| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 2 | * |
| 3 | * lttng-context-hostname.c |
| 4 | * |
| 5 | * LTTng hostname context. |
| 6 | * |
| 7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/utsname.h> |
| 14 | #include <lttng-events.h> |
| 15 | #include <wrapper/ringbuffer/frontend_types.h> |
| 16 | #include <wrapper/vmalloc.h> |
| 17 | #include <lttng-tracer.h> |
| 18 | |
| 19 | #define LTTNG_HOSTNAME_CTX_LEN (__NEW_UTS_LEN + 1) |
| 20 | |
| 21 | static |
| 22 | size_t hostname_get_size(size_t offset) |
| 23 | { |
| 24 | size_t size = 0; |
| 25 | |
| 26 | size += LTTNG_HOSTNAME_CTX_LEN; |
| 27 | return size; |
| 28 | } |
| 29 | |
| 30 | static |
| 31 | void hostname_record(struct lttng_ctx_field *field, |
| 32 | struct lib_ring_buffer_ctx *ctx, |
| 33 | struct lttng_channel *chan) |
| 34 | { |
| 35 | struct nsproxy *nsproxy; |
| 36 | struct uts_namespace *ns; |
| 37 | char *hostname; |
| 38 | |
| 39 | /* |
| 40 | * No need to take the RCU read-side lock to read current |
| 41 | * nsproxy. (documented in nsproxy.h) |
| 42 | */ |
| 43 | nsproxy = current->nsproxy; |
| 44 | if (nsproxy) { |
| 45 | ns = nsproxy->uts_ns; |
| 46 | hostname = ns->name.nodename; |
| 47 | chan->ops->event_write(ctx, hostname, |
| 48 | LTTNG_HOSTNAME_CTX_LEN); |
| 49 | } else { |
| 50 | chan->ops->event_memset(ctx, 0, |
| 51 | LTTNG_HOSTNAME_CTX_LEN); |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | static |
| 56 | void hostname_get_value(struct lttng_ctx_field *field, |
| 57 | struct lttng_probe_ctx *lttng_probe_ctx, |
| 58 | union lttng_ctx_value *value) |
| 59 | { |
| 60 | struct nsproxy *nsproxy; |
| 61 | struct uts_namespace *ns; |
| 62 | char *hostname; |
| 63 | |
| 64 | /* |
| 65 | * No need to take the RCU read-side lock to read current |
| 66 | * nsproxy. (documented in nsproxy.h) |
| 67 | */ |
| 68 | nsproxy = current->nsproxy; |
| 69 | if (nsproxy) { |
| 70 | ns = nsproxy->uts_ns; |
| 71 | hostname = ns->name.nodename; |
| 72 | } else { |
| 73 | hostname = ""; |
| 74 | } |
| 75 | value->str = hostname; |
| 76 | } |
| 77 | |
| 78 | int lttng_add_hostname_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, "hostname")) { |
| 86 | lttng_remove_context_field(ctx, field); |
| 87 | return -EEXIST; |
| 88 | } |
| 89 | field->event_field.name = "hostname"; |
| 90 | field->event_field.type.atype = atype_array; |
| 91 | field->event_field.type.u.array.elem_type.atype = atype_integer; |
| 92 | field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT; |
| 93 | field->event_field.type.u.array.elem_type.u.basic.integer.alignment = lttng_alignof(char) * CHAR_BIT; |
| 94 | field->event_field.type.u.array.elem_type.u.basic.integer.signedness = lttng_is_signed_type(char); |
| 95 | field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0; |
| 96 | field->event_field.type.u.array.elem_type.u.basic.integer.base = 10; |
| 97 | field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8; |
| 98 | field->event_field.type.u.array.length = LTTNG_HOSTNAME_CTX_LEN; |
| 99 | |
| 100 | field->get_size = hostname_get_size; |
| 101 | field->record = hostname_record; |
| 102 | field->get_value = hostname_get_value; |
| 103 | lttng_context_update(*ctx); |
| 104 | wrapper_vmalloc_sync_all(); |
| 105 | return 0; |
| 106 | } |
| 107 | EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx); |