On Mon, 2025-02-03 at 15:20 -0800, steven chen wrote:
> The amount of memory allocated at kexec load, even with the extra memory
> allocated, might not be large enough for the entire measurement list. The
> indeterminate interval between kexec 'load' and 'execute' could exacerbate
> this problem.
>
> Define two new IMA events, 'kexec_load' and 'kexec_execute', to be
> measured as critical data at kexec 'load' and 'execute' respectively.
> Report the allocated kexec segment size, IMA binary log size and the
> runtime measurements count as part of those events.
>
> These events, and the values reported through them, serve as markers in
> the IMA log to verify the IMA events are captured during kexec soft
> reboot. The presence of a 'kexec_load' event in between the last two
> 'boot_aggregate' events in the IMA log implies this is a kexec soft
> reboot, and not a cold-boot. And the absence of 'kexec_execute' event
> after kexec soft reboot implies missing events in that window which
> results in inconsistency with TPM PCR quotes, necessitating a cold boot
> for a successful remote attestation.
As a reminder, please include directions for verifying the buffer data hash
against
the buffer data. The directions would be similar to those in commit 6b4da8c0e7f
("IMA: Define a new template field buf").
>
> Reviewed-by: Stefan Berger <stef...@linux.ibm.com>
> Author: Tushar Sugandhi <tusha...@linux.microsoft.com>
> Signed-off-by: Tushar Sugandhi <tusha...@linux.microsoft.com>
> Signed-off-by: steven chen <chen...@linux.microsoft.com>
> ---
> security/integrity/ima/ima_kexec.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/security/integrity/ima/ima_kexec.c
> b/security/integrity/ima/ima_kexec.c
> index c9c916f69ca7..0342ddfa9342 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -17,6 +17,8 @@
> #include "ima.h"
>
> #ifdef CONFIG_IMA_KEXEC
> +#define IMA_KEXEC_EVENT_LEN 256
> +
> static struct seq_file ima_kexec_file;
> static void *ima_kexec_buffer;
> static size_t kexec_segment_size;
> @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
> ima_reset_kexec_file(sf);
> }
>
> +static void ima_measure_kexec_event(const char *event_name)
> +{
> + char ima_kexec_event[IMA_KEXEC_EVENT_LEN];
> + size_t buf_size = 0;
> + long len;
> +
> + buf_size = ima_get_binary_runtime_size();
> + len = atomic_long_read(&ima_htable.len);
> +
> + scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
> + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
> + "ima_runtime_measurements_count=%ld;",
> + kexec_segment_size, buf_size, len);
>From scripts/checkpatch.pl, "Alignment should match open parenthesis".
> +
> + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event,
> + strlen(ima_kexec_event), false, NULL,
> 0);
>From the kernel-doc scnprintf(), returns the number of bytes. There should be
>no
need to calculate it using strlen().
> +}
> +
> static int ima_alloc_kexec_file_buf(size_t segment_size)
> {
> /*
> @@ -60,6 +80,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
> out:
> ima_kexec_file.read_pos = 0;
> ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved
> space
> */
> + ima_measure_kexec_event("kexec_load");
>
> return 0;
> }
> @@ -201,6 +222,8 @@ static int ima_update_kexec_buffer(struct notifier_block
> *self,
> return ret;
> }
>
> + ima_measure_kexec_event("kexec_execute");
> +
> ret = ima_dump_measurement_list(&buf_size, &buf,
> kexec_segment_size);
>
After fixing up and applying this patch set to 6.14.0-rc1, I'm not seeing the
"kexec_execute". Even after changing the default extra memory, I'm still not
seeing
the measurement.
Mimi
