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