diff --git a/Makefile-libglnx.am b/Makefile-libglnx.am index 64d6a9adb62b3a64cac21810d285e4d17ade52c2..d3a46e55a619940a41226a517e13c667ec82c989 100644 --- a/Makefile-libglnx.am +++ b/Makefile-libglnx.am @@ -51,3 +51,10 @@ libglnx_la_SOURCES = \ libglnx_la_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags) libglnx_la_LDFLAGS = -avoid-version -Bsymbolic-functions -export-symbols-regex "^glnx_" -no-undefined -export-dynamic libglnx_la_LIBADD = $(libglnx_libs) + +TESTS += test-libglnx-xattrs + +check_PROGRAMS += test-libglnx-xattrs +test_libglnx_xattrs_SOURCES = $(libglnx_srcpath)/tests/test-libglnx-xattrs.c +test_libglnx_xattrs_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags) +test_libglnx_xattrs_LDADD = $(libglnx_libs) libglnx.la diff --git a/tests/test-libglnx-xattrs.c b/tests/test-libglnx-xattrs.c new file mode 100644 index 0000000000000000000000000000000000000000..9a398701c1911366a9cd5dc6411b206b83da418f --- /dev/null +++ b/tests/test-libglnx-xattrs.c @@ -0,0 +1,282 @@ +/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- + * + * Copyright (C) 2017 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 02111-1307, USA. + */ + +#include "config.h" +#include "libglnx.h" +#include <glib.h> +#include <stdlib.h> +#include <gio/gio.h> +#include <string.h> + +#define XATTR_THREAD_RUN_TIME_USECS (5 * G_USEC_PER_SEC) + +struct XattrWorker { + int dfd; + gboolean is_writer; + guint n_attrs_read; +}; + +typedef enum { + WRITE_RUN_MUTATE, + WRITE_RUN_CREATE, +} WriteType; + +static gboolean +set_random_xattr_value (int fd, const char *name, GError **error) +{ + const guint8 randxattrbyte = g_random_int_range (0, 256); + const guint32 randxattrvalue_len = g_random_int () % 256; /* Picked to be not too small or large */ + g_autofree char *randxattrvalue = g_malloc (randxattrvalue_len); + + memset (randxattrvalue, randxattrbyte, randxattrvalue_len); + + if (fsetxattr (fd, name, randxattrvalue, randxattrvalue_len, 0) < 0) + { + glnx_set_error_from_errno (error); + return FALSE; + } + + return TRUE; +} + +static gboolean +add_random_xattrs (int fd, GError **error) +{ + const guint nattrs = MIN (2, g_random_int () % 16); + + for (guint i = 0; i < nattrs; i++) + { + guint32 randxattrname_v = g_random_int (); + g_autofree char *randxattrname = g_strdup_printf ("user.test%u", randxattrname_v); + + if (!set_random_xattr_value (fd, randxattrname, error)) + return FALSE; + } + + return TRUE; +} + +static gboolean +do_write_run (GLnxDirFdIterator *dfd_iter, GError **error) +{ + WriteType wtype = g_random_int () % 2; + + if (wtype == WRITE_RUN_CREATE) + { + guint32 randname_v = g_random_int (); + g_autofree char *randname = g_strdup_printf ("file%u", randname_v); + glnx_fd_close int fd = -1; + + again: + fd = openat (dfd_iter->fd, randname, O_CREAT | O_EXCL, 0644); + if (fd < 0) + { + if (errno == EEXIST) + { + g_printerr ("Congratulations! I suggest purchasing a lottery ticket today!\n"); + goto again; + } + else + { + glnx_set_error_from_errno (error); + return FALSE; + } + } + + if (!add_random_xattrs (fd, error)) + return FALSE; + } + else if (wtype == WRITE_RUN_MUTATE) + { + while (TRUE) + { + g_autoptr(GVariant) current_xattrs = NULL; + glnx_fd_close int fd = -1; + + struct dirent *dent; + if (!glnx_dirfd_iterator_next_dent (dfd_iter, &dent, NULL, error)) + return FALSE; + if (!dent) + break; + + fd = openat (dfd_iter->fd, dent->d_name, O_RDONLY | O_CLOEXEC); + if (fd < 0) + { + glnx_set_error_from_errno (error); + return FALSE; + } + + if (!glnx_fd_get_all_xattrs (fd, ¤t_xattrs, NULL, error)) + return FALSE; + + for (int i = 0; i < g_variant_n_children (current_xattrs); i++) + { + const char *name, *value; + g_variant_get_child (current_xattrs, i, "(^&ay^&ay)", &name, &value); + + /* We don't want to potentially test/change xattrs like security.selinux + * that were injected by the system. + */ + if (!g_str_has_prefix (name, "user.test")) + continue; + + if (!set_random_xattr_value (fd, name, error)) + return FALSE; + } + } + } + else + g_assert_not_reached (); + + return TRUE; +} + +static gboolean +do_read_run (GLnxDirFdIterator *dfd_iter, + guint *out_n_read, + GError **error) +{ + guint nattrs = 0; + while (TRUE) + { + g_autoptr(GVariant) current_xattrs = NULL; + glnx_fd_close int fd = -1; + + struct dirent *dent; + if (!glnx_dirfd_iterator_next_dent (dfd_iter, &dent, NULL, error)) + return FALSE; + if (!dent) + break; + + fd = openat (dfd_iter->fd, dent->d_name, O_RDONLY | O_CLOEXEC); + if (fd < 0) + { + glnx_set_error_from_errno (error); + return FALSE; + } + + if (!glnx_fd_get_all_xattrs (fd, ¤t_xattrs, NULL, error)) + return FALSE; + + /* We don't actually care about the values, just use the variable + * to avoid compiler warnings. + */ + nattrs += g_variant_n_children (current_xattrs); + } + + *out_n_read = nattrs; + return TRUE; +} + +static gpointer +xattr_thread (gpointer data) +{ + g_autoptr(GError) local_error = NULL; + GError **error = &local_error; + struct XattrWorker *worker = data; + guint64 end_time = g_get_monotonic_time () + XATTR_THREAD_RUN_TIME_USECS; + guint n_read; + + while (g_get_monotonic_time () < end_time) + { + g_auto(GLnxDirFdIterator) dfd_iter = { 0, }; + + if (!glnx_dirfd_iterator_init_at (worker->dfd, ".", TRUE, &dfd_iter, error)) + goto out; + + if (worker->is_writer) + { + if (!do_write_run (&dfd_iter, error)) + goto out; + } + else + { + if (!do_read_run (&dfd_iter, &n_read, error)) + goto out; + } + } + + out: + g_assert_no_error (local_error); + + return GINT_TO_POINTER (n_read); +} + +static void +test_xattr_races (void) +{ + /* If for some reason we're built in a VM which only has one vcpu, let's still + * at least make the test do something. + */ + /* FIXME - this deadlocks for me on 4.9.4-201.fc25.x86_64, whether + * using overlayfs or xfs as source/dest. + */ + const guint nprocs = MAX (4, g_get_num_processors ()); + struct XattrWorker wdata[nprocs]; + GThread *threads[nprocs]; + g_autoptr(GError) local_error = NULL; + GError **error = &local_error; + glnx_fd_close int dfd = -1; + g_autofree char *tmpdir = g_strdup_printf ("%s/libglnx-xattrs-XXXXXX", + getenv ("TMPDIR") ?: "/var/tmp"); + guint nread = 0; + + if (!glnx_mkdtempat (AT_FDCWD, tmpdir, 0700, error)) + goto out; + + if (!glnx_opendirat (AT_FDCWD, tmpdir, TRUE, &dfd, error)) + goto out; + + for (guint i = 0; i < nprocs; i++) + { + struct XattrWorker *worker = &wdata[i]; + worker->dfd = dfd; + worker->is_writer = i % 2 == 0; + threads[i] = g_thread_new (NULL, xattr_thread, worker); + } + + for (guint i = 0; i < nprocs; i++) + { + if (wdata[i].is_writer) + (void) g_thread_join (threads[i]); + else + nread += GPOINTER_TO_UINT (g_thread_join (threads[i])); + } + + g_print ("Read %u xattrs race free!\n", nread); + + (void) glnx_shutil_rm_rf_at (AT_FDCWD, tmpdir, NULL, NULL); + + out: + g_assert_no_error (local_error); +} + +int main (int argc, char **argv) +{ + int ret; + + g_test_init (&argc, &argv, NULL); + + g_test_add_func ("/xattr-races", test_xattr_races); + + ret = g_test_run(); + + return ret; +}