From 6b0e1a3091d412273cf814bffb655c6e10073f0e Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 3 Jun 2019 14:22:03 +0200 Subject: rootless: block signals on re-exec we are allowed to use only signal safe functions between a fork of a multithreaded application and the next execve. Since setenv(3) is not signal safe, block signals. We are already doing it for creating a new namespace. This is mostly a cleanup since reexec_in_user_namespace_wait is used only only to join existing namespaces when we have not a pause.pid file. Signed-off-by: Giuseppe Scrivano --- pkg/rootless/rootless_linux.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/pkg/rootless/rootless_linux.c b/pkg/rootless/rootless_linux.c index a2425c83e..eb62d55e9 100644 --- a/pkg/rootless/rootless_linux.c +++ b/pkg/rootless/rootless_linux.c @@ -489,6 +489,7 @@ reexec_userns_join (int userns, int mountns, char *pause_pid_file_path) char **argv; int pid; char *cwd = getcwd (NULL, 0); + sigset_t sigset, oldsigset; if (cwd == NULL) { @@ -522,6 +523,22 @@ reexec_userns_join (int userns, int mountns, char *pause_pid_file_path) return pid; } + if (sigfillset (&sigset) < 0) + { + fprintf (stderr, "cannot fill sigset: %s\n", strerror (errno)); + _exit (EXIT_FAILURE); + } + if (sigdelset (&sigset, SIGCHLD) < 0) + { + fprintf (stderr, "cannot sigdelset(SIGCHLD): %s\n", strerror (errno)); + _exit (EXIT_FAILURE); + } + if (sigprocmask (SIG_BLOCK, &sigset, &oldsigset) < 0) + { + fprintf (stderr, "cannot block signals: %s\n", strerror (errno)); + _exit (EXIT_FAILURE); + } + setenv ("_CONTAINERS_USERNS_CONFIGURED", "init", 1); setenv ("_CONTAINERS_ROOTLESS_UID", uid, 1); setenv ("_CONTAINERS_ROOTLESS_GID", gid, 1); @@ -570,6 +587,11 @@ reexec_userns_join (int userns, int mountns, char *pause_pid_file_path) /* We ignore errors here as we didn't create the namespace anyway. */ create_pause_process (pause_pid_file_path, argv); } + if (sigprocmask (SIG_SETMASK, &oldsigset, NULL) < 0) + { + fprintf (stderr, "cannot block signals: %s\n", strerror (errno)); + _exit (EXIT_FAILURE); + } execvp (argv[0], argv); -- cgit v1.2.3-54-g00ecf