mppe.h

00001 /*
00002  * mppe.h - Definitions for MPPE
00003  *
00004  * Copyright (c) 2008 Paul Mackerras. All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  *
00010  * 1. Redistributions of source code must retain the above copyright
00011  *    notice, this list of conditions and the following disclaimer.
00012  *
00013  * 2. Redistributions in binary form must reproduce the above copyright
00014  *    notice, this list of conditions and the following disclaimer in
00015  *    the documentation and/or other materials provided with the
00016  *    distribution.
00017  *
00018  * 3. The name(s) of the authors of this software must not be used to
00019  *    endorse or promote products derived from this software without
00020  *    prior written permission.
00021  *
00022  * 4. Redistributions of any form whatsoever must retain the following
00023  *    acknowledgment:
00024  *    "This product includes software developed by Paul Mackerras
00025  *     <paulus@samba.org>".
00026  *
00027  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
00028  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
00029  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
00030  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
00031  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
00032  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
00033  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
00034  */
00035 
00036 #include "ppp_opts.h"
00037 #if PPP_SUPPORT && MPPE_SUPPORT  /* don't build if not configured for use in ppp_opts.h */
00038 
00039 #ifndef MPPE_H
00040 #define MPPE_H
00041 
00042 #include "pppcrypt.h"
00043 
00044 #ifdef __cplusplus
00045 extern "C" {
00046 #endif
00047 
00048 #define MPPE_PAD        4   /* MPPE growth per frame */
00049 #define MPPE_MAX_KEY_LEN    16  /* largest key length (128-bit) */
00050 
00051 /* option bits for ccp_options.mppe */
00052 #define MPPE_OPT_40     0x01    /* 40 bit */
00053 #define MPPE_OPT_128        0x02    /* 128 bit */
00054 #define MPPE_OPT_STATEFUL   0x04    /* stateful mode */
00055 /* unsupported opts */
00056 #define MPPE_OPT_56     0x08    /* 56 bit */
00057 #define MPPE_OPT_MPPC       0x10    /* MPPC compression */
00058 #define MPPE_OPT_D      0x20    /* Unknown */
00059 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
00060 #define MPPE_OPT_UNKNOWN    0x40    /* Bits !defined in RFC 3078 were set */
00061 
00062 /*
00063  * This is not nice ... the alternative is a bitfield struct though.
00064  * And unfortunately, we cannot share the same bits for the option
00065  * names above since C and H are the same bit.  We could do a u_int32
00066  * but then we have to do a ppp_htonl() all the time and/or we still need
00067  * to know which octet is which.
00068  */
00069 #define MPPE_C_BIT      0x01    /* MPPC */
00070 #define MPPE_D_BIT      0x10    /* Obsolete, usage unknown */
00071 #define MPPE_L_BIT      0x20    /* 40-bit */
00072 #define MPPE_S_BIT      0x40    /* 128-bit */
00073 #define MPPE_M_BIT      0x80    /* 56-bit, not supported */
00074 #define MPPE_H_BIT      0x01    /* Stateless (in a different byte) */
00075 
00076 /* Does not include H bit; used for least significant octet only. */
00077 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
00078 
00079 /* Build a CI from mppe opts (see RFC 3078) */
00080 #define MPPE_OPTS_TO_CI(opts, ci)       \
00081     do {                    \
00082     u_char *ptr = ci; /* u_char[4] */   \
00083                         \
00084     /* H bit */             \
00085     if (opts & MPPE_OPT_STATEFUL)       \
00086         *ptr++ = 0x0;           \
00087     else                    \
00088         *ptr++ = MPPE_H_BIT;        \
00089     *ptr++ = 0;             \
00090     *ptr++ = 0;             \
00091                         \
00092     /* S,L bits */              \
00093     *ptr = 0;               \
00094     if (opts & MPPE_OPT_128)        \
00095         *ptr |= MPPE_S_BIT;         \
00096     if (opts & MPPE_OPT_40)         \
00097         *ptr |= MPPE_L_BIT;         \
00098     /* M,D,C bits not supported */      \
00099     } while (/* CONSTCOND */ 0)
00100 
00101 /* The reverse of the above */
00102 #define MPPE_CI_TO_OPTS(ci, opts)       \
00103     do {                    \
00104     const u_char *ptr = ci; /* u_char[4] */ \
00105                         \
00106     opts = 0;               \
00107                         \
00108     /* H bit */             \
00109     if (!(ptr[0] & MPPE_H_BIT))     \
00110         opts |= MPPE_OPT_STATEFUL;      \
00111                         \
00112     /* S,L bits */              \
00113     if (ptr[3] & MPPE_S_BIT)        \
00114         opts |= MPPE_OPT_128;       \
00115     if (ptr[3] & MPPE_L_BIT)        \
00116         opts |= MPPE_OPT_40;        \
00117                         \
00118     /* M,D,C bits */            \
00119     if (ptr[3] & MPPE_M_BIT)        \
00120         opts |= MPPE_OPT_56;        \
00121     if (ptr[3] & MPPE_D_BIT)        \
00122         opts |= MPPE_OPT_D;         \
00123     if (ptr[3] & MPPE_C_BIT)        \
00124         opts |= MPPE_OPT_MPPC;      \
00125                         \
00126     /* Other bits */            \
00127     if (ptr[0] & ~MPPE_H_BIT)       \
00128         opts |= MPPE_OPT_UNKNOWN;       \
00129     if (ptr[1] || ptr[2])           \
00130         opts |= MPPE_OPT_UNKNOWN;       \
00131     if (ptr[3] & ~MPPE_ALL_BITS)        \
00132         opts |= MPPE_OPT_UNKNOWN;       \
00133     } while (/* CONSTCOND */ 0)
00134 
00135 /* Shared MPPE padding between MSCHAP and MPPE */
00136 #define SHA1_PAD_SIZE 40
00137 
00138 static const u8_t mppe_sha1_pad1[SHA1_PAD_SIZE] = {
00139   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00140   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00141   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00142   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
00143 };
00144 static const u8_t mppe_sha1_pad2[SHA1_PAD_SIZE] = {
00145   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00146   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00147   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
00148   0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
00149 };
00150 
00151 /*
00152  * State for an MPPE (de)compressor.
00153  */
00154 typedef struct ppp_mppe_state {
00155     ppp_arc4_context arc4;
00156     u8_t master_key[MPPE_MAX_KEY_LEN];
00157     u8_t session_key[MPPE_MAX_KEY_LEN];
00158     u8_t keylen;                /* key length in bytes */
00159     /* NB: 128-bit == 16, 40-bit == 8!
00160      * If we want to support 56-bit, the unit has to change to bits
00161      */
00162     u8_t bits;                  /* MPPE control bits */
00163     u16_t ccount;               /* 12-bit coherency count (seqno)  */
00164     u16_t sanity_errors;        /* take down LCP if too many */
00165     unsigned int stateful  :1;  /* stateful mode flag */
00166     unsigned int discard   :1;  /* stateful mode packet loss flag */
00167 } ppp_mppe_state;
00168 
00169 void mppe_set_key(ppp_pcb *pcb, ppp_mppe_state *state, u8_t *key);
00170 void mppe_init(ppp_pcb *pcb, ppp_mppe_state *state, u8_t options);
00171 void mppe_comp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
00172 err_t mppe_compress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb, u16_t protocol);
00173 void mppe_decomp_reset(ppp_pcb *pcb, ppp_mppe_state *state);
00174 err_t mppe_decompress(ppp_pcb *pcb, ppp_mppe_state *state, struct pbuf **pb);
00175 
00176 #ifdef __cplusplus
00177 }
00178 #endif
00179 
00180 #endif /* MPPE_H */
00181 #endif /* PPP_SUPPORT && MPPE_SUPPORT */