![Paul Burton](/assets/img/avatar_default.png)
The seq_send & seq_send64 fields in struct krb5_ctx are used as atomically incrementing counters. This is implemented using cmpxchg() & cmpxchg64() to implement what amount to custom versions of atomic_fetch_inc() & atomic64_fetch_inc(). Besides the duplication, using cmpxchg64() has another major drawback in that some 32 bit architectures don't provide it. As such commit571ed1fd23
("SUNRPC: Replace krb5_seq_lock with a lockless scheme") resulted in build failures for some architectures. Change seq_send to be an atomic_t and seq_send64 to be an atomic64_t, then use atomic(64)_* functions to manipulate the values. The atomic64_t type & associated functions are provided even on architectures which lack real 64 bit atomic memory access via CONFIG_GENERIC_ATOMIC64 which uses spinlocks to serialize access. This fixes the build failures for architectures lacking cmpxchg64(). A potential alternative that was raised would be to provide cmpxchg64() on the 32 bit architectures that currently lack it, using spinlocks. However this would provide a version of cmpxchg64() with semantics a little different to the implementations on architectures with real 64 bit atomics - the spinlock-based implementation would only work if all access to the memory used with cmpxchg64() is *always* performed using cmpxchg64(). That is not currently a requirement for users of cmpxchg64(), and making it one seems questionable. As such avoiding cmpxchg64() outside of architecture-specific code seems best, particularly in cases where atomic64_t seems like a better fit anyway. The CONFIG_GENERIC_ATOMIC64 implementation of atomic64_* functions will use spinlocks & so faces the same issue, but with the key difference that the memory backing an atomic64_t ought to always be accessed via the atomic64_* functions anyway making the issue moot. Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes:571ed1fd23
("SUNRPC: Replace krb5_seq_lock with a lockless scheme") Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Cc: J. Bruce Fields <bfields@fieldses.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: linux-nfs@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
224 lines
6.5 KiB
C
224 lines
6.5 KiB
C
/*
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* linux/net/sunrpc/gss_krb5_seal.c
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*
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* Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5seal.c
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*
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* Copyright (c) 2000-2008 The Regents of the University of Michigan.
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* All rights reserved.
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*
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* Andy Adamson <andros@umich.edu>
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* J. Bruce Fields <bfields@umich.edu>
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*/
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/*
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* Copyright 1993 by OpenVision Technologies, Inc.
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*
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* Permission to use, copy, modify, distribute, and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appears in all copies and
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* that both that copyright notice and this permission notice appear in
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* supporting documentation, and that the name of OpenVision not be used
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* in advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. OpenVision makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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* OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
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* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Copyright (C) 1998 by the FundsXpress, INC.
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*
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* All rights reserved.
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*
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* Export of this software from the United States of America may require
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* a specific license from the United States Government. It is the
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* responsibility of any person or organization contemplating export to
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* obtain such a license before exporting.
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*
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* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
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* distribute this software and its documentation for any purpose and
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* without fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright notice and
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* this permission notice appear in supporting documentation, and that
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* the name of FundsXpress. not be used in advertising or publicity pertaining
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* to distribution of the software without specific, written prior
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* permission. FundsXpress makes no representations about the suitability of
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* this software for any purpose. It is provided "as is" without express
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* or implied warranty.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <linux/types.h>
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#include <linux/jiffies.h>
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#include <linux/sunrpc/gss_krb5.h>
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#include <linux/random.h>
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#include <linux/crypto.h>
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#include <linux/atomic.h>
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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# define RPCDBG_FACILITY RPCDBG_AUTH
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#endif
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static void *
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setup_token(struct krb5_ctx *ctx, struct xdr_netobj *token)
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{
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u16 *ptr;
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void *krb5_hdr;
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int body_size = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
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token->len = g_token_size(&ctx->mech_used, body_size);
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ptr = (u16 *)token->data;
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g_make_token_header(&ctx->mech_used, body_size, (unsigned char **)&ptr);
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/* ptr now at start of header described in rfc 1964, section 1.2.1: */
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krb5_hdr = ptr;
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*ptr++ = KG_TOK_MIC_MSG;
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/*
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* signalg is stored as if it were converted from LE to host endian, even
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* though it's an opaque pair of bytes according to the RFC.
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*/
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*ptr++ = (__force u16)cpu_to_le16(ctx->gk5e->signalg);
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*ptr++ = SEAL_ALG_NONE;
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*ptr = 0xffff;
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return krb5_hdr;
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}
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static void *
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setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
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{
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u16 *ptr;
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void *krb5_hdr;
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u8 *p, flags = 0x00;
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if ((ctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
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flags |= 0x01;
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if (ctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY)
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flags |= 0x04;
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/* Per rfc 4121, sec 4.2.6.1, there is no header,
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* just start the token */
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krb5_hdr = ptr = (u16 *)token->data;
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*ptr++ = KG2_TOK_MIC;
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p = (u8 *)ptr;
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*p++ = flags;
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*p++ = 0xff;
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ptr = (u16 *)p;
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*ptr++ = 0xffff;
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*ptr = 0xffff;
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token->len = GSS_KRB5_TOK_HDR_LEN + ctx->gk5e->cksumlength;
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return krb5_hdr;
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}
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static u32
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gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
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struct xdr_netobj *token)
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{
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char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
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struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
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.data = cksumdata};
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void *ptr;
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s32 now;
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u32 seq_send;
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u8 *cksumkey;
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dprintk("RPC: %s\n", __func__);
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BUG_ON(ctx == NULL);
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now = get_seconds();
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ptr = setup_token(ctx, token);
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if (ctx->gk5e->keyed_cksum)
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cksumkey = ctx->cksum;
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else
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cksumkey = NULL;
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if (make_checksum(ctx, ptr, 8, text, 0, cksumkey,
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KG_USAGE_SIGN, &md5cksum))
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return GSS_S_FAILURE;
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memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
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seq_send = atomic_fetch_inc(&ctx->seq_send);
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if (krb5_make_seq_num(ctx, ctx->seq, ctx->initiate ? 0 : 0xff,
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seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))
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return GSS_S_FAILURE;
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return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
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}
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static u32
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gss_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
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struct xdr_netobj *token)
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{
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char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
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struct xdr_netobj cksumobj = { .len = sizeof(cksumdata),
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.data = cksumdata};
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void *krb5_hdr;
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s32 now;
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u8 *cksumkey;
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unsigned int cksum_usage;
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__be64 seq_send_be64;
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dprintk("RPC: %s\n", __func__);
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krb5_hdr = setup_token_v2(ctx, token);
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/* Set up the sequence number. Now 64-bits in clear
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* text and w/o direction indicator */
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seq_send_be64 = cpu_to_be64(atomic64_fetch_inc(&ctx->seq_send64));
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memcpy(krb5_hdr + 8, (char *) &seq_send_be64, 8);
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if (ctx->initiate) {
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cksumkey = ctx->initiator_sign;
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cksum_usage = KG_USAGE_INITIATOR_SIGN;
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} else {
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cksumkey = ctx->acceptor_sign;
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cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
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}
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if (make_checksum_v2(ctx, krb5_hdr, GSS_KRB5_TOK_HDR_LEN,
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text, 0, cksumkey, cksum_usage, &cksumobj))
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return GSS_S_FAILURE;
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memcpy(krb5_hdr + GSS_KRB5_TOK_HDR_LEN, cksumobj.data, cksumobj.len);
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now = get_seconds();
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return (ctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
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}
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u32
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gss_get_mic_kerberos(struct gss_ctx *gss_ctx, struct xdr_buf *text,
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struct xdr_netobj *token)
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{
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struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
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switch (ctx->enctype) {
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default:
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BUG();
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case ENCTYPE_DES_CBC_RAW:
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case ENCTYPE_DES3_CBC_RAW:
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case ENCTYPE_ARCFOUR_HMAC:
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return gss_get_mic_v1(ctx, text, token);
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case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
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case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
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return gss_get_mic_v2(ctx, text, token);
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}
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}
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