src/lttng-context-ipc-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-ipc-ns.c
   4  *
   5  * LTTng ipc 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/ipc_namespace.h>
  16 #include <lttng/events.h>
  17 #include <ringbuffer/frontend_types.h>
  18 #include <wrapper/vmalloc.h>
  19 #include <wrapper/namespace.h>
  20 #include <lttng/tracer.h>
  21
  22 #if defined(CONFIG_IPC_NS) && \
  23         (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,8,0))
  24
  25 static
  26 size_t ipc_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 ipc_ns_record(struct lttng_kernel_ctx_field *field,
  37                  struct lib_ring_buffer_ctx *ctx,
  38                  struct lttng_channel *chan)
  39 {
  40         unsigned int ipc_ns_inum = 0;
  41
  42         /*
  43          * nsproxy can be NULL when scheduled out of exit.
  44          *
  45          * As documented in 'linux/nsproxy.h' namespaces access rules, no
  46          * precautions should be taken when accessing the current task's
  47          * namespaces, just dereference the pointers.
  48          */
  49         if (current->nsproxy)
  50                 ipc_ns_inum = current->nsproxy->ipc_ns->lttng_ns_inum;
  51
  52         lib_ring_buffer_align_ctx(ctx, lttng_alignof(ipc_ns_inum));
  53         chan->ops->event_write(ctx, &ipc_ns_inum, sizeof(ipc_ns_inum));
  54 }
  55
  56 static
  57 void ipc_ns_get_value(struct lttng_kernel_ctx_field *field,
  58                 struct lttng_probe_ctx *lttng_probe_ctx,
  59                 union lttng_ctx_value *value)
  60 {
  61         unsigned int ipc_ns_inum = 0;
  62
  63         /*
  64          * nsproxy can be NULL when scheduled out of exit.
  65          *
  66          * As documented in 'linux/nsproxy.h' namespaces access rules, no
  67          * precautions should be taken when accessing the current task's
  68          * namespaces, just dereference the pointers.
  69          */
  70         if (current->nsproxy)
  71                 ipc_ns_inum = current->nsproxy->ipc_ns->lttng_ns_inum;
  72
  73         value->s64 = ipc_ns_inum;
  74 }
  75
  76 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(
  77         lttng_kernel_static_event_field("ipc_ns",
  78                 lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10),
  79                 false, false, false),
  80         ipc_ns_get_size,
  81         NULL,
  82         ipc_ns_record,
  83         ipc_ns_get_value,
  84         NULL, NULL);
  85
  86 int lttng_add_ipc_ns_to_ctx(struct lttng_kernel_ctx **ctx)
  87 {
  88         int ret;
  89
  90         if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name))
  91                 return -EEXIST;
  92         ret = lttng_kernel_context_append(ctx, ctx_field);
  93         wrapper_vmalloc_sync_mappings();
  94         return ret;
  95 }
  96 EXPORT_SYMBOL_GPL(lttng_add_ipc_ns_to_ctx);
  97
  98 #endif