Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 380 insertions, 0 deletions

diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
new file mode 100644
index 000000000..01502570b
--- /dev/null
+++ b/tools/perf/util/namespaces.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2017 Hari Bathini, IBM Corporation
+ */
+
+#include "namespaces.h"
+#include "event.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <sched.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <asm/bug.h>
+#include <linux/kernel.h>
+#include <linux/zalloc.h>
+
+static const char *perf_ns__names[] = {
+	[NET_NS_INDEX]		= "net",
+	[UTS_NS_INDEX]		= "uts",
+	[IPC_NS_INDEX]		= "ipc",
+	[PID_NS_INDEX]		= "pid",
+	[USER_NS_INDEX]		= "user",
+	[MNT_NS_INDEX]		= "mnt",
+	[CGROUP_NS_INDEX]	= "cgroup",
+};
+
+const char *perf_ns__name(unsigned int id)
+{
+	if (id >= ARRAY_SIZE(perf_ns__names))
+		return "UNKNOWN";
+	return perf_ns__names[id];
+}
+
+struct namespaces *namespaces__new(struct perf_record_namespaces *event)
+{
+	struct namespaces *namespaces;
+	u64 link_info_size = ((event ? event->nr_namespaces : NR_NAMESPACES) *
+			      sizeof(struct perf_ns_link_info));
+
+	namespaces = zalloc(sizeof(struct namespaces) + link_info_size);
+	if (!namespaces)
+		return NULL;
+
+	namespaces->end_time = -1;
+
+	if (event)
+		memcpy(namespaces->link_info, event->link_info, link_info_size);
+
+	return namespaces;
+}
+
+void namespaces__free(struct namespaces *namespaces)
+{
+	free(namespaces);
+}
+
+static int nsinfo__get_nspid(pid_t *tgid, pid_t *nstgid, bool *in_pidns, const char *path)
+{
+	FILE *f = NULL;
+	char *statln = NULL;
+	size_t linesz = 0;
+	char *nspid;
+
+	f = fopen(path, "r");
+	if (f == NULL)
+		return -1;
+
+	while (getline(&statln, &linesz, f) != -1) {
+		/* Use tgid if CONFIG_PID_NS is not defined. */
+		if (strstr(statln, "Tgid:") != NULL) {
+			*tgid = (pid_t)strtol(strrchr(statln, '\t'), NULL, 10);
+			*nstgid = *tgid;
+		}
+
+		if (strstr(statln, "NStgid:") != NULL) {
+			nspid = strrchr(statln, '\t');
+			*nstgid = (pid_t)strtol(nspid, NULL, 10);
+			/*
+			 * If innermost tgid is not the first, process is in a different
+			 * PID namespace.
+			 */
+			*in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
+			break;
+		}
+	}
+
+	fclose(f);
+	free(statln);
+	return 0;
+}
+
+int nsinfo__init(struct nsinfo *nsi)
+{
+	char oldns[PATH_MAX];
+	char spath[PATH_MAX];
+	char *newns = NULL;
+	struct stat old_stat;
+	struct stat new_stat;
+	int rv = -1;
+
+	if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
+		return rv;
+
+	if (asprintf(&newns, "/proc/%d/ns/mnt", nsinfo__pid(nsi)) == -1)
+		return rv;
+
+	if (stat(oldns, &old_stat) < 0)
+		goto out;
+
+	if (stat(newns, &new_stat) < 0)
+		goto out;
+
+	/* Check if the mount namespaces differ, if so then indicate that we
+	 * want to switch as part of looking up dso/map data.
+	 */
+	if (old_stat.st_ino != new_stat.st_ino) {
+		RC_CHK_ACCESS(nsi)->need_setns = true;
+		RC_CHK_ACCESS(nsi)->mntns_path = newns;
+		newns = NULL;
+	}
+
+	/* If we're dealing with a process that is in a different PID namespace,
+	 * attempt to work out the innermost tgid for the process.
+	 */
+	if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsinfo__pid(nsi)) >= PATH_MAX)
+		goto out;
+
+	rv = nsinfo__get_nspid(&RC_CHK_ACCESS(nsi)->tgid, &RC_CHK_ACCESS(nsi)->nstgid,
+			       &RC_CHK_ACCESS(nsi)->in_pidns, spath);
+
+out:
+	free(newns);
+	return rv;
+}
+
+static struct nsinfo *nsinfo__alloc(void)
+{
+	struct nsinfo *res;
+	RC_STRUCT(nsinfo) *nsi;
+
+	nsi = calloc(1, sizeof(*nsi));
+	if (ADD_RC_CHK(res, nsi))
+		refcount_set(&nsi->refcnt, 1);
+
+	return res;
+}
+
+struct nsinfo *nsinfo__new(pid_t pid)
+{
+	struct nsinfo *nsi;
+
+	if (pid == 0)
+		return NULL;
+
+	nsi = nsinfo__alloc();
+	if (!nsi)
+		return NULL;
+
+	RC_CHK_ACCESS(nsi)->pid = pid;
+	RC_CHK_ACCESS(nsi)->tgid = pid;
+	RC_CHK_ACCESS(nsi)->nstgid = pid;
+	nsinfo__clear_need_setns(nsi);
+	RC_CHK_ACCESS(nsi)->in_pidns = false;
+	/* Init may fail if the process exits while we're trying to look at its
+	 * proc information. In that case, save the pid but don't try to enter
+	 * the namespace.
+	 */
+	if (nsinfo__init(nsi) == -1)
+		nsinfo__clear_need_setns(nsi);
+
+	return nsi;
+}
+
+static const char *nsinfo__mntns_path(const struct nsinfo *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->mntns_path;
+}
+
+struct nsinfo *nsinfo__copy(const struct nsinfo *nsi)
+{
+	struct nsinfo *nnsi;
+
+	if (nsi == NULL)
+		return NULL;
+
+	nnsi = nsinfo__alloc();
+	if (!nnsi)
+		return NULL;
+
+	RC_CHK_ACCESS(nnsi)->pid = nsinfo__pid(nsi);
+	RC_CHK_ACCESS(nnsi)->tgid = nsinfo__tgid(nsi);
+	RC_CHK_ACCESS(nnsi)->nstgid = nsinfo__nstgid(nsi);
+	RC_CHK_ACCESS(nnsi)->need_setns = nsinfo__need_setns(nsi);
+	RC_CHK_ACCESS(nnsi)->in_pidns = nsinfo__in_pidns(nsi);
+	if (nsinfo__mntns_path(nsi)) {
+		RC_CHK_ACCESS(nnsi)->mntns_path = strdup(nsinfo__mntns_path(nsi));
+		if (!RC_CHK_ACCESS(nnsi)->mntns_path) {
+			nsinfo__put(nnsi);
+			return NULL;
+		}
+	}
+
+	return nnsi;
+}
+
+static refcount_t *nsinfo__refcnt(struct nsinfo *nsi)
+{
+	return &RC_CHK_ACCESS(nsi)->refcnt;
+}
+
+static void nsinfo__delete(struct nsinfo *nsi)
+{
+	if (nsi) {
+		WARN_ONCE(refcount_read(nsinfo__refcnt(nsi)) != 0, "nsinfo refcnt unbalanced\n");
+		zfree(&RC_CHK_ACCESS(nsi)->mntns_path);
+		RC_CHK_FREE(nsi);
+	}
+}
+
+struct nsinfo *nsinfo__get(struct nsinfo *nsi)
+{
+	struct nsinfo *result;
+
+	if (RC_CHK_GET(result, nsi))
+		refcount_inc(nsinfo__refcnt(nsi));
+
+	return result;
+}
+
+void nsinfo__put(struct nsinfo *nsi)
+{
+	if (nsi && refcount_dec_and_test(nsinfo__refcnt(nsi)))
+		nsinfo__delete(nsi);
+	else
+		RC_CHK_PUT(nsi);
+}
+
+bool nsinfo__need_setns(const struct nsinfo *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->need_setns;
+}
+
+void nsinfo__clear_need_setns(struct nsinfo *nsi)
+{
+	RC_CHK_ACCESS(nsi)->need_setns = false;
+}
+
+pid_t nsinfo__tgid(const struct nsinfo  *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->tgid;
+}
+
+pid_t nsinfo__nstgid(const struct nsinfo  *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->nstgid;
+}
+
+pid_t nsinfo__pid(const struct nsinfo  *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->pid;
+}
+
+bool nsinfo__in_pidns(const struct nsinfo *nsi)
+{
+	return RC_CHK_ACCESS(nsi)->in_pidns;
+}
+
+void nsinfo__set_in_pidns(struct nsinfo *nsi)
+{
+	RC_CHK_ACCESS(nsi)->in_pidns = true;
+}
+
+void nsinfo__mountns_enter(struct nsinfo *nsi,
+				  struct nscookie *nc)
+{
+	char curpath[PATH_MAX];
+	int oldns = -1;
+	int newns = -1;
+	char *oldcwd = NULL;
+
+	if (nc == NULL)
+		return;
+
+	nc->oldns = -1;
+	nc->newns = -1;
+
+	if (!nsi || !nsinfo__need_setns(nsi))
+		return;
+
+	if (!getcwd(curpath, sizeof(curpath)))
+		return;
+
+	oldcwd = strdup(curpath);
+	if (!oldcwd)
+		return;
+
+	oldns = open("/proc/self/ns/mnt", O_RDONLY);
+	if (oldns < 0)
+		goto errout;
+
+	newns = open(nsinfo__mntns_path(nsi), O_RDONLY);
+	if (newns < 0)
+		goto errout;
+
+	if (setns(newns, CLONE_NEWNS) < 0)
+		goto errout;
+
+	nc->oldcwd = oldcwd;
+	nc->oldns = oldns;
+	nc->newns = newns;
+	return;
+
+errout:
+	free(oldcwd);
+	if (oldns > -1)
+		close(oldns);
+	if (newns > -1)
+		close(newns);
+}
+
+void nsinfo__mountns_exit(struct nscookie *nc)
+{
+	if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
+		return;
+
+	setns(nc->oldns, CLONE_NEWNS);
+
+	if (nc->oldcwd) {
+		WARN_ON_ONCE(chdir(nc->oldcwd));
+		zfree(&nc->oldcwd);
+	}
+
+	if (nc->oldns > -1) {
+		close(nc->oldns);
+		nc->oldns = -1;
+	}
+
+	if (nc->newns > -1) {
+		close(nc->newns);
+		nc->newns = -1;
+	}
+}
+
+char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
+{
+	char *rpath;
+	struct nscookie nsc;
+
+	nsinfo__mountns_enter(nsi, &nsc);
+	rpath = realpath(path, NULL);
+	nsinfo__mountns_exit(&nsc);
+
+	return rpath;
+}
+
+int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
+{
+	int ret;
+	struct nscookie nsc;
+
+	nsinfo__mountns_enter(nsi, &nsc);
+	ret = stat(filename, st);
+	nsinfo__mountns_exit(&nsc);
+
+	return ret;
+}
+
+bool nsinfo__is_in_root_namespace(void)
+{
+	pid_t tgid = 0, nstgid = 0;
+	bool in_pidns = false;
+
+	nsinfo__get_nspid(&tgid, &nstgid, &in_pidns, "/proc/self/status");
+	return !in_pidns;
+}