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 #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 <lttng/events-internal.h>
  18 #include <ringbuffer/frontend_types.h>
  19 #include <wrapper/vmalloc.h>
  20 #include <wrapper/namespace.h>
  21 #include <lttng/tracer.h>
  22
  23 #if defined(CONFIG_USER_NS) && \
  24         (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,8,0))
  25
  26 static
  27 size_t user_ns_get_size(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, size_t offset)
  28 {
  29         size_t size = 0;
  30
  31         size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
  32         size += sizeof(unsigned int);
  33         return size;
  34 }
  35
  36 static
  37 void user_ns_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
  38                  struct lttng_kernel_ring_buffer_ctx *ctx,
  39                  struct lttng_kernel_channel_buffer *chan)
  40 {
  41         unsigned int user_ns_inum = 0;
  42
  43         if (current_user_ns())
  44                 user_ns_inum = current_user_ns()->lttng_ns_inum;
  45
  46         chan->ops->event_write(ctx, &user_ns_inum, sizeof(user_ns_inum), lttng_alignof(user_ns_inum));
  47 }
  48
  49 static
  50 void user_ns_get_value(void *priv,
  51                 struct lttng_kernel_probe_ctx *lttng_probe_ctx,
  52                 struct 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->u.s64 = user_ns_inum;
  60 }
  61
  62 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
  63         lttng_kernel_static_event_field("user_ns",
  64                 lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10),
  65                 false, false, false),
  66         user_ns_get_size,
  67         user_ns_record,
  68         user_ns_get_value,
  69         NULL, NULL);
  70
  71 int lttng_add_user_ns_to_ctx(struct lttng_kernel_ctx **ctx)
  72 {
  73         int ret;
  74
  75         if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
  76                 return -EEXIST;
  77         ret = lttng_kernel_context_append(ctx, ctx_field);
  78         wrapper_vmalloc_sync_mappings();
  79         return ret;
  80 }
  81 EXPORT_SYMBOL_GPL(lttng_add_user_ns_to_ctx);
  82
  83 #endif