lxc-attach: Clear environment and set container=lxc

src/lxc/attach.c

@@ -277,6 +277,21 @@ int lxc_attach_drop_privs(struct lxc_proc_context_info *ctx)
 	return 0;
 }
 
+int lxc_attach_set_environment()
+{
+	if (clearenv()) {
+		SYSERROR("failed to clear environment");
+		/* don't error out though */
+	}
+
+	if (putenv("container=lxc")) {
+		SYSERROR("failed to set environment variable");
+		return -1;
+	}
+
+	return 0;
+}
+
 char *lxc_attach_getpwshell(uid_t uid)
 {
 	/* local variables */

src/lxc/attach.h

@@ -37,6 +37,7 @@ extern struct lxc_proc_context_info *lxc_proc_get_context_info(pid_t pid);
 extern int lxc_attach_to_ns(pid_t other_pid, int which);
 extern int lxc_attach_remount_sys_proc();
 extern int lxc_attach_drop_privs(struct lxc_proc_context_info *ctx);
+extern int lxc_attach_set_environment();
 
 extern char *lxc_attach_getpwshell(uid_t uid);
 

src/lxc/lxc_attach.c

@@ -411,6 +411,11 @@ int main(int argc, char *argv[])
 			return -1;
 		}
 
+		if (lxc_attach_set_environment()) {
+			ERROR("could not set environment");
+			return -1;
+		}
+
 		/* tell parent we are done setting up the container and wait
 		 * until we have been put in the container's cgroup, if
 		 * applicable */