Re: [PATCH 10/64] lib80211: Use struct_group() for memcpy() region

Johannes Berg
2021-08-13T08:06:12Z

On Tue, 2021-07-27 at 13:58 -0700, Kees Cook wrote:
>
> +++ b/include/linux/ieee80211.h
> @@ -297,9 +297,11 @@ static inline u16 ieee80211_sn_sub(u16 sn1, u16 sn2)
>  struct ieee80211_hdr {
>   __le16 frame_control;
>   __le16 duration_id;
> - u8 addr1[ETH_ALEN];
> - u8 addr2[ETH_ALEN];
> - u8 addr3[ETH_ALEN];
> + struct_group(addrs,
> + u8 addr1[ETH_ALEN];
> + u8 addr2[ETH_ALEN];
> + u8 addr3[ETH_ALEN];
> + );
>   __le16 seq_ctrl;
>   u8 addr4[ETH_ALEN];
>  } __packed __aligned(2);

This file isn't really just lib80211, it's also used by everyone else
for 802.11, but I guess that's OK - after all, this doesn't really
result in any changes here.

> +++ b/net/wireless/lib80211_crypt_ccmp.c
> @@ -136,7 +136,8 @@ static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr,
>   pos = (u8 *) hdr;
>   aad[0] = pos[0] & 0x8f;
>   aad[1] = pos[1] & 0xc7;
> - memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN);
> + BUILD_BUG_ON(sizeof(hdr->addrs) != 3 * ETH_ALEN);
> + memcpy(aad + 2, &hdr->addrs, ETH_ALEN);

However, how is it you don't need the same change in net/mac80211/wpa.c?

We have three similar instances:

/* AAD (extra authenticate-only data) / masked 802.11 header
* FC | A1 | A2 | A3 | SC | [A4] | [QC] */
put_unaligned_be16(len_a, &aad[0]);
put_unaligned(mask_fc, (__le16 *)&aad[2]);
memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);

and

memcpy(&aad[4], &hdr->addr1, 3 * ETH_ALEN);

and

memcpy(aad + 2, &hdr->addr1, 3 * ETH_ALEN);

so those should also be changed, it seems?

In which case I'd probably prefer to do this separately from the staging
drivers ...

johannes