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/lttng-events.h>
  17 #include <ringbuffer/frontend_types.h>
  18 #include <lttng/lttng-tracer.h>
  19
  20 #if defined(CONFIG_USER_NS)
  21
  22 static
  23 size_t user_ns_get_size(size_t offset)
  24 {
  25         size_t size = 0;
  26
  27         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  28         size += sizeof(unsigned int);
  29         return size;
  30 }
  31
  32 static
  33 void user_ns_record(struct lttng_ctx_field *field,
  34                  struct lib_ring_buffer_ctx *ctx,
  35                  struct lttng_channel *chan)
  36 {
  37         unsigned int user_ns_inum = 0;
  38
  39         if (current_user_ns())
  40                 user_ns_inum = current_user_ns()->ns.inum;
  41
  42         lib_ring_buffer_align_ctx(ctx, lttng_alignof(user_ns_inum));
  43         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum));
  44 }
  45
  46 static
  47 void user_ns_get_value(struct lttng_ctx_field *field,
  48                 struct lttng_probe_ctx *lttng_probe_ctx,
  49                 union lttng_ctx_value *value)
  50 {
  51         unsigned int user_ns_inum = 0;
  52
  53         if (current_user_ns())
  54                 user_ns_inum = current_user_ns()->ns.inum;
  55
  56         value->s64 = user_ns_inum;
  57 }
  58
  59 int lttng_add_user_ns_to_ctx(struct lttng_ctx **ctx)
  60 {
  61         struct lttng_ctx_field *field;
  62
  63         field = lttng_append_context(ctx);
  64         if (!field)
  65                 return -ENOMEM;
  66         if (lttng_find_context(*ctx, "user_ns")) {
  67                 lttng_remove_context_field(ctx, field);
  68                 return -EEXIST;
  69         }
  70         field->event_field.name = "user_ns";
  71         field->event_field.type.atype = atype_integer;
  72         field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT;
  73         field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  74         field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int);
  75         field->event_field.type.u.integer.reverse_byte_order = 0;
  76         field->event_field.type.u.integer.base = 10;
  77         field->event_field.type.u.integer.encoding = lttng_encode_none;
  78         field->get_size = user_ns_get_size;
  79         field->record = user_ns_record;
  80         field->get_value = user_ns_get_value;
  81         lttng_context_update(*ctx);
  82         return 0;
  83 }
  84 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  85
  86 #endif