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conmon: Teach conmon --pid-namespace

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This allows us to launch containers that create new PID namespaces
within an existing PID namespace that differs from the host PID
namespace.  One use-case is launching containers into a pod in
per-container PID namespaces that are children of the pod's infra
containter PID namespace (similar to the existing
--enable-shared-pid-namespace, but where the worker containers cannot
see each other or back up into the infra container).

Signed-off-by: W. Trevor King <wking@tremily.us>
This commit is contained in:
W. Trevor King 2018-01-19 16:52:12 -08:00
parent 54e76afc03
commit 6bf8f2e920
1 changed files with 20 additions and 0 deletions
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20
conmon/conmon.c
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@ -18,6 +18,7 @@
#include <sys/uio.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <sched.h>
#include <syslog.h>
#include <unistd.h>
#include <inttypes.h>
@ -104,6 +105,7 @@ static char *opt_cuuid = NULL;
static char *opt_runtime_path = NULL;
static char *opt_bundle_path = NULL;
static char *opt_pid_file = NULL;
static char *opt_pid_namespace = NULL;
static bool opt_systemd_cgroup = false;
static bool opt_no_pivot = false;
static char *opt_exec_process_spec = NULL;
@ -123,6 +125,7 @@ static GOptionEntry opt_entries[] =
{ "no-pivot", 0, 0, G_OPTION_ARG_NONE, &opt_no_pivot, "do not use pivot_root", NULL },
{ "bundle", 'b', 0, G_OPTION_ARG_STRING, &opt_bundle_path, "Bundle path", NULL },
{ "pidfile", 'p', 0, G_OPTION_ARG_STRING, &opt_pid_file, "PID file", NULL },
{ "pid-namespace", 0, 0, G_OPTION_ARG_STRING, &opt_pid_namespace, "PID namespace", NULL },
{ "systemd-cgroup", 's', 0, G_OPTION_ARG_NONE, &opt_systemd_cgroup, "Enable systemd cgroup manager", NULL },
{ "exec", 'e', 0, G_OPTION_ARG_NONE, &opt_exec, "Exec a command in a running container", NULL },
{ "exec-process-spec", 0, 0, G_OPTION_ARG_STRING, &opt_exec_process_spec, "Path to the process spec for exec", NULL },
@ -1095,6 +1098,7 @@ int main(int argc, char *argv[])
int num_read;
int sync_pipe_fd = -1;
int start_pipe_fd = -1;
int pid_namespace_fd = -1;
GError *error = NULL;
GOptionContext *context;
GPtrArray *runtime_argv = NULL;
@ -1202,6 +1206,22 @@ int main(int argc, char *argv[])
pexit("Failed to set as subreaper");
}
if (opt_pid_namespace) {
pid_namespace_fd = open(opt_pid_namespace, O_RDONLY);
if (pid_namespace_fd == -1) {
pexit("Failed to open PID namespace at %s", opt_pid_namespace);
}
ret = setns(pid_namespace_fd, CLONE_NEWPID);
if (ret != 0) {
close(pid_namespace_fd);
pexit("Failed to join the PID namespace at %s: %s", opt_pid_namespace, strerror(errno));
}
ret = close(pid_namespace_fd);
if (ret != 0) {
pexit("Failed to close the PID namespace at %s", opt_pid_namespace);
}
}
if (opt_terminal) {
csname = setup_console_socket();
} else {