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In verdict map, string values are accidentally treated as verdicts.
For example:
table t {
map foo {
type ipv4_addr : verdict
elements = {
192.168.0.1 : bar
}
}
chain output {
type filter hook output priority mangle;
ip daddr vmap @foo
}
}
Though "bar" is not a valid verdict (should be "jump bar" or something),
the string is taken as the element value. Then NFTA_DATA_VALUE is sent
to the kernel instead of NFTA_DATA_VERDICT. This would be rejected by
recent kernels. On older ones (e.g. v5.4.x) that don't validate the
type, a warning can be seen when the rule is hit, because of the
corrupted verdict value:
[5120263.467627] WARNING: CPU: 12 PID: 303303 at net/netfilter/nf_tables_core.c:229 nft_do_chain+0x394/0x500 [nf_tables]
Indeed, we don't parse verdicts during evaluation, but only chain names,
which is of type string rather than verdict. For example, "jump $var" is
a verdict while "$var" is a string.
Fixes: c64457cff967 ("src: Allow goto and jump to a variable")
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
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