src/lttng-context-uts-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-uts-ns.c
   4  *
   5  * LTTng uts 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_UTS_NS
  13
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17 #include <linux/utsname.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 uts_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 uts_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         unsigned int uts_ns_inum = 0;
  40
  41         /*
  42          * nsproxy can be NULL when scheduled out of exit.
  43          *
  44          * As documented in 'linux/nsproxy.h' namespaces access rules, no
  45          * precautions should be taken when accessing the current task's
  46          * namespaces, just dereference the pointers.
  47          */
  48         if (current->nsproxy)
  49                 uts_ns_inum = current->nsproxy->uts_ns->ns.inum;
  50
  51         chan->ops->event_write(ctx, &uts_ns_inum, sizeof(uts_ns_inum), lttng_alignof(uts_ns_inum));
  52 }
  53
  54 static
  55 void uts_ns_get_value(void *priv,
  56                 struct lttng_kernel_probe_ctx *lttng_probe_ctx,
  57                 struct lttng_ctx_value *value)
  58 {
  59         unsigned int uts_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                 uts_ns_inum = current->nsproxy->uts_ns->ns.inum;
  70
  71         value->u.s64 = uts_ns_inum;
  72 }
  73
  74 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
  75         lttng_kernel_static_event_field("uts_ns",
  76                 lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10),
  77                 false, false),
  78         uts_ns_get_size,
  79         uts_ns_record,
  80         uts_ns_get_value,
  81         NULL, NULL);
  82
  83 int lttng_add_uts_ns_to_ctx(struct lttng_kernel_ctx **ctx)
  84 {
  85         int ret;
  86
  87         if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
  88                 return -EEXIST;
  89         ret = lttng_kernel_context_append(ctx, ctx_field);
  90         wrapper_vmalloc_sync_mappings();
  91         return ret;
  92 }
  93 EXPORT_SYMBOL_GPL(lttng_add_uts_ns_to_ctx);
  94
  95 #endif