lttng-context-pid-ns.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-context-pid-ns.c
   4  *
   5  * LTTng pid 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/pid_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_PID_NS) && \
  23         (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0))
  24
  25 static
  26 size_t pid_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 pid_ns_record(struct lttng_ctx_field *field,
  37                  struct lib_ring_buffer_ctx *ctx,
  38                  struct lttng_channel *chan)
  39 {
  40         struct pid_namespace *ns;
  41         unsigned int pid_ns_inum = 0;
  42
  43         /*
  44          * The pid namespace is an exception -- it's accessed using
  45          * task_active_pid_ns. The pid namespace in nsproxy is the
  46          * namespace that children will use.
  47          */
  48         ns = task_active_pid_ns(current);
  49
  50         if (ns)
  51                 pid_ns_inum = ns->lttng_ns_inum;
  52
  53         lib_ring_buffer_align_ctx(ctx, lttng_alignof(pid_ns_inum));
  54         chan->ops->event_write(ctx, &pid_ns_inum, sizeof(pid_ns_inum));
  55 }
  56
  57 static
  58 void pid_ns_get_value(struct lttng_ctx_field *field,
  59                 struct lttng_probe_ctx *lttng_probe_ctx,
  60                 union lttng_ctx_value *value)
  61 {
  62         struct pid_namespace *ns;
  63         unsigned int pid_ns_inum = 0;
  64
  65         /*
  66          * The pid namespace is an exception -- it's accessed using
  67          * task_active_pid_ns. The pid namespace in nsproxy is the
  68          * namespace that children will use.
  69          */
  70         ns = task_active_pid_ns(current);
  71
  72         if (ns)
  73                 pid_ns_inum = ns->lttng_ns_inum;
  74
  75         value->s64 = pid_ns_inum;
  76 }
  77
  78 int lttng_add_pid_ns_to_ctx(struct lttng_ctx **ctx)
  79 {
  80         struct lttng_ctx_field *field;
  81
  82         field = lttng_append_context(ctx);
  83         if (!field)
  84                 return -ENOMEM;
  85         if (lttng_find_context(*ctx, "pid_ns")) {
  86                 lttng_remove_context_field(ctx, field);
  87                 return -EEXIST;
  88         }
  89         field->event_field.name = "pid_ns";
  90         field->event_field.type.atype = atype_integer;
  91         field->event_field.type.u.basic.integer.size = sizeof(unsigned int) * CHAR_BIT;
  92         field->event_field.type.u.basic.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
  93         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(unsigned int);
  94         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  95         field->event_field.type.u.basic.integer.base = 10;
  96         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  97         field->get_size = pid_ns_get_size;
  98         field->record = pid_ns_record;
  99         field->get_value = pid_ns_get_value;
 100         lttng_context_update(*ctx);
 101         wrapper_vmalloc_sync_all();
 102         return 0;
 103 }
 104 EXPORT_SYMBOL_GPL(lttng_add_pid_ns_to_ctx);
 105
 106 #endif