Re: [PATCH 3/6] ima: Simplify policy_func_show.

From: Mimi Zohar
Date: Thu Apr 20 2017 - 08:15:07 EST


On Tue, 2017-04-18 at 17:17 -0300, Thiago Jung Bauermann wrote:
> If the func_tokens array uses the same indices as enum ima_hooks,
> policy_func_show can be a lot simpler, and the func_* enum becomes
> unnecessary.

My main concern with separating the enumeration from the string
definition is that they might become out of sync. ÂPerhaps using
macros, similar to those used for kernel_read_file_id_str(), would be
better?

> Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
> ---
> security/integrity/ima/ima_policy.c | 47 ++++++-------------------------------
> 1 file changed, 7 insertions(+), 40 deletions(-)
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index cfda5d7b17ec..158eafef64e8 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -896,20 +896,14 @@ static const char *const mask_tokens[] = {
> "MAY_APPEND"
> };
>
> -enum {
> - func_file = 0, func_mmap, func_bprm,
> - func_module, func_firmware, func_post,
> - func_kexec_kernel, func_kexec_initramfs,
> - func_policy
> -};
> -

At least, add a comment here and near the ima_hooks enumeration to
prevent them from becoming out of sync.

Mimi

> static const char *const func_tokens[] = {
> + NULL,
> "FILE_CHECK",
> "MMAP_CHECK",
> "BPRM_CHECK",
> + "POST_SETATTR",
> "MODULE_CHECK",
> "FIRMWARE_CHECK",
> - "POST_SETATTR",
> "KEXEC_KERNEL_CHECK",
> "KEXEC_INITRAMFS_CHECK",
> "POLICY_CHECK"
> @@ -949,48 +943,21 @@ void ima_policy_stop(struct seq_file *m, void *v)
>
> #define pt(token) policy_tokens[token + Opt_err].pattern
> #define mt(token) mask_tokens[token]
> -#define ft(token) func_tokens[token]
>
> /*
> * policy_func_show - display the ima_hooks policy rule
> */
> static void policy_func_show(struct seq_file *m, enum ima_hooks func)
> {
> - char tbuf[64] = {0,};
> + if (func > 0 && func < MAX_CHECK)
> + seq_printf(m, pt(Opt_func), func_tokens[func]);
> + else {
> + char tbuf[64] = {0,};
>
> - switch (func) {
> - case FILE_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_file));
> - break;
> - case MMAP_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_mmap));
> - break;
> - case BPRM_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_bprm));
> - break;
> - case MODULE_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_module));
> - break;
> - case FIRMWARE_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_firmware));
> - break;
> - case POST_SETATTR:
> - seq_printf(m, pt(Opt_func), ft(func_post));
> - break;
> - case KEXEC_KERNEL_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_kexec_kernel));
> - break;
> - case KEXEC_INITRAMFS_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
> - break;
> - case POLICY_CHECK:
> - seq_printf(m, pt(Opt_func), ft(func_policy));
> - break;
> - default:
> snprintf(tbuf, sizeof(tbuf), "%d", func);
> seq_printf(m, pt(Opt_func), tbuf);
> - break;
> }
> +
> seq_puts(m, " ");
> }
>