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SubjectRe: [PATCH 1/3] IMA:Define a new hook to measure the kexec boot command line arguments
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On Mon, 2019-06-17 at 11:35 -0700, Prakhar Srivastava wrote:
> Currently during soft reboot(kexec_file_load) boot command line
> arguments are not measured. Define hooks needed to measure kexec
> command line arguments during soft reboot(kexec_file_load).
>
> - A new ima hook ima_kexec_cmdline is defined to be called by the
> kexec code.
> - A new function process_buffer_measurement is defined to measure
> the buffer hash into the IMA measurement list.
> - A new func policy KEXEC_CMDLINE is defined to control the
> measurement.[Suggested by Mimi]
>
> Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>

With minor changes below, 
     Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

> ---

> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index af341a80118f..1e233417a7af 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -605,6 +605,80 @@ int ima_load_data(enum kernel_load_data_id id)
> return 0;
> }
>
> +/*
> + * process_buffer_measurement - Measure the buffer to ima log.
> + * @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.
> + *
> + * 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)
> +{
> + int ret = 0;
> + struct ima_template_entry *entry = NULL;
> + struct integrity_iint_cache iint = {};
> + struct ima_event_data event_data = {.iint = &iint };
> + 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))
> + goto out;

"out:" is a simple return, no freeing memory.  Just return here.

> +
> + event_data.filename = eventname;

No need to initialize even_data.filename, here initialize it when it
is defined.

> +
> + iint.ima_hash = &hash.hdr;
> + iint.ima_hash->algo = ima_hash_algo;
> + iint.ima_hash->length = hash_digest_size[ima_hash_algo];
> +
> + ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
> + if (ret < 0)
> + goto out;
> +
> + ret = ima_alloc_init_template(&event_data, &entry, template_desc);
> + if (ret < 0)
> + goto out;
> +
> + if (action & IMA_MEASURE)

Why is this test needed again?

Mimi

> + ret = ima_store_template(entry, violation, NULL, buf, pcr);
> +
> + if (ret < 0)
> + ima_free_template_entry(entry);
> +
> +out:
> + return;
> +}
> +
> +/**
> + * ima_kexec_cmdline - measure kexec cmdline boot args
> + * @buf: pointer to buffer
> + * @size: size of buffer
> + *
> + * Buffers can only be measured, not appraised.
> + */
> +void ima_kexec_cmdline(const void *buf, int size)
> +{
> + u32 secid;
> +
> + if (buf && size != 0) {
> + security_task_getsecid(current, &secid);
> + process_buffer_measurement(buf, size, "kexec-cmdline",
> + current_cred(), secid);
> + }
> +}
> +
> static int __init init_ima(void)
> {
> int error;
>

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