[RFC PATCH v9 14/16] scripts: add boot policy generation program

From: Deven Bowers <deven.desai(a)linux.microsoft.com&gt; 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: Deven Bowers <deven.desai(a)linux.microsoft.com&gt; Signed-off-by: Fan Wu <wufan(a)linux.microsoft.com&gt; --- v2: + No Changes v3: + No Changes v4: + No Changes v5: + No Changes v6: + No Changes v7: + Move from 01/11 to 14/16 + Don't return errno directly. + Make output of script more user-friendly + Add escaping for tab and '?' + Mark argv pointer const + Invert return code check in the boot policy parsing code path. v8: + No significant changes. v9: + no changes --- MAINTAINERS | 1 + scripts/Makefile | 1 + scripts/ipe/Makefile | 2 + scripts/ipe/polgen/.gitignore | 1 + scripts/ipe/polgen/Makefile | 6 ++ scripts/ipe/polgen/polgen.c | 145 ++++++++++++++++++++++++++++++++++ security/ipe/.gitignore | 1 + security/ipe/Kconfig | 10 +++ security/ipe/Makefile | 11 +++ security/ipe/fs.c | 8 ++ security/ipe/ipe.c | 19 +++++ 11 files changed, 205 insertions(+) create mode 100644 scripts/ipe/Makefile create mode 100644 scripts/ipe/polgen/.gitignore create mode 100644 scripts/ipe/polgen/Makefile create mode 100644 scripts/ipe/polgen/polgen.c create mode 100644 security/ipe/.gitignore diff --git a/MAINTAINERS b/MAINTAINERS index 5e27e84763cc..d5b4a6636b0d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -10276,6 +10276,7 @@ F: security/integrity/ INTEGRITY POLICY ENFORCEMENT (IPE) M: Fan Wu <wufan(a)linux.microsoft.com&gt; S: Supported +F: scripts/ipe/ F: security/ipe/ INTEL 810/815 FRAMEBUFFER DRIVER diff --git a/scripts/Makefile b/scripts/Makefile index 1575af84d557..5d1def33df82 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -41,6 +41,7 @@ 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 diff --git a/scripts/ipe/Makefile b/scripts/ipe/Makefile new file mode 100644 index 000000000000..e87553fbb8d6 --- /dev/null +++ b/scripts/ipe/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +subdir-y := polgen diff --git a/scripts/ipe/polgen/.gitignore b/scripts/ipe/polgen/.gitignore new file mode 100644 index 000000000000..80f32f25d200 --- /dev/null +++ b/scripts/ipe/polgen/.gitignore @@ -0,0 +1 @@ +polgen diff --git a/scripts/ipe/polgen/Makefile b/scripts/ipe/polgen/Makefile new file mode 100644 index 000000000000..066060c22b4a --- /dev/null +++ b/scripts/ipe/polgen/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0 +hostprogs-always-y := polgen +HOST_EXTRACFLAGS += \ + -I$(srctree)/include \ + -I$(srctree)/include/uapi \ + diff --git a/scripts/ipe/polgen/polgen.c b/scripts/ipe/polgen/polgen.c new file mode 100644 index 000000000000..40b6fe07f47b --- /dev/null +++ b/scripts/ipe/polgen/polgen.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 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) +{ + int rc = 0; + FILE *fd; + char *lbuf; + size_t fsize; + size_t read; + + 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[]) +{ + int rc = 0; + size_t len = 0; + char *policy = NULL; + + 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; +} diff --git a/security/ipe/.gitignore b/security/ipe/.gitignore new file mode 100644 index 000000000000..eca22ad5ed22 --- /dev/null +++ b/security/ipe/.gitignore @@ -0,0 +1 @@ +boot-policy.c \ No newline at end of file diff --git a/security/ipe/Kconfig b/security/ipe/Kconfig index dd9a066dd35a..691fdb9ae60e 100644 --- a/security/ipe/Kconfig +++ b/security/ipe/Kconfig @@ -17,6 +17,16 @@ menuconfig SECURITY_IPE If unsure, answer N. if SECURITY_IPE +config IPE_BOOT_POLICY + string "Integrity policy to apply on system startup" + help + This option specifies a filepath to a IPE policy that is compiled + into the kernel. This policy will be enforced until a policy update + is deployed via the $securityfs/ipe/policies/$policy_name/active + interface. + + If unsure, leave blank. + menu "IPE Trust Providers" config IPE_PROP_DM_VERITY diff --git a/security/ipe/Makefile b/security/ipe/Makefile index 90203daf0dbb..e6d5176bc20b 100644 --- a/security/ipe/Makefile +++ b/security/ipe/Makefile @@ -5,7 +5,16 @@ # Makefile for building the IPE module as part of the kernel tree. # +quiet_cmd_polgen = IPE_POL $(2) + cmd_polgen = scripts/ipe/polgen/polgen security/ipe/boot-policy.c $(2) + +targets += boot-policy.c + +$(obj)/boot-policy.c: scripts/ipe/polgen/polgen $(CONFIG_IPE_BOOT_POLICY) FORCE + $(call if_changed,polgen,$(CONFIG_IPE_BOOT_POLICY)) + obj-$(CONFIG_SECURITY_IPE) += \ + boot-policy.o \ digest.o \ eval.o \ fs.o \ @@ -16,3 +25,5 @@ obj-$(CONFIG_SECURITY_IPE) += \ policy_parser.o \ digest.o \ audit.o \ + +clean-files := boot-policy.c \ diff --git a/security/ipe/fs.c b/security/ipe/fs.c index bbee17b59b1b..0a371c785e3b 100644 --- a/security/ipe/fs.c +++ b/security/ipe/fs.c @@ -185,6 +185,7 @@ static const struct file_operations enforce_fops = { static int __init ipe_init_securityfs(void) { int rc = 0; + struct ipe_policy *p = NULL; if (!ipe_enabled) return -EOPNOTSUPP; @@ -221,6 +222,13 @@ static int __init ipe_init_securityfs(void) goto err; } + p = ipe_get_policy_rcu(ipe_active_policy); + if (p) { + rc = ipe_new_policyfs_node(p); + if (rc) + goto err; + } + return 0; err: securityfs_remove(np); diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c index 705ce9a003de..458f7a542c66 100644 --- a/security/ipe/ipe.c +++ b/security/ipe/ipe.c @@ -7,6 +7,7 @@ #include "hooks.h" #include "eval.h" +extern const char *const ipe_boot_policy; bool ipe_enabled; static struct lsm_blob_sizes ipe_blobs __lsm_ro_after_init = { @@ -64,10 +65,28 @@ static struct security_hook_list ipe_hooks[] __lsm_ro_after_init = { static int __init ipe_init(void) { int rc = 0; + struct ipe_policy *p = NULL; security_add_hooks(ipe_hooks, ARRAY_SIZE(ipe_hooks), "ipe"); ipe_enabled = true; + if (ipe_boot_policy) { + p = ipe_new_policy(ipe_boot_policy, strlen(ipe_boot_policy), + NULL, 0); + if (IS_ERR(p)) { + rc = PTR_ERR(p); + goto err; + } + + rc = ipe_set_active_pol(p); + if (rc) + goto err; + } + + goto out; +err: + ipe_free_policy(p); +out: return rc; } -- 2.39.0