Commit | Line | Data |
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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 user namespace context. |
735bef47 MJ |
8 | */ |
9 | ||
10 | #define _LGPL_SOURCE | |
9af5d97a | 11 | #include <limits.h> |
b4051ad8 | 12 | #include <stddef.h> |
735bef47 MJ |
13 | #include <sys/types.h> |
14 | #include <sys/stat.h> | |
15 | #include <unistd.h> | |
16 | #include <lttng/ust-events.h> | |
17 | #include <lttng/ust-tracer.h> | |
0466ac28 | 18 | #include <lttng/ringbuffer-context.h> |
735bef47 | 19 | |
fc80554e | 20 | #include "context-internal.h" |
735bef47 MJ |
21 | #include "ns.h" |
22 | ||
23 | /* | |
24 | * We cache the result to ensure we don't stat(2) the proc filesystem on | |
25 | * each event. The user namespace is global to the process. | |
26 | */ | |
27 | static ino_t cached_user_ns = NS_INO_UNINITIALIZED; | |
28 | ||
29 | static | |
30 | ino_t get_user_ns(void) | |
31 | { | |
32 | struct stat sb; | |
33 | ino_t user_ns; | |
34 | ||
35 | user_ns = CMM_LOAD_SHARED(cached_user_ns); | |
36 | ||
37 | /* | |
38 | * If the cache is populated, do nothing and return the | |
39 | * cached inode number. | |
40 | */ | |
41 | if (caa_likely(user_ns != NS_INO_UNINITIALIZED)) | |
42 | return user_ns; | |
43 | ||
44 | /* | |
45 | * At this point we have to populate the cache, set the initial | |
46 | * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode | |
47 | * number from the proc filesystem, this is the value we will | |
48 | * cache. | |
49 | */ | |
50 | user_ns = NS_INO_UNAVAILABLE; | |
51 | ||
52 | if (stat("/proc/self/ns/user", &sb) == 0) { | |
53 | user_ns = sb.st_ino; | |
54 | } | |
55 | ||
56 | /* | |
57 | * And finally, store the inode number in the cache. | |
58 | */ | |
59 | CMM_STORE_SHARED(cached_user_ns, user_ns); | |
60 | ||
61 | return user_ns; | |
62 | } | |
63 | ||
64 | /* | |
65 | * The user namespace can change for 3 reasons | |
66 | * * clone(2) called with CLONE_NEWUSER | |
67 | * * setns(2) called with the fd of a different user ns | |
68 | * * unshare(2) called with CLONE_NEWUSER | |
69 | */ | |
70 | void lttng_context_user_ns_reset(void) | |
71 | { | |
72 | CMM_STORE_SHARED(cached_user_ns, NS_INO_UNINITIALIZED); | |
73 | } | |
74 | ||
75 | static | |
2208d8b5 MJ |
76 | size_t user_ns_get_size(struct lttng_ust_ctx_field *field __attribute__((unused)), |
77 | size_t offset) | |
735bef47 MJ |
78 | { |
79 | size_t size = 0; | |
80 | ||
dc325c1d | 81 | size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(ino_t)); |
735bef47 MJ |
82 | size += sizeof(ino_t); |
83 | return size; | |
84 | } | |
85 | ||
86 | static | |
2208d8b5 | 87 | void user_ns_record(struct lttng_ust_ctx_field *field __attribute__((unused)), |
735bef47 | 88 | struct lttng_ust_lib_ring_buffer_ctx *ctx, |
e7bc0ef6 | 89 | struct lttng_ust_channel_buffer *chan) |
735bef47 MJ |
90 | { |
91 | ino_t user_ns; | |
92 | ||
93 | user_ns = get_user_ns(); | |
8936b6c0 | 94 | chan->ops->event_write(ctx, &user_ns, sizeof(user_ns), lttng_ust_rb_alignof(user_ns)); |
735bef47 MJ |
95 | } |
96 | ||
97 | static | |
2208d8b5 | 98 | void user_ns_get_value(struct lttng_ust_ctx_field *field __attribute__((unused)), |
daacdbfc | 99 | struct lttng_ust_ctx_value *value) |
735bef47 MJ |
100 | { |
101 | value->u.s64 = get_user_ns(); | |
102 | } | |
103 | ||
daacdbfc | 104 | int lttng_add_user_ns_to_ctx(struct lttng_ust_ctx **ctx) |
735bef47 | 105 | { |
daacdbfc | 106 | struct lttng_ust_ctx_field *field; |
a084756d MD |
107 | struct lttng_ust_type_common *type; |
108 | int ret; | |
109 | ||
110 | type = lttng_ust_create_type_integer(sizeof(ino_t) * CHAR_BIT, | |
dc325c1d | 111 | lttng_ust_rb_alignof(ino_t) * CHAR_BIT, |
eae3c729 | 112 | lttng_ust_is_signed_type(ino_t), |
a084756d MD |
113 | BYTE_ORDER, 10); |
114 | if (!type) | |
735bef47 | 115 | return -ENOMEM; |
a084756d MD |
116 | field = lttng_append_context(ctx); |
117 | if (!field) { | |
118 | ret = -ENOMEM; | |
119 | goto error_context; | |
120 | } | |
735bef47 | 121 | if (lttng_find_context(*ctx, "user_ns")) { |
a084756d MD |
122 | ret = -EEXIST; |
123 | goto error_find_context; | |
124 | } | |
125 | field->event_field->name = strdup("user_ns"); | |
126 | if (!field->event_field->name) { | |
127 | ret = -ENOMEM; | |
128 | goto error_name; | |
735bef47 | 129 | } |
a084756d | 130 | field->event_field->type = type; |
735bef47 MJ |
131 | field->get_size = user_ns_get_size; |
132 | field->record = user_ns_record; | |
133 | field->get_value = user_ns_get_value; | |
134 | lttng_context_update(*ctx); | |
135 | return 0; | |
a084756d MD |
136 | |
137 | error_name: | |
138 | error_find_context: | |
139 | lttng_remove_context_field(ctx, field); | |
140 | error_context: | |
141 | lttng_ust_destroy_type(type); | |
142 | return ret; | |
735bef47 | 143 | } |