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Date: Tue, 17 Feb 2015 11:20:20 +0300
From: Andrey Vagin <avagin@...nvz.org>
To: linux-kernel@...r.kernel.org
Cc: linux-api@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Cyrill Gorcunov <gorcunov@...nvz.org>,
Pavel Emelyanov <xemul@...allels.com>,
Roger Luethi <rl@...lgate.ch>, Andrey Vagin <avagin@...nvz.org>
Subject: [PATCH 1/7] kernel: add a netlink interface to get information about tasks
task_diag is based on netlink sockets and looks like socket-diag, which
is used to get information about sockets.
task_diag is a new interface which is going to raplace the proc file
system in cases when we need to get information in a binary format.
A request messages is described by the task_diag_pid structure:
struct task_diag_pid {
__u64 show_flags;
__u64 dump_stratagy;
__u32 pid;
};
A respone is a set of netlink messages. Each message describes one task.
All task properties are divided on groups. A message contains the
TASK_DIAG_MSG group, and other groups if they have been requested in
show_flags. For example, if show_flags contains TASK_DIAG_SHOW_CRED, a
response will contain the TASK_DIAG_CRED group which is described by the
task_diag_creds structure.
struct task_diag_msg {
__u32 tgid;
__u32 pid;
__u32 ppid;
__u32 tpid;
__u32 sid;
__u32 pgid;
__u8 state;
char comm[TASK_DIAG_COMM_LEN];
};
The dump_stratagy field will be used in following patches to request
information for a group of processes.
Signed-off-by: Andrey Vagin <avagin@...nvz.org>
---
include/uapi/linux/taskdiag.h | 64 +++++++++++++++
init/Kconfig | 12 +++
kernel/Makefile | 1 +
kernel/taskdiag.c | 179 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 256 insertions(+)
create mode 100644 include/uapi/linux/taskdiag.h
create mode 100644 kernel/taskdiag.c
diff --git a/include/uapi/linux/taskdiag.h b/include/uapi/linux/taskdiag.h
new file mode 100644
index 0000000..e1feb35
--- /dev/null
+++ b/include/uapi/linux/taskdiag.h
@@ -0,0 +1,64 @@
+#ifndef _LINUX_TASKDIAG_H
+#define _LINUX_TASKDIAG_H
+
+#include <linux/types.h>
+#include <linux/capability.h>
+
+#define TASKDIAG_GENL_NAME "TASKDIAG"
+#define TASKDIAG_GENL_VERSION 0x1
+
+enum {
+ /* optional attributes which can be specified in show_flags */
+
+ /* other attributes */
+ TASK_DIAG_MSG = 64,
+};
+
+enum {
+ TASK_DIAG_RUNNING,
+ TASK_DIAG_INTERRUPTIBLE,
+ TASK_DIAG_UNINTERRUPTIBLE,
+ TASK_DIAG_STOPPED,
+ TASK_DIAG_TRACE_STOP,
+ TASK_DIAG_DEAD,
+ TASK_DIAG_ZOMBIE,
+};
+
+#define TASK_DIAG_COMM_LEN 16
+
+struct task_diag_msg {
+ __u32 tgid;
+ __u32 pid;
+ __u32 ppid;
+ __u32 tpid;
+ __u32 sid;
+ __u32 pgid;
+ __u8 state;
+ char comm[TASK_DIAG_COMM_LEN];
+};
+
+enum {
+ TASKDIAG_CMD_UNSPEC = 0, /* Reserved */
+ TASKDIAG_CMD_GET,
+ __TASKDIAG_CMD_MAX,
+};
+#define TASKDIAG_CMD_MAX (__TASKDIAG_CMD_MAX - 1)
+
+#define TASK_DIAG_DUMP_ALL 0
+
+struct task_diag_pid {
+ __u64 show_flags;
+ __u64 dump_stratagy;
+
+ __u32 pid;
+};
+
+enum {
+ TASKDIAG_CMD_ATTR_UNSPEC = 0,
+ TASKDIAG_CMD_ATTR_GET,
+ __TASKDIAG_CMD_ATTR_MAX,
+};
+
+#define TASKDIAG_CMD_ATTR_MAX (__TASKDIAG_CMD_ATTR_MAX - 1)
+
+#endif /* _LINUX_TASKDIAG_H */
diff --git a/init/Kconfig b/init/Kconfig
index 9afb971..e959ae3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -430,6 +430,18 @@ config TASKSTATS
Say N if unsure.
+config TASK_DIAG
+ bool "Export task/process properties through netlink"
+ depends on NET
+ default n
+ help
+ Export selected properties for tasks/processes through the
+ generic netlink interface. Unlike the proc file system, task_diag
+ returns information in a binary format, allows to specify which
+ information are required.
+
+ Say N if unsure.
+
config TASK_DELAY_ACCT
bool "Enable per-task delay accounting"
depends on TASKSTATS
diff --git a/kernel/Makefile b/kernel/Makefile
index a59481a..2d4fc71 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
obj-$(CONFIG_TORTURE_TEST) += torture.o
+obj-$(CONFIG_TASK_DIAG) += taskdiag.o
$(obj)/configs.o: $(obj)/config_data.h
diff --git a/kernel/taskdiag.c b/kernel/taskdiag.c
new file mode 100644
index 0000000..5faf3f0
--- /dev/null
+++ b/kernel/taskdiag.c
@@ -0,0 +1,179 @@
+#include <uapi/linux/taskdiag.h>
+#include <net/genetlink.h>
+#include <linux/pid_namespace.h>
+#include <linux/ptrace.h>
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+
+static struct genl_family family = {
+ .id = GENL_ID_GENERATE,
+ .name = TASKDIAG_GENL_NAME,
+ .version = TASKDIAG_GENL_VERSION,
+ .maxattr = TASKDIAG_CMD_ATTR_MAX,
+ .netnsok = true,
+};
+
+static size_t taskdiag_packet_size(u64 show_flags)
+{
+ return nla_total_size(sizeof(struct task_diag_msg));
+}
+
+/*
+ * The task state array is a strange "bitmap" of
+ * reasons to sleep. Thus "running" is zero, and
+ * you can test for combinations of others with
+ * simple bit tests.
+ */
+static const __u8 task_state_array[] = {
+ TASK_DIAG_RUNNING,
+ TASK_DIAG_INTERRUPTIBLE,
+ TASK_DIAG_UNINTERRUPTIBLE,
+ TASK_DIAG_STOPPED,
+ TASK_DIAG_TRACE_STOP,
+ TASK_DIAG_DEAD,
+ TASK_DIAG_ZOMBIE,
+};
+
+static inline const __u8 get_task_state(struct task_struct *tsk)
+{
+ unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT;
+
+ BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1);
+
+ return task_state_array[fls(state)];
+}
+
+static int fill_task_msg(struct task_struct *p, struct sk_buff *skb)
+{
+ struct pid_namespace *ns = task_active_pid_ns(current);
+ struct task_diag_msg *msg;
+ struct nlattr *attr;
+ char tcomm[sizeof(p->comm)];
+ struct task_struct *tracer;
+
+ attr = nla_reserve(skb, TASK_DIAG_MSG, sizeof(struct task_diag_msg));
+ if (!attr)
+ return -EMSGSIZE;
+
+ msg = nla_data(attr);
+
+ rcu_read_lock();
+ msg->ppid = pid_alive(p) ?
+ task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
+
+ msg->tpid = 0;
+ tracer = ptrace_parent(p);
+ if (tracer)
+ msg->tpid = task_pid_nr_ns(tracer, ns);
+
+ msg->tgid = task_tgid_nr_ns(p, ns);
+ msg->pid = task_pid_nr_ns(p, ns);
+ msg->sid = task_session_nr_ns(p, ns);
+ msg->pgid = task_pgrp_nr_ns(p, ns);
+
+ rcu_read_unlock();
+
+ get_task_comm(tcomm, p);
+ memset(msg->comm, 0, TASK_DIAG_COMM_LEN);
+ strncpy(msg->comm, tcomm, TASK_DIAG_COMM_LEN);
+
+ msg->state = get_task_state(p);
+
+ return 0;
+}
+
+static int task_diag_fill(struct task_struct *tsk, struct sk_buff *skb,
+ u64 show_flags, u32 portid, u32 seq)
+{
+ void *reply;
+ int err;
+
+ reply = genlmsg_put(skb, portid, seq, &family, 0, TASKDIAG_CMD_GET);
+ if (reply == NULL)
+ return -EMSGSIZE;
+
+ err = fill_task_msg(tsk, skb);
+ if (err)
+ goto err;
+
+ return genlmsg_end(skb, reply);
+err:
+ genlmsg_cancel(skb, reply);
+ return err;
+}
+
+static int taskdiag_doit(struct sk_buff *skb, struct genl_info *info)
+{
+ struct task_struct *tsk = NULL;
+ struct task_diag_pid *req;
+ struct sk_buff *msg;
+ size_t size;
+ int rc;
+
+ req = nla_data(info->attrs[TASKDIAG_CMD_ATTR_GET]);
+ if (req == NULL)
+ return -EINVAL;
+
+ if (nla_len(info->attrs[TASKDIAG_CMD_ATTR_GET]) < sizeof(*req))
+ return -EINVAL;
+
+ size = taskdiag_packet_size(req->show_flags);
+ msg = genlmsg_new(size, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ rcu_read_lock();
+ tsk = find_task_by_vpid(req->pid);
+ if (tsk)
+ get_task_struct(tsk);
+ rcu_read_unlock();
+ if (!tsk) {
+ rc = -ESRCH;
+ goto err;
+ };
+
+ if (!ptrace_may_access(tsk, PTRACE_MODE_READ)) {
+ put_task_struct(tsk);
+ rc = -EPERM;
+ goto err;
+ }
+
+ rc = task_diag_fill(tsk, msg, req->show_flags,
+ info->snd_portid, info->snd_seq);
+ put_task_struct(tsk);
+ if (rc < 0)
+ goto err;
+
+ return genlmsg_reply(msg, info);
+err:
+ nlmsg_free(msg);
+ return rc;
+}
+
+static const struct nla_policy
+ taskstats_cmd_get_policy[TASKDIAG_CMD_ATTR_MAX+1] = {
+ [TASKDIAG_CMD_ATTR_GET] = { .type = NLA_UNSPEC,
+ .len = sizeof(struct task_diag_pid)
+ },
+};
+
+static const struct genl_ops taskdiag_ops[] = {
+ {
+ .cmd = TASKDIAG_CMD_GET,
+ .doit = taskdiag_doit,
+ .policy = taskstats_cmd_get_policy,
+ },
+};
+
+static int __init taskdiag_init(void)
+{
+ int rc;
+
+ rc = genl_register_family_with_ops(&family, taskdiag_ops);
+ if (rc)
+ return rc;
+
+ return 0;
+}
+
+late_initcall(taskdiag_init);
--
2.1.0
--
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