Message ID | 1473173035-2175-1-git-send-email-fgao@ikuai8.com |
---|---|
State | Changes Requested |
Delegated to: | Pablo Neira |
Headers | show |
fgao@ikuai8.com <fgao@ikuai8.com> wrote: > From: Gao Feng <fgao@ikuai8.com> > > When memory is exhausted, nfct_seqadj_ext_add may fail to add the seqadj > extension. But the function nf_ct_seqadj_init doesn't check if get valid > seqadj pointer by the nfct_seqadj. > > Now drop the packet directly when fail to add seqadj extension to avoid > dereference NULL pointer in nf_ct_seqadj_init. > > Signed-off-by: Gao Feng <fgao@ikuai8.com> > --- > v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info > v4: Drop the packet directly when fail to add seqadj extension; > v3: Remove the warning log when seqadj is null; > v2: Remove the unnessary seqadj check in nf_ct_seq_adjust > v1: Initial patch > > net/netfilter/nf_conntrack_core.c | 6 +++++- > net/netfilter/nf_nat_core.c | 3 ++- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c > index dd2c43a..dfa76ce 100644 > --- a/net/netfilter/nf_conntrack_core.c > +++ b/net/netfilter/nf_conntrack_core.c > @@ -1036,7 +1036,11 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, > return (struct nf_conntrack_tuple_hash *)ct; > > if (tmpl && nfct_synproxy(tmpl)) { > - nfct_seqadj_ext_add(ct); > + if (!nfct_seqadj_ext_add(ct)) { > + nf_conntrack_free(ct); > + pr_debug("Can't add seqadj extension\n"); > + return NULL; > + } if (!nfct_add_synrpxy(ct, tmpl)) { nf_conntrack_free(ct); return NULL; } static bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl) { if (tmpl && nfct_synproxy(tmpl)) { if (!nfct_seqadj_ext_add(ct)) return false; if (!nfct_synproxy_ext_add(ct)) return false; } return true; } > diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c > index de31818..f8b916a 100644 > --- a/net/netfilter/nf_nat_core.c > +++ b/net/netfilter/nf_nat_core.c > @@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct, > ct->status |= IPS_DST_NAT; > > if (nfct_help(ct)) > - nfct_seqadj_ext_add(ct); > + if (!nfct_seqadj_ext_add(ct)) > + return NF_ACCEPT; > } Hmm, why accept? We are asked to add extension to rewrite sequence numbers, but we cannot. How can the connection work if we cannot munge/track seqno rewrites? -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
inline On Tue, Sep 6, 2016 at 10:51 PM, Florian Westphal <fw@strlen.de> wrote: > fgao@ikuai8.com <fgao@ikuai8.com> wrote: >> From: Gao Feng <fgao@ikuai8.com> >> >> When memory is exhausted, nfct_seqadj_ext_add may fail to add the seqadj >> extension. But the function nf_ct_seqadj_init doesn't check if get valid >> seqadj pointer by the nfct_seqadj. >> >> Now drop the packet directly when fail to add seqadj extension to avoid >> dereference NULL pointer in nf_ct_seqadj_init. >> >> Signed-off-by: Gao Feng <fgao@ikuai8.com> >> --- >> v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info >> v4: Drop the packet directly when fail to add seqadj extension; >> v3: Remove the warning log when seqadj is null; >> v2: Remove the unnessary seqadj check in nf_ct_seq_adjust >> v1: Initial patch >> >> net/netfilter/nf_conntrack_core.c | 6 +++++- >> net/netfilter/nf_nat_core.c | 3 ++- >> 2 files changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c >> index dd2c43a..dfa76ce 100644 >> --- a/net/netfilter/nf_conntrack_core.c >> +++ b/net/netfilter/nf_conntrack_core.c >> @@ -1036,7 +1036,11 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, >> return (struct nf_conntrack_tuple_hash *)ct; >> >> if (tmpl && nfct_synproxy(tmpl)) { >> - nfct_seqadj_ext_add(ct); >> + if (!nfct_seqadj_ext_add(ct)) { >> + nf_conntrack_free(ct); >> + pr_debug("Can't add seqadj extension\n"); >> + return NULL; >> + } > > if (!nfct_add_synrpxy(ct, tmpl)) { > nf_conntrack_free(ct); > return NULL; > } > > static bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl) > { > if (tmpl && nfct_synproxy(tmpl)) { > if (!nfct_seqadj_ext_add(ct)) > return false; > > if (!nfct_synproxy_ext_add(ct)) > return false; > } > > return true; > } > >> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c >> index de31818..f8b916a 100644 >> --- a/net/netfilter/nf_nat_core.c >> +++ b/net/netfilter/nf_nat_core.c >> @@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct, >> ct->status |= IPS_DST_NAT; >> >> if (nfct_help(ct)) >> - nfct_seqadj_ext_add(ct); >> + if (!nfct_seqadj_ext_add(ct)) >> + return NF_ACCEPT; >> } > > Hmm, why accept? > > We are asked to add extension to rewrite sequence numbers, but > we cannot. How can the connection work if we cannot munge/track > seqno rewrites? I thought we should drop the packet in that case before. But Pablo point out one case that the ctnetlink also could add the seqadj extension too. There is one synchronization case. I think he is right. Then modify the patch according to his advice. Best Regards Feng -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Pablo, On Tue, Sep 6, 2016 at 10:54 PM, Gao Feng <fgao@ikuai8.com> wrote: > inline > > On Tue, Sep 6, 2016 at 10:51 PM, Florian Westphal <fw@strlen.de> wrote: >> fgao@ikuai8.com <fgao@ikuai8.com> wrote: >>> From: Gao Feng <fgao@ikuai8.com> >>> >>> When memory is exhausted, nfct_seqadj_ext_add may fail to add the seqadj >>> extension. But the function nf_ct_seqadj_init doesn't check if get valid >>> seqadj pointer by the nfct_seqadj. >>> >>> Now drop the packet directly when fail to add seqadj extension to avoid >>> dereference NULL pointer in nf_ct_seqadj_init. >>> >>> Signed-off-by: Gao Feng <fgao@ikuai8.com> >>> --- >>> v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info >>> v4: Drop the packet directly when fail to add seqadj extension; >>> v3: Remove the warning log when seqadj is null; >>> v2: Remove the unnessary seqadj check in nf_ct_seq_adjust >>> v1: Initial patch >>> >>> net/netfilter/nf_conntrack_core.c | 6 +++++- >>> net/netfilter/nf_nat_core.c | 3 ++- >>> 2 files changed, 7 insertions(+), 2 deletions(-) >>> >>> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c >>> index dd2c43a..dfa76ce 100644 >>> --- a/net/netfilter/nf_conntrack_core.c >>> +++ b/net/netfilter/nf_conntrack_core.c >>> @@ -1036,7 +1036,11 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, >>> return (struct nf_conntrack_tuple_hash *)ct; >>> >>> if (tmpl && nfct_synproxy(tmpl)) { >>> - nfct_seqadj_ext_add(ct); >>> + if (!nfct_seqadj_ext_add(ct)) { >>> + nf_conntrack_free(ct); >>> + pr_debug("Can't add seqadj extension\n"); >>> + return NULL; >>> + } >> >> if (!nfct_add_synrpxy(ct, tmpl)) { >> nf_conntrack_free(ct); >> return NULL; >> } >> >> static bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl) >> { >> if (tmpl && nfct_synproxy(tmpl)) { >> if (!nfct_seqadj_ext_add(ct)) >> return false; >> >> if (!nfct_synproxy_ext_add(ct)) >> return false; >> } >> >> return true; >> } >> >>> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c >>> index de31818..f8b916a 100644 >>> --- a/net/netfilter/nf_nat_core.c >>> +++ b/net/netfilter/nf_nat_core.c >>> @@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct, >>> ct->status |= IPS_DST_NAT; >>> >>> if (nfct_help(ct)) >>> - nfct_seqadj_ext_add(ct); >>> + if (!nfct_seqadj_ext_add(ct)) >>> + return NF_ACCEPT; >>> } >> >> Hmm, why accept? >> >> We are asked to add extension to rewrite sequence numbers, but >> we cannot. How can the connection work if we cannot munge/track >> seqno rewrites? > > I thought we should drop the packet in that case before. > But Pablo point out one case that the ctnetlink also could add the > seqadj extension too. > There is one synchronization case. > > I think he is right. Then modify the patch according to his advice. > > Best Regards > Feng I find the commit which uses seqadj extension firstly in ctnetlink. But I think it should be ok and reply the details in my "v4" patch of this subject. Could you check it please? If my understanding is wrong, I could send one patch to fix it. Regards Feng -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 06, 2016 at 04:51:17PM +0200, Florian Westphal wrote: > fgao@ikuai8.com <fgao@ikuai8.com> wrote: > > From: Gao Feng <fgao@ikuai8.com> > > > > When memory is exhausted, nfct_seqadj_ext_add may fail to add the seqadj > > extension. But the function nf_ct_seqadj_init doesn't check if get valid > > seqadj pointer by the nfct_seqadj. > > > > Now drop the packet directly when fail to add seqadj extension to avoid > > dereference NULL pointer in nf_ct_seqadj_init. > > > > Signed-off-by: Gao Feng <fgao@ikuai8.com> > > --- > > v5: Return NF_ACCEPT instead of NF_DROP when nfct_seqadj_ext_add failed in nf_nat_setup_info > > v4: Drop the packet directly when fail to add seqadj extension; > > v3: Remove the warning log when seqadj is null; > > v2: Remove the unnessary seqadj check in nf_ct_seq_adjust > > v1: Initial patch > > > > net/netfilter/nf_conntrack_core.c | 6 +++++- > > net/netfilter/nf_nat_core.c | 3 ++- > > 2 files changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c > > index dd2c43a..dfa76ce 100644 > > --- a/net/netfilter/nf_conntrack_core.c > > +++ b/net/netfilter/nf_conntrack_core.c > > @@ -1036,7 +1036,11 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, > > return (struct nf_conntrack_tuple_hash *)ct; > > > > if (tmpl && nfct_synproxy(tmpl)) { > > - nfct_seqadj_ext_add(ct); > > + if (!nfct_seqadj_ext_add(ct)) { > > + nf_conntrack_free(ct); > > + pr_debug("Can't add seqadj extension\n"); > > + return NULL; > > + } > > if (!nfct_add_synrpxy(ct, tmpl)) { > nf_conntrack_free(ct); > return NULL; > } > > static bool nf_ct_add_synproxy(struct nf_conn *ct, const struct nf_conn *tmpl) > { > if (tmpl && nfct_synproxy(tmpl)) { > if (!nfct_seqadj_ext_add(ct)) > return false; > > if (!nfct_synproxy_ext_add(ct)) > return false; > } > > return true; > } I like this helper idea, please send a v6 using this using what Florian is proposing. > > diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c > > index de31818..f8b916a 100644 > > --- a/net/netfilter/nf_nat_core.c > > +++ b/net/netfilter/nf_nat_core.c > > @@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct, > > ct->status |= IPS_DST_NAT; > > > > if (nfct_help(ct)) > > - nfct_seqadj_ext_add(ct); > > + if (!nfct_seqadj_ext_add(ct)) > > + return NF_ACCEPT; > > } > > Hmm, why accept? > > We are asked to add extension to rewrite sequence numbers, but > we cannot. How can the connection work if we cannot munge/track > seqno rewrites? Actually we could just NF_DROP, but if we add support for ctnetlink to inject entries with sequence adjustment with no NAT. I think we need this to get synproxy working with conntrackd state synchronization. Thanks! -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index dd2c43a..dfa76ce 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1036,7 +1036,11 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, return (struct nf_conntrack_tuple_hash *)ct; if (tmpl && nfct_synproxy(tmpl)) { - nfct_seqadj_ext_add(ct); + if (!nfct_seqadj_ext_add(ct)) { + nf_conntrack_free(ct); + pr_debug("Can't add seqadj extension\n"); + return NULL; + } nfct_synproxy_ext_add(ct); } diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index de31818..f8b916a 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -441,7 +441,8 @@ nf_nat_setup_info(struct nf_conn *ct, ct->status |= IPS_DST_NAT; if (nfct_help(ct)) - nfct_seqadj_ext_add(ct); + if (!nfct_seqadj_ext_add(ct)) + return NF_ACCEPT; } if (maniptype == NF_NAT_MANIP_SRC) {