Commit 7429b092 authored by Dmitry Kasatkin's avatar Dmitry Kasatkin Committed by Mimi Zohar
Browse files

ima: load policy using path 



We currently cannot do appraisal or signature vetting of IMA policies
since we currently can only load IMA policies by writing the contents
of the policy directly in, as follows:

cat policy-file > <securityfs>/ima/policy

If we provide the kernel the path to the IMA policy so it can load
the policy itself it'd be able to later appraise or vet the file
signature if it has one.  This patch adds support to load the IMA
policy with a given path as follows:

echo /etc/ima/ima_policy > /sys/kernel/security/ima/policy

Changelog v4+:
- moved kernel_read_file_from_path() error messages to callers
v3:
- moved kernel_read_file_from_path() to a separate patch
v2:
- after re-ordering the patches, replace calling integrity_kernel_read()
  to read the file with kernel_read_file_from_path() (Mimi)
- Patch description re-written by Luis R. Rodriguez

Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
parent d9ddf077

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -2581,6 +2581,7 @@ enum kernel_read_file_id { 
	READING_MODULE,

	READING_KEXEC_IMAGE,

	READING_KEXEC_INITRAMFS,

	READING_POLICY,

	READING_MAX_ID

};

security/integrity/ima/ima_fs.c

+43 −2
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/rculist.h>

#include <linux/rcupdate.h>

#include <linux/parser.h>

#include <linux/vmalloc.h>



#include "ima.h"
@@ -258,6 +259,43 @@ static const struct file_operations ima_ascii_measurements_ops = { 
	.release = seq_release,

};



static ssize_t ima_read_policy(char *path)

{

	void *data;

	char *datap;

	loff_t size;

	int rc, pathlen = strlen(path);



	char *p;



	/* remove \n */

	datap = path;

	strsep(&datap, "\n");



	rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);

	if (rc < 0) {

		pr_err("Unable to open file: %s (%d)", path, rc);

		return rc;

	}



	datap = data;

	while (size > 0 && (p = strsep(&datap, "\n"))) {

		pr_debug("rule: %s\n", p);

		rc = ima_parse_add_rule(p);

		if (rc < 0)

			break;

		size -= rc;

	}



	vfree(data);

	if (rc < 0)

		return rc;

	else if (size)

		return -EINVAL;

	else

		return pathlen;

}



static ssize_t ima_write_policy(struct file *file, const char __user *buf,

				size_t datalen, loff_t *ppos)

{
@@ -286,9 +324,12 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf, 
	result = mutex_lock_interruptible(&ima_write_mutex);

	if (result < 0)

		goto out_free;



	if (data[0] == '/')

		result = ima_read_policy(data);

	else 

		result = ima_parse_add_rule(data);

	mutex_unlock(&ima_write_mutex);



out_free:

	kfree(data);

out:

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