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authorLennart Poettering <lennart@poettering.net>2016-01-12 15:16:24 +0100
committerLennart Poettering <lennart@poettering.net>2016-01-12 15:16:24 +0100
commit1f52a79d4eb0216bf1f2d96539609f02d8bb9e71 (patch)
treed175e992048df607a2e851d51ca738e4f0e53d38 /src/core
parent4a6a24be180337f405591c7fa4fa112a765c53bb (diff)
parentece87975a97509b48a01b1e3da2e99c1c7dfd77a (diff)
Merge pull request #2265 from ipuustin/ambient
capabilities: added support for ambient capabilities.
Diffstat (limited to 'src/core')
-rw-r--r--src/core/dbus-execute.c23
-rw-r--r--src/core/execute.c100
-rw-r--r--src/core/execute.h4
-rw-r--r--src/core/load-fragment-gperf.gperf.m43
-rw-r--r--src/core/load-fragment.c29
-rw-r--r--src/core/load-fragment.h2
-rw-r--r--src/core/main.c10
-rw-r--r--src/core/unit.c2
8 files changed, 128 insertions, 45 deletions
diff --git a/src/core/dbus-execute.c b/src/core/dbus-execute.c
index 1f736b2686..c2238c8c43 100644
--- a/src/core/dbus-execute.c
+++ b/src/core/dbus-execute.c
@@ -293,9 +293,25 @@ 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_ambient_capabilities(
+ sd_bus *bus,
+ const char *path,
+ const char *interface,
+ const char *property,
+ sd_bus_message *reply,
+ void *userdata,
+ sd_bus_error *error) {
+
+ ExecContext *c = userdata;
+
+ assert(bus);
+ assert(reply);
+ assert(c);
+
+ return sd_bus_message_append(reply, "t", c->capability_ambient_set);
}
static int property_get_capabilities(
@@ -689,6 +705,7 @@ const sd_bus_vtable bus_exec_vtable[] = {
SD_BUS_PROPERTY("Capabilities", "s", property_get_capabilities, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("SecureBits", "i", bus_property_get_int, offsetof(ExecContext, secure_bits), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("CapabilityBoundingSet", "t", property_get_capability_bounding_set, 0, SD_BUS_VTABLE_PROPERTY_CONST),
+ SD_BUS_PROPERTY("AmbientCapabilities", "t", property_get_ambient_capabilities, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("User", "s", NULL, offsetof(ExecContext, user), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("Group", "s", NULL, offsetof(ExecContext, group), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("SupplementaryGroups", "as", NULL, offsetof(ExecContext, supplementary_groups), SD_BUS_VTABLE_PROPERTY_CONST),
diff --git a/src/core/execute.c b/src/core/execute.c
index 9b76861919..ac91568b63 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -737,12 +737,7 @@ static int enforce_user(const ExecContext *context, uid_t uid) {
/* Sets (but doesn't lookup) the uid and make sure we keep the
* capabilities while doing so. */
- if (context->capabilities) {
- _cleanup_cap_free_ cap_t d = NULL;
- static const cap_value_t bits[] = {
- CAP_SETUID, /* Necessary so that we can run setresuid() below */
- CAP_SETPCAP /* Necessary so that we can set PR_SET_SECUREBITS later on */
- };
+ if (context->capabilities || context->capability_ambient_set != 0) {
/* First step: If we need to keep capabilities but
* drop privileges we need to make sure we keep our
@@ -758,16 +753,24 @@ static int enforce_user(const ExecContext *context, uid_t uid) {
/* Second step: set the capabilities. This will reduce
* the capabilities to the minimum we need. */
- d = cap_dup(context->capabilities);
- if (!d)
- return -errno;
+ if (context->capabilities) {
+ _cleanup_cap_free_ cap_t d = NULL;
+ static const cap_value_t bits[] = {
+ CAP_SETUID, /* Necessary so that we can run setresuid() below */
+ CAP_SETPCAP /* Necessary so that we can set PR_SET_SECUREBITS later on */
+ };
- if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||
- cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0)
- return -errno;
+ d = cap_dup(context->capabilities);
+ if (!d)
+ return -errno;
- if (cap_set_proc(d) < 0)
- return -errno;
+ if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||
+ cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0)
+ return -errno;
+
+ if (cap_set_proc(d) < 0)
+ return -errno;
+ }
}
/* Third step: actually set the uids */
@@ -1856,6 +1859,8 @@ static int exec_child(
if (params->apply_permissions) {
+ int secure_bits = context->secure_bits;
+
for (i = 0; i < _RLIMIT_MAX; i++) {
if (!context->rlimit[i])
continue;
@@ -1866,28 +1871,71 @@ 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;
}
}
+ /* This is done before enforce_user, but ambient set
+ * does not survive over setresuid() if keep_caps is not set. */
+ if (context->capability_ambient_set != 0) {
+ r = capability_ambient_set_apply(context->capability_ambient_set, true);
+ if (r < 0) {
+ *exit_status = EXIT_CAPABILITIES;
+ return r;
+ }
+
+ if (context->capabilities) {
+
+ /* The capabilities in ambient set need to be also in the inherited
+ * set. If they aren't, trying to get them will fail. Add the ambient
+ * set inherited capabilities to the capability set in the context.
+ * This is needed because if capabilities are set (using "Capabilities="
+ * keyword), they will override whatever we set now. */
+
+ r = capability_update_inherited_set(context->capabilities, context->capability_ambient_set);
+ if (r < 0) {
+ *exit_status = EXIT_CAPABILITIES;
+ return r;
+ }
+ }
+ }
+
if (context->user) {
r = enforce_user(context, uid);
if (r < 0) {
*exit_status = EXIT_USER;
return r;
}
+ if (context->capability_ambient_set != 0) {
+
+ /* Fix the ambient capabilities after user change. */
+ r = capability_ambient_set_apply(context->capability_ambient_set, false);
+ if (r < 0) {
+ *exit_status = EXIT_CAPABILITIES;
+ return r;
+ }
+
+ /* If we were asked to change user and ambient capabilities
+ * were requested, we had to add keep-caps to the securebits
+ * so that we would maintain the inherited capability set
+ * through the setresuid(). Make sure that the bit is added
+ * also to the context secure_bits so that we don't try to
+ * drop the bit away next. */
+
+ secure_bits |= 1<<SECURE_KEEP_CAPS;
+ }
}
/* PR_GET_SECUREBITS is not privileged, while
* PR_SET_SECUREBITS is. So to suppress
* potential EPERMs we'll try not to call
* PR_SET_SECUREBITS unless necessary. */
- if (prctl(PR_GET_SECUREBITS) != context->secure_bits)
- if (prctl(PR_SET_SECUREBITS, context->secure_bits) < 0) {
+ if (prctl(PR_GET_SECUREBITS) != secure_bits)
+ if (prctl(PR_SET_SECUREBITS, secure_bits) < 0) {
*exit_status = EXIT_SECUREBITS;
return -errno;
}
@@ -2114,6 +2162,7 @@ void exec_context_init(ExecContext *c) {
c->timer_slack_nsec = NSEC_INFINITY;
c->personality = PERSONALITY_INVALID;
c->runtime_directory_mode = 0755;
+ c->capability_bounding_set = CAP_ALL;
}
void exec_context_done(ExecContext *c) {
@@ -2517,12 +2566,23 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
(c->secure_bits & 1<<SECURE_NOROOT) ? " noroot" : "",
(c->secure_bits & 1<<SECURE_NOROOT_LOCKED) ? "noroot-locked" : "");
- 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);
+ }
+
+ if (c->capability_ambient_set != 0) {
+ unsigned long l;
+ fprintf(f, "%sAmbientCapabilities:", prefix);
+
+ for (l = 0; l <= cap_last_cap(); l++)
+ if (c->capability_ambient_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 be5be9f531..8649620830 100644
--- a/src/core/execute.h
+++ b/src/core/execute.h
@@ -155,7 +155,9 @@ 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;
+
+ uint64_t capability_ambient_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 0408b9a829..29ab1b6b9e 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -47,7 +47,8 @@ $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.AmbientCapabilities, config_parse_capability_set, 0, offsetof($1, exec_context.capability_ambient_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 cb553e1252..d3880b4e3c 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -38,6 +38,7 @@
#include "bus-internal.h"
#include "bus-util.h"
#include "cap-list.h"
+#include "capability-util.h"
#include "cgroup.h"
#include "conf-parser.h"
#include "cpu-set-util.h"
@@ -1024,7 +1025,7 @@ 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,
@@ -1036,8 +1037,8 @@ 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;
@@ -1051,10 +1052,9 @@ 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 */
+ /* else "AmbientCapabilities" initialized to all bits off */
p = rvalue;
for (;;) {
@@ -1073,18 +1073,21 @@ int config_parse_bounding_set(
cap = capability_from_name(word);
if (cap < 0) {
- log_syntax(unit, LOG_ERR, filename, line, 0, "Failed to parse capability in bounding set, ignoring: %s", word);
+ log_syntax(unit, LOG_ERR, filename, line, 0, "Failed to parse capability in bounding/ambient set, ignoring: %s", word);
continue;
}
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;
}
@@ -4002,7 +4005,7 @@ 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 a451fc164a..f0027a6b43 100644
--- a/src/core/load-fragment.h
+++ b/src/core/load-fragment.h
@@ -56,7 +56,7 @@ 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 f9de54028e..7a428fcccf 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -117,7 +117,7 @@ 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;
@@ -644,7 +644,7 @@ 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
@@ -1631,14 +1631,14 @@ 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 b977ac7f0c..e1bc6c75cb 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -3231,7 +3231,7 @@ 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);