Messages in this thread | | | Subject | Re: Issues during assigning addresses on point to point interfaces | From | Nicolas Dichtel <> | Date | Thu, 24 Jun 2021 14:57:41 +0200 |
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Le 24/06/2021 à 12:45, Marek Behún a écrit : > On Sun, 6 Jun 2021 17:10:08 +0200 > Pali Rohár <pali@kernel.org> wrote: > >> Hello! >> >> Seems that there is a bug during assigning IP addresses on point to >> point interfaces. >> >> Assigning just one local address works fine: >> >> ip address add fe80::6 dev ppp1 --> inet6 fe80::6/128 scope link >> >> Assigning both local and remote peer address also works fine: >> >> ip address add fe80::7 peer fe80::8 dev ppp1 ---> inet6 fe80::7 >> peer fe80::8/128 scope link >> >> But trying to assign just remote peer address does not work. Moreover >> "ip address" call does not fail, it returns zero but instead of >> setting remote peer address, it sets local address: >> >> ip address add peer fe80::5 dev ppp1 --> inet6 fe80::5/128 scope >> link >> > > Adding some other people to Cc in order to get their opinions. > > It seems this bug is there from the beginning, from commit > caeaba79009c2 ("ipv6: add support of peer address") > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=caeaba79009c2 > > Maybe some older user-space utilities use IFA_ADDRESS instead of > IFA_LOCAL, and this was done in order to be compatible with them? If I remember well, there was an issue in the uAPI. IFA_LOCAL is supposed to be the address of the interface and IFA_ADDRESS is supposed to be the endpoint of a point-to-point interface. However, in case of IPv6, it was not the case. In netlink messages generated by the kernel, IFA_ADDRESS was used instead of IFA_LOCAL. The patch tried to keep the backward compatibility and the symmetry between msg from userland and notification from the kernel.
Regards, Nicolas
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