Commit ba199dc9 authored by Deven Bowers's avatar Deven Bowers Committed by Paul Moore
Browse files

scripts: add boot policy generation program 



Enables an IPE policy to be enforced from kernel start, enabling access
control based on trust from kernel startup. This is accomplished by
transforming an IPE policy indicated by CONFIG_IPE_BOOT_POLICY into a
c-string literal that is parsed at kernel startup as an unsigned policy.

Signed-off-by: default avatarDeven Bowers <deven.desai@linux.microsoft.com>
Signed-off-by: default avatarFan Wu <wufan@linux.microsoft.com>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 31f8c868

scripts/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ targets += module.lds 
subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins

subdir-$(CONFIG_MODVERSIONS) += genksyms

subdir-$(CONFIG_SECURITY_SELINUX) += selinux

subdir-$(CONFIG_SECURITY_IPE) += ipe



# Let clean descend into subdirs

subdir-	+= basic dtc gdb kconfig mod

scripts/ipe/Makefile

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+2 −0
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# SPDX-License-Identifier: GPL-2.0-only

subdir-y := polgen

scripts/ipe/polgen/.gitignore

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+2 −0
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# SPDX-License-Identifier: GPL-2.0-only

polgen

scripts/ipe/polgen/Makefile

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# SPDX-License-Identifier: GPL-2.0

hostprogs-always-y	:= polgen

HOST_EXTRACFLAGS += \

	-I$(srctree)/include \

	-I$(srctree)/include/uapi \

scripts/ipe/polgen/polgen.c

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+145 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.

 */



#include <stdlib.h>

#include <stddef.h>

#include <stdio.h>

#include <unistd.h>

#include <errno.h>



static void usage(const char *const name)

{

	printf("Usage: %s OutputFile (PolicyFile)\n", name);

	exit(EINVAL);

}



static int policy_to_buffer(const char *pathname, char **buffer, size_t *size)

{

	size_t fsize;

	size_t read;

	char *lbuf;

	int rc = 0;

	FILE *fd;



	fd = fopen(pathname, "r");

	if (!fd) {

		rc = errno;

		goto out;

	}



	fseek(fd, 0, SEEK_END);

	fsize = ftell(fd);

	rewind(fd);



	lbuf = malloc(fsize);

	if (!lbuf) {

		rc = ENOMEM;

		goto out_close;

	}



	read = fread((void *)lbuf, sizeof(*lbuf), fsize, fd);

	if (read != fsize) {

		rc = -1;

		goto out_free;

	}



	*buffer = lbuf;

	*size = fsize;

	fclose(fd);



	return rc;



out_free:

	free(lbuf);

out_close:

	fclose(fd);

out:

	return rc;

}



static int write_boot_policy(const char *pathname, const char *buf, size_t size)

{

	int rc = 0;

	FILE *fd;

	size_t i;



	fd = fopen(pathname, "w");

	if (!fd) {

		rc = errno;

		goto err;

	}



	fprintf(fd, "/* This file is automatically generated.");

	fprintf(fd, " Do not edit. */\n");

	fprintf(fd, "#include <linux/stddef.h>\n");

	fprintf(fd, "\nextern const char *const ipe_boot_policy;\n\n");

	fprintf(fd, "const char *const ipe_boot_policy =\n");



	if (!buf || size == 0) {

		fprintf(fd, "\tNULL;\n");

		fclose(fd);

		return 0;

	}



	fprintf(fd, "\t\"");



	for (i = 0; i < size; ++i) {

		switch (buf[i]) {

		case '"':

			fprintf(fd, "\\\"");

			break;

		case '\'':

			fprintf(fd, "'");

			break;

		case '\n':

			fprintf(fd, "\\n\"\n\t\"");

			break;

		case '\\':

			fprintf(fd, "\\\\");

			break;

		case '\t':

			fprintf(fd, "\\t");

			break;

		case '\?':

			fprintf(fd, "\\?");

			break;

		default:

			fprintf(fd, "%c", buf[i]);

		}

	}

	fprintf(fd, "\";\n");

	fclose(fd);



	return 0;



err:

	if (fd)

		fclose(fd);

	return rc;

}



int main(int argc, const char *const argv[])

{

	char *policy = NULL;

	size_t len = 0;

	int rc = 0;



	if (argc < 2)

		usage(argv[0]);



	if (argc > 2) {

		rc = policy_to_buffer(argv[2], &policy, &len);

		if (rc != 0)

			goto cleanup;

	}



	rc = write_boot_policy(argv[1], policy, len);

cleanup:

	if (policy)

		free(policy);

	if (rc != 0)

		perror("An error occurred during policy conversion: ");

	return rc;

}