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WPA: Extra defense against PTK reinstalls in 4-way handshake

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Currently, reinstallations of the PTK are prevented by (1) assuring the
same TPTK is only set once as the PTK, and (2) that one particular PTK
is only installed once. This patch makes it more explicit that point (1)
is required to prevent key reinstallations. At the same time, this patch
hardens wpa_supplicant such that future changes do not accidentally
break this property.

Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@cs.kuleuven.be>
This commit is contained in:
Mathy Vanhoef 2017-10-05 23:53:01 +02:00 committed by Jouni Malinen
parent f4528fbf51
commit a00e946c1c
1 changed files with 8 additions and 0 deletions
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8
src/rsn_supp/wpa.c
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@ -1729,6 +1729,14 @@ static int wpa_supplicant_verify_eapol_key_mic(struct wpa_sm *sm,
sm->ptk_set = 1; sm->ptk_set = 1;
os_memcpy(&sm->ptk, &sm->tptk, sizeof(sm->ptk)); os_memcpy(&sm->ptk, &sm->tptk, sizeof(sm->ptk));
os_memset(&sm->tptk, 0, sizeof(sm->tptk)); os_memset(&sm->tptk, 0, sizeof(sm->tptk));
/*
* This assures the same TPTK in sm->tptk can never be
* copied twice to sm->pkt as the new PTK. In
* combination with the installed flag in the wpa_ptk
* struct, this assures the same PTK is only installed
* once.
*/
sm->renew_snonce = 1;
} }
} }