[Bug 1464] Trying to populate a set raises a netlink error "Could not process rule: No space left on device"

[bugzilla-daemon at netfilter.org]

https://bugzilla.netfilter.org/show_bug.cgi?id=1464

--- Comment #10 from Pablo Neira Ayuso <pablo at netfilter.org> ---
(In reply to Pablo Neira Ayuso from comment #8)
> (In reply to kfm from comment #7)
> > Created attachment 618 [details]
> > bug-1464-strace-r1.txt
> > 
> > # strace -obug-1464-strace-r1.txt nft -f bug-1464-nft-input-stream.txt
> 
> Netlink message is sent:
> 
> sendmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000},
> msg_namelen=12, msg_iov=[{iov_base=[{{len=20, type=NFNL_MSG_BATCH_BEGIN,
> flags=NLM_F_REQUEST, seq=0, pid=0}, {nfgen_family=AF_UNSPEC,
> version=NFNETLINK_V0, res_id=htons(2560)}, {{len=40,
> type=NFNL_SUBSYS_NFTABLES<<8|NFT_MSG_DELSETELEM, flags=NLM_F_REQUEST, seq=1,
> pid=0}, {nfgen_family=AF_INET, version=NFNETLINK_V0, res_id=htons(0),
> [{{nla_len=11, nla_type=0x2}, "\x62\x6f\x67\x6f\x6e\x73\x00"}, {{nla_len=8,
> nla_type=NFNETLINK_V1}, "\x72\x61\x77\x00"}]}, {{len=51440,
> type=NFNL_SUBSYS_NFTABLES<<8|NFT_MSG_NEWSETELEM,
> flags=NLM_F_REQUEST|NLM_F_CREATE, seq=2, pid=0}, {nfgen_family=AF_INET,
> version=NFNETLINK_V0, res_id=htons(0), [{{nla_len=11, nla_type=0x2},
> "\x62\x6f\x67\x6f\x6e\x73\x00"}, {{nla_len=8, nla_type=0x4},
> "\x00\x00\x00\x1d"}, {{nla_len=8, nla_type=NFNETLINK_V1},
> "\x72\x61\x77\x00"}, {{nla_len=51392, nla_type=NLA_F_NESTED|0x3},
> "\x10\x00\x01\x80\x0c\x00\x01\x80\x08\x00\x01\x00\x00\x00\x00\x00\x18\x00\x02
> \x80\x08\x00\x03\x00\x00\x00\x00\x01\x0c\x00\x01\x80"...}]}, {{len=20,
> type=NFNL_MSG_BATCH_END, flags=NLM_F_REQUEST, seq=3, pid=0},
> {nfgen_family=AF_UNSPEC, version=NFNETLINK_V0, res_id=htons(2560)}],
> iov_len=51520}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 51520

The large message is send from userspace to the kernel:

{{len=51440, type=NFNL_SUBSYS_NFTABLES<<8|NFT_MSG_NEWSETELEM,

> Then, select() reports a reply message:
> 
> select(4, [3], NULL, NULL, {tv_sec=0, tv_usec=0}) = 1 (in [3], left
> {tv_sec=0, tv_usec=0})
> 
> And userspace gets it via recvmsg():
> 
> recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000},
> msg_namelen=12, msg_iov=[{iov_base={{len=51460, type=NLMSG_ERROR, flags=0,
> seq=2, pid=11881}, {error=-EEXIST, msg={{len=51440,
> type=NFNL_SUBSYS_NFTABLES<<8|NFT_MSG_NEWSETELEM,
> flags=NLM_F_REQUEST|NLM_F_CREATE, seq=2, pid=0}, {nfgen_family=AF_INET,
> version=NFNETLINK_V0, res_id=htons(0), [{{nla_len=11, nla_type=0x2},
> "\x62\x6f\x67\x6f\x6e\x73\x00"}, {{nla_len=8, nla_type=0x4},
> "\x00\x00\x00\x1d"}, {{nla_len=8, nla_type=NFNETLINK_V1},
> "\x72\x61\x77\x00"}, {{nla_len=51392, nla_type=NLA_F_NESTED|0x3},
> "\x10\x00\x01\x80\x0c\x00\x01\x80\x08\x00\x01\x00\x00\x00\x00\x00\x18\x00\x02
> \x80\x08\x00\x03\x00\x00\x00\x00\x01\x0c\x00\x01\x80"...}]}}},
> iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, 0) =
> 4096

Then the NLM_ERROR message contains the original message len=51440.

Looks like userspace is sending a malformed attribute:

{{nla_len=51392, nla_type=NLA_F_NESTED|0x3},
> "\x10\x00\x01\x80\x0c\x00\x01\x80\x08\x00\x01\x00\x00\x00\x00\x00\x18\x00\x02
> \x80\x08\x00\x03\x00\x00\x00\x00\x01\x0c\x00\x01\x80"...}]}}},

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