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authorGiuseppe Scrivano <gscrivan@redhat.com>2019-06-03 14:22:03 +0200
committerGiuseppe Scrivano <gscrivan@redhat.com>2019-06-03 14:25:10 +0200
commit6b0e1a3091d412273cf814bffb655c6e10073f0e (patch)
tree4fc0cab256dbd0c340e18b9538d9092cf7f19b05 /pkg
parent176a41c355bdc567978f4417e5bd2d3c7cdce914 (diff)
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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 <gscrivan@redhat.com>
Diffstat (limited to 'pkg')
-rw-r--r--pkg/rootless/rootless_linux.c22
1 files changed, 22 insertions, 0 deletions
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);