b3f9b92a6e
From: Matt Domsch <Matt_Domsch@dell.com> The patch below implements the Microsoft Point-to-Point Encryption method as a PPP compressor/decompressor. This is necessary for Linux clients and servers to interoperate with Microsoft Point-to-Point Tunneling Protocol (PPTP) servers (either Microsoft PPTP servers or the poptop project) which use MPPE to encrypt data when creating a VPN. This patch differs from the kernel_ppp_mppe DKMS pacakge at pptpclient.sourceforge.net by utilizing the kernel crypto routines rather than providing its own SHA1 and arcfour implementations. Minor changes to ppp_generic.c try to prevent a link from disabling compression (in our case, the encryption) after it has started using compression (encryption). Feedback to <pptpclient-devel@lists.sourceforge.net> please. Signed-off-by: Matt Domsch <Matt_Domsch@dell.com> Cc: James Cameron <james.cameron@hp.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
87 lines
4 KiB
C
87 lines
4 KiB
C
#define MPPE_PAD 4 /* MPPE growth per frame */
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#define MPPE_MAX_KEY_LEN 16 /* largest key length (128-bit) */
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/* option bits for ccp_options.mppe */
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#define MPPE_OPT_40 0x01 /* 40 bit */
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#define MPPE_OPT_128 0x02 /* 128 bit */
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#define MPPE_OPT_STATEFUL 0x04 /* stateful mode */
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/* unsupported opts */
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#define MPPE_OPT_56 0x08 /* 56 bit */
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#define MPPE_OPT_MPPC 0x10 /* MPPC compression */
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#define MPPE_OPT_D 0x20 /* Unknown */
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#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
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#define MPPE_OPT_UNKNOWN 0x40 /* Bits !defined in RFC 3078 were set */
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/*
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* This is not nice ... the alternative is a bitfield struct though.
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* And unfortunately, we cannot share the same bits for the option
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* names above since C and H are the same bit. We could do a u_int32
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* but then we have to do a htonl() all the time and/or we still need
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* to know which octet is which.
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*/
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#define MPPE_C_BIT 0x01 /* MPPC */
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#define MPPE_D_BIT 0x10 /* Obsolete, usage unknown */
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#define MPPE_L_BIT 0x20 /* 40-bit */
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#define MPPE_S_BIT 0x40 /* 128-bit */
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#define MPPE_M_BIT 0x80 /* 56-bit, not supported */
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#define MPPE_H_BIT 0x01 /* Stateless (in a different byte) */
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/* Does not include H bit; used for least significant octet only. */
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#define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
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/* Build a CI from mppe opts (see RFC 3078) */
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#define MPPE_OPTS_TO_CI(opts, ci) \
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do { \
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u_char *ptr = ci; /* u_char[4] */ \
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\
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/* H bit */ \
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if (opts & MPPE_OPT_STATEFUL) \
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*ptr++ = 0x0; \
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else \
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*ptr++ = MPPE_H_BIT; \
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*ptr++ = 0; \
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*ptr++ = 0; \
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\
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/* S,L bits */ \
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*ptr = 0; \
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if (opts & MPPE_OPT_128) \
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*ptr |= MPPE_S_BIT; \
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if (opts & MPPE_OPT_40) \
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*ptr |= MPPE_L_BIT; \
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/* M,D,C bits not supported */ \
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} while (/* CONSTCOND */ 0)
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/* The reverse of the above */
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#define MPPE_CI_TO_OPTS(ci, opts) \
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do { \
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u_char *ptr = ci; /* u_char[4] */ \
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\
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opts = 0; \
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\
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/* H bit */ \
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if (!(ptr[0] & MPPE_H_BIT)) \
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opts |= MPPE_OPT_STATEFUL; \
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\
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/* S,L bits */ \
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if (ptr[3] & MPPE_S_BIT) \
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opts |= MPPE_OPT_128; \
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if (ptr[3] & MPPE_L_BIT) \
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opts |= MPPE_OPT_40; \
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\
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/* M,D,C bits */ \
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if (ptr[3] & MPPE_M_BIT) \
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opts |= MPPE_OPT_56; \
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if (ptr[3] & MPPE_D_BIT) \
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opts |= MPPE_OPT_D; \
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if (ptr[3] & MPPE_C_BIT) \
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opts |= MPPE_OPT_MPPC; \
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\
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/* Other bits */ \
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if (ptr[0] & ~MPPE_H_BIT) \
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opts |= MPPE_OPT_UNKNOWN; \
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if (ptr[1] || ptr[2]) \
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opts |= MPPE_OPT_UNKNOWN; \
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if (ptr[3] & ~MPPE_ALL_BITS) \
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opts |= MPPE_OPT_UNKNOWN; \
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} while (/* CONSTCOND */ 0)
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