Last time I talked to Paul on MPPE he didn't like those hacks in
the ppp core.
> --- 1.45/drivers/net/ppp_generic.c 2004-04-09 18:21:06 -05:00
> +++ edited/drivers/net/ppp_generic.c 2004-06-18 09:47:10 -05:00
> @@ -1066,8 +1066,15 @@
> /* try to do packet compression */
> if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
> && proto != PPP_LCP && proto != PPP_CCP) {
> - new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
> - GFP_ATOMIC);
> + int new_skb_size = ppp->dev->mtu + ppp->dev->hard_header_len;
> + int compressor_skb_size = ppp->dev->mtu + PPP_HDRLEN;
> +
> + if (ppp->xcomp->compress_proto == CI_MPPE) {
> + /* CCP [must have] reduced MTU by MPPE_PAD. */
> + new_skb_size += MPPE_PAD;
> + compressor_skb_size += MPPE_PAD;
> + }
> + new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
> if (new_skb == 0) {
> printk(KERN_ERR "PPP: no memory (comp pkt)\n");
> goto drop;
> @@ -1079,15 +1086,27 @@
> /* compressor still expects A/C bytes in hdr */
> len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
> new_skb->data, skb->len + 2,
> - ppp->dev->mtu + PPP_HDRLEN);
> + compressor_skb_size);
> if (len > 0 && (ppp->flags & SC_CCP_UP)) {
> kfree_skb(skb);
> skb = new_skb;
> skb_put(skb, len);
> skb_pull(skb, 2); /* pull off A/C bytes */
> - } else {
> + } else if (len == 0) {
> /* didn't compress, or CCP not up yet */
> kfree_skb(new_skb);
> + } else {
> + /*
> + * (len < 0)
> + * MPPE requires that we do not send unencrypted
> + * frames. The compressor will return -1 if we
> + * should drop the frame. We cannot simply test
> + * the compress_proto because MPPE and MPPC share
> + * the same number.
> + */
> + printk(KERN_ERR "ppp: compressor dropped pkt\n");
> + kfree_skb(new_skb);
> + goto drop;
> }
> }
>
> @@ -1596,7 +1615,7 @@
> goto err;
>
> if (proto == PPP_COMP) {
> - ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
> + ns = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
> if (ns == 0) {
> printk(KERN_ERR "ppp_decompress_frame: no memory\n");
> goto err;
> ===== include/linux/ppp-comp.h 1.4 vs edited =====
> --- 1.4/include/linux/ppp-comp.h 2003-08-07 18:57:19 -05:00
> +++ edited/include/linux/ppp-comp.h 2004-06-18 09:46:32 -05:00
> @@ -191,6 +191,100 @@
> #define DEFLATE_CHK_SEQUENCE 0
>
> /*
> + * Definitions for MPPE.
> + */
> +
> +#define CI_MPPE 18 /* config option for MPPE */
> +#define CILEN_MPPE 6 /* length of config option */
> +
> +#define MPPE_PAD 8 /* 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)
> +
> +/*
> * Definitions for other, as yet unsupported, compression methods.
> */
>
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