/*
* linux/net/sunrpc/gss_krb5_crypto.c
*
* Copyright (c) 2000-2008 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <[email protected]>
* Bruce Fields <[email protected]>
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <crypto/hash.h>
#include <crypto/skcipher.h>
#include <crypto/utils.h>
#include <linux/err.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/random.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/sunrpc/xdr.h>
#include <kunit/visibility.h>
#include "gss_krb5_internal.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
/**
* krb5_make_confounder - Generate a confounder string
* @p: memory location into which to write the string
* @conflen: string length to write, in octets
*
* RFCs 1964 and 3961 mention only "a random confounder" without going
* into detail about its function or cryptographic requirements. The
* assumed purpose is to prevent repeated encryption of a plaintext with
* the same key from generating the same ciphertext. It is also used to
* pad minimum plaintext length to at least a single cipher block.
*
* However, in situations like the GSS Kerberos 5 mechanism, where the
* encryption IV is always all zeroes, the confounder also effectively
* functions like an IV. Thus, not only must it be unique from message
* to message, but it must also be difficult to predict. Otherwise an
* attacker can correlate the confounder to previous or future values,
* making the encryption easier to break.
*
* Given that the primary consumer of this encryption mechanism is a
* network storage protocol, a type of traffic that often carries
* predictable payloads (eg, all zeroes when reading unallocated blocks
* from a file), our confounder generation has to be cryptographically
* strong.
*/
void krb5_make_confounder(u8 *p, int conflen)
{
get_random_bytes(p, conflen);
}
/**
* krb5_encrypt - simple encryption of an RPCSEC GSS payload
* @tfm: initialized cipher transform
* @iv: pointer to an IV
* @in: plaintext to encrypt
* @out: OUT: ciphertext
* @length: length of input and output buffers, in bytes
*
* @iv may be NULL to force the use of an all-zero IV.
* The buffer containing the IV must be as large as the
* cipher's ivsize.
*
* Return values:
* %0: @in successfully encrypted into @out
* negative errno: @in not encrypted
*/
u32
krb5_encrypt(
struct crypto_sync_skcipher *tfm,
void * iv,
void * in,
void * out,
int length)
{
u32 ret = -EINVAL;
struct scatterlist sg[1];
u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
if (length % crypto_sync_skcipher_blocksize(tfm) != 0)
goto out;
if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
dprintk("RPC: gss_k5encrypt: tfm iv size too large %d\n",
crypto_sync_skcipher_ivsize(tfm));
goto out;
}
if (iv)
memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm));
memcpy(out, in, length);
sg_init_one(sg, out, length);
skcipher_request_set_sync_tfm(req, tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg, sg, length, local_iv);
ret = crypto_skcipher_encrypt(req);
skcipher_request_zero(req);
out:
dprintk("RPC: krb5_encrypt returns %d\n", ret);
return ret;
}
/**
* krb5_decrypt - simple decryption of an RPCSEC GSS payload
* @tfm: initialized cipher transform
* @iv: pointer to an IV
* @in: ciphertext to decrypt
* @out: OUT: plaintext
* @length: length of input and output buffers, in bytes
*
* @iv may be NULL to force the use of an all-zero IV.
* The buffer containing the IV must be as large as the
* cipher's ivsize.
*
* Return values:
* %0: @in successfully decrypted into @out
* negative errno: @in not decrypted
*/
u32
krb5_decrypt(
struct crypto_sync_skcipher *tfm,
void * iv,
void * in,
void * out,
int length)
{
u32 ret = -EINVAL;
struct scatterlist sg[1];
u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
if (length % crypto_sync_skcipher_blocksize(tfm) != 0)
goto out;
if (crypto_sync_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
dprintk("RPC: gss_k5decrypt: tfm iv size too large %d\n",
crypto_sync_skcipher_ivsize(tfm));
goto out;
}
if (iv)
memcpy(local_iv, iv, crypto_sync_skcipher_ivsize(tfm));
memcpy(out, in, length);
sg_init_one(sg, out, length);
skcipher_request_set_sync_tfm(req, tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg, sg, length, local_iv);
ret = crypto_skcipher_decrypt(req);
skcipher_request_zero(req);
out:
dprintk("RPC: gss_k5decrypt returns %d\n",ret);
return ret;
}
static int
checksummer(struct scatterlist *sg, void *data)
{
struct ahash_request *req = data;
ahash_request_set_crypt(req, sg, NULL, sg->length);
return crypto_ahash_update(req);
}
/*
* checksum the plaintext data and hdrlen bytes of the token header
* The checksum is performed over the first 8 bytes of the
* gss token header and then over the data body
*/
u32
make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
struct xdr_buf *body, int body_offset, u8 *cksumkey,
unsigned int usage, struct xdr_netobj *cksumout)
{
struct crypto_ahash *tfm;
struct ahash_request *req;
struct scatterlist sg[1];
int err = -1;
u8 *checksumdata;
unsigned int checksumlen;
if (cksumout->len < kctx->gk5e->cksumlength) {
dprintk("%s: checksum buffer length, %u, too small for %s\n",
__func__, cksumout->len, kctx->gk5e->name);
return GSS_S_FAILURE;
}
checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_KERNEL);
if (checksumdata == NULL)
return GSS_S_FAILURE;
tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto out_free_cksum;
req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto out_free_ahash;
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
checksumlen = crypto_ahash_digestsize(tfm);
if (cksumkey != NULL) {
err = crypto_ahash_setkey(tfm, cksumkey,
kctx->gk5e->keylength);
if (err)
goto out;
}
err = crypto_ahash_init(req);
if (err)
goto out;
sg_init_one(sg, header, hdrlen);
ahash_request_set_crypt(req, sg, NULL, hdrlen);
err = crypto_ahash_update(req);
if (err)
goto out;
err = xdr_process_buf(body, body_offset, body->len - body_offset,
checksummer, req);
if (err)
goto out;
ahash_request_set_crypt(req, NULL, checksumdata, 0);
err = crypto_ahash_final(req);
if (err)
goto out;
switch (kctx->gk5e->ctype) {
case CKSUMTYPE_RSA_MD5:
err = krb5_encrypt(kctx->seq, NULL, checksumdata,
checksumdata, checksumlen);
if (err)
goto out;
memcpy(cksumout->data,
checksumdata + checksumlen - kctx->gk5e->cksumlength,
kctx->gk5e->cksumlength);
break;
case CKSUMTYPE_HMAC_SHA1_DES3:
memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
break;
default:
BUG();
break;
}
cksumout->len = kctx->gk5e->cksumlength;
out:
ahash_request_free(req);
out_free_ahash:
crypto_free_ahash(tfm);
out_free_cksum:
kfree(checksumdata);
return err ? GSS_S_FAILURE : 0;
}
/**
* gss_krb5_checksum - Compute the MAC for a GSS Wrap or MIC token
* @tfm: an initialized hash transform
* @header: pointer to a buffer containing the token header, or NULL
* @hdrlen: number of octets in @header
* @body: xdr_buf containing an RPC message (body.len is the message length)
* @body_offset: byte offset into @body to start checksumming
* @cksumout: OUT: a buffer to be filled in with the computed HMAC
*
* Usually expressed as H = HMAC(K, message)[1..h] .
*
* Caller provides the truncation length of the output token (h) in
* cksumout.len.
*
* Return values:
* %GSS_S_COMPLETE: Digest computed, @cksumout filled in
* %GSS_S_FAILURE: Call failed
*/
u32
gss_krb5_checksum(struct crypto_ahash *tfm, char *header, int hdrlen,
const struct xdr_buf *body, int body_offset,
struct xdr_netobj *cksumout)
{
struct ahash_request *req;
int err = -ENOMEM;
u8 *checksumdata;
checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
if (!checksumdata)
return GSS_S_FAILURE;
req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto out_free_cksum;
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
err = crypto_ahash_init(req);
if (err)
goto out_free_ahash;
/*
* Per RFC 4121 Section 4.2.4, the checksum is performed over the
* data body first, then over the octets in "header".
*/
err = xdr_process_buf(body, body_offset, body->len - body_offset,
checksummer, req);
if (err)
goto out_free_ahash;
if (header) {
struct scatterlist sg[1];
sg_init_one(sg, header, hdrlen);
ahash_request_set_crypt(req, sg, NULL, hdrlen);
err = crypto_ahash_update(req);
if (err)
goto out_free_ahash;
}
ahash_request_set_crypt(req, NULL, checksumdata, 0);
err = crypto_ahash_final(req);
if (err)
goto out_free_ahash;
memcpy(cksumout->data, checksumdata,
min_t(int, cksumout->len, crypto_ahash_digestsize(tfm)));
out_free_ahash:
ahash_request_free(req);
out_free_cksum:
kfree_sensitive(checksumdata);
return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
}
EXPORT_SYMBOL_IF_KUNIT(gss_krb5_checksum);
struct encryptor_desc {
u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
struct skcipher_request *req;
int pos;
struct xdr_buf *outbuf;
struct page **pages;
struct scatterlist infrags[4];
struct scatterlist outfrags[4];
int fragno;
int fraglen;
};
static int
encryptor(struct scatterlist *sg, void *data)
{
struct encryptor_desc *desc = data;
struct xdr_buf *outbuf = desc->outbuf;
struct crypto_sync_skcipher *tfm =
crypto_sync_skcipher_reqtfm(desc->req);
struct page *in_page;
int thislen = desc->fraglen + sg->length;
int fraglen, ret;
int page_pos;
/* Worst case is 4 fragments: head, end of page 1, start
* of page 2, tail. Anything more is a bug. */
BUG_ON(desc->fragno > 3);
page_pos = desc->pos - outbuf->head[0].iov_len;
if (page_pos >= 0 && page_pos < outbuf->page_len) {
/* pages are not in place: */
int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
in_page = desc->pages[i];
} else {
in_page = sg_page(sg);
}
sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
sg->offset);
sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
sg->offset);
desc->fragno++;
desc->fraglen += sg->length;
desc->pos += sg->length;
fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
thislen -= fraglen;
if (thislen == 0)
return 0;
sg_mark_end(&desc->infrags[desc->fragno - 1]);
sg_mark_end(&desc->outfrags[desc->fragno - 1]);
skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
thislen, desc->iv);
ret = crypto_skcipher_encrypt(desc->req);
if (ret)
return ret;
sg_init_table(desc->infrags, 4);
sg_init_table(desc->outfrags, 4);
if (fraglen) {
sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
sg->offset + sg->length - fraglen);
desc->infrags[0] = desc->outfrags[0];
sg_assign_page(&desc->infrags[0], in_page);
desc->fragno = 1;
desc->fraglen = fraglen;
} else {
desc->fragno = 0;
desc->fraglen = 0;
}
return 0;
}
int
gss_encrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
int offset, struct page **pages)
{
int ret;
struct encryptor_desc desc;
SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
skcipher_request_set_sync_tfm(req, tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
memset(desc.iv, 0, sizeof(desc.iv));
desc.req = req;
desc.pos = offset;
desc.outbuf = buf;
desc.pages = pages;
desc.fragno = 0;
desc.fraglen = 0;
sg_init_table(desc.infrags, 4);
sg_init_table(desc.outfrags, 4);
ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
skcipher_request_zero(req);
return ret;
}
struct decryptor_desc {
u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
struct skcipher_request *req;
struct scatterlist frags[4];
int fragno;
int fraglen;
};
static int
decryptor(struct scatterlist *sg, void *data)
{
struct decryptor_desc *desc = data;
int thislen = desc->fraglen + sg->length;
struct crypto_sync_skcipher *tfm =
crypto_sync_skcipher_reqtfm(desc->req);
int fraglen, ret;
/* Worst case is 4 fragments: head, end of page 1, start
* of page 2, tail. Anything more is a bug. */
BUG_ON(desc->fragno > 3);
sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
sg->offset);
desc->fragno++;
desc->fraglen += sg->length;
fraglen = thislen & (crypto_sync_skcipher_blocksize(tfm) - 1);
thislen -= fraglen;
if (thislen == 0)
return 0;
sg_mark_end(&desc->frags[desc->fragno - 1]);
skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
thislen, desc->iv);
ret = crypto_skcipher_decrypt(desc->req);
if (ret)
return ret;
sg_init_table(desc->frags, 4);
if (fraglen) {
sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
sg->offset + sg->length - fraglen);
desc->fragno = 1;
desc->fraglen = fraglen;
} else {
desc->fragno = 0;
desc->fraglen = 0;
}
return 0;
}
int
gss_decrypt_xdr_buf(struct crypto_sync_skcipher *tfm, struct xdr_buf *buf,
int offset)
{
int ret;
struct decryptor_desc desc;
SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
/* XXXJBF: */
BUG_ON((buf->len - offset) % crypto_sync_skcipher_blocksize(tfm) != 0);
skcipher_request_set_sync_tfm(req, tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
memset(desc.iv, 0, sizeof(desc.iv));
desc.req = req;
desc.fragno = 0;
desc.fraglen = 0;
sg_init_table(desc.frags, 4);
ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
skcipher_request_zero(req);
return ret;
}
/*
* This function makes the assumption that it was ultimately called
* from gss_wrap().
*
* The client auth_gss code moves any existing tail data into a
* separate page before calling gss_wrap.
* The server svcauth_gss code ensures that both the head and the
* tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
*
* Even with that guarantee, this function may be called more than
* once in the processing of gss_wrap(). The best we can do is
* verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
* largest expected shift will fit within RPC_MAX_AUTH_SIZE.
* At run-time we can verify that a single invocation of this
* function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
*/
int
xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
{
u8 *p;
if (shiftlen == 0)
return 0;
BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
p = buf->head[0].iov_base + base;
memmove(p + shiftlen, p, buf->head[0].iov_len - base);
buf->head[0].iov_len += shiftlen;
buf->len += shiftlen;
return 0;
}
static u32
gss_krb5_cts_crypt(struct crypto_sync_skcipher *cipher, struct xdr_buf *buf,
u32 offset, u8 *iv, struct page **pages, int encrypt)
{
u32 ret;
struct scatterlist sg[1];
SYNC_SKCIPHER_REQUEST_ON_STACK(req, cipher);
u8 *data;
struct page **save_pages;
u32 len = buf->len - offset;
if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
WARN_ON(0);
return -ENOMEM;
}
data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_KERNEL);
if (!data)
return -ENOMEM;
/*
* For encryption, we want to read from the cleartext
* page cache pages, and write the encrypted data to
* the supplied xdr_buf pages.
*/
save_pages = buf->pages;
if (encrypt)
buf->pages = pages;
ret = read_bytes_from_xdr_buf(buf, offset, data, len);
buf->pages = save_pages;
if (ret)
goto out;
sg_init_one(sg, data, len);
skcipher_request_set_sync_tfm(req, cipher);
skcipher_request_set_callback(req, 0, NULL, NULL);
skcipher_request_set_crypt(req, sg, sg, len, iv);
if (encrypt)
ret = crypto_skcipher_encrypt(req);
else
ret = crypto_skcipher_decrypt(req);
skcipher_request_zero(req);
if (ret)
goto out;
ret = write_bytes_to_xdr_buf(buf, offset, data, len);
#if IS_ENABLED(CONFIG_KUNIT)
/*
* CBC-CTS does not define an output IV but RFC 3962 defines it as the
* penultimate block of ciphertext, so copy that into the IV buffer
* before returning.
*/
if (encrypt)
memcpy(iv, data, crypto_sync_skcipher_ivsize(cipher));
#endif
out:
kfree(data);
return ret;
}
/**
* krb5_cbc_cts_encrypt - encrypt in CBC mode with CTS
* @cts_tfm: CBC cipher with CTS
* @cbc_tfm: base CBC cipher
* @offset: starting byte offset for plaintext
* @buf: OUT: output buffer
* @pages: plaintext
* @iv: output CBC initialization vector, or NULL
* @ivsize: size of @iv, in octets
*
* To provide confidentiality, encrypt using cipher block chaining
* with ciphertext stealing. Message integrity is handled separately.
*
* Return values:
* %0: encryption successful
* negative errno: encryption could not be completed
*/
VISIBLE_IF_KUNIT
int krb5_cbc_cts_encrypt(struct crypto_sync_skcipher *cts_tfm,
struct crypto_sync_skcipher *cbc_tfm,
u32 offset, struct xdr_buf *buf, struct page **pages,
u8 *iv, unsigned int ivsize)
{
u32 blocksize, nbytes, nblocks, cbcbytes;
struct encryptor_desc desc;
int err;
blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
nbytes = buf->len - offset;
nblocks = (nbytes + blocksize - 1) / blocksize;
cbcbytes = 0;
if (nblocks > 2)
cbcbytes = (nblocks - 2) * blocksize;
memset(desc.iv, 0, sizeof(desc.iv));
/* Handle block-sized chunks of plaintext with CBC. */
if (cbcbytes) {
SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
desc.pos = offset;
desc.fragno = 0;
desc.fraglen = 0;
desc.pages = pages;
desc.outbuf = buf;
desc.req = req;
skcipher_request_set_sync_tfm(req, cbc_tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
sg_init_table(desc.infrags, 4);
sg_init_table(desc.outfrags, 4);
err = xdr_process_buf(buf, offset, cbcbytes, encryptor, &desc);
skcipher_request_zero(req);
if (err)
return err;
}
/* Remaining plaintext is handled with CBC-CTS. */
err = gss_krb5_cts_crypt(cts_tfm, buf, offset + cbcbytes,
desc.iv, pages, 1);
if (err)
return err;
if (unlikely(iv))
memcpy(iv, desc.iv, ivsize);
return 0;
}
EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_encrypt);
/**
* krb5_cbc_cts_decrypt - decrypt in CBC mode with CTS
* @cts_tfm: CBC cipher with CTS
* @cbc_tfm: base CBC cipher
* @offset: starting byte offset for plaintext
* @buf: OUT: output buffer
*
* Return values:
* %0: decryption successful
* negative errno: decryption could not be completed
*/
VISIBLE_IF_KUNIT
int krb5_cbc_cts_decrypt(struct crypto_sync_skcipher *cts_tfm,
struct crypto_sync_skcipher *cbc_tfm,
u32 offset, struct xdr_buf *buf)
{
u32 blocksize, nblocks, cbcbytes;
struct decryptor_desc desc;
int err;
blocksize = crypto_sync_skcipher_blocksize(cts_tfm);
nblocks = (buf->len + blocksize - 1) / blocksize;
cbcbytes = 0;
if (nblocks > 2)
cbcbytes = (nblocks - 2) * blocksize;
memset(desc.iv, 0, sizeof(desc.iv));
/* Handle block-sized chunks of plaintext with CBC. */
if (cbcbytes) {
SYNC_SKCIPHER_REQUEST_ON_STACK(req, cbc_tfm);
desc.fragno = 0;
desc.fraglen = 0;
desc.req = req;
skcipher_request_set_sync_tfm(req, cbc_tfm);
skcipher_request_set_callback(req, 0, NULL, NULL);
sg_init_table(desc.frags, 4);
err = xdr_process_buf(buf, 0, cbcbytes, decryptor, &desc);
skcipher_request_zero(req);
if (err)
return err;
}
/* Remaining plaintext is handled with CBC-CTS. */
return gss_krb5_cts_crypt(cts_tfm, buf, cbcbytes, desc.iv, NULL, 0);
}
EXPORT_SYMBOL_IF_KUNIT(krb5_cbc_cts_decrypt);
u32
gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
struct xdr_buf *buf, struct page **pages)
{
u32 err;
struct xdr_netobj hmac;
u8 *ecptr;
struct crypto_sync_skcipher *cipher, *aux_cipher;
struct crypto_ahash *ahash;
struct page **save_pages;
unsigned int conflen;
if (kctx->initiate) {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
ahash = kctx->initiator_integ;
} else {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
ahash = kctx->acceptor_integ;
}
conflen = crypto_sync_skcipher_blocksize(cipher);
/* hide the gss token header and insert the confounder */
offset += GSS_KRB5_TOK_HDR_LEN;
if (xdr_extend_head(buf, offset, conflen))
return GSS_S_FAILURE;
krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
offset -= GSS_KRB5_TOK_HDR_LEN;
if (buf->tail[0].iov_base != NULL) {
ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
} else {
buf->tail[0].iov_base = buf->head[0].iov_base
+ buf->head[0].iov_len;
buf->tail[0].iov_len = 0;
ecptr = buf->tail[0].iov_base;
}
/* copy plaintext gss token header after filler (if any) */
memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
buf->len += GSS_KRB5_TOK_HDR_LEN;
hmac.len = kctx->gk5e->cksumlength;
hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
/*
* When we are called, pages points to the real page cache
* data -- which we can't go and encrypt! buf->pages points
* to scratch pages which we are going to send off to the
* client/server. Swap in the plaintext pages to calculate
* the hmac.
*/
save_pages = buf->pages;
buf->pages = pages;
err = gss_krb5_checksum(ahash, NULL, 0, buf,
offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
buf->pages = save_pages;
if (err)
return GSS_S_FAILURE;
err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
offset + GSS_KRB5_TOK_HDR_LEN,
buf, pages, NULL, 0);
if (err)
return GSS_S_FAILURE;
/* Now update buf to account for HMAC */
buf->tail[0].iov_len += kctx->gk5e->cksumlength;
buf->len += kctx->gk5e->cksumlength;
return GSS_S_COMPLETE;
}
u32
gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
{
struct crypto_sync_skcipher *cipher, *aux_cipher;
struct crypto_ahash *ahash;
struct xdr_netobj our_hmac_obj;
u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
struct xdr_buf subbuf;
u32 ret = 0;
if (kctx->initiate) {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
ahash = kctx->acceptor_integ;
} else {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
ahash = kctx->initiator_integ;
}
/* create a segment skipping the header and leaving out the checksum */
xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
(len - offset - GSS_KRB5_TOK_HDR_LEN -
kctx->gk5e->cksumlength));
ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
if (ret)
goto out_err;
our_hmac_obj.len = kctx->gk5e->cksumlength;
our_hmac_obj.data = our_hmac;
ret = gss_krb5_checksum(ahash, NULL, 0, &subbuf, 0, &our_hmac_obj);
if (ret)
goto out_err;
/* Get the packet's hmac value */
ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
pkt_hmac, kctx->gk5e->cksumlength);
if (ret)
goto out_err;
if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
ret = GSS_S_BAD_SIG;
goto out_err;
}
*headskip = crypto_sync_skcipher_blocksize(cipher);
*tailskip = kctx->gk5e->cksumlength;
out_err:
if (ret && ret != GSS_S_BAD_SIG)
ret = GSS_S_FAILURE;
return ret;
}
/**
* krb5_etm_checksum - Compute a MAC for a GSS Wrap token
* @cipher: an initialized cipher transform
* @tfm: an initialized hash transform
* @body: xdr_buf containing an RPC message (body.len is the message length)
* @body_offset: byte offset into @body to start checksumming
* @cksumout: OUT: a buffer to be filled in with the computed HMAC
*
* Usually expressed as H = HMAC(K, IV | ciphertext)[1..h] .
*
* Caller provides the truncation length of the output token (h) in
* cksumout.len.
*
* Return values:
* %GSS_S_COMPLETE: Digest computed, @cksumout filled in
* %GSS_S_FAILURE: Call failed
*/
VISIBLE_IF_KUNIT
u32 krb5_etm_checksum(struct crypto_sync_skcipher *cipher,
struct crypto_ahash *tfm, const struct xdr_buf *body,
int body_offset, struct xdr_netobj *cksumout)
{
unsigned int ivsize = crypto_sync_skcipher_ivsize(cipher);
struct ahash_request *req;
struct scatterlist sg[1];
u8 *iv, *checksumdata;
int err = -ENOMEM;
checksumdata = kmalloc(crypto_ahash_digestsize(tfm), GFP_KERNEL);
if (!checksumdata)
return GSS_S_FAILURE;
/* For RPCSEC, the "initial cipher state" is always all zeroes. */
iv = kzalloc(ivsize, GFP_KERNEL);
if (!iv)
goto out_free_mem;
req = ahash_request_alloc(tfm, GFP_KERNEL);
if (!req)
goto out_free_mem;
ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
err = crypto_ahash_init(req);
if (err)
goto out_free_ahash;
sg_init_one(sg, iv, ivsize);
ahash_request_set_crypt(req, sg, NULL, ivsize);
err = crypto_ahash_update(req);
if (err)
goto out_free_ahash;
err = xdr_process_buf(body, body_offset, body->len - body_offset,
checksummer, req);
if (err)
goto out_free_ahash;
ahash_request_set_crypt(req, NULL, checksumdata, 0);
err = crypto_ahash_final(req);
if (err)
goto out_free_ahash;
memcpy(cksumout->data, checksumdata, cksumout->len);
out_free_ahash:
ahash_request_free(req);
out_free_mem:
kfree(iv);
kfree_sensitive(checksumdata);
return err ? GSS_S_FAILURE : GSS_S_COMPLETE;
}
EXPORT_SYMBOL_IF_KUNIT(krb5_etm_checksum);
/**
* krb5_etm_encrypt - Encrypt using the RFC 8009 rules
* @kctx: Kerberos context
* @offset: starting offset of the payload, in bytes
* @buf: OUT: send buffer to contain the encrypted payload
* @pages: plaintext payload
*
* The main difference with aes_encrypt is that "The HMAC is
* calculated over the cipher state concatenated with the AES
* output, instead of being calculated over the confounder and
* plaintext. This allows the message receiver to verify the
* integrity of the message before decrypting the message."
*
* RFC 8009 Section 5:
*
* encryption function: as follows, where E() is AES encryption in
* CBC-CS3 mode, and h is the size of truncated HMAC (128 bits or
* 192 bits as described above).
*
* N = random value of length 128 bits (the AES block size)
* IV = cipher state
* C = E(Ke, N | plaintext, IV)
* H = HMAC(Ki, IV | C)
* ciphertext = C | H[1..h]
*
* This encryption formula provides AEAD EtM with key separation.
*
* Return values:
* %GSS_S_COMPLETE: Encryption successful
* %GSS_S_FAILURE: Encryption failed
*/
u32
krb5_etm_encrypt(struct krb5_ctx *kctx, u32 offset,
struct xdr_buf *buf, struct page **pages)
{
struct crypto_sync_skcipher *cipher, *aux_cipher;
struct crypto_ahash *ahash;
struct xdr_netobj hmac;
unsigned int conflen;
u8 *ecptr;
u32 err;
if (kctx->initiate) {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
ahash = kctx->initiator_integ;
} else {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
ahash = kctx->acceptor_integ;
}
conflen = crypto_sync_skcipher_blocksize(cipher);
offset += GSS_KRB5_TOK_HDR_LEN;
if (xdr_extend_head(buf, offset, conflen))
return GSS_S_FAILURE;
krb5_make_confounder(buf->head[0].iov_base + offset, conflen);
offset -= GSS_KRB5_TOK_HDR_LEN;
if (buf->tail[0].iov_base) {
ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
} else {
buf->tail[0].iov_base = buf->head[0].iov_base
+ buf->head[0].iov_len;
buf->tail[0].iov_len = 0;
ecptr = buf->tail[0].iov_base;
}
memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
buf->len += GSS_KRB5_TOK_HDR_LEN;
err = krb5_cbc_cts_encrypt(cipher, aux_cipher,
offset + GSS_KRB5_TOK_HDR_LEN,
buf, pages, NULL, 0);
if (err)
return GSS_S_FAILURE;
hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
hmac.len = kctx->gk5e->cksumlength;
err = krb5_etm_checksum(cipher, ahash,
buf, offset + GSS_KRB5_TOK_HDR_LEN, &hmac);
if (err)
goto out_err;
buf->tail[0].iov_len += kctx->gk5e->cksumlength;
buf->len += kctx->gk5e->cksumlength;
return GSS_S_COMPLETE;
out_err:
return GSS_S_FAILURE;
}
/**
* krb5_etm_decrypt - Decrypt using the RFC 8009 rules
* @kctx: Kerberos context
* @offset: starting offset of the ciphertext, in bytes
* @len:
* @buf:
* @headskip: OUT: the enctype's confounder length, in octets
* @tailskip: OUT: the enctype's HMAC length, in octets
*
* RFC 8009 Section 5:
*
* decryption function: as follows, where D() is AES decryption in
* CBC-CS3 mode, and h is the size of truncated HMAC.
*
* (C, H) = ciphertext
* (Note: H is the last h bits of the ciphertext.)
* IV = cipher state
* if H != HMAC(Ki, IV | C)[1..h]
* stop, report error
* (N, P) = D(Ke, C, IV)
*
* Return values:
* %GSS_S_COMPLETE: Decryption successful
* %GSS_S_BAD_SIG: computed HMAC != received HMAC
* %GSS_S_FAILURE: Decryption failed
*/
u32
krb5_etm_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len,
struct xdr_buf *buf, u32 *headskip, u32 *tailskip)
{
struct crypto_sync_skcipher *cipher, *aux_cipher;
u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
struct xdr_netobj our_hmac_obj;
struct crypto_ahash *ahash;
struct xdr_buf subbuf;
u32 ret = 0;
if (kctx->initiate) {
cipher = kctx->acceptor_enc;
aux_cipher = kctx->acceptor_enc_aux;
ahash = kctx->acceptor_integ;
} else {
cipher = kctx->initiator_enc;
aux_cipher = kctx->initiator_enc_aux;
ahash = kctx->initiator_integ;
}
/* Extract the ciphertext into @subbuf. */
xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
(len - offset - GSS_KRB5_TOK_HDR_LEN -
kctx->gk5e->cksumlength));
our_hmac_obj.data = our_hmac;
our_hmac_obj.len = kctx->gk5e->cksumlength;
ret = krb5_etm_checksum(cipher, ahash, &subbuf, 0, &our_hmac_obj);
if (ret)
goto out_err;
ret = read_bytes_from_xdr_buf(buf, len - kctx->gk5e->cksumlength,
pkt_hmac, kctx->gk5e->cksumlength);
if (ret)
goto out_err;
if (crypto_memneq(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
ret = GSS_S_BAD_SIG;
goto out_err;
}
ret = krb5_cbc_cts_decrypt(cipher, aux_cipher, 0, &subbuf);
if (ret) {
ret = GSS_S_FAILURE;
goto out_err;
}
*headskip = crypto_sync_skcipher_blocksize(cipher);
*tailskip = kctx->gk5e->cksumlength;
return GSS_S_COMPLETE;
out_err:
if (ret != GSS_S_BAD_SIG)
ret = GSS_S_FAILURE;
return ret;
}
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