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 <wrapper/namespace.h>
  19 #include <lttng-tracer.h>
  20
  21 #if defined(CONFIG_USER_NS) && \
  22         (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
  23
  24 static
  25 size_t user_ns_get_size(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(struct lttng_ctx_field *field,
  36                  struct lib_ring_buffer_ctx *ctx,
  37                  struct lttng_channel *chan)
  38 {
  39         unsigned int user_ns_inum = 0;
  40
  41         if (current_user_ns())
  42                 user_ns_inum = current_user_ns()->lttng_ns_inum;
  43
  44         lib_ring_buffer_align_ctx(ctx, lttng_alignof(user_ns_inum));
  45         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum));
  46 }
  47
  48 static
  49 void user_ns_get_value(struct lttng_ctx_field *field,
  50                 struct lttng_probe_ctx *lttng_probe_ctx,
  51                 union lttng_ctx_value *value)
  52 {
  53         unsigned int user_ns_inum = 0;
  54
  55         if (current_user_ns())
  56                 user_ns_inum = current_user_ns()->lttng_ns_inum;
  57
  58         value->s64 = user_ns_inum;
  59 }
  60
  61 int lttng_add_user_ns_to_ctx(struct lttng_ctx **ctx)
  62 {
  63         struct lttng_ctx_field *field;
  64
  65         field = lttng_append_context(ctx);
  66         if (!field)
  67                 return -ENOMEM;
  68         if (lttng_find_context(*ctx, "user_ns")) {
  69                 lttng_remove_context_field(ctx, field);
  70                 return -EEXIST;
  71         }
  72         field->event_field.name = "user_ns";
  73         field->event_field.type.atype = atype_integer;
  74         field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT;
  75         field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  76         field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int);
  77         field->event_field.type.u.integer.reverse_byte_order = 0;
  78         field->event_field.type.u.integer.base = 10;
  79         field->event_field.type.u.integer.encoding = lttng_encode_none;
  80         field->get_size = user_ns_get_size;
  81         field->record = user_ns_record;
  82         field->get_value = user_ns_get_value;
  83         lttng_context_update(*ctx);
  84         return 0;
  85 }
  86 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  87
  88 #endif