X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=src%2Flib%2Flttng-ust%2Flttng-context-net-ns.c;fp=src%2Flib%2Flttng-ust%2Flttng-context-net-ns.c;h=e7c8f9f9c5a181a830af4d2544980c5600e0465c;hb=6339062a5bbe886493d0691d13e28e37a7206362;hp=0000000000000000000000000000000000000000;hpb=635ead38ff3308bd6475f088d6a58e6267e53d86;p=lttng-ust.git

diff --git a/src/lib/lttng-ust/lttng-context-net-ns.c b/src/lib/lttng-ust/lttng-context-net-ns.c
new file mode 100644
index 00000000..e7c8f9f9
--- /dev/null
+++ b/src/lib/lttng-ust/lttng-context-net-ns.c
@@ -0,0 +1,156 @@
+/*
+ * 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 net namespace 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 "common/compat/tid.h"
+#include <urcu/tls-compat.h>
+
+#include "context-internal.h"
+#include "lttng-tracer-core.h"
+#include "ns.h"
+
+/*
+ * We cache the result to ensure we don't stat(2) the proc filesystem on
+ * each event.
+ */
+static DEFINE_URCU_TLS_INIT(ino_t, cached_net_ns, NS_INO_UNINITIALIZED);
+
+static
+ino_t get_net_ns(void)
+{
+	struct stat sb;
+	ino_t net_ns;
+
+	net_ns = CMM_LOAD_SHARED(URCU_TLS(cached_net_ns));
+
+	/*
+	 * If the cache is populated, do nothing and return the
+	 * cached inode number.
+	 */
+	if (caa_likely(net_ns != NS_INO_UNINITIALIZED))
+		return net_ns;
+
+	/*
+	 * At this point we have to populate the cache, set the initial
+	 * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode
+	 * number from the proc filesystem, this is the value we will
+	 * cache.
+	 */
+	net_ns = NS_INO_UNAVAILABLE;
+
+	/*
+	 * /proc/thread-self was introduced in kernel v3.17
+	 */
+	if (stat("/proc/thread-self/ns/net", &sb) == 0) {
+		net_ns = sb.st_ino;
+	} else {
+		char proc_ns_path[LTTNG_PROC_NS_PATH_MAX];
+
+		if (snprintf(proc_ns_path, LTTNG_PROC_NS_PATH_MAX,
+				"/proc/self/task/%d/ns/net",
+				lttng_gettid()) >= 0) {
+
+			if (stat(proc_ns_path, &sb) == 0) {
+				net_ns = sb.st_ino;
+			}
+		}
+	}
+
+	/*
+	 * And finally, store the inode number in the cache.
+	 */
+	CMM_STORE_SHARED(URCU_TLS(cached_net_ns), net_ns);
+
+	return net_ns;
+}
+
+/*
+ * The net namespace can change for 3 reasons
+ *  * clone(2) called with CLONE_NEWNET
+ *  * setns(2) called with the fd of a different net ns
+ *  * unshare(2) called with CLONE_NEWNET
+ */
+void lttng_context_net_ns_reset(void)
+{
+	CMM_STORE_SHARED(URCU_TLS(cached_net_ns), NS_INO_UNINITIALIZED);
+}
+
+static
+size_t net_ns_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(ino_t));
+	size += sizeof(ino_t);
+	return size;
+}
+
+static
+void net_ns_record(void *priv __attribute__((unused)),
+		 struct lttng_ust_lib_ring_buffer_ctx *ctx,
+		 struct lttng_ust_channel_buffer *chan)
+{
+	ino_t net_ns;
+
+	net_ns = get_net_ns();
+	chan->ops->event_write(ctx, &net_ns, sizeof(net_ns), lttng_ust_rb_alignof(net_ns));
+}
+
+static
+void net_ns_get_value(void *priv __attribute__((unused)),
+		struct lttng_ust_ctx_value *value)
+{
+	value->u.s64 = get_net_ns();
+}
+
+static const struct lttng_ust_ctx_field *ctx_field = lttng_ust_static_ctx_field(
+	lttng_ust_static_event_field("net_ns",
+		lttng_ust_static_type_integer(sizeof(ino_t) * CHAR_BIT,
+				lttng_ust_rb_alignof(ino_t) * CHAR_BIT,
+				lttng_ust_is_signed_type(ino_t),
+				BYTE_ORDER, 10),
+		false, false),
+	net_ns_get_size,
+	net_ns_record,
+	net_ns_get_value,
+	NULL, NULL);
+
+int lttng_add_net_ns_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;
+}
+
+/*
+ *  * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ *   */
+void lttng_fixup_net_ns_tls(void)
+{
+	asm volatile ("" : : "m" (URCU_TLS(cached_net_ns)));
+}