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systemd-analyze: add new 'security' option to compare unit's overall exposure level with

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--threshold option added to work with security verb and with the --offline option so that
users can determine what qualifies as a security threat. The threshold set by the user is
compared with the overall exposure level assigned to a unit file and if the exposure is
higher than the threshold, 'security' will return a non-zero exit status. The default value
of the --threshold option is 100.

Example Run:

1. testcase.service is a unit file created for testing the --threshold option

    maanya-goenka@debian:~/systemd (systemd-security)$ cat<<EOF>testcase.service

    > [Service]
    > ExecStart = echo hello
    > EOF

    For the purposes of this demo, the security table outputted below has been cut to show only the first two security settings.

    maanya-goenka@debian:~/systemd (systemd-security)$ sudo build/systemd-analyze security --offline=true testcase.service
    /usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's
    process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'.
    Support for KillMode=none is deprecated and will eventually be removed.
    /usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your
    unit file, and consider removing the setting altogether.
    /usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating
    /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.

      NAME                                        DESCRIPTION                                                       EXPOSURE
    ✗ PrivateNetwork=                             Service has access to the host's network                          0.5
    ✗ User=/DynamicUser=                          Service runs as root user                                         0.4

    → Overall exposure level for testcase.service: 9.6 UNSAFE 😨

    maanya-goenka@debian:~/systemd (systemd-security)$ echo $? 0

2. Next, we use the same testcase.service file but add an additional --threshold=60 parameter. We would expect 'security' to exit
   with a non-zero status because the overall exposure level (= 96) is higher than the set threshold (= 60).

    maanya-goenka@debian:~/systemd (systemd-security)$ sudo build/systemd-analyze security --offline=true --threshold=60 testcase.service
    /usr/lib/systemd/system/plymouth-start.service:15: Unit configured to use KillMode=none. This is unsafe, as it disables systemd's
    process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'.
    Support for KillMode=none is deprecated and will eventually be removed.
    /usr/lib/systemd/system/gdm.service:30: Standard output type syslog is obsolete, automatically updating to journal. Please update your
    unit file, and consider removing the setting altogether.
    /usr/lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating
    /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.

      NAME                                        DESCRIPTION                                                       EXPOSURE
    ✗ PrivateNetwork=                             Service has access to the host's network                          0.5
    ✗ User=/DynamicUser=                          Service runs as root user                                         0.4

    → Overall exposure level for testcase.service: 9.6 UNSAFE 😨

    maanya-goenka@debian:~/systemd (systemd-security)$ echo $? 1
This commit is contained in:
Maanya Goenka 2021-08-17 10:40:15 -07:00
parent bb43d85319
commit dfbda8799c
6 changed files with 50 additions and 14 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
man/systemd-analyze.xml
View file

@ -782,6 +782,16 @@ Service b@0.service not loaded, b.socket cannot be started.
an error.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--threshold=<replaceable>NUMBER</replaceable></option></term>
<listitem><para>With <command>security</command>, allow the user to set a custom value
to compare the overall exposure level with, for the specified unit file(s). If a unit's
overall exposure level, is greater than that set by the user, <command>security</command>
will return an error. <option>--threshold=</option> can be used with <option>--offline=</option>
as well and its default value is 100.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--iterations=<replaceable>NUMBER</replaceable></option></term>

2
shell-completion/bash/systemd-analyze
View file

@ -144,7 +144,7 @@ _systemd_analyze() {
elif __contains_word "$verb" ${VERBS[SECURITY]}; then
if [[ $cur = -* ]]; then
comps='--help --version --no-pager --system --user -H --host -M --machine --offline'
comps='--help --version --no-pager --system --user -H --host -M --machine --offline --threshold'
else
if __contains_word "--user" ${COMP_WORDS[*]}; then
mode=--user

1
shell-completion/zsh/_systemd-analyze
View file

@ -91,6 +91,7 @@ _arguments \
'--image=[Add support for discrete images]:PATH' \
'--recursive-errors=[When verifying a unit, control dependency verification]:MODE' \
'--offline=[Perform a security review of the specified unit file(s)]:BOOL' \
'--threshold=[Set a value to compare the overall security exposure level with]: NUMBER' \
'--no-pager[Do not pipe output into a pager]' \
'--man=[Do (not) check for existence of man pages]:boolean:(1 0)' \
'--order[When generating graph for dot, show only order]' \

30
src/analyze/analyze-security.c
View file

@ -1527,7 +1527,7 @@ static const struct security_assessor security_assessor_table[] = {
},
};
static int assess(const SecurityInfo *info, Table *overview_table, AnalyzeSecurityFlags flags) {
static int assess(const SecurityInfo *info, Table *overview_table, AnalyzeSecurityFlags flags, unsigned threshold) {
static const struct {
uint64_t exposure;
const char *name;
@ -1723,6 +1723,10 @@ static int assess(const SecurityInfo *info, Table *overview_table, AnalyzeSecuri
return table_log_add_error(r);
}
/* Return error when overall exposure level is over threshold */
if (exposure > threshold)
return -EINVAL;
return 0;
}
@ -2188,7 +2192,9 @@ static int acquire_security_info(sd_bus *bus, const char *name, SecurityInfo *in
return 0;
}
static int analyze_security_one(sd_bus *bus, const char *name, Table *overview_table, AnalyzeSecurityFlags flags) {
static int analyze_security_one(sd_bus *bus, const char *name, Table *overview_table,
AnalyzeSecurityFlags flags, unsigned threshold) {
_cleanup_(security_info_freep) SecurityInfo *info = security_info_new();
if (!info)
return log_oom();
@ -2204,7 +2210,7 @@ static int analyze_security_one(sd_bus *bus, const char *name, Table *overview_t
if (r < 0)
return r;
r = assess(info, overview_table, flags);
r = assess(info, overview_table, flags, threshold);
if (r < 0)
return r;
@ -2390,7 +2396,7 @@ static int get_security_info(Unit *u, ExecContext *c, CGroupContext *g, Security
return 0;
}
static int offline_security_check(Unit *u) {
static int offline_security_check(Unit *u, unsigned threshold) {
_cleanup_(table_unrefp) Table *overview_table = NULL;
AnalyzeSecurityFlags flags = 0;
_cleanup_(security_info_freep) SecurityInfo *info = NULL;
@ -2405,10 +2411,10 @@ static int offline_security_check(Unit *u) {
if (r < 0)
return r;
return assess(info, overview_table, flags);
return assess(info, overview_table, flags, threshold);
}
static int offline_security_checks(char **filenames, UnitFileScope scope, bool check_man, bool run_generators, const char *root) {
static int offline_security_checks(char **filenames, UnitFileScope scope, bool check_man, bool run_generators, unsigned threshold, const char *root) {
const ManagerTestRunFlags flags =
MANAGER_TEST_RUN_MINIMAL |
MANAGER_TEST_RUN_ENV_GENERATORS |
@ -2467,7 +2473,7 @@ static int offline_security_checks(char **filenames, UnitFileScope scope, bool c
}
for (size_t i = 0; i < count; i++) {
k = offline_security_check(units[i]);
k = offline_security_check(units[i], threshold);
if (k < 0 && r == 0)
r = k;
}
@ -2475,14 +2481,16 @@ static int offline_security_checks(char **filenames, UnitFileScope scope, bool c
return r;
}
int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_man, bool run_generators, bool offline, const char *root, AnalyzeSecurityFlags flags) {
int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_man, bool run_generators,
bool offline, unsigned threshold, const char *root, AnalyzeSecurityFlags flags) {
_cleanup_(table_unrefp) Table *overview_table = NULL;
int ret = 0, r;
assert(bus);
if (offline)
return offline_security_checks(units, scope, check_man, run_generators, root);
return offline_security_checks(units, scope, check_man, run_generators, threshold, root);
if (strv_length(units) != 1) {
overview_table = table_new("unit", "exposure", "predicate", "happy");
@ -2542,7 +2550,7 @@ int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_
flags |= ANALYZE_SECURITY_SHORT|ANALYZE_SECURITY_ONLY_LOADED|ANALYZE_SECURITY_ONLY_LONG_RUNNING;
STRV_FOREACH(i, list) {
r = analyze_security_one(bus, *i, overview_table, flags);
r = analyze_security_one(bus, *i, overview_table, flags, threshold);
if (r < 0 && ret >= 0)
ret = r;
}
@ -2577,7 +2585,7 @@ int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_
} else
name = mangled;
r = analyze_security_one(bus, name, overview_table, flags);
r = analyze_security_one(bus, name, overview_table, flags, threshold);
if (r < 0 && ret >= 0)
ret = r;
}

3
src/analyze/analyze-security.h
View file

@ -13,4 +13,5 @@ typedef enum AnalyzeSecurityFlags {
ANALYZE_SECURITY_ONLY_LONG_RUNNING = 1 << 2,
} AnalyzeSecurityFlags;
int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_man, bool run_generators, bool offline, const char *root, AnalyzeSecurityFlags flags);
int analyze_security(sd_bus *bus, char **units, UnitFileScope scope, bool check_man, bool run_generators,
bool offline, unsigned threshold, const char *root, AnalyzeSecurityFlags flags);

18
src/analyze/analyze.c
View file

@ -92,6 +92,7 @@ static bool arg_generators = false;
static char *arg_root = NULL;
static char *arg_image = NULL;
static bool arg_offline = false;
static unsigned arg_threshold = 100;
static unsigned arg_iterations = 1;
static usec_t arg_base_time = USEC_INFINITY;
@ -2161,7 +2162,7 @@ static int do_security(int argc, char *argv[], void *userdata) {
(void) pager_open(arg_pager_flags);
return analyze_security(bus, strv_skip(argv, 1), arg_scope, arg_man, arg_generators, arg_offline, arg_root, 0);
return analyze_security(bus, strv_skip(argv, 1), arg_scope, arg_man, arg_generators, arg_offline, arg_threshold, arg_root, 0);
}
static int help(int argc, char *argv[], void *userdata) {
@ -2210,6 +2211,8 @@ static int help(int argc, char *argv[], void *userdata) {
" -h --help Show this help\n"
" --recursive-errors=MODE Control which units are verified\n"
" --offline=BOOL Perform a security review on unit file(s)\n"
" --threshold=N Exit with a non-zero status when overall\n"
" exposure level is over threshold value\n"
" --version Show package version\n"
" --no-pager Do not pipe output into a pager\n"
" --system Operate on system systemd instance\n"
@ -2262,6 +2265,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_BASE_TIME,
ARG_RECURSIVE_ERRORS,
ARG_OFFLINE,
ARG_THRESHOLD,
};
static const struct option options[] = {
@ -2273,6 +2277,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "image", required_argument, NULL, ARG_IMAGE },
{ "recursive-errors", required_argument, NULL, ARG_RECURSIVE_ERRORS },
{ "offline", required_argument, NULL, ARG_OFFLINE },
{ "threshold", required_argument, NULL, ARG_THRESHOLD },
{ "system", no_argument, NULL, ARG_SYSTEM },
{ "user", no_argument, NULL, ARG_USER },
{ "global", no_argument, NULL, ARG_GLOBAL },
@ -2397,6 +2402,13 @@ static int parse_argv(int argc, char *argv[]) {
return r;
break;
case ARG_THRESHOLD:
r = safe_atou(optarg, &arg_threshold);
if (r < 0 || arg_threshold > 100)
return log_error_errno(r < 0 ? r : SYNTHETIC_ERRNO(EINVAL), "Failed to parse threshold: %s", optarg);
break;
case ARG_ITERATIONS:
r = safe_atou(optarg, &arg_iterations);
if (r < 0)
@ -2422,6 +2434,10 @@ static int parse_argv(int argc, char *argv[]) {
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Option --offline= is only supported for security right now.");
if (arg_threshold != 100 && !streq_ptr(argv[optind], "security"))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Option --threshold= is only supported for security right now.");
if (arg_scope == UNIT_FILE_GLOBAL &&
!STR_IN_SET(argv[optind] ?: "time", "dot", "unit-paths", "verify"))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),