Date: Mon, 22 Jan 2018 17:47:09 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Yuri Pankov <yuripv@icloud.com> Cc: Li-Wen Hsu <lwhsu@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: Calling getaddrinfo(3) in 32-bit binary on 64-bit host Message-ID: <20180122154709.GF55707@kib.kiev.ua> In-Reply-To: <8c6dc5b5-7640-61fc-b687-08efd1e621ee@icloud.com> References: <CAKBkRUx14r%2B%2BZ-n64SNDd4uu=hoJv-KaXxeyUGM7f%2BDS2Ha%2BmQ@mail.gmail.com> <8c6dc5b5-7640-61fc-b687-08efd1e621ee@icloud.com>
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On Mon, Jan 22, 2018 at 02:33:12AM +0300, Yuri Pankov wrote: > On Mon, Jan 22, 2018 at 05:14:59AM +0800, Li-Wen Hsu wrote: > > Hi all, > > > > Recently I found a strange case: calling getaddrinfo(3) cannot resolve IPv6 > > address in 32-bit binary on 64-bit host. > > It happens on vanilla installed 11.1-R and also on r327788 snapshot build. > > > > For a program like this: > > https://gist.github.com/lwhsu/1288aa5be90b9e7da934a3e2bfc55aa3 > > > > It works fine when compiled as a 32-bit binary and run on a 32-bit host. > > As expected, It is also works fine when compiled as a 64-bit binary and run > > on a 64-bit host > > > > However, when taking the 32-bit binary and run on a 64 bit system (with > > /usr/lib32 installed), > > getaddrinfo(3) just returns: "Non-recoverable failure in name resolution" > > Apparently, it goes through addrconfig() down to getifaddrs() returning > bogus data for IPv6 addresses. This most likely has to with SALIGN > being incorrect for 32-bit binary trying to parse route messages from > 64-bit kernel. I'm not sure about proper fix here, but changing SALIGN > to be 7 (that is, "sizeof(long) - 1" on amd64 platform) makes your test > case return correct data. Thank you for the diagnostic. The following worked for me. Most likely there are may be more issues, since there are more SA_SIZE() uses from sysctl context. Also, it is probably impossible to provide COMPAT32 for rtsock itself. diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c index eea4cb9459d..26b888f2153 100644 --- a/sys/net/rtsock.c +++ b/sys/net/rtsock.c @@ -112,6 +112,12 @@ struct ifa_msghdrl32 { int32_t ifam_metric; struct if_data ifam_data; }; + +#define SA_SIZE32(sa) \ + ( (((struct sockaddr *)(sa))->sa_len == 0) ? \ + sizeof(int) : \ + 1 + ( (((struct sockaddr *)(sa))->sa_len - 1) | (sizeof(int) - 1) ) ) + #endif /* COMPAT_FREEBSD32 */ MALLOC_DEFINE(M_RTABLE, "routetbl", "routing tables"); @@ -1116,6 +1122,9 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int * struct sockaddr_storage ss; struct sockaddr_in6 *sin6; #endif +#ifdef COMPAT_FREEBSD32 + bool compat32 = false; +#endif switch (type) { @@ -1123,9 +1132,10 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int * case RTM_NEWADDR: if (w != NULL && w->w_op == NET_RT_IFLISTL) { #ifdef COMPAT_FREEBSD32 - if (w->w_req->flags & SCTL_MASK32) + if (w->w_req->flags & SCTL_MASK32) { len = sizeof(struct ifa_msghdrl32); - else + compat32 = true; + } else #endif len = sizeof(struct ifa_msghdrl); } else @@ -1139,6 +1149,7 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int * len = sizeof(struct if_msghdrl32); else len = sizeof(struct if_msghdr32); + compat32 = true; break; } #endif @@ -1169,7 +1180,12 @@ rtsock_msg_buffer(int type, struct rt_addrinfo *rtinfo, struct walkarg *w, int * if ((sa = rtinfo->rti_info[i]) == NULL) continue; rtinfo->rti_addrs |= (1 << i); - dlen = SA_SIZE(sa); +#ifdef COMPAT_FREEBSD32 + if (compat32) + dlen = SA_SIZE32(sa); + else +#endif + dlen = SA_SIZE(sa); if (cp != NULL && buflen >= dlen) { #ifdef INET6 if (V_deembed_scopeid && sa->sa_family == AF_INET6) {
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