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xfrm_user: uncoditionally validate esn replay attribute struct 

The sanity test added in ecd7918745 can be bypassed, validation
only occurs if XFRM_STATE_ESN flag is set, but rest of code doesn't care
and just checks if the attribute itself is present.

So always validate.  Alternative is to reject if we have the attribute
without the flag but that would change abi.

Reported-by: syzbot+0ab777c27d2bb7588f73@syzkaller.appspotmail.com
Cc: Mathias Krause <minipli@googlemail.com>
Fixes: ecd7918745 ("xfrm_user: ensure user supplied esn replay window is valid")
Fixes: d8647b79c3 ("xfrm: Add user interface for esn and big anti-replay windows")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Florian Westphal 2018-02-12 14:42:01 +01:00 committed by Steffen Klassert
parent 2471c98165
commit d97ca5d714
1 changed files with 10 additions and 15 deletions
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25
net/xfrm/xfrm_user.c
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@ -121,22 +121,17 @@ static inline int verify_replay(struct xfrm_usersa_info *p,
struct nlattr *rt = attrs[XFRMA_REPLAY_ESN_VAL];
struct xfrm_replay_state_esn *rs;
if (p->flags & XFRM_STATE_ESN) {
if (!rt)
return -EINVAL;
rs = nla_data(rt);
if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8)
return -EINVAL;
if (nla_len(rt) < (int)xfrm_replay_state_esn_len(rs) &&
nla_len(rt) != sizeof(*rs))
return -EINVAL;
}
if (!rt)
return 0;
return (p->flags & XFRM_STATE_ESN) ? -EINVAL : 0;
rs = nla_data(rt);
if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8)
return -EINVAL;
if (nla_len(rt) < (int)xfrm_replay_state_esn_len(rs) &&
nla_len(rt) != sizeof(*rs))
return -EINVAL;
/* As only ESP and AH support ESN feature. */
if ((p->id.proto != IPPROTO_ESP) && (p->id.proto != IPPROTO_AH))