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 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/sched.h>
  15 #include <linux/user_namespace.h>
  16 #include <lttng-events.h>
  17 #include <wrapper/ringbuffer/frontend_types.h>
  18 #include <lttng-tracer.h>
  19
  20 #if defined(CONFIG_USER_NS) && \
  21         (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
  22
  23 static
  24 size_t user_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 user_ns_record(struct lttng_ctx_field *field,
  35                  struct lib_ring_buffer_ctx *ctx,
  36                  struct lttng_channel *chan)
  37 {
  38         unsigned int user_ns_inum = 0;
  39
  40         if (current_user_ns())
  41                 user_ns_inum = current_user_ns()->ns.inum;
  42
  43         lib_ring_buffer_align_ctx(ctx, lttng_alignof(user_ns_inum));
  44         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum));
  45 }
  46
  47 static
  48 void user_ns_get_value(struct lttng_ctx_field *field,
  49                 struct lttng_probe_ctx *lttng_probe_ctx,
  50                 union 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->s64 = user_ns_inum;
  58 }
  59
  60 int lttng_add_user_ns_to_ctx(struct lttng_ctx **ctx)
  61 {
  62         struct lttng_ctx_field *field;
  63
  64         field = lttng_append_context(ctx);
  65         if (!field)
  66                 return -ENOMEM;
  67         if (lttng_find_context(*ctx, "user_ns")) {
  68                 lttng_remove_context_field(ctx, field);
  69                 return -EEXIST;
  70         }
  71         field->event_field.name = "user_ns";
  72         field->event_field.type.atype = atype_integer;
  73         field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT;
  74         field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  75         field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int);
  76         field->event_field.type.u.integer.reverse_byte_order = 0;
  77         field->event_field.type.u.integer.base = 10;
  78         field->event_field.type.u.integer.encoding = lttng_encode_none;
  79         field->get_size = user_ns_get_size;
  80         field->record = user_ns_record;
  81         field->get_value = user_ns_get_value;
  82         lttng_context_update(*ctx);
  83         return 0;
  84 }
  85 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  86
  87 #endif