1. 26 Oct, 2019 2 commits
    • Pablo Neira Ayuso's avatar
      netfilter: nf_tables_offload: add nft_chain_offload_cmd() · 6df5490f
      Pablo Neira Ayuso authored
      This patch adds the nft_chain_offload_cmd() helper function.
      Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
      6df5490f
    • Florian Westphal's avatar
      netfilter: ecache: don't look for ecache extension on dying/unconfirmed conntracks · ad88b7a6
      Florian Westphal authored
      syzbot reported following splat:
      BUG: KASAN: use-after-free in __nf_ct_ext_exist
      include/net/netfilter/nf_conntrack_extend.h:53 [inline]
      BUG: KASAN: use-after-free in nf_ct_deliver_cached_events+0x5c3/0x6d0
      net/netfilter/nf_conntrack_ecache.c:205
      nf_conntrack_confirm include/net/netfilter/nf_conntrack_core.h:65 [inline]
      nf_confirm+0x3d8/0x4d0 net/netfilter/nf_conntrack_proto.c:154
      [..]
      
      While there is no reproducer yet, the syzbot report contains one
      interesting bit of information:
      
      Freed by task 27585:
      [..]
       kfree+0x10a/0x2c0 mm/slab.c:3757
       nf_ct_ext_destroy+0x2ab/0x2e0 net/netfilter/nf_conntrack_extend.c:38
       nf_conntrack_free+0x8f/0xe0 net/netfilter/nf_conntrack_core.c:1418
       destroy_conntrack+0x1a2/0x270 net/netfilter/nf_conntrack_core.c:626
       nf_conntrack_put include/linux/netfilter/nf_conntrack_common.h:31 [inline]
       nf_ct_resolve_clash net/netfilter/nf_conntrack_core.c:915 [inline]
       ^^^^^^^^^^^^^^^^^^^
       __nf_conntrack_confirm+0x21ca/0x2830 net/netfilter/nf_conntrack_core.c:1038
       nf_conntrack_confirm include/net/netfilter/nf_conntrack_core.h:63 [inline]
       nf_confirm+0x3e7/0x4d0 net/netfilter/nf_conntrack_proto.c:154
      
      This is whats happening:
      
      1. a conntrack entry is about to be confirmed (added to hash table).
      2. a clash with existing entry is detected.
      3. nf_ct_resolve_clash() puts skb->nfct (the "losing" entry).
      4. this entry now has a refcount of 0 and is freed to SLAB_TYPESAFE_BY_RCU
         kmem cache.
      
      skb->nfct has been replaced by the one found in the hash.
      Problem is that nf_conntrack_confirm() uses the old ct:
      
      static inline int nf_conntrack_confirm(struct sk_buff *skb)
      {
       struct nf_conn *ct = (struct nf_conn *)skb_nfct(skb);
       int ret = NF_ACCEPT;
      
        if (ct) {
          if (!nf_ct_is_confirmed(ct))
             ret = __nf_conntrack_confirm(skb);
          if (likely(ret == NF_ACCEPT))
      	nf_ct_deliver_cached_events(ct); /* This ct has refcount 0! */
        }
        return ret;
      }
      
      As of "netfilter: conntrack: free extension area immediately", we can't
      access conntrack extensions in this case.
      
      To fix this, make sure we check the dying bit presence before attempting
      to get the eache extension.
      
      Reported-by: syzbot+c7aabc9fe93e7f3637ba@syzkaller.appspotmail.com
      Fixes: 2ad9d774 ("netfilter: conntrack: free extension area immediately")
      Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
      Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
      ad88b7a6
  2. 23 Oct, 2019 9 commits
  3. 17 Oct, 2019 6 commits
  4. 11 Oct, 2019 3 commits
  5. 08 Oct, 2019 3 commits
  6. 07 Oct, 2019 7 commits
  7. 05 Oct, 2019 10 commits