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/lttng-events.h>
  17 #include <ringbuffer/frontend_types.h>
  18 #include <lttng/lttng-tracer.h>
  19
  20 #if defined(CONFIG_PID_NS)
  21
  22 static
  23 size_t pid_ns_get_size(size_t offset)
  24 {
  25         size_t size = 0;
  26
  27         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  28         size += sizeof(unsigned int);
  29         return size;
  30 }
  31
  32 static
  33 void pid_ns_record(struct lttng_ctx_field *field,
  34                  struct lib_ring_buffer_ctx *ctx,
  35                  struct lttng_channel *chan)
  36 {
  37         struct pid_namespace *ns;
  38         unsigned int pid_ns_inum = 0;
  39
  40         /*
  41          * The pid namespace is an exception -- it's accessed using
  42          * task_active_pid_ns. The pid namespace in nsproxy is the
  43          * namespace that children will use.
  44          */
  45         ns = task_active_pid_ns(current);
  46
  47         if (ns)
  48                 pid_ns_inum = ns->ns.inum;
  49
  50         lib_ring_buffer_align_ctx(ctx, lttng_alignof(pid_ns_inum));
  51         chan->ops->event_write(ctx, &pid_ns_inum, sizeof(pid_ns_inum));
  52 }
  53
  54 static
  55 void pid_ns_get_value(struct lttng_ctx_field *field,
  56                 struct lttng_probe_ctx *lttng_probe_ctx,
  57                 union lttng_ctx_value *value)
  58 {
  59         struct pid_namespace *ns;
  60         unsigned int pid_ns_inum = 0;
  61
  62         /*
  63          * The pid namespace is an exception -- it's accessed using
  64          * task_active_pid_ns. The pid namespace in nsproxy is the
  65          * namespace that children will use.
  66          */
  67         ns = task_active_pid_ns(current);
  68
  69         if (ns)
  70                 pid_ns_inum = ns->ns.inum;
  71
  72         value->s64 = pid_ns_inum;
  73 }
  74
  75 int lttng_add_pid_ns_to_ctx(struct lttng_ctx **ctx)
  76 {
  77         struct lttng_ctx_field *field;
  78
  79         field = lttng_append_context(ctx);
  80         if (!field)
  81                 return -ENOMEM;
  82         if (lttng_find_context(*ctx, "pid_ns")) {
  83                 lttng_remove_context_field(ctx, field);
  84                 return -EEXIST;
  85         }
  86         field->event_field.name = "pid_ns";
  87         field->event_field.type.atype = atype_integer;
  88         field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT;
  89         field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  90         field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int);
  91         field->event_field.type.u.integer.reverse_byte_order = 0;
  92         field->event_field.type.u.integer.base = 10;
  93         field->event_field.type.u.integer.encoding = lttng_encode_none;
  94         field->get_size = pid_ns_get_size;
  95         field->record = pid_ns_record;
  96         field->get_value = pid_ns_get_value;
  97         lttng_context_update(*ctx);
  98         return 0;
  99 }
 100 EXPORT_SYMBOL_GPL(lttng_add_pid_ns_to_ctx);
 101
 102 #endif