lttng-context-net-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-net-ns.c
   4  *
   5  * LTTng net 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/nsproxy.h>
  16 #include <net/net_namespace.h>
  17 #include <lttng/lttng-events.h>
  18 #include <ringbuffer/frontend_types.h>
  19 #include <lttng/lttng-tracer.h>
  20
  21 #if defined(CONFIG_NET_NS)
  22
  23 static
  24 size_t net_ns_get_size(size_t offset)
  25 {
  26         size_t size = 0;
  27
  28         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  29         size += sizeof(unsigned int);
  30         return size;
  31 }
  32
  33 static
  34 void net_ns_record(struct lttng_ctx_field *field,
  35                  struct lib_ring_buffer_ctx *ctx,
  36                  struct lttng_channel *chan)
  37 {
  38         unsigned int net_ns_inum = 0;
  39
  40         /*
  41          * nsproxy can be NULL when scheduled out of exit.
  42          *
  43          * As documented in 'linux/nsproxy.h' namespaces access rules, no
  44          * precautions should be taken when accessing the current task's
  45          * namespaces, just dereference the pointers.
  46          */
  47         if (current->nsproxy)
  48                 net_ns_inum = current->nsproxy->net_ns->ns.inum;
  49
  50         lib_ring_buffer_align_ctx(ctx, lttng_alignof(net_ns_inum));
  51         chan->ops->event_write(ctx, &net_ns_inum, sizeof(net_ns_inum));
  52 }
  53
  54 static
  55 void net_ns_get_value(struct lttng_ctx_field *field,
  56                 struct lttng_probe_ctx *lttng_probe_ctx,
  57                 union lttng_ctx_value *value)
  58 {
  59         unsigned int net_ns_inum = 0;
  60
  61         /*
  62          * nsproxy can be NULL when scheduled out of exit.
  63          *
  64          * As documented in 'linux/nsproxy.h' namespaces access rules, no
  65          * precautions should be taken when accessing the current task's
  66          * namespaces, just dereference the pointers.
  67          */
  68         if (current->nsproxy)
  69                 net_ns_inum = current->nsproxy->net_ns->ns.inum;
  70
  71         value->s64 = net_ns_inum;
  72 }
  73
  74 int lttng_add_net_ns_to_ctx(struct lttng_ctx **ctx)
  75 {
  76         struct lttng_ctx_field *field;
  77
  78         field = lttng_append_context(ctx);
  79         if (!field)
  80                 return -ENOMEM;
  81         if (lttng_find_context(*ctx, "net_ns")) {
  82                 lttng_remove_context_field(ctx, field);
  83                 return -EEXIST;
  84         }
  85         field->event_field.name = "net_ns";
  86         field->event_field.type.atype = atype_integer;
  87         field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT;
  88         field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  89         field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int);
  90         field->event_field.type.u.integer.reverse_byte_order = 0;
  91         field->event_field.type.u.integer.base = 10;
  92         field->event_field.type.u.integer.encoding = lttng_encode_none;
  93         field->get_size = net_ns_get_size;
  94         field->record = net_ns_record;
  95         field->get_value = net_ns_get_value;
  96         lttng_context_update(*ctx);
  97         return 0;
  98 }
  99 EXPORT_SYMBOL_GPL(lttng_add_net_ns_to_ctx);
 100
 101 #endif