[PPP]: add PPP MPPE encryption module
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>
diff --git a/drivers/net/ppp_mppe.h b/drivers/net/ppp_mppe.h
new file mode 100644
index 0000000..7a14e05
--- /dev/null
+++ b/drivers/net/ppp_mppe.h
@@ -0,0 +1,86 @@
+#define MPPE_PAD 4 /* MPPE growth per frame */
+#define MPPE_MAX_KEY_LEN 16 /* largest key length (128-bit) */
+
+/* option bits for ccp_options.mppe */
+#define MPPE_OPT_40 0x01 /* 40 bit */
+#define MPPE_OPT_128 0x02 /* 128 bit */
+#define MPPE_OPT_STATEFUL 0x04 /* stateful mode */
+/* unsupported opts */
+#define MPPE_OPT_56 0x08 /* 56 bit */
+#define MPPE_OPT_MPPC 0x10 /* MPPC compression */
+#define MPPE_OPT_D 0x20 /* Unknown */
+#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
+#define MPPE_OPT_UNKNOWN 0x40 /* Bits !defined in RFC 3078 were set */
+
+/*
+ * This is not nice ... the alternative is a bitfield struct though.
+ * And unfortunately, we cannot share the same bits for the option
+ * names above since C and H are the same bit. We could do a u_int32
+ * but then we have to do a htonl() all the time and/or we still need
+ * to know which octet is which.
+ */
+#define MPPE_C_BIT 0x01 /* MPPC */
+#define MPPE_D_BIT 0x10 /* Obsolete, usage unknown */
+#define MPPE_L_BIT 0x20 /* 40-bit */
+#define MPPE_S_BIT 0x40 /* 128-bit */
+#define MPPE_M_BIT 0x80 /* 56-bit, not supported */
+#define MPPE_H_BIT 0x01 /* Stateless (in a different byte) */
+
+/* Does not include H bit; used for least significant octet only. */
+#define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
+
+/* Build a CI from mppe opts (see RFC 3078) */
+#define MPPE_OPTS_TO_CI(opts, ci) \
+ do { \
+ u_char *ptr = ci; /* u_char[4] */ \
+ \
+ /* H bit */ \
+ if (opts & MPPE_OPT_STATEFUL) \
+ *ptr++ = 0x0; \
+ else \
+ *ptr++ = MPPE_H_BIT; \
+ *ptr++ = 0; \
+ *ptr++ = 0; \
+ \
+ /* S,L bits */ \
+ *ptr = 0; \
+ if (opts & MPPE_OPT_128) \
+ *ptr |= MPPE_S_BIT; \
+ if (opts & MPPE_OPT_40) \
+ *ptr |= MPPE_L_BIT; \
+ /* M,D,C bits not supported */ \
+ } while (/* CONSTCOND */ 0)
+
+/* The reverse of the above */
+#define MPPE_CI_TO_OPTS(ci, opts) \
+ do { \
+ u_char *ptr = ci; /* u_char[4] */ \
+ \
+ opts = 0; \
+ \
+ /* H bit */ \
+ if (!(ptr[0] & MPPE_H_BIT)) \
+ opts |= MPPE_OPT_STATEFUL; \
+ \
+ /* S,L bits */ \
+ if (ptr[3] & MPPE_S_BIT) \
+ opts |= MPPE_OPT_128; \
+ if (ptr[3] & MPPE_L_BIT) \
+ opts |= MPPE_OPT_40; \
+ \
+ /* M,D,C bits */ \
+ if (ptr[3] & MPPE_M_BIT) \
+ opts |= MPPE_OPT_56; \
+ if (ptr[3] & MPPE_D_BIT) \
+ opts |= MPPE_OPT_D; \
+ if (ptr[3] & MPPE_C_BIT) \
+ opts |= MPPE_OPT_MPPC; \
+ \
+ /* Other bits */ \
+ if (ptr[0] & ~MPPE_H_BIT) \
+ opts |= MPPE_OPT_UNKNOWN; \
+ if (ptr[1] || ptr[2]) \
+ opts |= MPPE_OPT_UNKNOWN; \
+ if (ptr[3] & ~MPPE_ALL_BITS) \
+ opts |= MPPE_OPT_UNKNOWN; \
+ } while (/* CONSTCOND */ 0)