core: add Personality= option for units to set the personality for spawned processes

src/core/dbus-execute.c

@@ -482,6 +482,24 @@ static int property_get_selinux_context(
         return sd_bus_message_append(reply, "(bs)", c->selinux_context_ignore, c->selinux_context);
 }
 
+static int property_get_personality(
+                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, "s", personality_to_string(c->personality));
+}
+
 const sd_bus_vtable bus_exec_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("Environment", "as", NULL, offsetof(ExecContext, environment), SD_BUS_VTABLE_PROPERTY_CONST),
@@ -547,6 +565,7 @@ const sd_bus_vtable bus_exec_vtable[] = {
         SD_BUS_PROPERTY("SystemCallFilter", "(bas)", property_get_syscall_filter, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("SystemCallArchitectures", "as", property_get_syscall_archs, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("SystemCallErrorNumber", "i", property_get_syscall_errno, 0, SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("Personality", "s", property_get_personality, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_VTABLE_END
 };
 

src/core/execute.c

@@ -39,6 +39,7 @@
 #include <linux/oom.h>
 #include <sys/poll.h>
 #include <glob.h>
+#include <sys/personality.h>
 #include <libgen.h>
 #undef basename
 
@@ -1372,6 +1373,13 @@ int exec_spawn(ExecCommand *command,
                                 goto fail_child;
                         }
 
+                if (context->personality != 0xffffffffUL)
+                        if (personality(context->personality) < 0) {
+                                err = -errno;
+                                r = EXIT_PERSONALITY;
+                                goto fail_child;
+                        }
+
                 if (context->utmp_id)
                         utmp_put_init_process(context->utmp_id, getpid(), getsid(0), context->tty_path);
 
@@ -1683,6 +1691,7 @@ void exec_context_init(ExecContext *c) {
         c->syslog_level_prefix = true;
         c->ignore_sigpipe = true;
         c->timer_slack_nsec = (nsec_t) -1;
+        c->personality = 0xffffffffUL;
 }
 
 void exec_context_done(ExecContext *c) {
@@ -2130,6 +2139,11 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
                         "%sSELinuxContext: %s%s\n",
                         prefix, c->selinux_context_ignore ? "-" : "", c->selinux_context);
 
+        if (c->personality != 0xffffffffUL)
+                fprintf(f,
+                        "%sPersonality: %s\n",
+                        prefix, strna(personality_to_string(c->personality)));
+
         if (c->syscall_filter) {
 #ifdef HAVE_SECCOMP
                 Iterator j;

src/core/execute.h

@@ -168,6 +168,8 @@ struct ExecContext {
          * don't enter a trigger loop. */
         bool same_pgrp;
 
+        unsigned long personality;
+
         Set *syscall_filter;
         Set *syscall_archs;
         int syscall_errno;

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

@@ -79,6 +79,7 @@ $1.PrivateTmp,                   config_parse_bool,                  0,
 $1.PrivateNetwork,               config_parse_bool,                  0,                             offsetof($1, exec_context.private_network)
 $1.PrivateDevices,               config_parse_bool,                  0,                             offsetof($1, exec_context.private_devices)
 $1.MountFlags,                   config_parse_exec_mount_flags,      0,                             offsetof($1, exec_context)
+$1.Personality,                  config_parse_personality,           0,                             offsetof($1, exec_context.personality)
 m4_ifdef(`HAVE_LIBWRAP',
 `$1.TCPWrapName,                 config_parse_unit_string_printf,    0,                             offsetof($1, exec_context.tcpwrap_name)',
 `$1.TCPWrapName,                 config_parse_warn_compat,           0,                             0')

src/core/load-fragment.c

@@ -2566,6 +2566,36 @@ int config_parse_job_mode_isolate(
         return 0;
 }
 
+int config_parse_personality(
+                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) {
+
+        unsigned long *personality = data, p;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(personality);
+
+        p = personality_from_string(rvalue);
+        if (p == 0xffffffffUL) {
+                log_syntax(unit, LOG_ERR, filename, line, EINVAL,
+                           "Failed to parse personality, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        *personality = p;
+        return 0;
+}
+
 #define FOLLOW_MAX 8
 
 static int open_follow(char **filename, FILE **_f, Set *names, char **_final) {

src/core/load-fragment.h

@@ -88,6 +88,7 @@ int config_parse_blockio_bandwidth(const char *unit, const char *filename, unsig
 int config_parse_job_mode(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_job_mode_isolate(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_selinux_context(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_personality(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);
 
 /* gperf prototypes */
 const struct ConfigPerfItem* load_fragment_gperf_lookup(const char *key, unsigned length);