src/lttng-context-pid-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-pid-ns.c
   4  *
   5  * LTTng pid namespace context.
   6  *
   7  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *               2019 Michael Jeanson <mjeanson@efficios.com>
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/sched.h>
  15 #include <linux/pid_namespace.h>
  16 #include <lttng/events.h>
  17 #include <lttng/events-internal.h>
  18 #include <ringbuffer/frontend_types.h>
  19 #include <wrapper/vmalloc.h>
  20 #include <wrapper/namespace.h>
  21 #include <lttng/tracer.h>
  22
  23 #if defined(CONFIG_PID_NS) && \
  24         (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,8,0))
  25
  26 static
  27 size_t pid_ns_get_size(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, size_t offset)
  28 {
  29         size_t size = 0;
  30
  31         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  32         size += sizeof(unsigned int);
  33         return size;
  34 }
  35
  36 static
  37 void pid_ns_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
  38                  struct lttng_kernel_ring_buffer_ctx *ctx,
  39                  struct lttng_kernel_channel_buffer *chan)
  40 {
  41         struct pid_namespace *ns;
  42         unsigned int pid_ns_inum = 0;
  43
  44         /*
  45          * The pid namespace is an exception -- it's accessed using
  46          * task_active_pid_ns. The pid namespace in nsproxy is the
  47          * namespace that children will use.
  48          */
  49         ns = task_active_pid_ns(current);
  50
  51         if (ns)
  52                 pid_ns_inum = ns->lttng_ns_inum;
  53
  54         chan->ops->event_write(ctx, &pid_ns_inum, sizeof(pid_ns_inum), lttng_alignof(pid_ns_inum));
  55 }
  56
  57 static
  58 void pid_ns_get_value(void *priv,
  59                 struct lttng_kernel_probe_ctx *lttng_probe_ctx,
  60                 struct lttng_ctx_value *value)
  61 {
  62         struct pid_namespace *ns;
  63         unsigned int pid_ns_inum = 0;
  64
  65         /*
  66          * The pid namespace is an exception -- it's accessed using
  67          * task_active_pid_ns. The pid namespace in nsproxy is the
  68          * namespace that children will use.
  69          */
  70         ns = task_active_pid_ns(current);
  71
  72         if (ns)
  73                 pid_ns_inum = ns->lttng_ns_inum;
  74
  75         value->u.s64 = pid_ns_inum;
  76 }
  77
  78 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
  79         lttng_kernel_static_event_field("pid_ns",
  80                 lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10),
  81                 false, false, false),
  82         pid_ns_get_size,
  83         pid_ns_record,
  84         pid_ns_get_value,
  85         NULL, NULL);
  86
  87 int lttng_add_pid_ns_to_ctx(struct lttng_kernel_ctx **ctx)
  88 {
  89         int ret;
  90
  91         if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
  92                 return -EEXIST;
  93         ret = lttng_kernel_context_append(ctx, ctx_field);
  94         wrapper_vmalloc_sync_mappings();
  95         return ret;
  96 }
  97 EXPORT_SYMBOL_GPL(lttng_add_pid_ns_to_ctx);
  98
  99 #endif