[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <b1e0bda36bae96297cc4dedfa3bfff85388e05ad.1460716337.git.zhaolei@cn.fujitsu.com>
Date: Wed, 11 May 2016 09:27:19 +0800
From: Zhao Lei <zhaolei@...fujitsu.com>
To: <linux-kernel@...r.kernel.org>
CC: <containers@...ts.linux-foundation.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Mateusz Guzik <mguzik@...hat.com>,
Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Zhao Lei <zhaolei@...fujitsu.com>
Subject: [PATCH 1/3] Save dump_root into pid_namespace
In current system, when we set core_pattern to a pipe, both pipe program
and program's output are in host's filesystem.
But when we set core_pattern to a file, the container will write dump
into container's filesystem.
Reason of above different is:
In pipe_mode dump_pattern setting, the process who write the dumpfile
is a kernel thread, whose fs_root always point to host's root fs.
This patch save the dump_root into pid_namespace, and when a crach
happened in container, this dump_root can be used as fs_root of
dump_writter_thread.
Signed-off-by: Zhao Lei <zhaolei@...fujitsu.com>
---
include/linux/pid_namespace.h | 3 +++
kernel/pid.c | 1 +
kernel/pid_namespace.c | 6 ++++++
kernel/sysctl.c | 30 ++++++++++++++++++++++++++----
4 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 918b117..535a532 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -9,6 +9,7 @@
#include <linux/nsproxy.h>
#include <linux/kref.h>
#include <linux/ns_common.h>
+#include <linux/path.h>
struct pidmap {
atomic_t nr_free;
@@ -45,6 +46,8 @@ struct pid_namespace {
int hide_pid;
int reboot; /* group exit code if this pidns was rebooted */
struct ns_common ns;
+ spinlock_t root_for_dump_lock;
+ struct path root_for_dump;
};
extern struct pid_namespace init_pid_ns;
diff --git a/kernel/pid.c b/kernel/pid.c
index 4d73a83..7207184 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -83,6 +83,7 @@ struct pid_namespace init_pid_ns = {
#ifdef CONFIG_PID_NS
.ns.ops = &pidns_operations,
#endif
+ .root_for_dump_lock = __SPIN_LOCK_UNLOCKED(init_pid_ns.root_for_dump_lock),
};
EXPORT_SYMBOL_GPL(init_pid_ns);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a65ba13..3d0eced 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -123,6 +123,8 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
for (i = 1; i < PIDMAP_ENTRIES; i++)
atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
+ spin_lock_init(&ns->root_for_dump_lock);
+
return ns;
out_free_map:
@@ -147,6 +149,10 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
for (i = 0; i < PIDMAP_ENTRIES; i++)
kfree(ns->pidmap[i].page);
put_user_ns(ns->user_ns);
+
+ if (ns->root_for_dump.mnt)
+ path_put(&ns->root_for_dump);
+
call_rcu(&ns->rcu, delayed_free_pidns);
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 725587f..5e0af77 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -65,6 +65,7 @@
#include <linux/sched/sysctl.h>
#include <linux/kexec.h>
#include <linux/bpf.h>
+#include <linux/fs_struct.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -2344,10 +2345,31 @@ static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
static int proc_dostring_coredump(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
- int error = proc_dostring(table, write, buffer, lenp, ppos);
- if (!error)
- validate_coredump_safety();
- return error;
+ struct pid_namespace *pid_ns;
+ int error;
+
+ error = proc_dostring(table, write, buffer, lenp, ppos);
+ if (error)
+ return error;
+
+ pid_ns = task_active_pid_ns(current);
+ if (WARN_ON(!pid_ns))
+ return -EINVAL;
+
+ spin_lock(&pid_ns->root_for_dump_lock);
+
+ if (pid_ns->root_for_dump.mnt)
+ path_put(&pid_ns->root_for_dump);
+
+ spin_lock(¤t->fs->lock);
+ pid_ns->root_for_dump = current->fs->root;
+ path_get(&pid_ns->root_for_dump);
+ spin_unlock(¤t->fs->lock);
+
+ spin_unlock(&pid_ns->root_for_dump_lock);
+
+ validate_coredump_safety();
+ return 0;
}
#endif
--
1.8.5.1
Powered by blists - more mailing lists