core: be stricter when parsing User=/Group= fields

Let's verify the validity of the syntax of the user/group names set.

3 files changed, 125 insertions, 5 deletions

diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index 6a5c16a000..7f7c2fe185 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -19,9 +19,9 @@ m4_dnl Define the context options only once
 m4_define(`EXEC_CONTEXT_CONFIG_ITEMS',
 `$1.WorkingDirectory,            config_parse_working_directory,     0,                             offsetof($1, exec_context)
 $1.RootDirectory,                config_parse_unit_path_printf,      0,                             offsetof($1, exec_context.root_directory)
-$1.User,                         config_parse_unit_string_printf,    0,                             offsetof($1, exec_context.user)
-$1.Group,                        config_parse_unit_string_printf,    0,                             offsetof($1, exec_context.group)
-$1.SupplementaryGroups,          config_parse_strv,                  0,                             offsetof($1, exec_context.supplementary_groups)
+$1.User,                         config_parse_user_group,            0,                             offsetof($1, exec_context.user)
+$1.Group,                        config_parse_user_group,            0,                             offsetof($1, exec_context.group)
+$1.SupplementaryGroups,          config_parse_user_group_strv,       0,                             offsetof($1, exec_context.supplementary_groups)
 $1.Nice,                         config_parse_exec_nice,             0,                             offsetof($1, exec_context)
 $1.OOMScoreAdjust,               config_parse_exec_oom_score_adjust, 0,                             offsetof($1, exec_context)
 $1.IOSchedulingClass,            config_parse_exec_io_class,         0,                             offsetof($1, exec_context)
@@ -285,8 +285,8 @@ Socket.ExecStartPost,            config_parse_exec,                  SOCKET_EXEC
 Socket.ExecStopPre,              config_parse_exec,                  SOCKET_EXEC_STOP_PRE,          offsetof(Socket, exec_command)
 Socket.ExecStopPost,             config_parse_exec,                  SOCKET_EXEC_STOP_POST,         offsetof(Socket, exec_command)
 Socket.TimeoutSec,               config_parse_sec,                   0,                             offsetof(Socket, timeout_usec)
-Socket.SocketUser,               config_parse_unit_string_printf,    0,                             offsetof(Socket, user)
-Socket.SocketGroup,              config_parse_unit_string_printf,    0,                             offsetof(Socket, group)
+Socket.SocketUser,               config_parse_user_group,            0,                             offsetof(Socket, user)
+Socket.SocketGroup,              config_parse_user_group,            0,                             offsetof(Socket, group)
 Socket.SocketMode,               config_parse_mode,                  0,                             offsetof(Socket, socket_mode)
 Socket.DirectoryMode,            config_parse_mode,                  0,                             offsetof(Socket, directory_mode)
 Socket.Accept,                   config_parse_bool,                  0,                             offsetof(Socket, accept)
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index 782e420e4c..d8aaf4ef40 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -64,6 +64,7 @@
 #include "unit-name.h"
 #include "unit-printf.h"
 #include "unit.h"
+#include "user-util.h"
 #include "utf8.h"
 #include "web-util.h"
 
@@ -1763,6 +1764,123 @@ int config_parse_sec_fix_0(
         return 0;
 }
 
+int config_parse_user_group(
+                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) {
+
+        char **user = data, *n;
+        Unit *u = userdata;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(u);
+
+        if (isempty(rvalue))
+                n = NULL;
+        else {
+                _cleanup_free_ char *k = NULL;
+
+                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;
+                }
+
+                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;
+                }
+
+                n = k;
+                k = NULL;
+        }
+
+        free(*user);
+        *user = n;
+
+        return 0;
+}
+
+int config_parse_user_group_strv(
+                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) {
+
+        char ***users = data;
+        Unit *u = userdata;
+        const char *p;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(u);
+
+        if (isempty(rvalue)) {
+                char **empty;
+
+                empty = new0(char*, 1);
+                if (!empty)
+                        return log_oom();
+
+                strv_free(*users);
+                *users = empty;
+
+                return 0;
+        }
+
+        p = rvalue;
+        for (;;) {
+                _cleanup_free_ char *word = NULL, *k = NULL;
+
+                r = extract_first_word(&p, &word, WHITESPACE, 0);
+                if (r == 0)
+                        break;
+                if (r == -ENOMEM)
+                        return log_oom();
+                if (r < 0) {
+                        log_syntax(unit, LOG_ERR, filename, line, r, "Invalid syntax, ignoring: %s", rvalue);
+                        break;
+                }
+
+                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;
+                }
+
+                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;
+                }
+
+                r = strv_push(users, k);
+                if (r < 0)
+                        return log_oom();
+
+                k = NULL;
+        }
+
+        return 0;
+}
+
 int config_parse_busname_service(
                 const char *unit,
                 const char *filename,
diff --git a/src/core/load-fragment.h b/src/core/load-fragment.h
index b36a2e3a02..213bce55a7 100644
--- a/src/core/load-fragment.h
+++ b/src/core/load-fragment.h
@@ -111,6 +111,8 @@ int config_parse_exec_utmp_mode(const char *unit, const char *filename, unsigned
 int config_parse_working_directory(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_fdname(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_fix_0(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_user_group(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_user_group_strv(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);