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It can be accessed and reviewed at: https://github.com/lxc/lxd/pull/6841
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=== Description (from pull-request) ===
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
From 37b4d1576fe7fc68a1052da7d9ebebe7921800e7 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Wed, 5 Feb 2020 20:17:50 +0100
Subject: [PATCH 1/4] lxd/main_checkfeature: add explicit _exit() even if it's
not needed
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/main_checkfeature.go | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/lxd/main_checkfeature.go b/lxd/main_checkfeature.go
index 403dcfb231..42aae72f31 100644
--- a/lxd/main_checkfeature.go
+++ b/lxd/main_checkfeature.go
@@ -266,8 +266,11 @@ static void is_user_notification_continue_aware(void)
if (pid < 0)
return;
- if (pid == 0)
+ if (pid == 0) {
__do_user_notification_continue();
+ // Should not be reached.
+ _exit(EXIT_FAILURE);
+ }
ret = waitpid(pid, &status, 0);
if ((ret == pid) && WIFEXITED(status) && !WEXITSTATUS(status))
From 445de54e319348b938cbe0d343ff092ad8c94226 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Wed, 5 Feb 2020 20:20:35 +0100
Subject: [PATCH 2/4] lxd/main_checkfeature: s/exit()/_exit()/g
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/main_checkfeature.go | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/lxd/main_checkfeature.go b/lxd/main_checkfeature.go
index 42aae72f31..77d80386be 100644
--- a/lxd/main_checkfeature.go
+++ b/lxd/main_checkfeature.go
@@ -178,11 +178,11 @@ __noreturn static void
__do_user_notification_continue(void)
listener = user_trap_syscall(__NR_dup,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
if (listener < 0)
- exit(1);
+ _exit(EXIT_FAILURE);
pid = fork();
if (pid < 0)
- exit(1);
+ _exit(EXIT_FAILURE);
if (pid == 0) {
int dup_fd, pipe_fds[2];
@@ -192,21 +192,21 @@ __noreturn static void
__do_user_notification_continue(void)
// will be closed anyway.
ret = pipe(pipe_fds);
if (ret < 0)
- exit(1);
+ _exit(EXIT_FAILURE);
// O_CLOEXEC doesn't matter as we're in the child and we're
// not going to exec.
dup_fd = dup(pipe_fds[0]);
if (dup_fd < 0)
- exit(1);
+ _exit(EXIT_FAILURE);
self = getpid();
ret = filecmp(self, self, pipe_fds[0], dup_fd);
if (ret)
- exit(2);
+ _exit(EXIT_FAILURE);
- exit(0);
+ _exit(EXIT_SUCCESS);
}
pollfd.fd = listener;
@@ -249,8 +249,8 @@ __noreturn static void __do_user_notification_continue(void)
cleanup_wait:
ret = waitpid(pid, &status, 0);
if ((ret != pid) || !WIFEXITED(status) || WEXITSTATUS(status))
- exit(1);
- exit(0);
+ _exit(EXIT_FAILURE);
+ _exit(EXIT_SUCCESS);
cleanup_sigkill:
kill(pid, SIGKILL);
From 9e89729860828215070a03529c7bffcdd8683567 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Wed, 5 Feb 2020 20:26:11 +0100
Subject: [PATCH 3/4] cgo: export wait_for_pid() helper
to handle being interrupted by a signal in other parts of the codebase.
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/main_checkfeature.go | 15 ++++++++-------
lxd/main_forkproxy.go | 19 +------------------
lxd/main_nsexec.go | 19 +++++++++++++++++++
3 files changed, 28 insertions(+), 25 deletions(-)
diff --git a/lxd/main_checkfeature.go b/lxd/main_checkfeature.go
index 77d80386be..aa50fa9fe6 100644
--- a/lxd/main_checkfeature.go
+++ b/lxd/main_checkfeature.go
@@ -17,10 +17,10 @@ import (
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
+#include <signal.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
-#include <sys/wait.h>
#include <unistd.h>
#include <syscall.h>
#include <linux/seccomp.h>
@@ -39,6 +39,7 @@ __ro_after_init int seccomp_notify_aware = 0;
__ro_after_init char errbuf[4096];
extern int can_inject_uevent(const char *uevent, size_t len);
+extern int wait_for_pid(pid_t pid);
static int netns_set_nsid(int fd)
{
@@ -171,7 +172,7 @@ __noreturn static void __do_user_notification_continue(void)
{
pid_t pid;
int ret;
- int status, listener;
+ int listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
struct pollfd pollfd;
@@ -247,8 +248,8 @@ __noreturn static void __do_user_notification_continue(void)
}
cleanup_wait:
- ret = waitpid(pid, &status, 0);
- if ((ret != pid) || !WIFEXITED(status) || WEXITSTATUS(status))
+ ret = wait_for_pid(pid);
+ if (ret)
_exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
@@ -259,7 +260,7 @@ cleanup_sigkill:
static void is_user_notification_continue_aware(void)
{
- int ret, status;
+ int ret;
pid_t pid;
pid = fork();
@@ -272,8 +273,8 @@ static void is_user_notification_continue_aware(void)
_exit(EXIT_FAILURE);
}
- ret = waitpid(pid, &status, 0);
- if ((ret == pid) && WIFEXITED(status) && !WEXITSTATUS(status))
+ ret = wait_for_pid(pid);
+ if (!ret)
seccomp_notify_aware = 2;
}
diff --git a/lxd/main_forkproxy.go b/lxd/main_forkproxy.go
index ec758b3a73..8bf38af7e4 100644
--- a/lxd/main_forkproxy.go
+++ b/lxd/main_forkproxy.go
@@ -41,6 +41,7 @@ import (
extern char* advance_arg(bool required);
extern void attach_userns(int pid);
extern int dosetns(int pid, char *nstype);
+extern int wait_for_pid(pid_t pid);
int whoami = -ESRCH;
@@ -59,24 +60,6 @@ static int switch_uid_gid(uint32_t uid, uint32_t gid)
return 0;
}
-static int wait_for_pid(pid_t pid)
-{
- int status, ret;
-
-again:
- ret = waitpid(pid, &status, 0);
- if (ret == -1) {
- if (errno == EINTR)
- goto again;
- return -1;
- }
- if (ret != pid)
- goto again;
- if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
- return -1;
- return 0;
-}
-
static int lxc_epoll_wait_nointr(int epfd, struct epoll_event* events,
int maxevents, int timeout)
{
diff --git a/lxd/main_nsexec.go b/lxd/main_nsexec.go
index 5e98408f1e..79ce48570e 100644
--- a/lxd/main_nsexec.go
+++ b/lxd/main_nsexec.go
@@ -33,6 +33,7 @@ package main
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
+#include <sys/wait.h>
#include <unistd.h>
#include "include/memory_utils.h"
@@ -51,6 +52,24 @@ char *cmdline_buf = NULL;
char *cmdline_cur = NULL;
ssize_t cmdline_size = -1;
+int wait_for_pid(pid_t pid)
+{
+ int status, ret;
+
+again:
+ ret = waitpid(pid, &status, 0);
+ if (ret == -1) {
+ if (errno == EINTR)
+ goto again;
+ return -1;
+ }
+ if (ret != pid)
+ goto again;
+ if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+ return -1;
+ return 0;
+}
+
char* advance_arg(bool required) {
while (*cmdline_cur != 0)
cmdline_cur++;
From 2df51307cf58fc7a046579ea693f13d9543baa73 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Wed, 5 Feb 2020 20:30:06 +0100
Subject: [PATCH 4/4] lxd/main_checkfeature: close listener
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
lxd/main_checkfeature.go | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lxd/main_checkfeature.go b/lxd/main_checkfeature.go
index aa50fa9fe6..a584b00e8a 100644
--- a/lxd/main_checkfeature.go
+++ b/lxd/main_checkfeature.go
@@ -170,9 +170,9 @@ static int filecmp(pid_t pid1, pid_t pid2, int fd1, int fd2)
__noreturn static void __do_user_notification_continue(void)
{
+ __do_close_prot_errno int listener = -EBADF;
pid_t pid;
int ret;
- int listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
struct pollfd pollfd;
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