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735bef47 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
735bef47 MJ |
3 | * |
4 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
c0c0989a | 5 | * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com> |
735bef47 | 6 | * |
c0c0989a | 7 | * LTTng UST net namespace context. |
735bef47 MJ |
8 | */ |
9 | ||
10 | #define _LGPL_SOURCE | |
b4051ad8 | 11 | #include <stddef.h> |
735bef47 MJ |
12 | #include <sys/types.h> |
13 | #include <sys/stat.h> | |
14 | #include <unistd.h> | |
15 | #include <lttng/ust-events.h> | |
16 | #include <lttng/ust-tracer.h> | |
0466ac28 | 17 | #include <lttng/ringbuffer-context.h> |
ae4b659d | 18 | #include <ust-tid.h> |
735bef47 | 19 | #include <urcu/tls-compat.h> |
fc80554e MJ |
20 | |
21 | #include "context-internal.h" | |
735bef47 MJ |
22 | #include "lttng-tracer-core.h" |
23 | #include "ns.h" | |
24 | ||
735bef47 MJ |
25 | /* |
26 | * We cache the result to ensure we don't stat(2) the proc filesystem on | |
27 | * each event. | |
28 | */ | |
a251a209 | 29 | static DEFINE_URCU_TLS_INIT(ino_t, cached_net_ns, NS_INO_UNINITIALIZED); |
735bef47 MJ |
30 | |
31 | static | |
32 | ino_t get_net_ns(void) | |
33 | { | |
34 | struct stat sb; | |
35 | ino_t net_ns; | |
36 | ||
37 | net_ns = CMM_LOAD_SHARED(URCU_TLS(cached_net_ns)); | |
38 | ||
39 | /* | |
40 | * If the cache is populated, do nothing and return the | |
41 | * cached inode number. | |
42 | */ | |
43 | if (caa_likely(net_ns != NS_INO_UNINITIALIZED)) | |
44 | return net_ns; | |
45 | ||
46 | /* | |
47 | * At this point we have to populate the cache, set the initial | |
48 | * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode | |
49 | * number from the proc filesystem, this is the value we will | |
50 | * cache. | |
51 | */ | |
52 | net_ns = NS_INO_UNAVAILABLE; | |
53 | ||
54 | /* | |
55 | * /proc/thread-self was introduced in kernel v3.17 | |
56 | */ | |
57 | if (stat("/proc/thread-self/ns/net", &sb) == 0) { | |
58 | net_ns = sb.st_ino; | |
59 | } else { | |
60 | char proc_ns_path[LTTNG_PROC_NS_PATH_MAX]; | |
61 | ||
62 | if (snprintf(proc_ns_path, LTTNG_PROC_NS_PATH_MAX, | |
63 | "/proc/self/task/%d/ns/net", | |
64 | lttng_gettid()) >= 0) { | |
65 | ||
66 | if (stat(proc_ns_path, &sb) == 0) { | |
67 | net_ns = sb.st_ino; | |
68 | } | |
69 | } | |
70 | } | |
71 | ||
72 | /* | |
73 | * And finally, store the inode number in the cache. | |
74 | */ | |
75 | CMM_STORE_SHARED(URCU_TLS(cached_net_ns), net_ns); | |
76 | ||
77 | return net_ns; | |
78 | } | |
79 | ||
80 | /* | |
81 | * The net namespace can change for 3 reasons | |
82 | * * clone(2) called with CLONE_NEWNET | |
83 | * * setns(2) called with the fd of a different net ns | |
84 | * * unshare(2) called with CLONE_NEWNET | |
85 | */ | |
86 | void lttng_context_net_ns_reset(void) | |
87 | { | |
88 | CMM_STORE_SHARED(URCU_TLS(cached_net_ns), NS_INO_UNINITIALIZED); | |
89 | } | |
90 | ||
91 | static | |
daacdbfc | 92 | size_t net_ns_get_size(struct lttng_ust_ctx_field *field, size_t offset) |
735bef47 MJ |
93 | { |
94 | size_t size = 0; | |
95 | ||
96 | size += lib_ring_buffer_align(offset, lttng_alignof(ino_t)); | |
97 | size += sizeof(ino_t); | |
98 | return size; | |
99 | } | |
100 | ||
101 | static | |
daacdbfc | 102 | void net_ns_record(struct lttng_ust_ctx_field *field, |
735bef47 | 103 | struct lttng_ust_lib_ring_buffer_ctx *ctx, |
e7bc0ef6 | 104 | struct lttng_ust_channel_buffer *chan) |
735bef47 MJ |
105 | { |
106 | ino_t net_ns; | |
107 | ||
108 | net_ns = get_net_ns(); | |
109 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(net_ns)); | |
110 | chan->ops->event_write(ctx, &net_ns, sizeof(net_ns)); | |
111 | } | |
112 | ||
113 | static | |
daacdbfc MD |
114 | void net_ns_get_value(struct lttng_ust_ctx_field *field, |
115 | struct lttng_ust_ctx_value *value) | |
735bef47 MJ |
116 | { |
117 | value->u.s64 = get_net_ns(); | |
118 | } | |
119 | ||
daacdbfc | 120 | int lttng_add_net_ns_to_ctx(struct lttng_ust_ctx **ctx) |
735bef47 | 121 | { |
daacdbfc | 122 | struct lttng_ust_ctx_field *field; |
a084756d MD |
123 | struct lttng_ust_type_common *type; |
124 | int ret; | |
125 | ||
126 | type = lttng_ust_create_type_integer(sizeof(ino_t) * CHAR_BIT, | |
127 | lttng_alignof(ino_t) * CHAR_BIT, | |
128 | lttng_is_signed_type(ino_t), | |
129 | BYTE_ORDER, 10); | |
130 | if (!type) | |
735bef47 | 131 | return -ENOMEM; |
a084756d MD |
132 | field = lttng_append_context(ctx); |
133 | if (!field) { | |
134 | ret = -ENOMEM; | |
135 | goto error_context; | |
136 | } | |
735bef47 | 137 | if (lttng_find_context(*ctx, "net_ns")) { |
a084756d MD |
138 | ret = -EEXIST; |
139 | goto error_find_context; | |
140 | } | |
141 | field->event_field->name = strdup("net_ns"); | |
142 | if (!field->event_field->name) { | |
143 | ret = -ENOMEM; | |
144 | goto error_name; | |
735bef47 | 145 | } |
a084756d | 146 | field->event_field->type = type; |
735bef47 MJ |
147 | field->get_size = net_ns_get_size; |
148 | field->record = net_ns_record; | |
149 | field->get_value = net_ns_get_value; | |
150 | lttng_context_update(*ctx); | |
151 | return 0; | |
a084756d MD |
152 | |
153 | error_name: | |
154 | error_find_context: | |
155 | lttng_remove_context_field(ctx, field); | |
156 | error_context: | |
157 | lttng_ust_destroy_type(type); | |
158 | return ret; | |
735bef47 MJ |
159 | } |
160 | ||
161 | /* | |
162 | * * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
163 | * */ | |
164 | void lttng_fixup_net_ns_tls(void) | |
165 | { | |
166 | asm volatile ("" : : "m" (URCU_TLS(cached_net_ns))); | |
167 | } |