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[PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute

steven chen posted 7 patches 10 months ago
There is a newer version of this series
[PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute
Posted by steven chen 10 months ago 
ima_dump_measurement_list() is called during kexec 'load', which may
result in loss of IMA measurements during kexec soft reboot.  It needs
to be called during kexec 'execute'.

This patch includes the following changes:
 - Implement kimage_file_post_load() function to be invoked after the new
   Kernel image has been loaded for kexec.
 - Call kimage_file_post_load() from kexec_file_load() syscall only for
   kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH.  It will
   map the IMA segment, and register reboot notifier for the function
   ima_update_kexec_buffer() which would copy the IMA log at kexec soft
   reboot.
 - Make kexec_segment_size variable local static to the file, for it to be
   accessible both during kexec 'load' and 'execute'.
 - Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
   to ima_update_kexec_buffer().
 - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
   that the buffer is being copied at kexec 'execute', and resetting the
   file at kexec 'load' will corrupt the buffer.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
---
 kernel/kexec_file.c                |  8 ++++++
 security/integrity/ima/ima_kexec.c | 43 +++++++++++++++++++-----------
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 606132253c79..76b6a877b842 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -201,6 +201,11 @@ kimage_validate_signature(struct kimage *image)
 }
 #endif
 
+static void kimage_file_post_load(struct kimage *image)
+{
+	ima_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
@@ -428,6 +433,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 
 	kimage_terminate(image);
 
+	if (!(flags & KEXEC_FILE_ON_CRASH))
+		kimage_file_post_load(image);
+
 	ret = machine_kexec_post_load(image);
 	if (ret)
 		goto out;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 0fa65f91414b..f9dd7ff95b84 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -19,6 +19,7 @@
 #ifdef CONFIG_IMA_KEXEC
 static struct seq_file ima_kexec_file;
 static void *ima_kexec_buffer;
+static size_t kexec_segment_size;
 static bool ima_kexec_update_registered;
 
 static void ima_reset_kexec_file(struct seq_file *sf)
@@ -129,7 +130,6 @@ void ima_add_kexec_buffer(struct kimage *image)
 	/* use more understandable variable names than defined in kbuf */
 	void *kexec_buffer = NULL;
 	size_t kexec_buffer_size = 0;
-	size_t kexec_segment_size;
 	int ret;
 
 	/*
@@ -154,13 +154,6 @@ void ima_add_kexec_buffer(struct kimage *image)
 		return;
 	}
 
-	ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
-					kexec_segment_size);
-	if (ret < 0) {
-		pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
-		return;
-	}
-
 	kbuf.buffer = kexec_buffer;
 	kbuf.bufsz = kexec_buffer_size;
 	kbuf.memsz = kexec_segment_size;
@@ -178,12 +171,6 @@ void ima_add_kexec_buffer(struct kimage *image)
 	image->ima_segment_index = image->nr_segments - 1;
 	image->is_ima_segment_index_set = true;
 
-	/*
-	 * kexec owns kexec_buffer after kexec_add_buffer() is called
-	 * and it will vfree() that buffer.
-	 */
-	ima_reset_kexec_file(&ima_kexec_file);
-
 	kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
 		      kbuf.mem);
 }
@@ -194,7 +181,33 @@ 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;
+	void *buf = NULL;
+	size_t buf_size = 0;
+	int ret = NOTIFY_OK;
+
+	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;
 }
 
 struct notifier_block update_buffer_nb = {
-- 
2.25.1
Re: [PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute
Posted by kernel test robot 10 months ago 
Hi steven,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.14-rc3 next-20250219]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/steven-chen/ima-define-and-call-ima_alloc_kexec_file_buf/20250219-065931
base:   linus/master
patch link:    https://lore.kernel.org/r/20250218225502.747963-6-chenste%40linux.microsoft.com
patch subject: [PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute
config: x86_64-buildonly-randconfig-001-20250220 (https://download.01.org/0day-ci/archive/20250220/202502200920.rOyK1770-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250220/202502200920.rOyK1770-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502200920.rOyK1770-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/kexec_file.c: In function 'kimage_file_post_load':
>> kernel/kexec_file.c:206:9: error: implicit declaration of function 'ima_kexec_post_load'; did you mean 'machine_kexec_post_load'? [-Werror=implicit-function-declaration]
     206 |         ima_kexec_post_load(image);
         |         ^~~~~~~~~~~~~~~~~~~
         |         machine_kexec_post_load
   cc1: some warnings being treated as errors


vim +206 kernel/kexec_file.c

   203	
   204	static void kimage_file_post_load(struct kimage *image)
   205	{
 > 206		ima_kexec_post_load(image);
   207	}
   208	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Re: [PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute
Posted by Stefan Berger 10 months ago 

On 2/18/25 5:55 PM, steven chen wrote:
> ima_dump_measurement_list() is called during kexec 'load', which may
> result in loss of IMA measurements during kexec soft reboot.  It needs

... due to missed measurements that only occurred after kexec 'load'. 
Therefore, this function needs to be ...

> to be called during kexec 'execute'.
> 
> This patch includes the following changes:
>   - Implement kimage_file_post_load() function to be invoked after the new
>     Kernel image has been loaded for kexec.

s/Kernel/kernel

>   - Call kimage_file_post_load() from kexec_file_load() syscall only for
>     kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH.  It will
>     map the IMA segment, and register reboot notifier for the function
>     ima_update_kexec_buffer() which would copy the IMA log at kexec soft
>     reboot.
>   - Make kexec_segment_size variable local static to the file, for it to be

... to the file so that it becomes accessible ...

>     accessible both during kexec 'load' and 'execute'.
>   - Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
>     to ima_update_kexec_buffer().
>   - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
>     that the buffer is being copied at kexec 'execute', and resetting the
>     file at kexec 'load' will corrupt the buffer.

s/will/would

> 
> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
> Signed-off-by: steven chen <chenste@linux.microsoft.com>

With  the above changes:

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>

> ---
>   kernel/kexec_file.c                |  8 ++++++
>   security/integrity/ima/ima_kexec.c | 43 +++++++++++++++++++-----------
>   2 files changed, 36 insertions(+), 15 deletions(-)
> 
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 606132253c79..76b6a877b842 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -201,6 +201,11 @@ kimage_validate_signature(struct kimage *image)
>   }
>   #endif
>   
> +static void kimage_file_post_load(struct kimage *image)
> +{
> +	ima_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
> @@ -428,6 +433,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
>   
>   	kimage_terminate(image);
>   
> +	if (!(flags & KEXEC_FILE_ON_CRASH))
> +		kimage_file_post_load(image);
> +
>   	ret = machine_kexec_post_load(image);
>   	if (ret)
>   		goto out;
> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
> index 0fa65f91414b..f9dd7ff95b84 100644
> --- a/security/integrity/ima/ima_kexec.c
> +++ b/security/integrity/ima/ima_kexec.c
> @@ -19,6 +19,7 @@
>   #ifdef CONFIG_IMA_KEXEC
>   static struct seq_file ima_kexec_file;
>   static void *ima_kexec_buffer;
> +static size_t kexec_segment_size;
>   static bool ima_kexec_update_registered;
>   
>   static void ima_reset_kexec_file(struct seq_file *sf)
> @@ -129,7 +130,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>   	/* use more understandable variable names than defined in kbuf */
>   	void *kexec_buffer = NULL;
>   	size_t kexec_buffer_size = 0;
> -	size_t kexec_segment_size;
>   	int ret;
>   
>   	/*
> @@ -154,13 +154,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>   		return;
>   	}
>   
> -	ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
> -					kexec_segment_size);
> -	if (ret < 0) {
> -		pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
> -		return;
> -	}
> -
>   	kbuf.buffer = kexec_buffer;
>   	kbuf.bufsz = kexec_buffer_size;
>   	kbuf.memsz = kexec_segment_size;
> @@ -178,12 +171,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>   	image->ima_segment_index = image->nr_segments - 1;
>   	image->is_ima_segment_index_set = true;
>   
> -	/*
> -	 * kexec owns kexec_buffer after kexec_add_buffer() is called
> -	 * and it will vfree() that buffer.
> -	 */
> -	ima_reset_kexec_file(&ima_kexec_file);
> -
>   	kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
>   		      kbuf.mem);
>   }
> @@ -194,7 +181,33 @@ 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;
> +	void *buf = NULL;
> +	size_t buf_size = 0;
> +	int ret = NOTIFY_OK;
> +
> +	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;
>   }
>   
>   struct notifier_block update_buffer_nb = {
Re: [PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute
Posted by steven chen 10 months ago 
On 2/19/2025 7:57 AM, Stefan Berger wrote:
>
>
> On 2/18/25 5:55 PM, steven chen wrote:
>> ima_dump_measurement_list() is called during kexec 'load', which may
>> result in loss of IMA measurements during kexec soft reboot.  It needs
>
> ... due to missed measurements that only occurred after kexec 'load'. 
> Therefore, this function needs to be ...
>
>> to be called during kexec 'execute'.
>>
>> This patch includes the following changes:
>>   - Implement kimage_file_post_load() function to be invoked after 
>> the new
>>     Kernel image has been loaded for kexec.
>
> s/Kernel/kernel
>
>>   - Call kimage_file_post_load() from kexec_file_load() syscall only for
>>     kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH.  It 
>> will
>>     map the IMA segment, and register reboot notifier for the function
>>     ima_update_kexec_buffer() which would copy the IMA log at kexec soft
>>     reboot.
>>   - Make kexec_segment_size variable local static to the file, for it 
>> to be
>
> ... to the file so that it becomes accessible ...
>
>>     accessible both during kexec 'load' and 'execute'.
>>   - Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
>>     to ima_update_kexec_buffer().
>>   - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
>>     that the buffer is being copied at kexec 'execute', and resetting 
>> the
>>     file at kexec 'load' will corrupt the buffer.
>
> s/will/would
>
>>
>> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
>> Signed-off-by: steven chen <chenste@linux.microsoft.com>
>
> With  the above changes:
>
> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
>
>> ---
>>   kernel/kexec_file.c                |  8 ++++++
>>   security/integrity/ima/ima_kexec.c | 43 +++++++++++++++++++-----------
>>   2 files changed, 36 insertions(+), 15 deletions(-)
>>
>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>> index 606132253c79..76b6a877b842 100644
>> --- a/kernel/kexec_file.c
>> +++ b/kernel/kexec_file.c
>> @@ -201,6 +201,11 @@ kimage_validate_signature(struct kimage *image)
>>   }
>>   #endif
>>   +static void kimage_file_post_load(struct kimage *image)
>> +{
>> +    ima_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
>> @@ -428,6 +433,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, 
>> int, initrd_fd,
>>         kimage_terminate(image);
>>   +    if (!(flags & KEXEC_FILE_ON_CRASH))
>> +        kimage_file_post_load(image);
>> +
>>       ret = machine_kexec_post_load(image);
>>       if (ret)
>>           goto out;
>> diff --git a/security/integrity/ima/ima_kexec.c 
>> b/security/integrity/ima/ima_kexec.c
>> index 0fa65f91414b..f9dd7ff95b84 100644
>> --- a/security/integrity/ima/ima_kexec.c
>> +++ b/security/integrity/ima/ima_kexec.c
>> @@ -19,6 +19,7 @@
>>   #ifdef CONFIG_IMA_KEXEC
>>   static struct seq_file ima_kexec_file;
>>   static void *ima_kexec_buffer;
>> +static size_t kexec_segment_size;
>>   static bool ima_kexec_update_registered;
>>     static void ima_reset_kexec_file(struct seq_file *sf)
>> @@ -129,7 +130,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>>       /* use more understandable variable names than defined in kbuf */
>>       void *kexec_buffer = NULL;
>>       size_t kexec_buffer_size = 0;
>> -    size_t kexec_segment_size;
>>       int ret;
>>         /*
>> @@ -154,13 +154,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>>           return;
>>       }
>>   -    ret = ima_dump_measurement_list(&kexec_buffer_size, 
>> &kexec_buffer,
>> -                    kexec_segment_size);
>> -    if (ret < 0) {
>> -        pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
>> -        return;
>> -    }
>> -
>>       kbuf.buffer = kexec_buffer;
>>       kbuf.bufsz = kexec_buffer_size;
>>       kbuf.memsz = kexec_segment_size;
>> @@ -178,12 +171,6 @@ void ima_add_kexec_buffer(struct kimage *image)
>>       image->ima_segment_index = image->nr_segments - 1;
>>       image->is_ima_segment_index_set = true;
>>   -    /*
>> -     * kexec owns kexec_buffer after kexec_add_buffer() is called
>> -     * and it will vfree() that buffer.
>> -     */
>> -    ima_reset_kexec_file(&ima_kexec_file);
>> -
>>       kexec_dprintk("kexec measurement buffer for the loaded kernel 
>> at 0x%lx.\n",
>>                 kbuf.mem);
>>   }
>> @@ -194,7 +181,33 @@ 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;
>> +    void *buf = NULL;
>> +    size_t buf_size = 0;
>> +    int ret = NOTIFY_OK;
>> +
>> +    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;
>>   }
>>     struct notifier_block update_buffer_nb = {

Hi Stefan, thanks for your comments. I will update in next version.

Patchew 2.1-devel-b67e4c2

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