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iproute: force rtm_dst_len to 32/128 

Since NETLINK_GET_STRICT_CHK was enabled, the kernel rejects commands
that pass a prefix length, eg:

 ip route get `1.0.0.0/1
  Error: ipv4: Invalid values in header for route get request.
 ip route get 0.0.0.0/0
  Error: ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4

Since there's no point in setting a rtm_dst_len that we know is going
to be rejected, just force it to the right value if it's passed on
the command line. Print a warning to stderr to notify users.

Bug-Debian: https://bugs.debian.org/944730
Reported-By: Clément 'wxcafé' Hertling <wxcafe@wxcafe.net>
Signed-off-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Luca Boccassi 2021-01-24 17:36:58 +00:00 committed by Stephen Hemminger
parent 38957a2f6c
commit 5a37254b71
1 changed files with 12 additions and 1 deletions
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13
ip/iproute.c
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@ -2069,7 +2069,18 @@ static int iproute_get(int argc, char **argv)
if (addr.bytelen)
addattr_l(&req.n, sizeof(req),
RTA_DST, &addr.data, addr.bytelen);
req.r.rtm_dst_len = addr.bitlen;
if (req.r.rtm_family == AF_INET && addr.bitlen != 32) {
fprintf(stderr,
"Warning: /%u as prefix is invalid, only /32 (or none) is supported.\n",
addr.bitlen);
req.r.rtm_dst_len = 32;
} else if (req.r.rtm_family == AF_INET6 && addr.bitlen != 128) {
fprintf(stderr,
"Warning: /%u as prefix is invalid, only /128 (or none) is supported.\n",
addr.bitlen);
req.r.rtm_dst_len = 128;
} else
req.r.rtm_dst_len = addr.bitlen;
address_found = true;
}
argc--; argv++;