linux-kernel - Re: [PATCH v8 24/40] x86/compressed/acpi: move EFI system table lookup to helper

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <YdYuqFcFkcK1d+XP@zn.tnic>
Date:   Thu, 6 Jan 2022 00:50:00 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v8 24/40] x86/compressed/acpi: move EFI system table
 lookup to helper

On Fri, Dec 10, 2021 at 09:43:16AM -0600, Brijesh Singh wrote:
> +int efi_get_system_table(struct boot_params *boot_params, unsigned long *sys_tbl_pa,
> +			 bool *is_efi_64)

Nah, that's doing two things in one function.

The signature should be a lot simpler:

unsigned long efi_get_system_table(struct boot_params *bp)

returns 0 on failure, non-null on success and then it returns the
physical address of the system table.

> +{
> +	unsigned long sys_tbl;
> +	struct efi_info *ei;
> +	bool efi_64;
> +	char *sig;
> +
> +	if (!sys_tbl_pa || !is_efi_64)
> +		return -EINVAL;
> +

This...

> +	ei = &boot_params->efi_info;
> +	sig = (char *)&ei->efi_loader_signature;
> +
> +	if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
> +		efi_64 = true;
> +	} else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
> +		efi_64 = false;
> +	} else {
> +		debug_putstr("Wrong EFI loader signature.\n");
> +		return -EOPNOTSUPP;
> +	}

... up to here needs to be another function:

enum get_efi_type(sig)

where enum is { EFI64, EFI32, INVALID } or so.

And you call this function at the call sites:

	if (efi_get_type(sig) == INVALID)
		error...

	sys_tbl_pa = efi_get_system_table(bp);
	if (!sys_tbl_pa)
		error...


Completely pseudo but you get the idea.

Thx.

-- 
Regards/Gruss,
    Boris.

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