systemd: refuse to load units with errors (CVE-2017-1000082)

If a unit has a statement such as User=0day where the username exists but is
strictly speaking invalid, the unit will be started as the root user instead.

Backport a patch from upstream to mitigate this by refusing to start units such
as this.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 330 insertions, 0 deletions

diff --git a/meta/recipes-core/systemd/systemd/0001-core-load-fragment-refuse-units-with-errors-in-certa.patch b/meta/recipes-core/systemd/systemd/0001-core-load-fragment-refuse-units-with-errors-in-certa.patch
new file mode 100644
index 0000000000..80948b2cee
--- /dev/null
+++ b/meta/recipes-core/systemd/systemd/0001-core-load-fragment-refuse-units-with-errors-in-certa.patch
@@ -0,0 +1,329 @@
+If a user is created with a strictly-speaking invalid name such as '0day' and a
+unit created to run as that user, systemd rejects the username and runs the unit
+as root.
+
+CVE: CVE-2017-1000082
+Upstream-Status: Backport
+Signed-off-by: Ross Burton <ross.burton@intel.com>
+
+From d8e1310e1ed7b6f122bc7eb8ba061fbd088783c0 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
+Date: Thu, 6 Jul 2017 13:28:19 -0400
+Subject: [PATCH] core/load-fragment: refuse units with errors in certain
+ directives
+
+If an error is encountered in any of the Exec* lines, WorkingDirectory,
+SELinuxContext, ApparmorProfile, SmackProcessLabel, Service (in .socket
+units), User, or Group, refuse to load the unit. If the config stanza
+has support, ignore the failure if '-' is present.
+
+For those configuration directives, even if we started the unit, it's
+pretty likely that it'll do something unexpected (like write files
+in a wrong place, or with a wrong context, or run with wrong permissions,
+etc). It seems better to refuse to start the unit and have the admin
+clean up the configuration without giving the service a chance to mess
+up stuff.
+
+Note that all "security" options that restrict what the unit can do
+(Capabilities, AmbientCapabilities, Restrict*, SystemCallFilter, Limit*,
+PrivateDevices, Protect*, etc) are _not_ treated like this. Such options are
+only supplementary, and are not always available depending on the architecture
+and compilation options, so unit authors have to make sure that the service
+runs correctly without them anyway.
+
+Fixes #6237, #6277.
+
+Signed-off-by: Ross Burton <ross.burton@intel.com>
+---
+ src/core/load-fragment.c  | 104 ++++++++++++++++++++++++++++------------------
+ src/test/test-unit-file.c |  14 +++----
+ 2 files changed, 70 insertions(+), 48 deletions(-)
+
+diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
+index cbc826809..2047974f4 100644
+--- a/src/core/load-fragment.c
++++ b/src/core/load-fragment.c
+@@ -630,20 +630,28 @@ int config_parse_exec(
+ 
+                 if (isempty(f)) {
+                         /* First word is either "-" or "@" with no command. */
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Empty path in command line, ignoring: \"%s\"", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Empty path in command line%s: \"%s\"",
++                                   ignore ? ", ignoring" : "", rvalue);
++                        return ignore ? 0 : -ENOEXEC;
+                 }
+                 if (!string_is_safe(f)) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Executable path contains special characters, ignoring: %s", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Executable path contains special characters%s: %s",
++                                   ignore ? ", ignoring" : "", rvalue);
++                        return ignore ? 0 : -ENOEXEC;
+                 }
+                 if (!path_is_absolute(f)) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Executable path is not absolute, ignoring: %s", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Executable path is not absolute%s: %s",
++                                   ignore ? ", ignoring" : "", rvalue);
++                        return ignore ? 0 : -ENOEXEC;
+                 }
+                 if (endswith(f, "/")) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Executable path specifies a directory, ignoring: %s", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Executable path specifies a directory%s: %s",
++                                   ignore ? ", ignoring" : "", rvalue);
++                        return ignore ? 0 : -ENOEXEC;
+                 }
+ 
+                 if (f == firstword) {
+@@ -699,7 +707,7 @@ int config_parse_exec(
+                         if (r == 0)
+                                 break;
+                         else if (r < 0)
+-                                return 0;
++                                return ignore ? 0 : -ENOEXEC;
+ 
+                         if (!GREEDY_REALLOC(n, nbufsize, nlen + 2))
+                                 return log_oom();
+@@ -709,8 +717,10 @@ int config_parse_exec(
+                 }
+ 
+                 if (!n || !n[0]) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Empty executable name or zeroeth argument, ignoring: %s", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Empty executable name or zeroeth argument%s: %s",
++                                   ignore ? ", ignoring" : "", rvalue);
++                        return ignore ? 0 : -ENOEXEC;
+                 }
+ 
+                 nce = new0(ExecCommand, 1);
+@@ -1315,8 +1325,10 @@ int config_parse_exec_selinux_context(
+ 
+         r = unit_name_printf(u, rvalue, &k);
+         if (r < 0) {
+-                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve specifiers, ignoring: %m");
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, r,
++                           "Failed to resolve specifiers%s: %m",
++                           ignore ? ", ignoring" : "");
++                return ignore ? 0 : -ENOEXEC;
+         }
+ 
+         free(c->selinux_context);
+@@ -1363,8 +1375,10 @@ int config_parse_exec_apparmor_profile(
+ 
+         r = unit_name_printf(u, rvalue, &k);
+         if (r < 0) {
+-                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve specifiers, ignoring: %m");
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, r,
++                           "Failed to resolve specifiers%s: %m",
++                           ignore ? ", ignoring" : "");
++                return ignore ? 0 : -ENOEXEC;
+         }
+ 
+         free(c->apparmor_profile);
+@@ -1411,8 +1425,10 @@ int config_parse_exec_smack_process_label(
+ 
+         r = unit_name_printf(u, rvalue, &k);
+         if (r < 0) {
+-                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve specifiers, ignoring: %m");
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, r,
++                           "Failed to resolve specifiers%s: %m",
++                           ignore ? ", ignoring" : "");
++                return ignore ? 0 : -ENOEXEC;
+         }
+ 
+         free(c->smack_process_label);
+@@ -1630,19 +1646,19 @@ int config_parse_socket_service(
+ 
+         r = unit_name_printf(UNIT(s), rvalue, &p);
+         if (r < 0) {
+-                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve specifiers, ignoring: %s", rvalue);
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve specifiers: %s", rvalue);
++                return -ENOEXEC;
+         }
+ 
+         if (!endswith(p, ".service")) {
+-                log_syntax(unit, LOG_ERR, filename, line, 0, "Unit must be of type service, ignoring: %s", rvalue);
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, 0, "Unit must be of type service: %s", rvalue);
++                return -ENOEXEC;
+         }
+ 
+         r = manager_load_unit(UNIT(s)->manager, p, NULL, &error, &x);
+         if (r < 0) {
+-                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to load unit %s, ignoring: %s", rvalue, bus_error_message(&error, r));
+-                return 0;
++                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to load unit %s: %s", rvalue, bus_error_message(&error, r));
++                return -ENOEXEC;
+         }
+ 
+         unit_ref_set(&s->service, x);
+@@ -1893,13 +1909,13 @@ int config_parse_user_group(
+ 
+                 r = unit_full_printf(u, rvalue, &k);
+                 if (r < 0) {
+-                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve unit specifiers in %s, ignoring: %m", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve unit specifiers in %s: %m", rvalue);
++                        return -ENOEXEC;
+                 }
+ 
+                 if (!valid_user_group_name_or_id(k)) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Invalid user/group name or numeric ID, ignoring: %s", k);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0, "Invalid user/group name or numeric ID: %s", k);
++                        return -ENOEXEC;
+                 }
+ 
+                 n = k;
+@@ -1957,19 +1973,19 @@ int config_parse_user_group_strv(
+                 if (r == -ENOMEM)
+                         return log_oom();
+                 if (r < 0) {
+-                        log_syntax(unit, LOG_ERR, filename, line, r, "Invalid syntax, ignoring: %s", rvalue);
+-                        break;
++                        log_syntax(unit, LOG_ERR, filename, line, r, "Invalid syntax: %s", rvalue);
++                        return -ENOEXEC;
+                 }
+ 
+                 r = unit_full_printf(u, word, &k);
+                 if (r < 0) {
+-                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve unit specifiers in %s, ignoring: %m", word);
+-                        continue;
++                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve unit specifiers in %s: %m", word);
++                        return -ENOEXEC;
+                 }
+ 
+                 if (!valid_user_group_name_or_id(k)) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Invalid user/group name or numeric ID, ignoring: %s", k);
+-                        continue;
++                        log_syntax(unit, LOG_ERR, filename, line, 0, "Invalid user/group name or numeric ID: %s", k);
++                        return -ENOEXEC;
+                 }
+ 
+                 r = strv_push(users, k);
+@@ -2128,25 +2144,28 @@ int config_parse_working_directory(
+ 
+                 r = unit_full_printf(u, rvalue, &k);
+                 if (r < 0) {
+-                        log_syntax(unit, LOG_ERR, filename, line, r, "Failed to resolve unit specifiers in working directory path '%s', ignoring: %m", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, r,
++                                   "Failed to resolve unit specifiers in working directory path '%s'%s: %m",
++                                   rvalue, missing_ok ? ", ignoring" : "");
++                        return missing_ok ? 0 : -ENOEXEC;
+                 }
+ 
+                 path_kill_slashes(k);
+ 
+                 if (!utf8_is_valid(k)) {
+                         log_syntax_invalid_utf8(unit, LOG_ERR, filename, line, rvalue);
+-                        return 0;
++                        return missing_ok ? 0 : -ENOEXEC;
+                 }
+ 
+                 if (!path_is_absolute(k)) {
+-                        log_syntax(unit, LOG_ERR, filename, line, 0, "Working directory path '%s' is not absolute, ignoring.", rvalue);
+-                        return 0;
++                        log_syntax(unit, LOG_ERR, filename, line, 0,
++                                   "Working directory path '%s' is not absolute%s.",
++                                   rvalue, missing_ok ? ", ignoring" : "");
++                        return missing_ok ? 0 : -ENOEXEC;
+                 }
+ 
+-                free_and_replace(c->working_directory, k);
+-
+                 c->working_directory_home = false;
++                free_and_replace(c->working_directory, k);
+         }
+ 
+         c->working_directory_missing_ok = missing_ok;
+@@ -4228,8 +4247,11 @@ int unit_load_fragment(Unit *u) {
+                         return r;
+ 
+                 r = load_from_path(u, k);
+-                if (r < 0)
++                if (r < 0) {
++                        if (r == -ENOEXEC)
++                                log_unit_notice(u, "Unit configuration has fatal error, unit will not be started.");
+                         return r;
++                }
+ 
+                 if (u->load_state == UNIT_STUB) {
+                         SET_FOREACH(t, u->names, i) {
+diff --git a/src/test/test-unit-file.c b/src/test/test-unit-file.c
+index 12f48bf43..fd797b587 100644
+--- a/src/test/test-unit-file.c
++++ b/src/test/test-unit-file.c
+@@ -146,7 +146,7 @@ static void test_config_parse_exec(void) {
+         r = config_parse_exec(NULL, "fake", 4, "section", 1,
+                               "LValue", 0, "/RValue/ argv0 r1",
+                               &c, u);
+-        assert_se(r == 0);
++        assert_se(r == -ENOEXEC);
+         assert_se(c1->command_next == NULL);
+ 
+         log_info("/* honour_argv0 */");
+@@ -161,7 +161,7 @@ static void test_config_parse_exec(void) {
+         r = config_parse_exec(NULL, "fake", 3, "section", 1,
+                               "LValue", 0, "@/RValue",
+                               &c, u);
+-        assert_se(r == 0);
++        assert_se(r == -ENOEXEC);
+         assert_se(c1->command_next == NULL);
+ 
+         log_info("/* no command, whitespace only, reset */");
+@@ -220,7 +220,7 @@ static void test_config_parse_exec(void) {
+                               "-@/RValue argv0 r1 ; ; "
+                               "/goo/goo boo",
+                               &c, u);
+-        assert_se(r >= 0);
++        assert_se(r == -ENOEXEC);
+         c1 = c1->command_next;
+         check_execcommand(c1, "/RValue", "argv0", "r1", NULL, true);
+ 
+@@ -374,7 +374,7 @@ static void test_config_parse_exec(void) {
+                 r = config_parse_exec(NULL, "fake", 4, "section", 1,
+                                       "LValue", 0, path,
+                                       &c, u);
+-                assert_se(r == 0);
++                assert_se(r == -ENOEXEC);
+                 assert_se(c1->command_next == NULL);
+         }
+ 
+@@ -401,21 +401,21 @@ static void test_config_parse_exec(void) {
+         r = config_parse_exec(NULL, "fake", 4, "section", 1,
+                               "LValue", 0, "/path\\",
+                               &c, u);
+-        assert_se(r == 0);
++        assert_se(r == -ENOEXEC);
+         assert_se(c1->command_next == NULL);
+ 
+         log_info("/* missing ending ' */");
+         r = config_parse_exec(NULL, "fake", 4, "section", 1,
+                               "LValue", 0, "/path 'foo",
+                               &c, u);
+-        assert_se(r == 0);
++        assert_se(r == -ENOEXEC);
+         assert_se(c1->command_next == NULL);
+ 
+         log_info("/* missing ending ' with trailing backslash */");
+         r = config_parse_exec(NULL, "fake", 4, "section", 1,
+                               "LValue", 0, "/path 'foo\\",
+                               &c, u);
+-        assert_se(r == 0);
++        assert_se(r == -ENOEXEC);
+         assert_se(c1->command_next == NULL);
+ 
+         log_info("/* invalid space between modifiers */");
+-- 
+2.11.0
diff --git a/meta/recipes-core/systemd/systemd_232.bb b/meta/recipes-core/systemd/systemd_232.bb
index e8292ab388..9c533ea4c8 100644
--- a/meta/recipes-core/systemd/systemd_232.bb
+++ b/meta/recipes-core/systemd/systemd_232.bb
@@ -32,6 +32,7 @@ SRC_URI += " \
            file://0020-back-port-233-don-t-use-the-unified-hierarchy-for-the-systemd.patch \
            file://0021-build-sys-check-for-lz4-in-the-old-and-new-numbering.patch \
            file://0022-parse-util-Do-not-include-unneeded-xlocale.h.patch \
+           file://0001-core-load-fragment-refuse-units-with-errors-in-certa.patch \
            "
 SRC_URI_append_qemuall = " file://0001-core-device.c-Change-the-default-device-timeout-to-2.patch"