/*
* COPYRIGHT (c) 2008
* The Regents of the University of Michigan
* ALL RIGHTS RESERVED
*
* Permission is granted to use, copy, create derivative works
* and redistribute this software and such derivative works
* for any purpose, so long as the name of The University of
* Michigan is not used in any advertising or publicity
* pertaining to the use of distribution of this software
* without specific, written prior authorization. If the
* above copyright notice or any other identification of the
* University of Michigan is included in any copy of any
* portion of this software, then the disclaimer below must
* also be included.
*
* THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
* FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
* PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
* MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
* WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
* REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
* FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
* CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
* OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
* IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGES.
*/
#include <crypto/skcipher.h>
#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/pagemap.h>
#include "gss_krb5_internal.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
/*
* We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need
* to do more than that, we shift repeatedly. Kevin Coffman reports
* seeing 28 bytes as the value used by Microsoft clients and servers
* with AES, so this constant is chosen to allow handling 28 in one pass
* without using too much stack space.
*
* If that proves to a problem perhaps we could use a more clever
* algorithm.
*/
#define LOCAL_BUF_LEN 32u
static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
{
char head[LOCAL_BUF_LEN];
char tmp[LOCAL_BUF_LEN];
unsigned int this_len, i;
BUG_ON(shift > LOCAL_BUF_LEN);
read_bytes_from_xdr_buf(buf, 0, head, shift);
for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
write_bytes_to_xdr_buf(buf, i, tmp, this_len);
}
write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
}
static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
{
int shifted = 0;
int this_shift;
shift %= buf->len;
while (shifted < shift) {
this_shift = min(shift - shifted, LOCAL_BUF_LEN);
rotate_buf_a_little(buf, this_shift);
shifted += this_shift;
}
}
static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
{
struct xdr_buf subbuf;
xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
_rotate_left(&subbuf, shift);
}
u32
gss_krb5_wrap_v2(struct krb5_ctx *kctx, int offset,
struct xdr_buf *buf, struct page **pages)
{
u8 *ptr;
time64_t now;
u8 flags = 0x00;
__be16 *be16ptr;
__be64 *be64ptr;
u32 err;
dprintk("RPC: %s\n", __func__);
/* make room for gss token header */
if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
return GSS_S_FAILURE;
/* construct gss token header */
ptr = buf->head[0].iov_base + offset;
*ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
*ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
/* We always do confidentiality in wrap tokens */
flags |= KG2_TOKEN_FLAG_SEALED;
*ptr++ = flags;
*ptr++ = 0xff;
be16ptr = (__be16 *)ptr;
*be16ptr++ = 0;
/* "inner" token header always uses 0 for RRC */
*be16ptr++ = 0;
be64ptr = (__be64 *)be16ptr;
*be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
err = (*kctx->gk5e->encrypt)(kctx, offset, buf, pages);
if (err)
return err;
now = ktime_get_real_seconds();
return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
}
u32
gss_krb5_unwrap_v2(struct krb5_ctx *kctx, int offset, int len,
struct xdr_buf *buf, unsigned int *slack,
unsigned int *align)
{
time64_t now;
u8 *ptr;
u8 flags = 0x00;
u16 ec, rrc;
int err;
u32 headskip, tailskip;
u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
unsigned int movelen;
dprintk("RPC: %s\n", __func__);
ptr = buf->head[0].iov_base + offset;
if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
return GSS_S_DEFECTIVE_TOKEN;
flags = ptr[2];
if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
(kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
return GSS_S_BAD_SIG;
if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
dprintk("%s: token missing expected sealed flag\n", __func__);
return GSS_S_DEFECTIVE_TOKEN;
}
if (ptr[3] != 0xff)
return GSS_S_DEFECTIVE_TOKEN;
ec = be16_to_cpup((__be16 *)(ptr + 4));
rrc = be16_to_cpup((__be16 *)(ptr + 6));
/*
* NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
* doesn't want it checked; see page 6 of rfc 2203.
*/
if (rrc != 0)
rotate_left(offset + 16, buf, rrc);
err = (*kctx->gk5e->decrypt)(kctx, offset, len, buf,
&headskip, &tailskip);
if (err)
return GSS_S_FAILURE;
/*
* Retrieve the decrypted gss token header and verify
* it against the original
*/
err = read_bytes_from_xdr_buf(buf,
len - GSS_KRB5_TOK_HDR_LEN - tailskip,
decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
if (err) {
dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
return GSS_S_FAILURE;
}
if (memcmp(ptr, decrypted_hdr, 6)
|| memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
return GSS_S_FAILURE;
}
/* do sequencing checks */
/* it got through unscathed. Make sure the context is unexpired */
now = ktime_get_real_seconds();
if (now > kctx->endtime)
return GSS_S_CONTEXT_EXPIRED;
/*
* Move the head data back to the right position in xdr_buf.
* We ignore any "ec" data since it might be in the head or
* the tail, and we really don't need to deal with it.
* Note that buf->head[0].iov_len may indicate the available
* head buffer space rather than that actually occupied.
*/
movelen = min_t(unsigned int, buf->head[0].iov_len, len);
movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
buf->head[0].iov_len);
memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);
/* Trim off the trailing "extra count" and checksum blob */
xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
*align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
*slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
return GSS_S_COMPLETE;
}
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