lttng-context-user-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   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/vmalloc.h>
  19 #include <wrapper/namespace.h>
  20 #include <lttng-tracer.h>
  21
  22 #if defined(CONFIG_USER_NS) && \
  23         (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
  24
  25 static
  26 size_t user_ns_get_size(size_t offset)
  27 {
  28         size_t size = 0;
  29
  30         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  31         size += sizeof(unsigned int);
  32         return size;
  33 }
  34
  35 static
  36 void user_ns_record(struct lttng_ctx_field *field,
  37                  struct lib_ring_buffer_ctx *ctx,
  38                  struct lttng_channel *chan)
  39 {
  40         unsigned int user_ns_inum = 0;
  41
  42         if (current_user_ns())
  43                 user_ns_inum = current_user_ns()->lttng_ns_inum;
  44
  45         lib_ring_buffer_align_ctx(ctx, lttng_alignof(user_ns_inum));
  46         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum));
  47 }
  48
  49 static
  50 void user_ns_get_value(struct lttng_ctx_field *field,
  51                 struct lttng_probe_ctx *lttng_probe_ctx,
  52                 union lttng_ctx_value *value)
  53 {
  54         unsigned int user_ns_inum = 0;
  55
  56         if (current_user_ns())
  57                 user_ns_inum = current_user_ns()->lttng_ns_inum;
  58
  59         value->s64 = user_ns_inum;
  60 }
  61
  62 int lttng_add_user_ns_to_ctx(struct lttng_ctx **ctx)
  63 {
  64         struct lttng_ctx_field *field;
  65
  66         field = lttng_append_context(ctx);
  67         if (!field)
  68                 return -ENOMEM;
  69         if (lttng_find_context(*ctx, "user_ns")) {
  70                 lttng_remove_context_field(ctx, field);
  71                 return -EEXIST;
  72         }
  73         field->event_field.name = "user_ns";
  74         field->event_field.type.atype = atype_integer;
  75         field->event_field.type.u.basic.integer.size = sizeof(unsigned int) * CHAR_BIT;
  76         field->event_field.type.u.basic.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  77         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(unsigned int);
  78         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  79         field->event_field.type.u.basic.integer.base = 10;
  80         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  81         field->get_size = user_ns_get_size;
  82         field->record = user_ns_record;
  83         field->get_value = user_ns_get_value;
  84         lttng_context_update(*ctx);
  85         wrapper_vmalloc_sync_all();
  86         return 0;
  87 }
  88 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  89
  90 #endif