ima_dump_measurement_list() is called during kexec 'load', which may
result in loss of IMA measurements during kexec soft reboot. Due to 
missed measurements that only occurred after kexec 'load', this function 
needs to be called during kexec 'execute'.

Make the kexec_segment_size variable a local static variable within the 
file, so it can be accessed during both kexec 'load' and 'execute'.
 
Implement the kexec_post_load() function to be invoked after the new kernel
image has been loaded for kexec. Instead of calling machine_kexec_post_load()
directly from the kexec_file_load() syscall, call kexec_post_load(), which in
turn calls machine_kexec_post_load() to maintain the original image processing.
 
Invoke ima_kexec_post_load() within the kexec_post_load() API only for kexec 
soft reboot scenarios, excluding KEXEC_FILE_ON_CRASH.
 
Register a reboot notifier for the ima_update_kexec_buffer() API within 
ima_kexec_post_load() to ensure it is called upon receiving a reboot 
notification.
 
Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to 
ima_update_kexec_buffer() to copy the IMA log at the kexec 'execute' stage.
 
When there is insufficient memory to copy all the measurement logs, copy as
much of the measurement list as possible.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com> 
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
 kernel/kexec_file.c                | 11 +++++++-
 security/integrity/ima/ima_kexec.c | 43 ++++++++++++++++++++----------
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 606132253c79..b3eb515ca051 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -201,6 +201,15 @@ kimage_validate_signature(struct kimage *image)
 }
 #endif
 
+static int kexec_post_load(struct kimage *image, unsigned long flags)
+{
+#ifdef CONFIG_IMA_KEXEC
+	if (!(flags & KEXEC_FILE_ON_CRASH))
+		ima_kexec_post_load(image);
+#endif
+	return machine_kexec_post_load(image);
+}
+
 /*
  * In file mode list of segments is prepared by kernel. Copy relevant
  * data from user space, do error checking, prepare segment list
@@ -428,7 +437,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 
 	kimage_terminate(image);
 
-	ret = machine_kexec_post_load(image);
+	ret = kexec_post_load(image, flags);
 	if (ret)
 		goto out;
 
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index e79f6caf895b..5c3b3e0b2186 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -19,6 +19,7 @@
 #ifdef CONFIG_IMA_KEXEC
 static bool ima_kexec_update_registered;
 static struct seq_file ima_kexec_file;
+static size_t kexec_segment_size;
 static void *ima_kexec_buffer;
 
 static void ima_free_kexec_file_buf(struct seq_file *sf)
@@ -72,9 +73,6 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 		}
 	}
 
-	if (ret < 0)
-		goto out;
-
 	/*
 	 * fill in reserved space with some buffer details
 	 * (eg. version, buffer size, number of measurements)
@@ -94,7 +92,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 
 	*buffer_size = ima_kexec_file.count;
 	*buffer = ima_kexec_file.buf;
-out:
+
 	return ret;
 }
 
@@ -112,9 +110,8 @@ void ima_add_kexec_buffer(struct kimage *image)
 	unsigned long binary_runtime_size;
 
 	/* use more understandable variable names than defined in kbuf */
+	size_t kexec_buffer_size = 0;
 	void *kexec_buffer = NULL;
-	size_t kexec_buffer_size;
-	size_t kexec_segment_size;
 	int ret;
 
 	/*
@@ -139,13 +136,6 @@ void ima_add_kexec_buffer(struct kimage *image)
 		return;
 	}
 
-	ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
-				  kexec_segment_size);
-	if (!kexec_buffer) {
-		pr_err("Not enough memory for the kexec measurement buffer.\n");
-		return;
-	}
-
 	kbuf.buffer = kexec_buffer;
 	kbuf.bufsz = kexec_buffer_size;
 	kbuf.memsz = kexec_segment_size;
@@ -173,7 +163,32 @@ void ima_add_kexec_buffer(struct kimage *image)
 static int ima_update_kexec_buffer(struct notifier_block *self,
 				   unsigned long action, void *data)
 {
-	return NOTIFY_OK;
+	size_t buf_size = 0;
+	int ret = NOTIFY_OK;
+	void *buf = NULL;
+
+	if (!kexec_in_progress) {
+		pr_info("No kexec in progress.\n");
+		return ret;
+	}
+
+	if (!ima_kexec_buffer) {
+		pr_err("Kexec buffer not set.\n");
+		return ret;
+	}
+
+	ret = ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size);
+
+	if (ret)
+		pr_err("Dump measurements failed. Error:%d\n", ret);
+
+	if (buf_size != 0)
+		memcpy(ima_kexec_buffer, buf, buf_size);
+
+	kimage_unmap_segment(ima_kexec_buffer);
+	ima_kexec_buffer = NULL;
+
+	return ret;
 }
 
 static struct notifier_block update_buffer_nb = {
-- 
2.25.1

On Wed, 2025-04-02 at 05:47 -0700, steven chen wrote:
> ima_dump_measurement_list() is called during kexec 'load', which may
> result in loss of IMA measurements during kexec soft reboot. Due to 
> missed measurements that only occurred after kexec 'load', this function 
> needs to be called during kexec 'execute'.

Re-use the motivation from 5/9 (with tweak):

The IMA log is currently copied to the new kernel during kexec 'load' using
ima_dump_measurement_list(). However, the IMA measurement list copied at kexec
'load' may result in loss of IMA measurements records that only occurred after
the kexec 'load'.

And finish the paragraph with:
Move the IMA measurement list log copy from kexec 'load' to 'execute'.

> 
> Make the kexec_segment_size variable a local static variable within the 
> file, so it can be accessed during both kexec 'load' and 'execute'.

>  
> Implement the kexec_post_load() function to be invoked after the new kernel
> image has been loaded for kexec. Instead of calling machine_kexec_post_load()
> directly from the kexec_file_load() syscall, call kexec_post_load(), which in
> turn calls machine_kexec_post_load() to maintain the original image processing.

Define kexec_post_load() as a wrapper for calling ima_kexec_post_load() and
machine_kexec_post_load().  Replace the existing direct call to
machine_kexec_post_load() with kexec_post_load().

>  
> Invoke ima_kexec_post_load() within the kexec_post_load() API only for kexec 
> soft reboot scenarios, excluding KEXEC_FILE_ON_CRASH.

"Don't call ima_kexec_post_load() on KEXEC_FILE_ON_CRASH" would be listed in the
Changelog if it changed, not here in the patch description.  Please remove.

>  
> Register a reboot notifier for the ima_update_kexec_buffer() API within 
> ima_kexec_post_load() to ensure it is called upon receiving a reboot 
> notification.

Registering the reboot notifier was done in "[PATCH v11 5/9] ima: kexec: define
functions to copy IMA log at soft boot", not here.  Please remove.

>  
> Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to 
> ima_update_kexec_buffer() to copy the IMA log at the kexec 'execute' stage.

This information was already stated in the first paragraph as part of the
motivation for the patch.  Please remove.

>  
> When there is insufficient memory to copy all the measurement logs, copy as
> much of the measurement list as possible.

Is this comment still applicable to this patch?

Please review your patch descriptions before posting, making sure that
everything is still applicable.

thanks,

Mimi

> 
> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Baoquan He <bhe@redhat.com> 
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Dave Young <dyoung@redhat.com>
> Signed-off-by: steven chen <chenste@linux.microsoft.com>
> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>

On 4/8/2025 9:17 AM, Mimi Zohar wrote:
> On Wed, 2025-04-02 at 05:47 -0700, steven chen wrote:
>> ima_dump_measurement_list() is called during kexec 'load', which may
>> result in loss of IMA measurements during kexec soft reboot. Due to
>> missed measurements that only occurred after kexec 'load', this function
>> needs to be called during kexec 'execute'.
> Re-use the motivation from 5/9 (with tweak):
>
> The IMA log is currently copied to the new kernel during kexec 'load' using
> ima_dump_measurement_list(). However, the IMA measurement list copied at kexec
> 'load' may result in loss of IMA measurements records that only occurred after
> the kexec 'load'.
>
> And finish the paragraph with:
> Move the IMA measurement list log copy from kexec 'load' to 'execute'.
>
>> Make the kexec_segment_size variable a local static variable within the
>> file, so it can be accessed during both kexec 'load' and 'execute'.
>>   
>> Implement the kexec_post_load() function to be invoked after the new kernel
>> image has been loaded for kexec. Instead of calling machine_kexec_post_load()
>> directly from the kexec_file_load() syscall, call kexec_post_load(), which in
>> turn calls machine_kexec_post_load() to maintain the original image processing.
> Define kexec_post_load() as a wrapper for calling ima_kexec_post_load() and
> machine_kexec_post_load().  Replace the existing direct call to
> machine_kexec_post_load() with kexec_post_load().
>
>>   
>> Invoke ima_kexec_post_load() within the kexec_post_load() API only for kexec
>> soft reboot scenarios, excluding KEXEC_FILE_ON_CRASH.
> "Don't call ima_kexec_post_load() on KEXEC_FILE_ON_CRASH" would be listed in the
> Changelog if it changed, not here in the patch description.  Please remove.
>
>>   
>> Register a reboot notifier for the ima_update_kexec_buffer() API within
>> ima_kexec_post_load() to ensure it is called upon receiving a reboot
>> notification.
> Registering the reboot notifier was done in "[PATCH v11 5/9] ima: kexec: define
> functions to copy IMA log at soft boot", not here.  Please remove.
>
>>   
>> Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to
>> ima_update_kexec_buffer() to copy the IMA log at the kexec 'execute' stage.
> This information was already stated in the first paragraph as part of the
> motivation for the patch.  Please remove.
>
>>   
>> When there is insufficient memory to copy all the measurement logs, copy as
>> much of the measurement list as possible.
> Is this comment still applicable to this patch?
>
> Please review your patch descriptions before posting, making sure that
> everything is still applicable.
>
> thanks,
>
> Mimi

Hi Mimi,

Thanks for your comments. I will update in next version.

Steven

>> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
>> Cc: Eric Biederman <ebiederm@xmission.com>
>> Cc: Baoquan He <bhe@redhat.com>
>> Cc: Vivek Goyal <vgoyal@redhat.com>
>> Cc: Dave Young <dyoung@redhat.com>
>> Signed-off-by: steven chen <chenste@linux.microsoft.com>
>> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>