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a6cf40a4 MJ |
1 | /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1) |
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 MJ |
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(LTTNG_MNT_NS_MISSING_HEADER) && \ | |
23 | (LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0)) | |
24 | ||
25 | #include <../fs/mount.h> | |
26 | ||
27 | static | |
28 | size_t mnt_ns_get_size(size_t offset) | |
29 | { | |
30 | size_t size = 0; | |
31 | ||
32 | size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int)); | |
33 | size += sizeof(unsigned int); | |
34 | return size; | |
35 | } | |
36 | ||
37 | static | |
38 | void mnt_ns_record(struct lttng_ctx_field *field, | |
39 | struct lib_ring_buffer_ctx *ctx, | |
40 | struct lttng_channel *chan) | |
41 | { | |
42 | unsigned int mnt_ns_inum = 0; | |
43 | ||
44 | /* | |
45 | * nsproxy can be NULL when scheduled out of exit. | |
46 | * | |
47 | * As documented in 'linux/nsproxy.h' namespaces access rules, no | |
48 | * precautions should be taken when accessing the current task's | |
49 | * namespaces, just dereference the pointers. | |
50 | */ | |
51 | if (current->nsproxy) | |
52 | mnt_ns_inum = current->nsproxy->mnt_ns->lttng_ns_inum; | |
53 | ||
54 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(mnt_ns_inum)); | |
55 | chan->ops->event_write(ctx, &mnt_ns_inum, sizeof(mnt_ns_inum)); | |
56 | } | |
57 | ||
58 | static | |
59 | void mnt_ns_get_value(struct lttng_ctx_field *field, | |
60 | struct lttng_probe_ctx *lttng_probe_ctx, | |
61 | union lttng_ctx_value *value) | |
62 | { | |
63 | unsigned int mnt_ns_inum = 0; | |
64 | ||
65 | /* | |
66 | * nsproxy can be NULL when scheduled out of exit. | |
67 | * | |
68 | * As documented in 'linux/nsproxy.h' namespaces access rules, no | |
69 | * precautions should be taken when accessing the current task's | |
70 | * namespaces, just dereference the pointers. | |
71 | */ | |
72 | if (current->nsproxy) | |
73 | mnt_ns_inum = current->nsproxy->mnt_ns->lttng_ns_inum; | |
74 | ||
75 | value->s64 = mnt_ns_inum; | |
76 | } | |
77 | ||
78 | int lttng_add_mnt_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, "mnt_ns")) { | |
86 | lttng_remove_context_field(ctx, field); | |
87 | return -EEXIST; | |
88 | } | |
89 | field->event_field.name = "mnt_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 = mnt_ns_get_size; | |
98 | field->record = mnt_ns_record; | |
99 | field->get_value = mnt_ns_get_value; | |
100 | lttng_context_update(*ctx); | |
ea53823c | 101 | wrapper_vmalloc_sync_mappings(); |
a6cf40a4 MJ |
102 | return 0; |
103 | } | |
104 | EXPORT_SYMBOL_GPL(lttng_add_mnt_ns_to_ctx); | |
105 | ||
106 | #endif |