_buffer() -
	518	*
	519	* Frees the buffer allocated for crypto operation.
	520	*/
	521	void ext4_fname_crypto_free_buffer(struct ext4_str *crypto_str)
	522	{
	523	if (!crypto_str)
	524	return;
	525	kfree(crypto_str->name);
	526	crypto_str->name = NULL;
	527	}
	528
	529	/**
	530	* ext4_fname_disk_to_usr() - converts a filename from disk space to user space
	531	*/
	532	int _ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
5de0b4d0 TT	533	struct dx_hash_info *hinfo,
	534	const struct ext4_str *iname,
	535	struct ext4_str *oname)
d5d0e8c7	536	{
5de0b4d0 TT	537	char buf[24];
	538	int ret;
	539
d5d0e8c7 MH	540	if (ctx == NULL)
	541	return -EIO;
	542	if (iname->len < 3) {
	543	/Check for . and .. /
	544	if (iname->name[0] == '.' && iname->name[iname->len-1] == '.') {
	545	oname->name[0] = '.';
	546	oname->name[iname->len-1] = '.';
	547	oname->len = iname->len;
	548	return oname->len;
	549	}
	550	}
	551	if (ctx->has_valid_key)
	552	return ext4_fname_decrypt(ctx, iname, oname);
5de0b4d0 TT	553
	554	if (iname->len <= EXT4_FNAME_CRYPTO_DIGEST_SIZE) {
	555	ret = digest_encode(iname->name, iname->len, oname->name);
	556	oname->len = ret;
	557	return ret;
	558	}
	559	if (hinfo) {
	560	memcpy(buf, &hinfo->hash, 4);
	561	memcpy(buf+4, &hinfo->minor_hash, 4);
	562	} else
	563	memset(buf, 0, 8);
	564	memcpy(buf + 8, iname->name + iname->len - 16, 16);
	565	oname->name[0] = '_';
	566	ret = digest_encode(buf, 24, oname->name+1);
	567	oname->len = ret + 1;
	568	return ret + 1;
d5d0e8c7 MH	569	}
	570
	571	int ext4_fname_disk_to_usr(struct ext4_fname_crypto_ctx *ctx,
5de0b4d0	572	struct dx_hash_info *hinfo,
d5d0e8c7 MH	573	const struct ext4_dir_entry_2 *de,
	574	struct ext4_str *oname)
	575	{
	576	struct ext4_str iname = {.name = (unsigned char *) de->name,
	577	.len = de->name_len };
	578
5de0b4d0	579	return _ext4_fname_disk_to_usr(ctx, hinfo, &iname, oname);
d5d0e8c7 MH	580	}
	581
	582
	583	/**
	584	* ext4_fname_usr_to_disk() - converts a filename from user space to disk space
	585	*/
	586	int ext4_fname_usr_to_disk(struct ext4_fname_crypto_ctx *ctx,
	587	const struct qstr *iname,
	588	struct ext4_str *oname)
	589	{
	590	int res;
	591
	592	if (ctx == NULL)
	593	return -EIO;
	594	if (iname->len < 3) {
	595	/Check for . and .. /
	596	if (iname->name[0] == '.' &&
	597	iname->name[iname->len-1] == '.') {
	598	oname->name[0] = '.';
	599	oname->name[iname->len-1] = '.';
	600	oname->len = iname->len;
	601	return oname->len;
	602	}
	603	}
	604	if (ctx->has_valid_key) {
	605	res = ext4_fname_encrypt(ctx, iname, oname);
	606	return res;
	607	}
	608	/* Without a proper key, a user is not allowed to modify the filenames
	609	* in a directory. Consequently, a user space name cannot be mapped to
	610	* a disk-space name */
	611	return -EACCES;
	612	}
	613
	614	/*
	615	* Calculate the htree hash from a filename from user space
	616	*/
	617	int ext4_fname_usr_to_hash(struct ext4_fname_crypto_ctx *ctx,
	618	const struct qstr *iname,
	619	struct dx_hash_info *hinfo)
	620	{
5de0b4d0	621	struct ext4_str tmp;
d5d0e8c7	622	int ret = 0;
5de0b4d0	623	char buf[EXT4_FNAME_CRYPTO_DIGEST_SIZE+1];
d5d0e8c7	624
5de0b4d0	625	if (!ctx \|\|
d5d0e8c7 MH	626	((iname->name[0] == '.') &&
	627	((iname->len == 1) \|\|
	628	((iname->name[1] == '.') && (iname->len == 2))))) {
	629	ext4fs_dirhash(iname->name, iname->len, hinfo);
	630	return 0;
	631	}
	632
5de0b4d0 TT	633	if (!ctx->has_valid_key && iname->name[0] == '_') {
	634	if (iname->len != 33)
	635	return -ENOENT;
	636	ret = digest_decode(iname->name+1, iname->len, buf);
	637	if (ret != 24)
	638	return -ENOENT;
	639	memcpy(&hinfo->hash, buf, 4);
	640	memcpy(&hinfo->minor_hash, buf + 4, 4);
	641	return 0;
	642	}
	643
	644	if (!ctx->has_valid_key && iname->name[0] != '_') {
	645	if (iname->len > 43)
	646	return -ENOENT;
	647	ret = digest_decode(iname->name, iname->len, buf);
	648	ext4fs_dirhash(buf, ret, hinfo);
	649	return 0;
	650	}
	651
d5d0e8c7 MH	652	/* First encrypt the plaintext name */
	653	ret = ext4_fname_crypto_alloc_buffer(ctx, iname->len, &tmp);
	654	if (ret < 0)
	655	return ret;
	656
	657	ret = ext4_fname_encrypt(ctx, iname, &tmp);
5de0b4d0 TT	658	if (ret >= 0) {
	659	ext4fs_dirhash(tmp.name, tmp.len, hinfo);
	660	ret = 0;
d5d0e8c7 MH	661	}
d5d0e8c7 MH	662
d5d0e8c7 MH	663	ext4_fname_crypto_free_buffer(&tmp);
	664	return ret;
	665	}
	666
5de0b4d0 TT	667	int ext4_fname_match(struct ext4_fname_crypto_ctx ctx, struct ext4_str cstr,
	668	int len, const char * const name,
	669	struct ext4_dir_entry_2 *de)
d5d0e8c7	670	{
5de0b4d0 TT	671	int ret = -ENOENT;
5de0b4d0 TT	672	int bigname = (*name == '_');
d5d0e8c7	673
5de0b4d0 TT	674	if (ctx->has_valid_key) {
	675	if (cstr->name == NULL) {
	676	struct qstr istr;
	677
	678	ret = ext4_fname_crypto_alloc_buffer(ctx, len, cstr);
	679	if (ret < 0)
	680	goto errout;
	681	istr.name = name;
	682	istr.len = len;
	683	ret = ext4_fname_encrypt(ctx, &istr, cstr);
	684	if (ret < 0)
	685	goto errout;
	686	}
	687	} else {
	688	if (cstr->name == NULL) {
	689	cstr->name = kmalloc(32, GFP_KERNEL);
	690	if (cstr->name == NULL)
	691	return -ENOMEM;
	692	if ((bigname && (len != 33)) \|\|
	693	(!bigname && (len > 43)))
	694	goto errout;
	695	ret = digest_decode(name+bigname, len-bigname,
	696	cstr->name);
	697	if (ret < 0) {
	698	ret = -ENOENT;
	699	goto errout;
	700	}
	701	cstr->len = ret;
	702	}
	703	if (bigname) {
	704	if (de->name_len < 16)
	705	return 0;
	706	ret = memcmp(de->name + de->name_len - 16,
	707	cstr->name + 8, 16);
	708	return (ret == 0) ? 1 : 0;
	709	}
d5d0e8c7	710	}
5de0b4d0 TT	711	if (de->name_len != cstr->len)
	712	return 0;
	713	ret = memcmp(de->name, cstr->name, cstr->len);
	714	return (ret == 0) ? 1 : 0;
	715	errout:
	716	kfree(cstr->name);
	717	cstr->name = NULL;
d5d0e8c7 MH	718	return ret;
d5d0e8c7 MH	719	}