Verify validity of session name when received from outside

Only ASCII letters and digits are allowed.

Makefile.am

@@ -2324,7 +2324,10 @@ if HAVE_ACL
 libudev_core_la_SOURCES += \
 	src/udev/udev-builtin-uaccess.c \
 	src/login/logind-acl.c \
-	src/login/sd-login.c
+	src/login/sd-login.c \
+	src/systemd/sd-login.h \
+	src/login/login-shared.c \
+	src/login/login-shared.h
 
 libudev_core_la_LIBADD += \
 	libsystemd-acl.la
@@ -3759,7 +3762,9 @@ libsystemd_logind_core_la_SOURCES = \
 	src/login/logind-session-dbus.c \
 	src/login/logind-seat-dbus.c \
 	src/login/logind-user-dbus.c \
-	src/login/logind-acl.h
+	src/login/logind-acl.h \
+	src/login/login-shared.c \
+	src/login/login-shared.h
 
 libsystemd_logind_core_la_CFLAGS = \
 	$(AM_CFLAGS) \
@@ -3860,7 +3865,10 @@ tests += \
 	test-login-tables
 
 libsystemd_login_la_SOURCES = \
-	src/login/sd-login.c
+	src/login/sd-login.c \
+	src/systemd/sd-login.h \
+	src/login/login-shared.c \
+	src/login/login-shared.h
 
 libsystemd_login_la_CFLAGS = \
 	$(AM_CFLAGS) \

TODO

@@ -142,9 +142,6 @@ Features:
 
 * journald: make sure ratelimit is actually really per-service with the new cgroup changes
 
-* libsystemd-logind: sd_session_is_active() and friends: verify
-  validity of session name before appending it to a path
-
 * gparted needs to disable auto-activation of mount units somehow, or
   maybe we should stop doing auto-activation of this after boot
   entirely. https://bugzilla.gnome.org/show_bug.cgi?id=701676

src/login/login-shared.c

@@ -0,0 +1,8 @@
+#include "login-shared.h"
+#include "def.h"
+
+bool session_id_valid(const char *id) {
+        assert(id);
+
+        return id + strspn(id, LETTERS DIGITS) == '\0';
+}

src/login/login-shared.h

@@ -0,0 +1,3 @@
+#include <stdbool.h>
+
+bool session_id_valid(const char *id);

src/login/logind-dbus.c

@@ -554,6 +554,7 @@ static int bus_manager_create_session(Manager *m, DBusMessage *message) {
                  * the audit data and let's better register a new
                  * ID */
                 if (hashmap_get(m->sessions, id)) {
+                        log_warning("Existing logind session ID %s used by new audit session, ignoring", id);
                         audit_id = 0;
 
                         free(id);

src/login/logind-session.c

@@ -41,6 +41,7 @@ Session* session_new(Manager *m, const char *id) {
 
         assert(m);
         assert(id);
+        assert(session_id_valid(id));
 
         s = new0(Session, 1);
         if (!s)

src/login/logind-session.h

@@ -29,6 +29,7 @@ typedef enum KillWho KillWho;
 #include "logind.h"
 #include "logind-seat.h"
 #include "logind-user.h"
+#include "login-shared.h"
 
 typedef enum SessionState {
         SESSION_OPENING,  /* Session scope is being created */

src/login/logind.c

@@ -684,6 +684,12 @@ int manager_enumerate_sessions(Manager *m) {
                 if (!dirent_is_file(de))
                         continue;
 
+                if (!session_id_valid(de->d_name)) {
+                        log_warning("Invalid session file name '%s', ignoring.", de->d_name);
+                        r = -EINVAL;
+                        continue;
+                }
+
                 k = manager_add_session(m, de->d_name, &s);
                 if (k < 0) {
                         log_error("Failed to add session by file name %s: %s", de->d_name, strerror(-k));

src/login/sd-login.c

@@ -31,6 +31,7 @@
 #include "sd-login.h"
 #include "strv.h"
 #include "fileio.h"
+#include "login-shared.h"
 
 _public_ int sd_pid_get_session(pid_t pid, char **session) {
         if (pid < 0)
@@ -226,17 +227,19 @@ static int file_of_session(const char *session, char **_p) {
 
         assert(_p);
 
-        if (session)
+        if (session) {
+                if (!session_id_valid(session))
+                        return -EINVAL;
+
                 p = strappend("/run/systemd/sessions/", session);
-        else {
+        } else {
-                char *buf;
+                _cleanup_free_ char *buf = NULL;
 
                 r = sd_pid_get_session(0, &buf);
                 if (r < 0)
                         return r;
 
                 p = strappend("/run/systemd/sessions/", buf);
-                free(buf);
         }
 
         if (!p)
@@ -255,7 +258,6 @@ _public_ int sd_session_is_active(const char *session) {
                 return r;
 
         r = parse_env_file(p, NEWLINE, "ACTIVE", &s, NULL);
-
         if (r < 0)
                 return r;
 

src/shared/cgroup-util.c

@@ -1511,9 +1511,7 @@ char *cg_unescape(const char *p) {
 }
 
 #define CONTROLLER_VALID                        \
-        "0123456789"                            \
+        DIGITS LETTERS                          \
-        "abcdefghijklmnopqrstuvwxyz"            \
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"            \
         "_"
 
 bool cg_controller_is_valid(const char *p, bool allow_named) {

src/shared/def.h

@@ -33,3 +33,8 @@
 
 #define SIGNALS_CRASH_HANDLER SIGSEGV,SIGILL,SIGFPE,SIGBUS,SIGQUIT,SIGABRT
 #define SIGNALS_IGNORE SIGPIPE
+
+#define DIGITS            "0123456789"
+#define LOWERCASE_LETTERS "abcdefghijklmnopqrstuvwxyz"
+#define UPPERCASE_LETTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+#define LETTERS LOWERCASE_LETTERS UPPERCASE_LETTERS

src/shared/env-util.c

@@ -27,11 +27,10 @@
 #include "utf8.h"
 #include "util.h"
 #include "env-util.h"
+#include "def.h"
 
 #define VALID_CHARS_ENV_NAME                    \
-        "0123456789"                            \
+        DIGITS LETTERS                          \
-        "abcdefghijklmnopqrstuvwxyz"            \
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"            \
         "_"
 
 #ifndef ARG_MAX

src/shared/replace-var.c

@@ -24,6 +24,7 @@
 #include "macro.h"
 #include "util.h"
 #include "replace-var.h"
+#include "def.h"
 
 /*
  * Generic infrastructure for replacing @FOO@ style variables in
@@ -40,7 +41,7 @@ static int get_variable(const char *b, char **r) {
         if (*b != '@')
                 return 0;
 
-        k = strspn(b + 1, "ABCDEFGHIJKLMNOPQRSTUVWXYZ_");
+        k = strspn(b + 1, UPPERCASE_LETTERS "_");
         if (k <= 0 || b[k+1] != '@')
                 return 0;
 

src/shared/unit-name.c

@@ -26,11 +26,10 @@
 #include "path-util.h"
 #include "util.h"
 #include "unit-name.h"
+#include "def.h"
 
 #define VALID_CHARS                             \
-        "0123456789"                            \
+        DIGITS LETTERS                          \
-        "abcdefghijklmnopqrstuvwxyz"            \
-        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"            \
         ":-_.\\"
 
 static const char* const unit_type_table[_UNIT_TYPE_MAX] = {