| Message ID | 20200925044256.GA18246@gondor.apana.org.au |
|---|---|
| State | New |
| Headers | show |
| Series | xfrm: Use correct address family in xfrm_state_find | expand |
On Fri, Sep 25, 2020 at 02:42:56PM +1000, Herbert Xu wrote: > Resend with proper subject. > > ---8<--- > The struct flowi must never be interpreted by itself as its size > depends on the address family. Therefore it must always be grouped > with its original family value. > > In this particular instance, the original family value is lost in > the function xfrm_state_find. Therefore we get a bogus read when > it's coupled with the wrong family which would occur with inter- > family xfrm states. > > This patch fixes it by keeping the original family value. > > Note that the same bug could potentially occur in LSM through > the xfrm_state_pol_flow_match hook. I checked the current code > there and it seems to be safe for now as only secid is used which > is part of struct flowi_common. But that API should be changed > so that so that we don't get new bugs in the future. We could > do that by replacing fl with just secid or adding a family field. > > Reported-by: syzbot+577fbac3145a6eb2e7a5@syzkaller.appspotmail.com > Fixes: 48b8d78315bf ("[XFRM]: State selection update to use inner...") > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Applied, thanks a lot Herbert!
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 69520ad3d83b..9b5f2c2b9770 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1019,7 +1019,8 @@ static void xfrm_state_look_at(struct xfrm_policy *pol, struct xfrm_state *x, */ if (x->km.state == XFRM_STATE_VALID) { if ((x->sel.family && - !xfrm_selector_match(&x->sel, fl, x->sel.family)) || + (x->sel.family != family || + !xfrm_selector_match(&x->sel, fl, family))) || !security_xfrm_state_pol_flow_match(x, pol, fl)) return; @@ -1032,7 +1033,9 @@ static void xfrm_state_look_at(struct xfrm_policy *pol, struct xfrm_state *x, *acq_in_progress = 1; } else if (x->km.state == XFRM_STATE_ERROR || x->km.state == XFRM_STATE_EXPIRED) { - if (xfrm_selector_match(&x->sel, fl, x->sel.family) && + if ((!x->sel.family || + (x->sel.family == family && + xfrm_selector_match(&x->sel, fl, family))) && security_xfrm_state_pol_flow_match(x, pol, fl)) *error = -ESRCH; } @@ -1072,7 +1075,7 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr, tmpl->mode == x->props.mode && tmpl->id.proto == x->id.proto && (tmpl->id.spi == x->id.spi || !tmpl->id.spi)) - xfrm_state_look_at(pol, x, fl, encap_family, + xfrm_state_look_at(pol, x, fl, family, &best, &acquire_in_progress, &error); } if (best || acquire_in_progress) @@ -1089,7 +1092,7 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr, tmpl->mode == x->props.mode && tmpl->id.proto == x->id.proto && (tmpl->id.spi == x->id.spi || !tmpl->id.spi)) - xfrm_state_look_at(pol, x, fl, encap_family, + xfrm_state_look_at(pol, x, fl, family, &best, &acquire_in_progress, &error); }
Resend with proper subject. ---8<--- The struct flowi must never be interpreted by itself as its size depends on the address family. Therefore it must always be grouped with its original family value. In this particular instance, the original family value is lost in the function xfrm_state_find. Therefore we get a bogus read when it's coupled with the wrong family which would occur with inter- family xfrm states. This patch fixes it by keeping the original family value. Note that the same bug could potentially occur in LSM through the xfrm_state_pol_flow_match hook. I checked the current code there and it seems to be safe for now as only secid is used which is part of struct flowi_common. But that API should be changed so that so that we don't get new bugs in the future. We could do that by replacing fl with just secid or adding a family field. Reported-by: syzbot+577fbac3145a6eb2e7a5@syzkaller.appspotmail.com Fixes: 48b8d78315bf ("[XFRM]: State selection update to use inner...") Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>