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Merge pull request #23122 from poettering/creds-has-tpm2

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tpm2: beef up tpm2 support checks
This commit is contained in:
Lennart Poettering 2022-04-20 23:18:02 +02:00 committed by GitHub
parent ebf3ee4105 eb81249e8a
commit 231a1caf5e
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 125 additions and 30 deletions
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28
man/systemd-creds.xml
View file

@ -163,6 +163,20 @@
and thus decryption is entirely automatic.</para></listitem>
</varlistentry>
<varlistentry>
<term><command>has-tpm2</command></term>
<listitem><para>Reports whether the system is equipped with a TPM2 device usable for protecting
credentials. If the a TPM2 device has been discovered, is supported, and is being used by firmware,
by the OS kernel drivers and by userspace (i.e. systemd) this prints <literal>yes</literal> and exits
with exit status zero. If no such device is discovered/supported/used, prints
<literal>no</literal>. Otherwise prints <literal>partial</literal>. In either of these two cases
exits with non-zero exit status. It also shows three lines indicating separately whether drivers,
firmware and the system discovered/support/use TPM2.</para>
<para>Combine with <option>--quiet</option> to suppress the output.</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
@ -314,6 +328,14 @@
<citerefentry><refentrytitle>systemd-cryptenroll</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--quiet</option></term>
<term><option>-q</option></term>
<listitem><para>When used with <command>has-tpm2</command> suppresses the output, and only returns an
exit status indicating support for TPM2.</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="no-pager" />
<xi:include href="standard-options.xml" xpointer="no-legend" />
<xi:include href="standard-options.xml" xpointer="json" />
@ -324,6 +346,12 @@
<title>Exit status</title>
<para>On success, 0 is returned.</para>
<para>In case of the <command>has-tpm2</command> command returns 0 if a TPM2 device is discovered,
supported and used by firmware, driver, and userspace (i.e. systemd). Otherwise returns the OR
combination of the value 1 (in case firmware support is missing), 2 (in case driver support is missing)
and 4 (in case userspace support is missing). If no TPM2 support is available at all, value 7 is hence
returned.</para>
</refsect1>
<refsect1>

13
src/boot/bootctl.c
View file

@ -47,6 +47,7 @@
#include "terminal-util.h"
#include "tmpfile-util.h"
#include "tmpfile-util-label.h"
#include "tpm2-util.h"
#include "umask-util.h"
#include "utf8.h"
#include "util.h"
@ -1697,10 +1698,10 @@ static int verb_status(int argc, char *argv[], void *userdata) {
{ EFI_LOADER_FEATURE_RANDOM_SEED, "Support for passing random seed to OS" },
{ EFI_LOADER_FEATURE_LOAD_DRIVER, "Load drop-in drivers" },
};
_cleanup_free_ char *fw_type = NULL, *fw_info = NULL, *loader = NULL, *loader_path = NULL, *stub = NULL;
sd_id128_t loader_part_uuid = SD_ID128_NULL;
uint64_t loader_features = 0;
Tpm2Support s;
int have;
read_efi_var(EFI_LOADER_VARIABLE(LoaderFirmwareType), &fw_type);
@ -1723,7 +1724,15 @@ static int verb_status(int argc, char *argv[], void *userdata) {
printf(" Secure Boot: %sd (%s)\n",
enable_disable(IN_SET(secure, SECURE_BOOT_USER, SECURE_BOOT_DEPLOYED)),
secure_boot_mode_to_string(secure));
printf(" TPM2 Support: %s\n", yes_no(efi_has_tpm2()));
s = tpm2_support();
printf(" TPM2 Support: %s%s%s\n",
FLAGS_SET(s, TPM2_SUPPORT_FIRMWARE|TPM2_SUPPORT_DRIVER) ? ansi_highlight_green() :
(s & (TPM2_SUPPORT_FIRMWARE|TPM2_SUPPORT_DRIVER)) != 0 ? ansi_highlight_red() : ansi_highlight_yellow(),
FLAGS_SET(s, TPM2_SUPPORT_FIRMWARE|TPM2_SUPPORT_DRIVER) ? "yes" :
(s & TPM2_SUPPORT_FIRMWARE) ? "firmware only, driver unavailable" :
(s & TPM2_SUPPORT_DRIVER) ? "driver only, firmware unavailable" : "no",
ansi_normal());
k = efi_get_reboot_to_firmware();
if (k > 0)

51
src/creds/creds.c
View file

@ -48,6 +48,7 @@ static bool arg_name_any = false;
static usec_t arg_timestamp = USEC_INFINITY;
static usec_t arg_not_after = USEC_INFINITY;
static bool arg_pretty = false;
static bool arg_quiet = false;
static const char* transcode_mode_table[_TRANSCODE_MAX] = {
[TRANSCODE_OFF] = "off",
@ -525,6 +526,34 @@ static int verb_setup(int argc, char **argv, void *userdata) {
return EXIT_SUCCESS;
}
static int verb_has_tpm2(int argc, char **argv, void *userdata) {
Tpm2Support s;
s = tpm2_support();
if (!arg_quiet) {
if (s == TPM2_SUPPORT_FULL)
puts("yes");
else if (s == TPM2_SUPPORT_NONE)
puts("no");
else
puts("partial");
printf("%sfirmware\n"
"%sdriver\n"
"%ssystem\n",
plus_minus(s & TPM2_SUPPORT_FIRMWARE),
plus_minus(s & TPM2_SUPPORT_DRIVER),
plus_minus(s & TPM2_SUPPORT_SYSTEM));
}
/* Return inverted bit flags. So that TPM2_SUPPORT_FULL becomes EXIT_SUCCESS and the other values
* become some reasonable values 1…7. i.e. the flags we return here tell what is missing rather than
* what is there, acknowledging the fact that for process exit statusses it is customary to return
* zero (EXIT_FAILURE) when all is good, instead of all being bad. */
return ~s & TPM2_SUPPORT_FULL;
}
static int verb_help(int argc, char **argv, void *userdata) {
_cleanup_free_ char *link = NULL;
int r;
@ -543,6 +572,7 @@ static int verb_help(int argc, char **argv, void *userdata) {
" ciphertext credential file\n"
" decrypt INPUT [OUTPUT] Decrypt ciphertext credential file and write to\n"
" plaintext credential file\n"
" has-tpm2 Report whether TPM2 support is available\n"
" -h --help Show this help\n"
" --version Show package version\n"
"\n%3$sOptions:%4$s\n"
@ -568,6 +598,7 @@ static int verb_help(int argc, char **argv, void *userdata) {
" Pick TPM2 device\n"
" --tpm2-pcrs=PCR1+PCR2+PCR3+…\n"
" Specify TPM2 PCRs to seal against\n"
" -q --quiet Suppress output for 'has-tpm2' verb\n"
"\nSee the %2$s for details.\n"
, program_invocation_short_name
, link
@ -612,6 +643,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "name", required_argument, NULL, ARG_NAME },
{ "timestamp", required_argument, NULL, ARG_TIMESTAMP },
{ "not-after", required_argument, NULL, ARG_NOT_AFTER },
{ "quiet", no_argument, NULL, 'q' },
{}
};
@ -620,7 +652,7 @@ static int parse_argv(int argc, char *argv[]) {
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "hHTp", options, NULL)) >= 0) {
while ((c = getopt_long(argc, argv, "hHTpq", options, NULL)) >= 0) {
switch (c) {
@ -761,6 +793,10 @@ static int parse_argv(int argc, char *argv[]) {
break;
case 'q':
arg_quiet = true;
break;
case '?':
return -EINVAL;
@ -778,12 +814,13 @@ static int parse_argv(int argc, char *argv[]) {
static int creds_main(int argc, char *argv[]) {
static const Verb verbs[] = {
{ "list", VERB_ANY, 1, VERB_DEFAULT, verb_list },
{ "cat", 2, VERB_ANY, 0, verb_cat },
{ "encrypt", 3, 3, 0, verb_encrypt },
{ "decrypt", 2, 3, 0, verb_decrypt },
{ "setup", VERB_ANY, 1, 0, verb_setup },
{ "help", VERB_ANY, 1, 0, verb_help },
{ "list", VERB_ANY, 1, VERB_DEFAULT, verb_list },
{ "cat", 2, VERB_ANY, 0, verb_cat },
{ "encrypt", 3, 3, 0, verb_encrypt },
{ "decrypt", 2, 3, 0, verb_decrypt },
{ "setup", VERB_ANY, 1, 0, verb_setup },
{ "help", VERB_ANY, 1, 0, verb_help },
{ "has-tpm2", VERB_ANY, 1, 0, verb_has_tpm2 },
{}
};

28
src/shared/condition.c
View file

@ -50,6 +50,7 @@
#include "string-table.h"
#include "string-util.h"
#include "tomoyo-util.h"
#include "tpm2-util.h"
#include "udev-util.h"
#include "uid-alloc-range.h"
#include "user-util.h"
@ -623,29 +624,14 @@ static int condition_test_ac_power(Condition *c, char **env) {
}
static int has_tpm2(void) {
int r;
/* Checks whether the system has at least one TPM2 resource manager device, i.e. at least one "tpmrm"
* class device */
* class device. Alternatively, we are also happy if the firmware reports support (this is to cover
* for cases where we simply haven't loaded the driver for it yet, i.e. during early boot where we
* very likely want to use this condition check).
*
* Note that we don't check if we ourselves are built with TPM2 support here! */
r = dir_is_empty("/sys/class/tpmrm");
if (r == 0)
return true; /* nice! we have a device */
/* Hmm, so Linux doesn't know of the TPM2 device (or we couldn't check for it), most likely because
* the driver wasn't loaded yet. Let's see if the firmware knows about a TPM2 device, in this
* case. This way we can answer the TPM2 question already during early boot (where we most likely
* need it) */
if (efi_has_tpm2())
return true;
/* OK, this didn't work either, in this case propagate the original errors */
if (r == -ENOENT)
return false;
if (r < 0)
return log_debug_errno(r, "Failed to determine whether system has TPM2 support: %m");
return !r;
return (tpm2_support() & (TPM2_SUPPORT_DRIVER|TPM2_SUPPORT_FIRMWARE)) != 0;
}
static int condition_test_security(Condition *c, char **env) {

23
src/shared/tpm2-util.c
View file

@ -1,7 +1,9 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "efi-api.h"
#include "extract-word.h"
#include "parse-util.h"
#include "stat-util.h"
#include "tpm2-util.h"
#if HAVE_TPM2
@ -1453,3 +1455,24 @@ int tpm2_primary_alg_from_string(const char *alg) {
return TPM2_ALG_RSA;
return -EINVAL;
}
Tpm2Support tpm2_support(void) {
Tpm2Support support = TPM2_SUPPORT_NONE;
int r;
r = dir_is_empty("/sys/class/tpmrm");
if (r < 0) {
if (r != -ENOENT)
log_debug_errno(r, "Unable to test whether /sys/class/tpmrm/ exists and is populated, assuming it is not: %m");
} else if (r == 0) /* populated! */
support |= TPM2_SUPPORT_DRIVER;
if (efi_has_tpm2())
support |= TPM2_SUPPORT_FIRMWARE;
#if HAVE_TPM2
support |= TPM2_SUPPORT_SYSTEM;
#endif
return support;
}

12
src/shared/tpm2-util.h
View file

@ -89,3 +89,15 @@ typedef struct {
uint32_t search_pcr_mask;
const char *device;
} systemd_tpm2_plugin_params;
typedef enum Tpm2Support {
/* NOTE! The systemd-creds tool returns these flags 1:1 as exit status. Hence these flags are pretty
* much ABI! Hence, be extra careful when changing/extending these definitions. */
TPM2_SUPPORT_NONE = 0, /* no support */
TPM2_SUPPORT_FIRMWARE = 1 << 0, /* firmware reports TPM2 was used */
TPM2_SUPPORT_DRIVER = 1 << 1, /* the kernel has a driver loaded for it */
TPM2_SUPPORT_SYSTEM = 1 << 2, /* we support it ourselves */
TPM2_SUPPORT_FULL = TPM2_SUPPORT_FIRMWARE|TPM2_SUPPORT_DRIVER|TPM2_SUPPORT_SYSTEM,
} Tpm2Support;
Tpm2Support tpm2_support(void);