On 30 August 2013 00:46, Laurent Vivier <[email protected]> wrote:
> The binfmt_misc module can calculate the credentials and security
> token according to the binary instead of to the interpreter if the
> 'C' flag is enabled.
>
> To be able to execute non-readable binaries, this flag implies 'O'
> flag. When 'O' flag is enabled, bintfmt_misc opens the file for
> reading and pass the file descriptor to the interpreter.
>
> References:
> linux/Documentation/binfmt_misc.txt ['O' and 'C' description]
> linux/fs/binfmt_misc.c linux/fs/binfmt_elf.c [ AT_EXECFD usage ]
> +static int get_execfd(char **envp)
> +{
> + typedef struct {
> + long a_type;
> + long a_val;
> + } auxv_t;
> + auxv_t *auxv;
> +
> + while (*envp++ != NULL) {
> + ;
> + }
> +
> + for (auxv = (auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
> + if (auxv->a_type == AT_EXECFD) {
> + return auxv->a_val;
> + }
> + }
> + return -1;
> +}
This looks OK in principle, but this is going to clash
with RTH's auxval related patchset
http://patchwork.ozlabs.org/patch/268006/
so some coordination might be a good idea.
thanks
-- PMM
