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Commit b0935123 authored by Prakhar Srivastava's avatar Prakhar Srivastava Committed by Mimi Zohar
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IMA: Define a new hook to measure the kexec boot command line arguments 



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.

Signed-off-by: default avatarPrakhar Srivastava <prsriva02@gmail.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
parent 19453ce0

Documentation/ABI/testing/ima_policy

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ Description: 
		base: 	func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK][MODULE_CHECK]

				[FIRMWARE_CHECK]

				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]

				[KEXEC_CMDLINE]

			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]

			       [[^]MAY_EXEC]

			fsmagic:= hex value

include/linux/ima.h

+2 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 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_kexec_cmdline(const void *buf, int size);



#ifdef CONFIG_IMA_KEXEC

extern void ima_add_kexec_buffer(struct kimage *image);
@@ -92,6 +93,7 @@ static inline void ima_post_path_mknod(struct dentry *dentry) 
	return;

}



static inline void ima_kexec_cmdline(const void *buf, int size) {}

#endif /* CONFIG_IMA */



#ifndef CONFIG_IMA_KEXEC

security/integrity/ima/ima.h

+1 −0
Original line number Diff line number Diff line
@@ -190,6 +190,7 @@ static inline unsigned long ima_hash_key(u8 *digest) 
	hook(KEXEC_KERNEL_CHECK)	\

	hook(KEXEC_INITRAMFS_CHECK)	\

	hook(POLICY_CHECK)		\

	hook(KEXEC_CMDLINE)		\

	hook(MAX_CHECK)

#define __ima_hook_enumify(ENUM)	ENUM,

security/integrity/ima/ima_api.c

+1 −0
Original line number Diff line number Diff line
@@ -178,6 +178,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename, 
 *		subj=, obj=, type=, func=, mask=, fsmagic=

 *	subj,obj, and type: are LSM specific.

 *	func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK

 *	| KEXEC_CMDLINE

 *	mask: contains the permission mask

 *	fsmagic: hex value

 *

security/integrity/ima/ima_main.c

+72 −0
Original line number Diff line number Diff line
@@ -609,6 +609,78 @@ 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,

					    .filename = eventname};

	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))

		return;



	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;



	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;