+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-only
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
- *
- * LTTng UST namespaced effective group ID context.
- */
-
-#define _LGPL_SOURCE
-#include <limits.h>
-#include <stddef.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#include <lttng/ust-events.h>
-#include <lttng/ust-tracer.h>
-#include <lttng/ringbuffer-context.h>
-
-#include "context-internal.h"
-#include "creds.h"
-
-
-/*
- * At the kernel level, user IDs and group IDs are a per-thread attribute.
- * However, POSIX requires that all threads in a process share the same
- * credentials. The NPTL threading implementation handles the POSIX
- * requirements by providing wrapper functions for the various system calls
- * that change process UIDs and GIDs. These wrapper functions (including those
- * for setreuid() and setregid()) employ a signal-based technique to ensure
- * that when one thread changes credentials, all of the other threads in the
- * process also change their credentials.
- */
-
-/*
- * We cache the result to ensure we don't trigger a system call for
- * each event. User / group IDs are global to the process.
- */
-static gid_t cached_vegid = INVALID_GID;
-
-static
-gid_t get_vegid(void)
-{
- gid_t vegid;
-
- vegid = CMM_LOAD_SHARED(cached_vegid);
-
- if (caa_unlikely(vegid == INVALID_GID)) {
- vegid = getegid();
- CMM_STORE_SHARED(cached_vegid, vegid);
- }
-
- return vegid;
-}
-
-/*
- * The vegid can change on setuid, setreuid, setresuid and seteuid.
- */
-void lttng_context_vegid_reset(void)
-{
- CMM_STORE_SHARED(cached_vegid, INVALID_GID);
-}
-
-static
-size_t vegid_get_size(void *priv __attribute__((unused)),
- size_t offset)
-{
- size_t size = 0;
-
- size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(gid_t));
- size += sizeof(gid_t);
- return size;
-}
-
-static
-void vegid_record(void *priv __attribute__((unused)),
- struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct lttng_ust_channel_buffer *chan)
-{
- gid_t vegid;
-
- vegid = get_vegid();
- chan->ops->event_write(ctx, &vegid, sizeof(vegid), lttng_ust_rb_alignof(vegid));
-}
-
-static
-void vegid_get_value(void *priv __attribute__((unused)),
- struct lttng_ust_ctx_value *value)
-{
- value->u.s64 = get_vegid();
-}
-
-static const struct lttng_ust_ctx_field *ctx_field = lttng_ust_static_ctx_field(
- lttng_ust_static_event_field("vegid",
- lttng_ust_static_type_integer(sizeof(gid_t) * CHAR_BIT,
- lttng_ust_rb_alignof(gid_t) * CHAR_BIT,
- lttng_ust_is_signed_type(gid_t),
- BYTE_ORDER, 10),
- false, false),
- vegid_get_size,
- vegid_record,
- vegid_get_value,
- NULL, NULL);
-
-int lttng_add_vegid_to_ctx(struct lttng_ust_ctx **ctx)
-{
- int ret;
-
- if (lttng_find_context(*ctx, ctx_field->event_field->name)) {
- ret = -EEXIST;
- goto error_find_context;
- }
- ret = lttng_ust_context_append(ctx, ctx_field);
- if (ret)
- return ret;
- return 0;
-
-error_find_context:
- return ret;
-}