[PATCH v3 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

Hari Bathini
2016-12-12T18:19:57Z

With the advert of container technologies like docker, that depend
on namespaces for isolation, there is a need for tracing support for
namespaces. This patch introduces new PERF_RECORD_NAMESPACES event
for tracing based on namespaces related info.

Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
---

Changes from v2:
* Use time value from sample_id.

include/linux/perf_event.h | 2 +
include/uapi/linux/perf_event.h | 27 ++++++++
kernel/events/core.c | 134 +++++++++++++++++++++++++++++++++++++++
kernel/fork.c | 3 +
kernel/nsproxy.c | 5 +
5 files changed, 170 insertions(+), 1 deletion(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 4741ecd..42d8aa6 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1110,6 +1110,7 @@ extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks

extern void perf_event_exec(void);
extern void perf_event_comm(struct task_struct *tsk, bool exec);
+extern void perf_event_namespaces(struct task_struct *tsk);
extern void perf_event_fork(struct task_struct *tsk);

/* Callchains */
@@ -1312,6 +1313,7 @@ static inline int perf_unregister_guest_info_callbacks
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
static inline void perf_event_exec(void) { }
static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
+static inline void perf_event_namespaces(struct task_struct *tsk) { }
static inline void perf_event_fork(struct task_struct *tsk) { }
static inline void perf_event_init(void) { }
static inline int perf_swevent_get_recursion_context(void) { return -1; }
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index c66a485..2a48fc6 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -344,7 +344,8 @@ struct perf_event_attr {
use_clockid : 1, /* use @clockid for time fields */
context_switch : 1, /* context switch data */
write_backward : 1, /* Write ring buffer from end to beginning */
- __reserved_1 : 36;
+ namespaces : 1, /* include namespaces data */
+ __reserved_1 : 35;

union {
__u32 wakeup_events; /* wakeup every n events */
@@ -610,6 +611,18 @@ struct perf_event_header {
__u16 size;
};

+enum {
+ NET_NS_INDEX = 0,
+ UTS_NS_INDEX = 1,
+ IPC_NS_INDEX = 2,
+ PID_NS_INDEX = 3,
+ USER_NS_INDEX = 4,
+ MNT_NS_INDEX = 5,
+ CGROUP_NS_INDEX = 6,
+
+ NAMESPACES_MAX, /* maximum available namespaces */
+};
+
enum perf_event_type {

/*
@@ -862,6 +875,18 @@ enum perf_event_type {
*/
PERF_RECORD_SWITCH_CPU_WIDE = 15,

+ /*
+ * struct {
+ * struct perf_event_header header;
+ *
+ * u32 pid, tid;
+ * u64 dev_num;
+ * u64 inode_num[NAMESPACES_MAX];
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_NAMESPACES = 16,
+
PERF_RECORD_MAX, /* non-ABI */
};

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 02c8421..eb9c812 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -46,6 +46,10 @@
#include <linux/filter.h>
#include <linux/namei.h>
#include <linux/parser.h>
+#include <linux/proc_ns.h>
+#include <linux/mount.h>
+#include <linux/ipc_namespace.h>
+#include <linux/utsname.h>

#include "internal.h"

@@ -375,6 +379,7 @@ static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);

static atomic_t nr_mmap_events __read_mostly;
static atomic_t nr_comm_events __read_mostly;
+static atomic_t nr_namespaces_events __read_mostly;
static atomic_t nr_task_events __read_mostly;
static atomic_t nr_freq_events __read_mostly;
static atomic_t nr_switch_events __read_mostly;
@@ -3882,6 +3887,8 @@ static void unaccount_event(struct perf_event *event)
atomic_dec(&nr_mmap_events);
if (event->attr.comm)
atomic_dec(&nr_comm_events);
+ if (event->attr.namespaces)
+ atomic_dec(&nr_namespaces_events);
if (event->attr.task)
atomic_dec(&nr_task_events);
if (event->attr.freq)
@@ -6382,6 +6389,7 @@ static void perf_event_task(struct task_struct *task,
void perf_event_fork(struct task_struct *task)
{
perf_event_task(task, NULL, 1);
+ perf_event_namespaces(task);
}

/*
@@ -6484,6 +6492,125 @@ void perf_event_comm(struct task_struct *task, bool exec)
}

/*
+ * namespaces tracking
+ */
+
+struct namespaces_event_id {
+ struct perf_event_header header;
+ u32 pid;
+ u32 tid;
+ u64 dev_num;
+ u64 inode_num[NAMESPACES_MAX];
+};
+
+struct perf_namespaces_event {
+ struct task_struct *task;
+
+ struct namespaces_event_id event_id;
+};
+
+static int perf_event_namespaces_match(struct perf_event *event)
+{
+ return event->attr.namespaces;
+}
+
+static void perf_event_namespaces_output(struct perf_event *event,
+ void *data)
+{
+ struct perf_namespaces_event *namespaces_event = data;
+ struct perf_output_handle handle;
+ struct perf_sample_data sample;
+ struct path ns_path;
+ struct task_struct *task = namespaces_event->task;
+ struct namespaces_event_id *ei = &namespaces_event->event_id;
+ struct ns_common *ns_common;
+ struct nsproxy *nsproxy;
+ void *error;
+ int ret;
+
+ if (!perf_event_namespaces_match(event))
+ return;
+
+ perf_event_header__init_id(&ei->header, &sample, event);
+ ret = perf_output_begin(&handle, event, ei->header.size);
+ if (ret)
+ return;
+
+ ei->pid = perf_event_pid(event, task);
+ ei->tid = perf_event_tid(event, task);
+
+ error = ns_get_path(&ns_path, task, &mntns_operations);
+ if (!error)
+ ei->dev_num = ns_path.mnt->mnt_sb->s_dev;
+
+ ns_common = mntns_operations.get(task);
+ ei->inode_num[MNT_NS_INDEX] = ns_common->inum;
+ mntns_operations.put(ns_common);
+
+#ifdef CONFIG_USER_NS
+ ei->inode_num[USER_NS_INDEX] = __task_cred(task)->user_ns->ns.inum;
+#endif
+
+ if (task != current)
+ task_lock(task);
+
+ nsproxy = task->nsproxy;
+ if (nsproxy != NULL) {
+#ifdef CONFIG_NET_NS
+ ei->inode_num[NET_NS_INDEX] = nsproxy->net_ns->ns.inum;
+#endif
+#ifdef CONFIG_UTS_NS
+ ei->inode_num[UTS_NS_INDEX] = nsproxy->uts_ns->ns.inum;
+#endif
+#ifdef CONFIG_IPC_NS
+ ei->inode_num[IPC_NS_INDEX] = nsproxy->ipc_ns->ns.inum;
+#endif
+#ifdef CONFIG_PID_NS
+ ei->inode_num[PID_NS_INDEX] = nsproxy->pid_ns_for_children->ns.inum;
+#endif
+#ifdef CONFIG_CGROUPS
+ ei->inode_num[CGROUP_NS_INDEX] = nsproxy->cgroup_ns->ns.inum;
+#endif
+ }
+
+ if (task != current)
+ task_unlock(task);
+
+ perf_output_put(&handle, namespaces_event->event_id);
+
+ perf_event__output_id_sample(event, &handle, &sample);
+
+ perf_output_end(&handle);
+}
+
+void perf_event_namespaces(struct task_struct *task)
+{
+ struct perf_namespaces_event namespaces_event;
+
+ if (!atomic_read(&nr_namespaces_events))
+ return;
+
+ namespaces_event = (struct perf_namespaces_event){
+ .task = task,
+ .event_id = {
+ .header = {
+ .type = PERF_RECORD_NAMESPACES,
+ .misc = 0,
+ .size = sizeof(namespaces_event.event_id),
+ },
+ /* .pid */
+ /* .tid */
+ /* .dev_num */
+ /* .inode_num[NAMESPACES_MAX] */
+ },
+ };
+
+ perf_iterate_sb(perf_event_namespaces_output,
+ &namespaces_event,
+ NULL);
+}
+
+/*
* mmap tracking
*/

@@ -9028,6 +9155,8 @@ static void account_event(struct perf_event *event)
atomic_inc(&nr_mmap_events);
if (event->attr.comm)
atomic_inc(&nr_comm_events);
+ if (event->attr.namespaces)
+ atomic_inc(&nr_namespaces_events);
if (event->attr.task)
atomic_inc(&nr_task_events);
if (event->attr.freq)
@@ -9542,6 +9671,11 @@ SYSCALL_DEFINE5(perf_event_open,
return -EACCES;
}

+ if (attr.namespaces) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+ }
+
if (attr.freq) {
if (attr.sample_freq > sysctl_perf_event_sample_rate)
return -EINVAL;
diff --git a/kernel/fork.c b/kernel/fork.c
index 997ac1d..399a44b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2280,6 +2280,9 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
free_fs_struct(new_fs);

bad_unshare_out:
+ if (!err)
+ perf_event_namespaces(current);
+
return err;
}

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 782102e..4c25e6e 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -26,6 +26,7 @@
#include <linux/file.h>
#include <linux/syscalls.h>
#include <linux/cgroup.h>
+#include <linux/perf_event.h>

static struct kmem_cache *nsproxy_cachep;

@@ -264,6 +265,10 @@ SYSCALL_DEFINE2(setns, int, fd, int, nstype)
switch_task_namespaces(tsk, new_nsproxy);
out:
fput(file);
+
+ if (!err)
+ perf_event_namespaces(tsk);
+
return err;
}