The following pull request was submitted through Github. It can be accessed and reviewed at: https://github.com/lxc/lxc/pull/2977
This e-mail was sent by the LXC bot, direct replies will not reach the author unless they happen to be subscribed to this list. === Description (from pull-request) === Well, I added this syscall so we better use it. :) Signed-off-by: Christian Brauner <[email protected]>
From d9bb2fbab6c0f9a502408a4aa9bfbd9951c1b568 Mon Sep 17 00:00:00 2001 From: Christian Brauner <[email protected]> Date: Mon, 6 May 2019 10:49:31 +0200 Subject: [PATCH] raw_syscalls: add initial support for pidfd_send_signal() Well, I added this syscall so we better use it. :) Signed-off-by: Christian Brauner <[email protected]> --- src/lxc/raw_syscalls.c | 11 +++++++++++ src/lxc/raw_syscalls.h | 4 ++++ src/lxc/start.c | 44 +++++++++++++++++++++++++++++++++++++++--- src/lxc/start.h | 6 ++++++ 4 files changed, 62 insertions(+), 3 deletions(-) diff --git a/src/lxc/raw_syscalls.c b/src/lxc/raw_syscalls.c index 2e15575870..a16f6edf76 100644 --- a/src/lxc/raw_syscalls.c +++ b/src/lxc/raw_syscalls.c @@ -108,3 +108,14 @@ pid_t lxc_raw_clone_cb(int (*fn)(void *), void *args, unsigned long flags) return pid; } + +int lxc_raw_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, + unsigned int flags) +{ +#ifdef __NR_pidfd_send_signal + syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags); +#else + errno = ENOSYS; +#endif + return -1; +} diff --git a/src/lxc/raw_syscalls.h b/src/lxc/raw_syscalls.h index 224cf92fca..6c27f26a0b 100644 --- a/src/lxc/raw_syscalls.h +++ b/src/lxc/raw_syscalls.h @@ -26,6 +26,7 @@ #include <sched.h> #include <stdio.h> #include <stdlib.h> +#include <signal.h> #include <sys/syscall.h> #include <unistd.h> @@ -92,4 +93,7 @@ static inline pid_t lxc_raw_gettid(void) #endif } +extern int lxc_raw_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, + unsigned int flags); + #endif /* __LXC_RAW_SYSCALL_H */ diff --git a/src/lxc/start.c b/src/lxc/start.c index 5209af3586..651511dbe3 100644 --- a/src/lxc/start.c +++ b/src/lxc/start.c @@ -406,14 +406,21 @@ static int signal_handler(int fd, uint32_t events, void *data, } if (siginfo.ssi_signo == SIGHUP) { - kill(hdlr->pid, SIGTERM); + if (hdlr->proc_pidfd >= 0) + lxc_raw_pidfd_send_signal(hdlr->proc_pidfd, SIGTERM, NULL, 0); + else + kill(hdlr->pid, SIGTERM); INFO("Killing %d since terminal hung up", hdlr->pid); return hdlr->init_died ? LXC_MAINLOOP_CLOSE : LXC_MAINLOOP_CONTINUE; } if (siginfo.ssi_signo != SIGCHLD) { - kill(hdlr->pid, siginfo.ssi_signo); + if (hdlr->proc_pidfd >= 0) + lxc_raw_pidfd_send_signal(hdlr->proc_pidfd, + siginfo.ssi_signo, NULL, 0); + else + kill(hdlr->pid, siginfo.ssi_signo); INFO("Forwarded signal %d to pid %d", siginfo.ssi_signo, hdlr->pid); return hdlr->init_died ? LXC_MAINLOOP_CLOSE : LXC_MAINLOOP_CONTINUE; @@ -658,6 +665,8 @@ void lxc_zero_handler(struct lxc_handler *handler) handler->pinfd = -1; + handler->proc_pidfd = -EBADF; + handler->sigfd = -1; for (i = 0; i < LXC_NS_MAX; i++) @@ -678,6 +687,9 @@ void lxc_free_handler(struct lxc_handler *handler) if (handler->pinfd >= 0) close(handler->pinfd); + if (handler->proc_pidfd >= 0) + close(handler->proc_pidfd); + if (handler->sigfd >= 0) close(handler->sigfd); @@ -722,6 +734,7 @@ struct lxc_handler *lxc_init_handler(const char *name, struct lxc_conf *conf, handler->conf = conf; handler->lxcpath = lxcpath; handler->pinfd = -1; + handler->proc_pidfd = -EBADF; handler->sigfd = -EBADF; handler->init_died = false; handler->state_socket_pair[0] = handler->state_socket_pair[1] = -1; @@ -1088,7 +1101,7 @@ void lxc_abort(const char *name, struct lxc_handler *handler) lxc_set_state(name, handler, ABORTING); if (handler->pid > 0) { - ret = kill(handler->pid, SIGKILL); + ret = lxc_raw_pidfd_send_signal(handler->proc_pidfd, SIGKILL, NULL, 0); if (ret < 0) SYSERROR("Failed to send SIGKILL to %d", handler->pid); } @@ -1595,6 +1608,27 @@ static inline int do_share_ns(void *arg) return 0; } +static int proc_pidfd_open(pid_t pid) +{ + __do_close_prot_errno int proc_pidfd = -EBADF; + char path[100]; + + snprintf(path, sizeof(path), "/proc/%d", pid); + proc_pidfd = open(path, O_DIRECTORY | O_RDONLY | O_CLOEXEC); + if (proc_pidfd < 0) { + SYSERROR("Failed to open %s", path); + return -1; + } + + /* Test whether we can send signals. */ + if (lxc_raw_pidfd_send_signal(proc_pidfd, 0, NULL, 0)) { + SYSERROR("Failed to send signal through pidfd"); + return -1; + } + + return move_fd(proc_pidfd); +} + /* lxc_spawn() performs crucial setup tasks and clone()s the new process which * exec()s the requested container binary. * Note that lxc_spawn() runs in the parent namespaces. Any operations performed @@ -1722,6 +1756,10 @@ static int lxc_spawn(struct lxc_handler *handler) } TRACE("Cloned child process %d", handler->pid); + handler->proc_pidfd = proc_pidfd_open(handler->pid); + if (handler->proc_pidfd < 0 && (errno != ENOSYS)) + goto out_delete_net; + for (i = 0; i < LXC_NS_MAX; i++) if (handler->ns_on_clone_flags & ns_info[i].clone_flag) INFO("Cloned %s", ns_info[i].flag_name); diff --git a/src/lxc/start.h b/src/lxc/start.h index 60607ccc12..305782f272 100644 --- a/src/lxc/start.h +++ b/src/lxc/start.h @@ -102,6 +102,12 @@ struct lxc_handler { /* The child's pid. */ pid_t pid; + /* + * File descriptor for the /proc/<pid> directory of the container's + * init process. + */ + int proc_pidfd; + /* The monitor's pid. */ pid_t monitor_pid;
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