net80211: allow to override SWCRYPT/SWMIC bits in the driver

[avos]

Summary

Add IEEE80211_KEY_SWCRYPT / IEEE80211_KEY_SWMIC bits to the IEEE80211_KEY_DEVICE mask - as a result, such bits will be preserved during group key handshake.
A driver can set them in iv_key_alloc() in case when hardware crypto support is not possible. For example:

• multi-vap without multicast key search support;
• IBSS RSN for devices w/ fixed storage for group keys;

Test Plan

wlan2 -> AP (sw crypto), wlan3 -> STA (group - sw, pair - hw)

wlan3: link state changed to UP
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x3 keyix 65535
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 0 flags 0x103 mac c4:e9:84:01:02:03 rsc 0 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 2
wlan2: ieee80211_crypto_newkey: cipher 3 flags 0x3 keyix 65535
wlan2: wlan3: ieee80211_crypto_newkey: no h/w support for cipher AES-CCM, falling back to s/w
wlan2: ieee80211_crypto_setkey: AES-CCM keyix 0 flags 0x133 mac 6c:72:20:01:02:03 rsc 0 tsc 0 len 16
ieee80211_crypto_newkey: driver override for cipher AES-CCM, flags 0x3 -> 0x36
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 2 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 4 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 1
wlan3: ieee80211_crypto_newkey: driver override for cipher AES-CCM, flags 0x3 -> 0x36
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 1 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan2: ieee80211_crypto_newkey: cipher 3 flags 0x87 keyix 1
wlan2: ieee80211_crypto_newkey: no h/w support for cipher AES-CCM, falling back to s/w
wlan2: ieee80211_crypto_setkey: AES-CCM keyix 1 flags 0x137 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 2
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 2 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan2: ieee80211_crypto_newkey: cipher 3 flags 0x87 keyix 2
wlan2: ieee80211_crypto_newkey: no h/w support for cipher AES-CCM, falling back to s/w
wlan2: ieee80211_crypto_setkey: AES-CCM keyix 2 flags 0x137 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 1
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 1 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan2: ieee80211_crypto_newkey: cipher 3 flags 0x87 keyix 1
wlan2: ieee80211_crypto_newkey: no h/w support for cipher AES-CCM, falling back to s/w
wlan2: ieee80211_crypto_setkey: AES-CCM keyix 1 flags 0x137 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 2
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 2 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan2: ieee80211_crypto_newkey: cipher 3 flags 0x87 keyix 2
wlan2: ieee80211_crypto_newkey: no h/w support for cipher AES-CCM, falling back to s/w
wlan2: ieee80211_crypto_setkey: AES-CCM keyix 2 flags 0x137 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16
wlan3: ieee80211_crypto_newkey: cipher 3 flags 0x6 keyix 1
wlan3: ieee80211_crypto_setkey: AES-CCM keyix 1 flags 0x136 mac ff:ff:ff:ff:ff:ff rsc 0 tsc 0 len 16 << SWCRYPT bits are preserved (0x30)

[adrian]

hm, interesting! So this means the driver can run out of hardware keycache slots and we still would do the right thing in software?

(With driver changes, of course, so there is a fallback key for "don't decrypt" if necessary?)

[avos]

Probably, yes (e.g., 88EU supports 64 MAC ID slots but has only 32 key slots; 12AU/21AU - 128 MAC ID slots, 64 key slots)

P.S. Yes, this is pretty device-dependent (e.g., (u)rtwn shouldn't decrypt a frame, when 'crypto algo + mac addr' combination was not found (with default SECCFG setup)).

[adrian]

ok I like this!

We should later on add the ability to swap hardware/software keys around in the hardware so we can support lots of stations in hostap mode and only populate crypto keys for the most traffic-heavy users.