infinite loop in esp6_ctlinput()?

[JINMEI Tatuya / 神明達哉]

At Tue, 28 Aug 2007 10:15:31 +0800,
blue <susan.lan at zyxel.com.tw> wrote:

> When receiving a "packet too big" ICMP error message, FreeBSD will call 
> the ctlinput() function of the upper protocol. If the preceding packet 
> is an ESP  IPv6 packet, then FreeBSD will call esp6_ctlinput(). In 
> esp6_ctlinput(), pfctlinput2() will be executed to traverse all possible 
> upper protocols, and call their registered ctlinput() function. However, 
> that would call esp6_ctlinput() again since ESP is one of the upper 
> protocols! Then an infinite loop occurs!!

From a quick look at the code, there's a slight difference between the
IPSEC (netinet6/esp_input.c) and FAST_IPSEC (netipsec/ipsec_input.c)
implementations.  I suspect the loop doesn't occur at least for the
esp_input.c version.  Did you actually see the loop for both, or are
you guessing from the code?

> After comparing both IPSEC and FAST_IPSEC, the operations are exactly 
> the same. Is it a bug?

If it actually causes an infinite loop, it's a bug, of course.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					jinmei at isl.rdc.toshiba.co.jp