Re: [PATCH 3 of 4] ima: Linux Security Module implementation

From: Greg KH
Date: Sat May 21 2005 - 01:25:19 EST


On Fri, May 20, 2005 at 09:43:34AM -0400, Reiner Sailer wrote:
> +/* security structure appended to inodes */
> +#define IMA_MAGIC 0x9999
> +struct ima_inode {
> + unsigned short magic;
> + atomic_t measure_count; /* # processes currently using this file in measure-mode */
> + ima_entry_flags dirty;
> + char *file_name; /* points to measure entry->fileName */
> +};
> +
> +/* security structure appended to measured files*/
> +struct ima_file {
> + unsigned short magic; /* identify our struct format */
> + char is_measuring; /* identify fds that are "measuring" */
> +};

magic values for structures protect you from nothing. Do not use them.


> +static u32 decode_u32(u8 * buf)
> +{
> + u32 val = buf[0];
> + val = (val << 8) | (u8) buf[1];
> + val = (val << 8) | (u8) buf[2];
> + val = (val << 8) | (u8) buf[3];
> + return val;
> +}
> +
> +static void encode_u32(u8 * buf, u32 val)
> +{
> + buf[0] = (u8) val >> 24;
> + buf[1] = (u8) val >> 16;
> + buf[2] = (u8) val >> 8;
> + buf[3] = (u8) val >> 0;
> +}

Hm, what's wrong with the standard kernel functions to do this kind of
thing?


> diff -uprN linux-2.6.12-rc4/security/ima/INSTALL linux-2.6.12-rc4-ima/security/ima/INSTALL
> --- linux-2.6.12-rc4/security/ima/INSTALL 1969-12-31 19:00:00.000000000 -0500
> +++ linux-2.6.12-rc4-ima/security/ima/INSTALL 2005-05-19 17:59:20.000000000 -0400

Kernel directories do not get a INSTALL file. Stuff like that goes into
the Documentation/ directory.

greg k-h
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