Fix: rcu: Fix data-race due to atomic_t copy-by-value (5.5.6, 5.4.22)
[lttng-modules.git] / lttng-context-euid.c
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1/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
2 *
3 * lttng-context-euid.c
4 *
5 * LTTng effective user ID 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/sched.h>
14#include <lttng-events.h>
15#include <lttng-tracer.h>
16#include <wrapper/ringbuffer/frontend_types.h>
17#include <wrapper/vmalloc.h>
18#include <wrapper/user_namespace.h>
19
20static
21size_t euid_get_size(size_t offset)
22{
23 size_t size = 0;
24
25 size += lib_ring_buffer_align(offset, lttng_alignof(uid_t));
26 size += sizeof(uid_t);
27 return size;
28}
29
30static
31void euid_record(struct lttng_ctx_field *field,
32 struct lib_ring_buffer_ctx *ctx,
33 struct lttng_channel *chan)
34{
35 uid_t euid;
36
37 euid = lttng_current_euid();
38 lib_ring_buffer_align_ctx(ctx, lttng_alignof(euid));
39 chan->ops->event_write(ctx, &euid, sizeof(euid));
40}
41
42static
43void euid_get_value(struct lttng_ctx_field *field,
44 struct lttng_probe_ctx *lttng_probe_ctx,
45 union lttng_ctx_value *value)
46{
47 value->s64 = lttng_current_euid();
48}
49
50int lttng_add_euid_to_ctx(struct lttng_ctx **ctx)
51{
52 struct lttng_ctx_field *field;
53
54 field = lttng_append_context(ctx);
55 if (!field)
56 return -ENOMEM;
57 if (lttng_find_context(*ctx, "euid")) {
58 lttng_remove_context_field(ctx, field);
59 return -EEXIST;
60 }
61 field->event_field.name = "euid";
62 field->event_field.type.atype = atype_integer;
63 field->event_field.type.u.basic.integer.size = sizeof(uid_t) * CHAR_BIT;
64 field->event_field.type.u.basic.integer.alignment = lttng_alignof(uid_t) * CHAR_BIT;
65 field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(uid_t);
66 field->event_field.type.u.basic.integer.reverse_byte_order = 0;
67 field->event_field.type.u.basic.integer.base = 10;
68 field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
69 field->get_size = euid_get_size;
70 field->record = euid_record;
71 field->get_value = euid_get_value;
72 lttng_context_update(*ctx);
73 wrapper_vmalloc_sync_all();
74 return 0;
75}
76EXPORT_SYMBOL_GPL(lttng_add_euid_to_ctx);
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