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DEFINITIONS
This source file includes following definitions.
- gss_krb5_padding
- gss_krb5_add_padding
- gss_krb5_remove_padding
- make_confounder
- gss_wrap_kerberos
- gss_unwrap_kerberos
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/random.h>
#include <linux/pagemap.h>
#include <linux/crypto.h>
#ifdef RPC_DEBUG
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
static inline int
gss_krb5_padding(int blocksize, int length)
{
/* Most of the code is block-size independent but currently we
* use only 8: */
BUG_ON(blocksize != 8);
return 8 - (length & 7);
}
static inline void
gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
{
int padding = gss_krb5_padding(blocksize, buf->len - offset);
char *p;
struct kvec *iov;
if (buf->page_len || buf->tail[0].iov_len)
iov = &buf->tail[0];
else
iov = &buf->head[0];
p = iov->iov_base + iov->iov_len;
iov->iov_len += padding;
buf->len += padding;
memset(p, padding, padding);
}
static inline int
gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
{
u8 *ptr;
u8 pad;
size_t len = buf->len;
if (len <= buf->head[0].iov_len) {
pad = *(u8 *)(buf->head[0].iov_base + len - 1);
if (pad > buf->head[0].iov_len)
return -EINVAL;
buf->head[0].iov_len -= pad;
goto out;
} else
len -= buf->head[0].iov_len;
if (len <= buf->page_len) {
unsigned int last = (buf->page_base + len - 1)
>>PAGE_CACHE_SHIFT;
unsigned int offset = (buf->page_base + len - 1)
& (PAGE_CACHE_SIZE - 1);
ptr = kmap_atomic(buf->pages[last], KM_USER0);
pad = *(ptr + offset);
kunmap_atomic(ptr, KM_USER0);
goto out;
} else
len -= buf->page_len;
BUG_ON(len > buf->tail[0].iov_len);
pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
out:
/* XXX: NOTE: we do not adjust the page lengths--they represent
* a range of data in the real filesystem page cache, and we need
* to know that range so the xdr code can properly place read data.
* However adjusting the head length, as we do above, is harmless.
* In the case of a request that fits into a single page, the server
* also uses length and head length together to determine the original
* start of the request to copy the request for deferal; so it's
* easier on the server if we adjust head and tail length in tandem.
* It's not really a problem that we don't fool with the page and
* tail lengths, though--at worst badly formed xdr might lead the
* server to attempt to parse the padding.
* XXX: Document all these weird requirements for gss mechanism
* wrap/unwrap functions. */
if (pad > blocksize)
return -EINVAL;
if (buf->len > pad)
buf->len -= pad;
else
return -EINVAL;
return 0;
}
static void
make_confounder(char *p, u32 conflen)
{
static u64 i = 0;
u64 *q = (u64 *)p;
/* rfc1964 claims this should be "random". But all that's really
* necessary is that it be unique. And not even that is necessary in
* our case since our "gssapi" implementation exists only to support
* rpcsec_gss, so we know that the only buffers we will ever encrypt
* already begin with a unique sequence number. Just to hedge my bets
* I'll make a half-hearted attempt at something unique, but ensuring
* uniqueness would mean worrying about atomicity and rollover, and I
* don't care enough. */
/* initialize to random value */
if (i == 0) {
i = random32();
i = (i << 32) | random32();
}
switch (conflen) {
case 16:
*q++ = i++;
/* fall through */
case 8:
*q++ = i++;
break;
default:
BUG();
}
}
/* Assumptions: the head and tail of inbuf are ours to play with.
* The pages, however, may be real pages in the page cache and we replace
* them with scratch pages from **pages before writing to them. */
/* XXX: obviously the above should be documentation of wrap interface,
* and shouldn't be in this kerberos-specific file. */
/* XXX factor out common code with seal/unseal. */
u32
gss_wrap_kerberos(struct gss_ctx *ctx, int offset,
struct xdr_buf *buf, struct page **pages)
{
struct krb5_ctx *kctx = ctx->internal_ctx_id;
char cksumdata[16];
struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
int blocksize = 0, plainlen;
unsigned char *ptr, *msg_start;
s32 now;
int headlen;
struct page **tmp_pages;
u32 seq_send;
dprintk("RPC: gss_wrap_kerberos\n");
now = get_seconds();
blocksize = crypto_blkcipher_blocksize(kctx->enc);
gss_krb5_add_padding(buf, offset, blocksize);
BUG_ON((buf->len - offset) % blocksize);
plainlen = blocksize + buf->len - offset;
headlen = g_token_size(&kctx->mech_used, 24 + plainlen) -
(buf->len - offset);
ptr = buf->head[0].iov_base + offset;
/* shift data to make room for header. */
/* XXX Would be cleverer to encrypt while copying. */
/* XXX bounds checking, slack, etc. */
memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset);
buf->head[0].iov_len += headlen;
buf->len += headlen;
BUG_ON((buf->len - offset - headlen) % blocksize);
g_make_token_header(&kctx->mech_used,
GSS_KRB5_TOK_HDR_LEN + 8 + plainlen, &ptr);
/* ptr now at header described in rfc 1964, section 1.2.1: */
ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
msg_start = ptr + 24;
*(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5);
memset(ptr + 4, 0xff, 4);
*(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES);
make_confounder(msg_start, blocksize);
/* XXXJBF: UGH!: */
tmp_pages = buf->pages;
buf->pages = pages;
if (make_checksum("md5", ptr, 8, buf,
offset + headlen - blocksize, &md5cksum))
return GSS_S_FAILURE;
buf->pages = tmp_pages;
if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
md5cksum.data, md5cksum.len))
return GSS_S_FAILURE;
memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);
spin_lock(&krb5_seq_lock);
seq_send = kctx->seq_send++;
spin_unlock(&krb5_seq_lock);
/* XXX would probably be more efficient to compute checksum
* and encrypt at the same time: */
if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff,
seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
return GSS_S_FAILURE;
if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
pages))
return GSS_S_FAILURE;
return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
}
u32
gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf)
{
struct krb5_ctx *kctx = ctx->internal_ctx_id;
int signalg;
int sealalg;
char cksumdata[16];
struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
s32 now;
int direction;
s32 seqnum;
unsigned char *ptr;
int bodysize;
void *data_start, *orig_start;
int data_len;
int blocksize;
dprintk("RPC: gss_unwrap_kerberos\n");
ptr = (u8 *)buf->head[0].iov_base + offset;
if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
buf->len - offset))
return GSS_S_DEFECTIVE_TOKEN;
if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
(ptr[1] != (KG_TOK_WRAP_MSG & 0xff)))
return GSS_S_DEFECTIVE_TOKEN;
/* XXX sanity-check bodysize?? */
/* get the sign and seal algorithms */
signalg = ptr[2] + (ptr[3] << 8);
if (signalg != SGN_ALG_DES_MAC_MD5)
return GSS_S_DEFECTIVE_TOKEN;
sealalg = ptr[4] + (ptr[5] << 8);
if (sealalg != SEAL_ALG_DES)
return GSS_S_DEFECTIVE_TOKEN;
if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
return GSS_S_DEFECTIVE_TOKEN;
if (gss_decrypt_xdr_buf(kctx->enc, buf,
ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base))
return GSS_S_DEFECTIVE_TOKEN;
if (make_checksum("md5", ptr, 8, buf,
ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base, &md5cksum))
return GSS_S_FAILURE;
if (krb5_encrypt(kctx->seq, NULL, md5cksum.data,
md5cksum.data, md5cksum.len))
return GSS_S_FAILURE;
if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8))
return GSS_S_BAD_SIG;
/* it got through unscathed. Make sure the context is unexpired */
now = get_seconds();
if (now > kctx->endtime)
return GSS_S_CONTEXT_EXPIRED;
/* do sequencing checks */
if (krb5_get_seq_num(kctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
&direction, &seqnum))
return GSS_S_BAD_SIG;
if ((kctx->initiate && direction != 0xff) ||
(!kctx->initiate && direction != 0))
return GSS_S_BAD_SIG;
/* Copy the data back to the right position. XXX: Would probably be
* better to copy and encrypt at the same time. */
blocksize = crypto_blkcipher_blocksize(kctx->enc);
data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + blocksize;
orig_start = buf->head[0].iov_base + offset;
data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
memmove(orig_start, data_start, data_len);
buf->head[0].iov_len -= (data_start - orig_start);
buf->len -= (data_start - orig_start);
if (gss_krb5_remove_padding(buf, blocksize))
return GSS_S_DEFECTIVE_TOKEN;
return GSS_S_COMPLETE;
}