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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
a6cf40a4 MJ |
2 | * |
3 | * lttng-context-mnt-ns.c | |
4 | * | |
5 | * LTTng mount 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 <lttng-events.h> | |
7b1edb4c | 16 | #include <linux/nsproxy.h> |
a6cf40a4 | 17 | #include <wrapper/ringbuffer/frontend_types.h> |
a6cf40a4 MJ |
18 | #include <lttng-tracer.h> |
19 | ||
9f920259 | 20 | #if !defined(LTTNG_MNT_NS_MISSING_HEADER) |
a6cf40a4 MJ |
21 | |
22 | #include <../fs/mount.h> | |
23 | ||
24 | static | |
25 | size_t mnt_ns_get_size(size_t offset) | |
26 | { | |
27 | size_t size = 0; | |
28 | ||
29 | size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int)); | |
30 | size += sizeof(unsigned int); | |
31 | return size; | |
32 | } | |
33 | ||
34 | static | |
35 | void mnt_ns_record(struct lttng_ctx_field *field, | |
36 | struct lib_ring_buffer_ctx *ctx, | |
37 | struct lttng_channel *chan) | |
38 | { | |
39 | unsigned int mnt_ns_inum = 0; | |
40 | ||
41 | /* | |
42 | * nsproxy can be NULL when scheduled out of exit. | |
43 | * | |
44 | * As documented in 'linux/nsproxy.h' namespaces access rules, no | |
45 | * precautions should be taken when accessing the current task's | |
46 | * namespaces, just dereference the pointers. | |
47 | */ | |
48 | if (current->nsproxy) | |
6388029c | 49 | mnt_ns_inum = current->nsproxy->mnt_ns->ns.inum; |
a6cf40a4 MJ |
50 | |
51 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(mnt_ns_inum)); | |
52 | chan->ops->event_write(ctx, &mnt_ns_inum, sizeof(mnt_ns_inum)); | |
53 | } | |
54 | ||
55 | static | |
56 | void mnt_ns_get_value(struct lttng_ctx_field *field, | |
57 | struct lttng_probe_ctx *lttng_probe_ctx, | |
58 | union lttng_ctx_value *value) | |
59 | { | |
60 | unsigned int mnt_ns_inum = 0; | |
61 | ||
62 | /* | |
63 | * nsproxy can be NULL when scheduled out of exit. | |
64 | * | |
65 | * As documented in 'linux/nsproxy.h' namespaces access rules, no | |
66 | * precautions should be taken when accessing the current task's | |
67 | * namespaces, just dereference the pointers. | |
68 | */ | |
69 | if (current->nsproxy) | |
6388029c | 70 | mnt_ns_inum = current->nsproxy->mnt_ns->ns.inum; |
a6cf40a4 MJ |
71 | |
72 | value->s64 = mnt_ns_inum; | |
73 | } | |
74 | ||
75 | int lttng_add_mnt_ns_to_ctx(struct lttng_ctx **ctx) | |
76 | { | |
77 | struct lttng_ctx_field *field; | |
78 | ||
79 | field = lttng_append_context(ctx); | |
80 | if (!field) | |
81 | return -ENOMEM; | |
82 | if (lttng_find_context(*ctx, "mnt_ns")) { | |
83 | lttng_remove_context_field(ctx, field); | |
84 | return -EEXIST; | |
85 | } | |
86 | field->event_field.name = "mnt_ns"; | |
87 | field->event_field.type.atype = atype_integer; | |
ceabb767 MD |
88 | field->event_field.type.u.integer.size = sizeof(unsigned int) * CHAR_BIT; |
89 | field->event_field.type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT; | |
90 | field->event_field.type.u.integer.signedness = lttng_is_signed_type(unsigned int); | |
91 | field->event_field.type.u.integer.reverse_byte_order = 0; | |
92 | field->event_field.type.u.integer.base = 10; | |
93 | field->event_field.type.u.integer.encoding = lttng_encode_none; | |
a6cf40a4 MJ |
94 | field->get_size = mnt_ns_get_size; |
95 | field->record = mnt_ns_record; | |
96 | field->get_value = mnt_ns_get_value; | |
97 | lttng_context_update(*ctx); | |
a6cf40a4 MJ |
98 | return 0; |
99 | } | |
100 | EXPORT_SYMBOL_GPL(lttng_add_mnt_ns_to_ctx); | |
101 | ||
102 | #endif |