src/lttng-context-user-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-user-ns.c
   4  *
   5  * LTTng user 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_USER_NS
  13
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17 #include <linux/user_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 user_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 user_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 user_ns_inum = 0;
  40
  41         if (current_user_ns())
  42                 user_ns_inum = current_user_ns()->ns.inum;
  43
  44         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum), lttng_alignof(user_ns_inum));
  45 }
  46
  47 static
  48 void user_ns_get_value(void *priv,
  49                 struct lttng_kernel_probe_ctx *lttng_probe_ctx,
  50                 struct lttng_ctx_value *value)
  51 {
  52         unsigned int user_ns_inum = 0;
  53
  54         if (current_user_ns())
  55                 user_ns_inum = current_user_ns()->ns.inum;
  56
  57         value->u.s64 = user_ns_inum;
  58 }
  59
  60 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
  61         lttng_kernel_static_event_field("user_ns",
  62                 lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10),
  63                 false, false),
  64         user_ns_get_size,
  65         user_ns_record,
  66         user_ns_get_value,
  67         NULL, NULL);
  68
  69 int lttng_add_user_ns_to_ctx(struct lttng_kernel_ctx **ctx)
  70 {
  71         int ret;
  72
  73         if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
  74                 return -EEXIST;
  75         ret = lttng_kernel_context_append(ctx, ctx_field);
  76         wrapper_vmalloc_sync_mappings();
  77         return ret;
  78 }
  79 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  80
  81 #endif