netdev - Re: [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of bss

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Y3uN07qSlGqo0dNO@zn.tnic>
Date:   Mon, 21 Nov 2022 15:40:19 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     hpa@...or.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, luto@...nel.org,
        peterz@...radead.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, lpieralisi@...nel.org,
        robh@...nel.org, kw@...ux.com, bhelgaas@...gle.com, arnd@...db.de,
        hch@...radead.org, m.szyprowski@...sung.com, robin.murphy@....com,
        thomas.lendacky@....com, brijesh.singh@....com, tglx@...utronix.de,
        mingo@...hat.com, dave.hansen@...ux.intel.com,
        Tianyu.Lan@...rosoft.com, kirill.shutemov@...ux.intel.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, dan.j.williams@...el.com,
        jane.chu@...cle.com, seanjc@...gle.com, tony.luck@...el.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-arch@...r.kernel.org,
        iommu@...ts.linux.dev
Subject: Re: [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of
 bss_decrypted consistently

On Wed, Nov 16, 2022 at 10:41:28AM -0800, Michael Kelley wrote:
> Current code in sme_postprocess_startup() decrypts the bss_decrypted
> section when sme_me_mask is non-zero.  But code in
> mem_encrypt_free_decrytped_mem() re-encrypts the unused portion based
			^^

letters flipped.

> @@ -513,10 +513,14 @@ void __init mem_encrypt_free_decrypted_mem(void)
>  	npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
>  
>  	/*
> -	 * The unused memory range was mapped decrypted, change the encryption
> -	 * attribute from decrypted to encrypted before freeing it.
> +	 * If the unused memory range was mapped decrypted, change the encryption
> +	 * attribute from decrypted to encrypted before freeing it. Base the
> +	 * re-encryption on the same condition used for the decryption in
> +	 * sme_postprocess_startup(). Higher level abstractions, such as
> +	 * CC_ATTR_MEM_ENCRYPT, aren't necessarily equivalent in a Hyper-V VM
> +	 * using vTOM, where sme_me_mask is always zero.

Good, an example why one needs to pay attention here.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette