linux-kernel - Re: [PATCH 5/5] lguest: loading bzImage directly

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: <1191404221.17247.15.camel@feisty>
Date:	Wed, 03 Oct 2007 10:37:01 +0100
From:	Chris Malley <mail@...ismalley.co.uk>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	lguest <lguest@...abs.org>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Vivek Goyal <vgoyal@...ibm.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 5/5] lguest: loading bzImage directly

Hi guys

Would it not be clearer to #include <asm/bootparam.h> and use 
the relevant named members of struct setup_header / struct boot_params
rather than the hard-coded values 0x202, 0x1F1, 0x214 ?

--
Chris


On Wed, 2007-10-03 at 09:40 +1000, Rusty Russell wrote:
[snip]
> +	u8 hdr[1024];
> +	int r;
> +	/* Modern bzImages get loaded at 1M. */
> +	void *p = from_guest_phys(0x100000);
> +
> +	/* Go back to the start of the file and read the header.  It should be
> +	 * a Linux boot header (see Documentation/i386/boot.txt) */
> +	lseek(fd, 0, SEEK_SET);
> +	read(fd, hdr, sizeof(hdr));
> +
> +	/* At offset 0x202, we expect the magic "HdrS" */
> +	if (memcmp(hdr + 0x202, "HdrS", 4) != 0)
> +		errx(1, "This doesn't look like a bzImage to me");
> +
> +	/* The byte at 0x1F1 tells us how many extra sectors of
> +	 * header: skip over them all. */
> +	lseek(fd, (unsigned long)(hdr[0x1F1]+1) * 512, SEEK_SET);
> +
> +	/* Now read everything into memory. in nice big chunks. */
> +	while ((r = read(fd, p, 65536)) > 0)
> +		p += r;
> +
> +	/* Finally, 0x214 tells us where to start the kernel. */
> +	return *(unsigned long *)&hdr[0x214];
>  }
>  
>  /*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels
> 


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/