Re: [PATCH v1 2/6] KEYS: ima: Refactored process_buffer_measurement function so that it can measure any buffer (and not just KEXEC_CMDLINE one)

Mimi Zohar
2019-10-23T13:21:37Z

On Tue, 2019-10-22 at 17:18 -0700, Lakshmi Ramasubramanian wrote:

> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 584019728660..8e965d18fb21 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -610,14 +610,14 @@ int ima_load_data(enum kernel_load_data_id id)
> * @buf: pointer to the buffer that needs to be added to the log.
> * @size: size of buffer(in bytes).
> * @eventname: event name to be used for the buffer entry.
> - * @cred: a pointer to a credentials structure for user validation.
> - * @secid: the secid of the task to be validated.
> + * @pcr: pcr to extend the measurement
> + * @template_desc: template description
> *
> * Based on policy, the buffer is measured into the ima log.
> */
> -static void process_buffer_measurement(const void *buf, int size,
> - const char *eventname,
> - const struct cred *cred, u32 secid)
> +void process_buffer_measurement(const void *buf, int size,
> + const char *eventname, int pcr,
> + struct ima_template_desc *template_desc)
> {
> int ret = 0;
> struct ima_template_entry *entry = NULL;
> @@ -626,19 +626,11 @@ static void process_buffer_measurement(const void *buf, int size,
> .filename = eventname,
> .buf = buf,
> .buf_len = size};
> - struct ima_template_desc *template_desc = NULL;
> struct {
> struct ima_digest_data hdr;
> char digest[IMA_MAX_DIGEST_SIZE];
> } hash = {};
> int violation = 0;
> - int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
> - int action = 0;
> -
> - action = ima_get_action(NULL, cred, secid, 0, KEXEC_CMDLINE, &pcr,
> - &template_desc);
> - if (!(action & IMA_MEASURE))
> - return;
>
> iint.ima_hash = &hash.hdr;
> iint.ima_hash->algo = ima_hash_algo;

This patch is based on Nayna's version of this change, without any
acknowledgment.  Moving this code out of process_buffer_measurement is
going to result in code duplication.  Nayna has posted a newer version
of this patch without the code duplication.  As soon as she posts the
patch with an updated patch description, I plan on picking up that
version.

Mimi

> @@ -670,12 +662,19 @@ static void process_buffer_measurement(const void *buf, int size,
> */
> void ima_kexec_cmdline(const void *buf, int size)
> {
> + int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
> + struct ima_template_desc *template_desc = ima_template_desc_current();
> + int action;
> u32 secid;
>
> if (buf && size != 0) {
> security_task_getsecid(current, &secid);
> - process_buffer_measurement(buf, size, "kexec-cmdline",
> - current_cred(), secid);
> + action = ima_get_action(NULL, current_cred(), secid, 0,
> + KEXEC_CMDLINE, &pcr, &template_desc);
> + if (!(action & IMA_MEASURE))
> + return;
> + process_buffer_measurement(buf, size, "kexec-cmdline", pcr,
> + template_desc);
> }
> }
>