From 201006fa521199ebf109016c9dd22812c435dfe9 Mon Sep 17 00:00:00 2001

From: Ismo Puustinen <ismo.puustinen@intel.com>

Date: Fri, 8 Jan 2016 00:00:04 +0200

Subject: [PATCH] capabilities: keep bounding set in non-inverted format.

Change the capability bounding set parser and logic so that the bounding

set is kept as a positive set internally. This means that the set

reflects those capabilities that we want to keep instead of drop.

Resolves: #1387398

---

 src/core/dbus-execute.c               |  4 +-

 src/core/execute.c                    |  9 ++--

 src/core/execute.h                    |  2 +-

 src/core/load-fragment-gperf.gperf.m4 |  2 +-

 src/core/load-fragment.c              | 25 +++++-----

 src/core/load-fragment.h              |  2 +-

 src/core/main.c                       | 10 ++--

 src/core/unit.c                       |  2 +-

 src/import/import-common.c            |  2 +-

 src/nspawn/nspawn.c                   |  2 +-

 src/shared/capability.c               | 16 +++----

 src/shared/capability.h               | 12 ++++-

 src/test/test-unit-file.c             | 89 +++++++++++++++++++----------------

 13 files changed, 96 insertions(+), 81 deletions(-)

diff --git a/src/core/dbus-execute.c b/src/core/dbus-execute.c

index da8b10d..a564c53 100644

--- a/src/core/dbus-execute.c

+++ b/src/core/dbus-execute.c

@@ -324,9 +324,7 @@ static int property_get_capability_bounding_set(

         assert(reply);

         assert(c);

-        /* We store this negated internally, to match the kernel, but

-         * we expose it normalized. */

-        return sd_bus_message_append(reply, "t", ~c->capability_bounding_set_drop);

+        return sd_bus_message_append(reply, "t", c->capability_bounding_set);

 }

 static int property_get_capabilities(

diff --git a/src/core/execute.c b/src/core/execute.c

index f72b209..40db11e 100644

--- a/src/core/execute.c

+++ b/src/core/execute.c

@@ -1733,8 +1733,8 @@ static int exec_child(

                         }

                 }

-                if (context->capability_bounding_set_drop) {

-                        r = capability_bounding_set_drop(context->capability_bounding_set_drop, false);

+                if (!cap_test_all(context->capability_bounding_set)) {

+                        r = capability_bounding_set_drop(context->capability_bounding_set, false);

                         if (r < 0) {

                                 *exit_status = EXIT_CAPABILITIES;

                                 return r;

@@ -1988,6 +1988,7 @@ void exec_context_init(ExecContext *c) {

         c->timer_slack_nsec = NSEC_INFINITY;

         c->personality = 0xffffffffUL;

         c->runtime_directory_mode = 0755;

+        c->capability_bounding_set = CAP_ALL;

 }

 void exec_context_done(ExecContext *c) {

@@ -2419,12 +2420,12 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {

                         (c->secure_bits & 1<

                         (c->secure_bits & 1<

-        if (c->capability_bounding_set_drop) {

+        if (c->capability_bounding_set != CAP_ALL) {

                 unsigned long l;

                 fprintf(f, "%sCapabilityBoundingSet:", prefix);

                 for (l = 0; l <= cap_last_cap(); l++)

-                        if (!(c->capability_bounding_set_drop & ((uint64_t) 1ULL << (uint64_t) l)))

+                        if (c->capability_bounding_set & (UINT64_C(1) << l))

                                 fprintf(f, " %s", strna(capability_to_name(l)));

                 fputs("\n", f);

diff --git a/src/core/execute.h b/src/core/execute.h

index cadd0e6..40f7b79 100644

--- a/src/core/execute.h

+++ b/src/core/execute.h

@@ -150,7 +150,7 @@ struct ExecContext {

         char **read_write_dirs, **read_only_dirs, **inaccessible_dirs;

         unsigned long mount_flags;

-        uint64_t capability_bounding_set_drop;

+        uint64_t capability_bounding_set;

         cap_t capabilities;

         int secure_bits;

diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4

index b50fe45..e4ce292 100644

--- a/src/core/load-fragment-gperf.gperf.m4

+++ b/src/core/load-fragment-gperf.gperf.m4

@@ -47,7 +47,7 @@ $1.SyslogLevel,                  config_parse_log_level,             0,

 $1.SyslogLevelPrefix,            config_parse_bool,                  0,                             offsetof($1, exec_context.syslog_level_prefix)

 $1.Capabilities,                 config_parse_exec_capabilities,     0,                             offsetof($1, exec_context)

 $1.SecureBits,                   config_parse_exec_secure_bits,      0,                             offsetof($1, exec_context)

-$1.CapabilityBoundingSet,        config_parse_bounding_set,          0,                             offsetof($1, exec_context.capability_bounding_set_drop)

+$1.CapabilityBoundingSet,        config_parse_capability_set,        0,                             offsetof($1, exec_context.capability_bounding_set)

 $1.TimerSlackNSec,               config_parse_nsec,                  0,                             offsetof($1, exec_context.timer_slack_nsec)

 $1.NoNewPrivileges,              config_parse_no_new_privileges,     0,                             offsetof($1, exec_context)

 m4_ifdef(`HAVE_SECCOMP',

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c

index ab3b0c2..dbaaf2f 100644

--- a/src/core/load-fragment.c

+++ b/src/core/load-fragment.c

@@ -1015,7 +1015,7 @@ int config_parse_exec_secure_bits(const char *unit,

         return 0;

 }

-int config_parse_bounding_set(

+int config_parse_capability_set(

                 const char *unit,

                 const char *filename,

                 unsigned line,

@@ -1027,8 +1027,8 @@ int config_parse_bounding_set(

                 void *data,

                 void *userdata) {

-        uint64_t *capability_bounding_set_drop = data;

-        uint64_t capability_bounding_set, sum = 0;

+        uint64_t *capability_set = data;

+        uint64_t sum = 0, initial = 0;

         bool invert = false;

         const char *p;

@@ -1042,10 +1042,8 @@ int config_parse_bounding_set(

                 rvalue++;

         }

-        /* Note that we store this inverted internally, since the

-         * kernel wants it like this. But we actually expose it

-         * non-inverted everywhere to have a fully normalized

-         * interface. */

+        if (strcmp(lvalue, "CapabilityBoundingSet") == 0)

+                initial = CAP_ALL; /* initialized to all bits on */

         p = rvalue;

         for (;;) {

@@ -1071,11 +1069,14 @@ int config_parse_bounding_set(

                 sum |= ((uint64_t) UINT64_C(1)) << (uint64_t) cap;

         }

-        capability_bounding_set = invert ? ~sum : sum;

-        if (*capability_bounding_set_drop != 0 && capability_bounding_set != 0)

-                *capability_bounding_set_drop = ~(~*capability_bounding_set_drop | capability_bounding_set);

+        sum = invert ? ~sum : sum;

+

+        if (sum == 0 || *capability_set == initial)

+                /* "" or uninitialized data -> replace */

+                *capability_set = sum;

         else

-                *capability_bounding_set_drop = ~capability_bounding_set;

+                /* previous data -> merge */

+                *capability_set |= sum;

         return 0;

 }

@@ -4050,7 +4051,7 @@ void unit_dump_config_items(FILE *f) {

                 { config_parse_log_level,             "LEVEL" },

                 { config_parse_exec_capabilities,     "CAPABILITIES" },

                 { config_parse_exec_secure_bits,      "SECUREBITS" },

-                { config_parse_bounding_set,          "BOUNDINGSET" },

+                { config_parse_capability_set,        "BOUNDINGSET" },

                 { config_parse_limit,                 "LIMIT" },

                 { config_parse_unit_deps,             "UNIT [...]" },

                 { config_parse_exec,                  "PATH [ARGUMENT [...]]" },

diff --git a/src/core/load-fragment.h b/src/core/load-fragment.h

index 9dd7d1b..2059353 100644

--- a/src/core/load-fragment.h

+++ b/src/core/load-fragment.h

@@ -54,7 +54,7 @@ int config_parse_exec_cpu_sched_prio(const char *unit, const char *filename, uns

 int config_parse_exec_cpu_affinity(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_exec_capabilities(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_exec_secure_bits(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

-int config_parse_bounding_set(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

+int config_parse_capability_set(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_limit(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_bytes_limit(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

 int config_parse_sec_limit(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);

diff --git a/src/core/main.c b/src/core/main.c

index a0df1e5..cba992c 100644

--- a/src/core/main.c

+++ b/src/core/main.c

@@ -108,7 +108,7 @@ static usec_t arg_runtime_watchdog = 0;

 static usec_t arg_shutdown_watchdog = 10 * USEC_PER_MINUTE;

 static char **arg_default_environment = NULL;

 static struct rlimit *arg_default_rlimit[_RLIMIT_MAX] = {};

-static uint64_t arg_capability_bounding_set_drop = 0;

+static uint64_t arg_capability_bounding_set = CAP_ALL;

 static nsec_t arg_timer_slack_nsec = NSEC_INFINITY;

 static usec_t arg_default_timer_accuracy_usec = 1 * USEC_PER_MINUTE;

 static Set* arg_syscall_archs = NULL;

@@ -642,7 +642,7 @@ static int parse_config_file(void) {

                 { "Manager", "JoinControllers",           config_parse_join_controllers, 0, &arg_join_controllers                  },

                 { "Manager", "RuntimeWatchdogSec",        config_parse_sec,              0, &arg_runtime_watchdog                  },

                 { "Manager", "ShutdownWatchdogSec",       config_parse_sec,              0, &arg_shutdown_watchdog                 },

-                { "Manager", "CapabilityBoundingSet",     config_parse_bounding_set,     0, &arg_capability_bounding_set_drop      },

+                { "Manager", "CapabilityBoundingSet",     config_parse_capability_set,   0, &arg_capability_bounding_set           },

 #ifdef HAVE_SECCOMP

                 { "Manager", "SystemCallArchitectures",   config_parse_syscall_archs,    0, &arg_syscall_archs                     },

 #endif

@@ -1622,14 +1622,14 @@ int main(int argc, char *argv[]) {

                 if (prctl(PR_SET_TIMERSLACK, arg_timer_slack_nsec) < 0)

                         log_error_errno(errno, "Failed to adjust timer slack: %m");

-        if (arg_capability_bounding_set_drop) {

-                r = capability_bounding_set_drop_usermode(arg_capability_bounding_set_drop);

+        if (!cap_test_all(arg_capability_bounding_set)) {

+                r = capability_bounding_set_drop_usermode(arg_capability_bounding_set);

                 if (r < 0) {

                         log_emergency_errno(r, "Failed to drop capability bounding set of usermode helpers: %m");

                         error_message = "Failed to drop capability bounding set of usermode helpers";

                         goto finish;

                 }

-                r = capability_bounding_set_drop(arg_capability_bounding_set_drop, true);

+                r = capability_bounding_set_drop(arg_capability_bounding_set, true);

                 if (r < 0) {

                         log_emergency_errno(r, "Failed to drop capability bounding set: %m");

                         error_message = "Failed to drop capability bounding set";

diff --git a/src/core/unit.c b/src/core/unit.c

index 4eb0d78..103f920 100644

--- a/src/core/unit.c

+++ b/src/core/unit.c

@@ -3213,7 +3213,7 @@ int unit_patch_contexts(Unit *u) {

                         ec->no_new_privileges = true;

                 if (ec->private_devices)

-                        ec->capability_bounding_set_drop |= (uint64_t) 1ULL << (uint64_t) CAP_MKNOD;

+                        ec->capability_bounding_set &= ~(UINT64_C(1) << CAP_MKNOD);

         }

         cc = unit_get_cgroup_context(u);

diff --git a/src/import/import-common.c b/src/import/import-common.c

index f10a453..243e657 100644

--- a/src/import/import-common.c

+++ b/src/import/import-common.c

@@ -526,7 +526,7 @@ int import_fork_tar(const char *path, pid_t *ret) {

                 if (unshare(CLONE_NEWNET) < 0)

                         log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");

-                r = capability_bounding_set_drop(~retain, true);

+                r = capability_bounding_set_drop(retain, true);

                 if (r < 0)

                         log_error_errno(r, "Failed to drop capabilities, ignoring: %m");

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c

index a37b640..d0003d3 100644

--- a/src/nspawn/nspawn.c

+++ b/src/nspawn/nspawn.c

@@ -1863,7 +1863,7 @@ static int setup_journal(const char *directory) {

 }

 static int drop_capabilities(void) {

-        return capability_bounding_set_drop(~arg_retain, false);

+        return capability_bounding_set_drop(arg_retain, false);

 }

 static int register_machine(pid_t pid, int local_ifindex) {

diff --git a/src/shared/capability.c b/src/shared/capability.c

index 2b963fd..3ed31df 100644

--- a/src/shared/capability.c

+++ b/src/shared/capability.c

@@ -98,7 +98,7 @@ unsigned long cap_last_cap(void) {

         return p;

 }

-int capability_bounding_set_drop(uint64_t drop, bool right_now) {

+int capability_bounding_set_drop(uint64_t keep, bool right_now) {

         _cleanup_cap_free_ cap_t after_cap = NULL;

         cap_flag_value_t fv;

         unsigned long i;

@@ -139,7 +139,7 @@ int capability_bounding_set_drop(uint64_t drop, bool right_now) {

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

-                if (drop & ((uint64_t) 1ULL << (uint64_t) i)) {

+                if (!(keep & (UINT64_C(1) << i))) {

                         cap_value_t v;

                         /* Drop it from the bounding set */

@@ -178,7 +178,7 @@ finish:

         return r;

 }

-static int drop_from_file(const char *fn, uint64_t drop) {

+static int drop_from_file(const char *fn, uint64_t keep) {

         int r, k;

         uint32_t hi, lo;

         uint64_t current, after;

@@ -198,7 +198,7 @@ static int drop_from_file(const char *fn, uint64_t drop) {

                 return -EIO;

         current = (uint64_t) lo | ((uint64_t) hi << 32ULL);

-        after = current & ~drop;

+        after = current & keep;

         if (current == after)

                 return 0;

@@ -215,14 +215,14 @@ static int drop_from_file(const char *fn, uint64_t drop) {

         return r;

 }

-int capability_bounding_set_drop_usermode(uint64_t drop) {

+int capability_bounding_set_drop_usermode(uint64_t keep) {

         int r;

-        r = drop_from_file("/proc/sys/kernel/usermodehelper/inheritable", drop);

+        r = drop_from_file("/proc/sys/kernel/usermodehelper/inheritable", keep);

         if (r < 0)

                 return r;

-        r = drop_from_file("/proc/sys/kernel/usermodehelper/bset", drop);

+        r = drop_from_file("/proc/sys/kernel/usermodehelper/bset", keep);

         if (r < 0)

                 return r;

@@ -259,7 +259,7 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {

                 return log_error_errno(errno, "Failed to disable keep capabilities flag: %m");

         /* Drop all caps from the bounding set, except the ones we want */

-        r = capability_bounding_set_drop(~keep_capabilities, true);

+        r = capability_bounding_set_drop(keep_capabilities, true);

         if (r < 0)

                 return log_error_errno(r, "Failed to drop capabilities: %m");

diff --git a/src/shared/capability.h b/src/shared/capability.h

index 6f2f6f9..04cd6e5 100644

--- a/src/shared/capability.h

+++ b/src/shared/capability.h

@@ -27,10 +27,12 @@

 #include "util.h"

+#define CAP_ALL (uint64_t) -1

+

 unsigned long cap_last_cap(void);

 int have_effective_cap(int value);

-int capability_bounding_set_drop(uint64_t drop, bool right_now);

-int capability_bounding_set_drop_usermode(uint64_t drop);

+int capability_bounding_set_drop(uint64_t keep, bool right_now);

+int capability_bounding_set_drop_usermode(uint64_t keep);

 int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilites);

@@ -44,3 +46,9 @@ static inline void cap_free_charpp(char **p) {

                 cap_free(*p);

 }

 #define _cleanup_cap_free_charp_ _cleanup_(cap_free_charpp)

+

+static inline bool cap_test_all(uint64_t caps) {

+        uint64_t m;

+        m = (UINT64_C(1) << (cap_last_cap() + 1)) - 1;

+        return (caps & m) == m;

+}

diff --git a/src/test/test-unit-file.c b/src/test/test-unit-file.c

index 0f00a8f..38ecfe9 100644

--- a/src/test/test-unit-file.c

+++ b/src/test/test-unit-file.c

@@ -550,6 +550,53 @@ static uint64_t make_cap(int cap) {

         return ((uint64_t) 1ULL << (uint64_t) cap);

 }

+static void test_config_parse_capability_set(void) {

+        /* int config_parse_capability_set(

+                 const char *unit,

+                 const char *filename,

+                 unsigned line,

+                 const char *section,

+                 unsigned section_line,

+                 const char *lvalue,

+                 int ltype,

+                 const char *rvalue,

+                 void *data,

+                 void *userdata) */

+        int r;

+        uint64_t capability_bounding_set = 0;

+

+        r = config_parse_capability_set(NULL, "fake", 1, "section", 1,

+                              "CapabilityBoundingSet", 0, "CAP_NET_RAW",

+                              &capability_bounding_set, NULL);

+        assert_se(r >= 0);

+        assert_se(capability_bounding_set == make_cap(CAP_NET_RAW));

+

+        r = config_parse_capability_set(NULL, "fake", 1, "section", 1,

+                              "CapabilityBoundingSet", 0, "CAP_NET_ADMIN",

+                              &capability_bounding_set, NULL);

+        assert_se(r >= 0);

+        assert_se(capability_bounding_set == (make_cap(CAP_NET_RAW) | make_cap(CAP_NET_ADMIN)));

+

+        r = config_parse_capability_set(NULL, "fake", 1, "section", 1,

+                              "CapabilityBoundingSet", 0, "",

+                              &capability_bounding_set, NULL);

+        assert_se(r >= 0);

+        assert_se(capability_bounding_set == UINT64_C(0));

+

+        r = config_parse_capability_set(NULL, "fake", 1, "section", 1,

+                              "CapabilityBoundingSet", 0, "~",

+                              &capability_bounding_set, NULL);

+        assert_se(r >= 0);

+        assert_se(cap_test_all(capability_bounding_set));

+

+        capability_bounding_set = 0;

+        r = config_parse_capability_set(NULL, "fake", 1, "section", 1,

+                              "CapabilityBoundingSet", 0, "  'CAP_NET_RAW' WAT_CAP??? CAP_NET_ADMIN CAP'_trailing_garbage",

+                              &capability_bounding_set, NULL);

+        assert_se(r >= 0);

+        assert_se(capability_bounding_set == (make_cap(CAP_NET_RAW) | make_cap(CAP_NET_ADMIN)));

+}

+

 static void test_config_parse_rlimit(void) {

         struct rlimit * rl[_RLIMIT_MAX] = {};

@@ -665,46 +712,6 @@ static void test_config_parse_rlimit(void) {

         free(rl[RLIMIT_RTTIME]);

 }

-static void test_config_parse_bounding_set(void) {

-        /* int config_parse_bounding_set(

-                 const char *unit,

-                 const char *filename,

-                 unsigned line,

-                 const char *section,

-                 unsigned section_line,

-                 const char *lvalue,

-                 int ltype,

-                 const char *rvalue,

-                 void *data,

-                 void *userdata) */

-        int r;

-        uint64_t capability_bounding_set_drop = 0;

-

-        r = config_parse_bounding_set(NULL, "fake", 1, "section", 1,

-                              "CapabilityBoundingSet", 0, "CAP_NET_RAW",

-                              &capability_bounding_set_drop, NULL);

-        assert_se(r >= 0);

-        assert_se(capability_bounding_set_drop == ~make_cap(CAP_NET_RAW));

-

-        r = config_parse_bounding_set(NULL, "fake", 1, "section", 1,

-                              "CapabilityBoundingSet", 0, "CAP_NET_ADMIN",

-                              &capability_bounding_set_drop, NULL);

-        assert_se(r >= 0);

-        assert_se(capability_bounding_set_drop == ~(make_cap(CAP_NET_RAW) | make_cap(CAP_NET_ADMIN)));

-

-        r = config_parse_bounding_set(NULL, "fake", 1, "section", 1,

-                              "CapabilityBoundingSet", 0, "",

-                              &capability_bounding_set_drop, NULL);

-        assert_se(r >= 0);

-        assert_se(capability_bounding_set_drop == ~((uint64_t) 0ULL));

-

-        r = config_parse_bounding_set(NULL, "fake", 1, "section", 1,

-                              "CapabilityBoundingSet", 0, "~",

-                              &capability_bounding_set_drop, NULL);

-        assert_se(r >= 0);

-        assert_se(capability_bounding_set_drop == (uint64_t) 0ULL);

-}

-

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

         int r;

@@ -713,8 +720,8 @@ int main(int argc, char *argv[]) {

         r = test_unit_file_get_set();

         test_config_parse_exec();

+        test_config_parse_capability_set();

         test_config_parse_rlimit();

-        test_config_parse_bounding_set();

         test_load_env_file_1();

         test_load_env_file_2();

         test_load_env_file_3();