| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 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 | #ifndef LTTNG_MNT_NS_MISSING_HEADER |
| 13 | |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/slab.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <lttng/events.h> |
| 18 | #include <lttng/events-internal.h> |
| 19 | #include <linux/nsproxy.h> |
| 20 | #include <ringbuffer/frontend_types.h> |
| 21 | #include <wrapper/vmalloc.h> |
| 22 | #include <lttng/tracer.h> |
| 23 | |
| 24 | #include <../fs/mount.h> |
| 25 | |
| 26 | static |
| 27 | size_t mnt_ns_get_size(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, size_t offset) |
| 28 | { |
| 29 | size_t size = 0; |
| 30 | |
| 31 | size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int)); |
| 32 | size += sizeof(unsigned int); |
| 33 | return size; |
| 34 | } |
| 35 | |
| 36 | static |
| 37 | void mnt_ns_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx, |
| 38 | struct lttng_kernel_ring_buffer_ctx *ctx, |
| 39 | struct lttng_kernel_channel_buffer *chan) |
| 40 | { |
| 41 | unsigned int mnt_ns_inum = 0; |
| 42 | |
| 43 | /* |
| 44 | * nsproxy can be NULL when scheduled out of exit. |
| 45 | * |
| 46 | * As documented in 'linux/nsproxy.h' namespaces access rules, no |
| 47 | * precautions should be taken when accessing the current task's |
| 48 | * namespaces, just dereference the pointers. |
| 49 | */ |
| 50 | if (current->nsproxy) |
| 51 | mnt_ns_inum = current->nsproxy->mnt_ns->ns.inum; |
| 52 | |
| 53 | chan->ops->event_write(ctx, &mnt_ns_inum, sizeof(mnt_ns_inum), lttng_alignof(mnt_ns_inum)); |
| 54 | } |
| 55 | |
| 56 | static |
| 57 | void mnt_ns_get_value(void *priv, |
| 58 | struct lttng_kernel_probe_ctx *lttng_probe_ctx, |
| 59 | struct lttng_ctx_value *value) |
| 60 | { |
| 61 | unsigned int mnt_ns_inum = 0; |
| 62 | |
| 63 | /* |
| 64 | * nsproxy can be NULL when scheduled out of exit. |
| 65 | * |
| 66 | * As documented in 'linux/nsproxy.h' namespaces access rules, no |
| 67 | * precautions should be taken when accessing the current task's |
| 68 | * namespaces, just dereference the pointers. |
| 69 | */ |
| 70 | if (current->nsproxy) |
| 71 | mnt_ns_inum = current->nsproxy->mnt_ns->ns.inum; |
| 72 | |
| 73 | value->u.s64 = mnt_ns_inum; |
| 74 | } |
| 75 | |
| 76 | static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field( |
| 77 | lttng_kernel_static_event_field("mnt_ns", |
| 78 | lttng_kernel_static_type_integer_from_type(unsigned int, __BYTE_ORDER, 10), |
| 79 | false, false), |
| 80 | mnt_ns_get_size, |
| 81 | mnt_ns_record, |
| 82 | mnt_ns_get_value, |
| 83 | NULL, NULL); |
| 84 | |
| 85 | int lttng_add_mnt_ns_to_ctx(struct lttng_kernel_ctx **ctx) |
| 86 | { |
| 87 | int ret; |
| 88 | |
| 89 | if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name)) |
| 90 | return -EEXIST; |
| 91 | ret = lttng_kernel_context_append(ctx, ctx_field); |
| 92 | wrapper_vmalloc_sync_mappings(); |
| 93 | return ret; |
| 94 | } |
| 95 | EXPORT_SYMBOL_GPL(lttng_add_mnt_ns_to_ctx); |
| 96 | |
| 97 | #endif |