Implement name_to_handle_at and open_by_handle_at syscalls decoding

* file_handle.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* linux/dummy.h (sys_name_to_handle_at, sys_open_by_handle_at):
Remove stub aliases.
* pathtrace.c (pathtrace_match): Add SEN_name_to_handle_at.
* tests/file_handle.c: New file.
* tests/file_handle.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add file_handle.
(TESTS): Add file_handle.test.
* tests/.gitignore: Add file_handle.

Author: ldv-alt

Makefile.am

@@ -63,6 +63,7 @@ strace_SOURCES =	\
 	fcntl.c		\
 	fetch_seccomp_fprog.c \
 	file.c		\
+	file_handle.c	\
 	flock.c		\
 	futex.c		\
 	get_robust_list.c \

file_handle.c

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2015 Dmitry V. Levin <[email protected]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "defs.h"
+
+#ifndef MAX_HANDLE_SZ
+# define MAX_HANDLE_SZ 128
+#endif
+
+typedef struct {
+	unsigned int handle_bytes;
+	int handle_type;
+} file_handle_header;
+
+SYS_FUNC(name_to_handle_at)
+{
+	file_handle_header h;
+	const long addr = tcp->u_arg[2];
+
+	if (entering(tcp)) {
+		/* dirfd */
+		print_dirfd(tcp, tcp->u_arg[0]);
+
+		/* pathname */
+		printpath(tcp, tcp->u_arg[1]);
+		tprints(", ");
+
+		/* handle */
+		if (umove_or_printaddr(tcp, addr, &h)) {
+			tprints(", ");
+
+			/* mount_id */
+			printaddr(tcp->u_arg[3]);
+			tprints(", ");
+
+			/* flags */
+			printflags(at_flags, tcp->u_arg[4], "AT_???");
+
+			return RVAL_DECODED;
+		}
+		tprintf("{handle_bytes=%u", h.handle_bytes);
+
+		/*
+		 * Abusing tcp->auxstr as a temporary storage.
+		 * Will be used and cleared on syscall exit.
+		 */
+		tcp->auxstr = (void *) (unsigned long) h.handle_bytes;
+
+		return 0;
+	} else {
+		unsigned int i = (unsigned long) tcp->auxstr;
+
+		if ((!syserror(tcp) || EOVERFLOW == tcp->u_error)
+		    && !umove(tcp, addr, &h)) {
+			unsigned char f_handle[MAX_HANDLE_SZ];
+
+			if (i != h.handle_bytes)
+				tprintf(" => %u", h.handle_bytes);
+			if (!syserror(tcp)) {
+				tprintf(", handle_type=%d", h.handle_type);
+				if (h.handle_bytes > MAX_HANDLE_SZ)
+					h.handle_bytes = MAX_HANDLE_SZ;
+				if (!umoven(tcp, addr + sizeof(h), h.handle_bytes,
+					    f_handle)) {
+					tprints(", f_handle=0x");
+					for (i = 0; i < h.handle_bytes; ++i)
+						tprintf("%02x", f_handle[i]);
+				}
+			}
+		}
+		tprints("}, ");
+		tcp->auxstr = NULL;
+
+		/* mount_id */
+		printnum_int(tcp, tcp->u_arg[3], "%d");
+		tprints(", ");
+
+		/* flags */
+		printflags(at_flags, tcp->u_arg[4], "AT_???");
+	}
+	return 0;
+}
+
+SYS_FUNC(open_by_handle_at)
+{
+	file_handle_header h;
+	const long addr = tcp->u_arg[1];
+
+	/* mount_fd */
+	printfd(tcp, tcp->u_arg[0]);
+	tprints(", ");
+
+	/* handle */
+	if (!umove_or_printaddr(tcp, addr, &h)) {
+		unsigned char f_handle[MAX_HANDLE_SZ];
+
+		tprintf("{handle_bytes=%u, handle_type=%d",
+			h.handle_bytes, h.handle_type);
+		if (h.handle_bytes > MAX_HANDLE_SZ)
+			h.handle_bytes = MAX_HANDLE_SZ;
+		if (!umoven(tcp, addr + sizeof(h), h.handle_bytes, &f_handle)) {
+			unsigned int i;
+
+			tprints(", f_handle=0x");
+			for (i = 0; i < h.handle_bytes; ++i)
+				tprintf("%02x", f_handle[i]);
+		}
+		tprints("}");
+	}
+	tprints(", ");
+
+	/* flags */
+	tprint_open_modes(tcp->u_arg[2]);
+
+	return RVAL_DECODED;
+}

linux/dummy.h

@@ -32,8 +32,6 @@
 #endif
 
 /* still unfinished */
-#define	sys_name_to_handle_at	printargs
-#define	sys_open_by_handle_at	printargs
 #define	sys_sysfs		printargs
 #define	sys_vm86		printargs
 #define	sys_vm86old		printargs

pathtrace.c

@@ -178,6 +178,7 @@ pathtrace_match(struct tcb *tcp)
 	case SEN_inotify_add_watch:
 	case SEN_mkdirat:
 	case SEN_mknodat:
+	case SEN_name_to_handle_at:
 	case SEN_newfstatat:
 	case SEN_openat:
 	case SEN_pipe2:

tests/.gitignore

@@ -9,6 +9,7 @@ eventfd
 execve
 execveat
 fanotify_mark
+file_handle
 filter-unavailable
 getdents
 getdents64

tests/Makefile.am

@@ -22,6 +22,7 @@ check_PROGRAMS = \
 	execve \
 	execveat \
 	fanotify_mark \
+	file_handle \
 	filter-unavailable \
 	getdents \
 	getdents64 \
@@ -122,6 +123,7 @@ TESTS = \
 	execve.test \
 	execveat.test \
 	fanotify_mark.test \
+	file_handle.test \
 	filter-unavailable.test \
 	getdents.test \
 	getdents64.test \

tests/file_handle.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2015 Dmitry V. Levin <[email protected]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <alloca.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#ifdef MAX_HANDLE_SZ
+
+int
+main(void)
+{
+	struct file_handle *handle =
+		alloca(sizeof(struct file_handle) + MAX_HANDLE_SZ);
+	const int dirfd = AT_FDCWD;
+	const int flags = AT_SYMLINK_FOLLOW;
+	int mount_id;
+	unsigned int i;
+
+	handle->handle_bytes = 0;
+
+	if (name_to_handle_at(dirfd, ".", handle, &mount_id, flags | 1) != -1
+	    || EINVAL != errno) {
+		perror("name_to_handle_at");
+		return 77;
+	}
+	printf("name_to_handle_at(AT_FDCWD, \".\", {handle_bytes=0}, %p"
+	       ", AT_SYMLINK_FOLLOW|0x1) = -1 EINVAL (Invalid argument)\n",
+	       &mount_id);
+
+	if (name_to_handle_at(dirfd, ".", handle, &mount_id, flags) != -1
+	    || EOVERFLOW != errno) {
+		perror("name_to_handle_at");
+		return 77;
+	}
+	printf("name_to_handle_at(AT_FDCWD, \".\", {handle_bytes=0 => %u}"
+	       ", %p, AT_SYMLINK_FOLLOW) = -1 EOVERFLOW"
+	       " (Value too large for defined data type)\n",
+	       handle->handle_bytes, &mount_id);
+
+	assert(!name_to_handle_at(dirfd, ".", handle, &mount_id, flags));
+	printf("name_to_handle_at(AT_FDCWD, \".\", {handle_bytes=%u"
+	       ", handle_type=%d, f_handle=0x",
+	       handle->handle_bytes, handle->handle_type);
+	for (i = 0; i < handle->handle_bytes; ++i)
+		printf("%02x", handle->f_handle[i]);
+	printf("}, [%d], AT_SYMLINK_FOLLOW) = 0\n", mount_id);
+
+	assert(open_by_handle_at(-1, handle, O_RDONLY | O_DIRECTORY));
+	printf("open_by_handle_at(-1, {handle_bytes=%u, handle_type=1, f_handle=0x",
+	       handle->handle_bytes);
+	for (i = 0; i < handle->handle_bytes; ++i)
+		printf("%02x", handle->f_handle[i]);
+	printf("}, O_RDONLY|O_DIRECTORY) = -1 %s\n",
+	       EPERM == errno ? "EPERM (Operation not permitted)" :
+	       EINVAL == errno ? "EINVAL (Invalid argument)" :
+				 "EBADF (Bad file descriptor)");
+
+	puts("+++ exited with 0 +++");
+	return 0;
+}
+
+#else
+
+int
+main(void)
+{
+	return 77;
+}
+
+#endif

tests/file_handle.test

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# Check name_to_handle_at and open_by_handle_at syscalls decoding.
+
+. "${srcdir=.}/init.sh"
+
+run_prog > /dev/null
+
+OUT="$LOG.out"
+run_strace -ename_to_handle_at,open_by_handle_at $args > "$OUT"
+
+match_diff "$OUT" "$LOG"
+rm -f "$OUT"
+
+exit 0