Re: [PATCH v2 2/5 RFC] use event name instead of enum to make the call generic

[Nayna <nayna@linux.vnet.ibm.com>]

On 04/23/2019 08:15 PM, Prakhar Srivastava wrote:
> From: Prakhar Srivastava <prsriva02@gmail.com>
>
> Signed-off-by: Prakhar Srivastava <prsriva@microsoft.com>
> ---
>
> Currently for soft reboot(kexec_file_load) the kernel file and
> signature is measured by IMA. The cmdline args used to load the kernel
> is not measured.
> The boot aggregate that gets calculated will have no change since the
> EFI loader has not been triggered.
> Adding the kexec cmdline args measure and kernel version will add some
> attestable criteria.
>

Any reason for including the whole commit message after "---"

Anything after "---" is not included in the patch description when patch 
is applied.

This comment applies to all the patches in this patchset.

> remove enums to control type of buffers entries, instead pass the event name to be used.

Is the last statement meant to be a Changelog from v1-> v2 ? Only the 
changelog has to be after "---"

Also, If posting more than one patch, it is preferrable to add a 
cover-letter.


>   include/linux/ima.h               | 10 ++--------
>   kernel/kexec_file.c               |  3 +++
>   security/integrity/ima/ima.h      |  2 +-
>   security/integrity/ima/ima_main.c | 30 ++++++++++--------------------
>   4 files changed, 16 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index 733d0cb9dedc..5e41507c57e5 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -14,12 +14,6 @@
>   #include <linux/kexec.h>
>   struct linux_binprm;
>
> -enum __buffer_id {
> -	KERNEL_VERSION,
> -	KEXEC_CMDLINE,
> -	MAX_BUFFER_ID = KEXEC_CMDLINE
> -} buffer_id;
> -

Is the v2 version created on top of the v1 version that was posted ?

The v2 version has to be on top of the HEAD of the repository itself, 
and not on the v1 version. Only the final reviewed and tested version 
makes to the upstream.

Btw, which repository and its branch are you using ?

Thanks & Regards,
       - Nayna




>   #ifdef CONFIG_IMA
>   extern int ima_bprm_check(struct linux_binprm *bprm);
>   extern int ima_file_check(struct file *file, int mask, int opened);
> @@ -29,7 +23,7 @@ extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
>   extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
>   			      enum kernel_read_file_id id);
>   extern void ima_post_path_mknod(struct dentry *dentry);
> -extern void ima_buffer_check(const void *buff, int size, enum buffer_id id);
> +extern void ima_buffer_check(const void *buff, int size, char *eventname);
>   #ifdef CONFIG_IMA_KEXEC
>   extern void ima_add_kexec_buffer(struct kimage *image);
>   #endif
> @@ -72,7 +66,7 @@ static inline void ima_post_path_mknod(struct dentry *dentry)
>   }
>
>   static inline void ima_buffer_check(const void *buff, int size,
> -			enum buffer_id id)
> +			char *eventname)
>   {
>   	return;
>   }
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b118735fea9d..2a5234eb4b28 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -182,6 +182,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
>   			ret = -EINVAL;
>   			goto out;
>   		}
> +
> +		ima_buffer_check(image->cmdline_buf, cmdline_len - 1,
> +				"kexec_cmdline");
>   	}
>
>   	/* Call arch image load handlers */
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index b71f2f6f7421..fcade3c103ed 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -181,8 +181,8 @@ enum ima_hooks {
>   	FIRMWARE_CHECK,
>   	KEXEC_KERNEL_CHECK,
>   	KEXEC_INITRAMFS_CHECK,
> -	BUFFER_CHECK,
>   	POLICY_CHECK,
> +	BUFFER_CHECK,
>   	MAX_CHECK
>   };
>
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 6408cadaadbb..da82c705a5ed 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -160,8 +160,7 @@ void ima_file_free(struct file *file)
>    * (Instead of using the file hash the buffer hash is used).
>    * @buff - The buffer that needs to be added to the log
>    * @size - size of buffer(in bytes)
> - * @id - buffer id, this is differentiator for the various buffers
> - * that can be measured.
> + * @id - eventname, event name to be used for buffer measurement.
>    *
>    * The buffer passed is added to the ima logs.
>    * If the sig template is used, then the sig field contains the buffer.
> @@ -170,7 +169,7 @@ void ima_file_free(struct file *file)
>    * On error cases surface errors from ima calls.
>    */
>   static int process_buffer_measurement(const void *buff, int size,
> -				enum buffer_id id)
> +				char *eventname)
>   {
>   	int ret = -EINVAL;
>   	struct ima_template_entry *entry = NULL;
> @@ -185,23 +184,13 @@ static int process_buffer_measurement(const void *buff, int size,
>   	int violation = 0;
>   	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
>
> -	if (!buff || size ==  0)
> +	if (!buff || size ==  0 || !eventname)
>   		goto err_out;
>
>   	if (ima_get_action(NULL, 0, BUFFER_CHECK, &pcr) != IMA_MEASURE)
>   		goto err_out;
>
> -	switch (buffer_id) {
> -	case KERNEL_VERSION:
> -		name = "Kernel-version";
> -		break;
> -	case KEXEC_CMDLINE:
> -		name = "Kexec-cmdline";
> -		break;
> -	default:
> -		goto err_out;
> -	}
> -
> +	name = eventname;
>   	memset(iint, 0, sizeof(*iint));
>   	memset(&hash, 0, sizeof(hash));
>
> @@ -452,15 +441,16 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
>    * ima_buffer_check - based on policy, collect & store buffer measurement
>    * @buf: pointer to buffer
>    * @size: size of buffer
> - * @buffer_id: caller identifier
> + * @eventname: caller identifier
>    *
>    * Buffers can only be measured, not appraised.  The buffer identifier
> - * is used as the measurement list entry name (eg. boot_cmdline).
> + * is used as the measurement list entry name (eg. boot_cmdline,
> + * kernel_version).
>    */
> -void ima_buffer_check(const void *buf, int size, enum buffer_id id)
> +void ima_buffer_check(const void *buf, int size, char *eventname)
>   {
> -	if (buf && size != 0)
> -		process_buffer_measurement(buf, size, id);
> +	if (buf && size != 0 && eventname)
> +		process_buffer_measurement(buf, size, eventname);
>
>   	return;
>   }