Usermode helper upcalls are all the rage these days for infrequent
upcalls, since they make it rather idiot-proof. No running daemon is
required, so there's really no setup beyond ensuring that the callout
exists and is runnable.
This program adds a callout program to nfs-utils for that purpose. The
storage engine on the backend is identical to the one used by nfsdcld.
This just adds a new frontend for it.
For now, building with --enable-nfsdcltrack gives you both nfsdcld and
nfsdcltrack programs. A later patch will remove nfsdcld altogether.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
utils/nfsdcltrack/Makefile.am | 6 +-
utils/nfsdcltrack/nfsdcltrack.c | 441 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 445 insertions(+), 2 deletions(-)
create mode 100644 utils/nfsdcltrack/nfsdcltrack.c
diff --git a/utils/nfsdcltrack/Makefile.am b/utils/nfsdcltrack/Makefile.am
index 073a71b..afae455 100644
--- a/utils/nfsdcltrack/Makefile.am
+++ b/utils/nfsdcltrack/Makefile.am
@@ -4,11 +4,13 @@ man8_MANS = nfsdcld.man
EXTRA_DIST = $(man8_MANS)
AM_CFLAGS += -D_LARGEFILE64_SOURCE
-sbin_PROGRAMS = nfsdcld
+sbin_PROGRAMS = nfsdcld nfsdcltrack
nfsdcld_SOURCES = nfsdcld.c sqlite.c
-
nfsdcld_LDADD = ../../support/nfs/libnfs.a $(LIBEVENT) $(LIBSQLITE) $(LIBCAP)
+nfsdcltrack_SOURCES = nfsdcltrack.c sqlite.c
+nfsdcltrack_LDADD = ../../support/nfs/libnfs.a $(LIBSQLITE) $(LIBCAP)
+
MAINTAINERCLEANFILES = Makefile.in
diff --git a/utils/nfsdcltrack/nfsdcltrack.c b/utils/nfsdcltrack/nfsdcltrack.c
new file mode 100644
index 0000000..f8c3810
--- /dev/null
+++ b/utils/nfsdcltrack/nfsdcltrack.c
@@ -0,0 +1,441 @@
+/*
+ * nfsdcltrack.c -- NFSv4 client name tracking program
+ *
+ * Copyright (C) 2012 Jeff Layton <jlayton@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <getopt.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <sys/inotify.h>
+#ifdef HAVE_SYS_CAPABILITY_H
+#include <sys/prctl.h>
+#include <sys/capability.h>
+#endif
+
+#include "xlog.h"
+#include "sqlite.h"
+
+#ifndef CLD_DEFAULT_STORAGEDIR
+#define CLD_DEFAULT_STORAGEDIR NFS_STATEDIR "/nfsdcltrack"
+#endif
+
+/* defined by RFC 3530 */
+#define NFS4_OPAQUE_LIMIT 1024
+
+/* private data structures */
+struct cltrack_cmd {
+ char *name;
+ bool needs_arg;
+ int (*func)(const char *arg);
+};
+
+/* forward declarations */
+static int cltrack_init(const char *unused);
+static int cltrack_create(const char *id);
+static int cltrack_remove(const char *id);
+static int cltrack_check(const char *id);
+static int cltrack_gracedone(const char *gracetime);
+
+/* global variables */
+static struct option longopts[] =
+{
+ { "help", 0, NULL, 'h' },
+ { "debug", 0, NULL, 'd' },
+ { "foreground", 0, NULL, 'f' },
+ { "storagedir", 1, NULL, 's' },
+ { NULL, 0, 0, 0 },
+};
+
+static struct cltrack_cmd commands[] =
+{
+ { "init", false, cltrack_init },
+ { "create", true, cltrack_create },
+ { "remove", true, cltrack_remove },
+ { "check", true, cltrack_check },
+ { "gracedone", true, cltrack_gracedone },
+ { NULL, false, NULL },
+};
+
+static char *storagedir = CLD_DEFAULT_STORAGEDIR;
+
+/* common buffer for holding id4 blobs */
+static unsigned char blob[NFS4_OPAQUE_LIMIT];
+
+static void
+usage(char *progname)
+{
+ printf("%s [ -hfd ] [ -s dir ] < cmd > < arg >\n", progname);
+ printf("Where < cmd > is one of the following and takes the following < arg >:\n");
+ printf(" init\n");
+ printf(" create <nfs_client_id4>\n");
+ printf(" remove <nfs_client_id4>\n");
+ printf(" check <nfs_client_id4>\n");
+ printf(" gracedone <epoch time>\n");
+}
+
+
+/**
+ * hex_to_bin - convert a hex digit to its real value
+ * @ch: ascii character represents hex digit
+ *
+ * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad
+ * input.
+ *
+ * Note: borrowed from lib/hexdump.c in the Linux kernel sources.
+ */
+static int
+hex_to_bin(char ch)
+{
+ if ((ch >= '0') && (ch <= '9'))
+ return ch - '0';
+ ch = tolower(ch);
+ if ((ch >= 'a') && (ch <= 'f'))
+ return ch - 'a' + 10;
+ return -1;
+}
+
+/**
+ * hex_str_to_bin - convert a hexidecimal string into a binary blob
+ *
+ * @src: string of hex digit pairs
+ * @dst: destination buffer to hold binary data
+ * @dstsize: size of the destination buffer
+ *
+ * Walk a string of hex digit pairs and convert them into binary data. Returns
+ * the resulting length of the binary data or a negative error code. If the
+ * data will not fit in the buffer, it returns -ENOBUFS (but will likely have
+ * clobbered the dst buffer in the process of determining that). If there are
+ * non-hexidecimal characters in the src, or an odd number of them then it
+ * returns -EINVAL.
+ */
+static ssize_t
+hex_str_to_bin(const char *src, unsigned char *dst, ssize_t dstsize)
+{
+ unsigned char *tmpdst = dst;
+
+ while (*src) {
+ int hi, lo;
+
+ /* make sure we don't overrun the dst buffer */
+ if ((tmpdst - dst) >= dstsize)
+ return -ENOBUFS;
+
+ hi = hex_to_bin(*src++);
+
+ /* did we get an odd number of characters? */
+ if (!*src)
+ return -EINVAL;
+ lo = hex_to_bin(*src++);
+
+ /* one of the characters isn't a hex digit */
+ if (hi < 0 || lo < 0)
+ return -EINVAL;
+
+ /* now place it in the dst buffer */
+ *tmpdst++ = (hi << 4) | lo;
+ }
+
+ return (ssize_t)(tmpdst - dst);
+}
+
+/*
+ * This program will almost always be run with root privileges since the
+ * kernel will call out to run it. Drop all capabilities prior to doing
+ * anything important to limit the exposure to potential compromise.
+ *
+ * FIXME: should we setuid to a different user early on instead?
+ */
+static int
+cltrack_set_caps(void)
+{
+ int ret = 0;
+#ifdef HAVE_SYS_CAPABILITY_H
+ unsigned long i;
+ cap_t caps;
+
+ /* prune the bounding set to nothing */
+ for (i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0 ; ++i) {
+ ret = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
+ if (ret) {
+ xlog(L_ERROR, "Unable to prune capability %lu from "
+ "bounding set: %m", i);
+ return -errno;
+ }
+ }
+
+ /* get a blank capset */
+ caps = cap_init();
+ if (caps == NULL) {
+ xlog(L_ERROR, "Unable to get blank capability set: %m");
+ return -errno;
+ }
+
+ /* reset the process capabilities */
+ if (cap_set_proc(caps) != 0) {
+ xlog(L_ERROR, "Unable to set process capabilities: %m");
+ ret = -errno;
+ }
+ cap_free(caps);
+#endif
+ return ret;
+}
+
+static int
+cltrack_init(const char __attribute__((unused)) *unused)
+{
+ int ret;
+
+ /*
+ * see if the storagedir is writable by root w/o CAP_DAC_OVERRIDE.
+ * If it isn't then give the user a warning but proceed as if
+ * everything is OK. If the DB has already been created, then
+ * everything might still work. If it doesn't exist at all, then
+ * assume that the maindb init will be able to create it. Fail on
+ * anything else.
+ */
+ if (access(storagedir, W_OK) == -1) {
+ switch (errno) {
+ case EACCES:
+ xlog(L_WARNING, "Storage directory %s is not writable. "
+ "Should be owned by root and writable "
+ "by owner!", storagedir);
+ break;
+ case ENOENT:
+ /* ignore and assume that we can create dir as root */
+ break;
+ default:
+ xlog(L_ERROR, "Unexpected error when checking access "
+ "on %s: %m", storagedir);
+ return -errno;
+ }
+ }
+
+ /* set up storage db */
+ ret = sqlite_maindb_init(storagedir);
+ if (ret) {
+ xlog(L_ERROR, "Failed to init database: %d", ret);
+ /*
+ * Convert any error here into -EACCES. It's not truly
+ * accurate in all cases, but it should cause the kernel to
+ * stop upcalling until the problem is resolved.
+ */
+ ret = -EACCES;
+ }
+ return ret;
+}
+
+static int
+cltrack_create(const char *id)
+{
+ int ret;
+ ssize_t len;
+
+ xlog(D_GENERAL, "%s: create client record.", __func__);
+
+ ret = sqlite_prepare_dbh(storagedir);
+ if (ret)
+ return ret;
+
+ len = hex_str_to_bin(id, blob, sizeof(blob));
+ if (len < 0)
+ return (int)len;
+
+ ret = sqlite_insert_client(blob, len);
+
+ return ret ? -EREMOTEIO : ret;
+}
+
+static int
+cltrack_remove(const char *id)
+{
+ int ret;
+ ssize_t len;
+
+ xlog(D_GENERAL, "%s: remove client record.", __func__);
+
+ ret = sqlite_prepare_dbh(storagedir);
+ if (ret)
+ return ret;
+
+ len = hex_str_to_bin(id, blob, sizeof(blob));
+ if (len < 0)
+ return (int)len;
+
+ ret = sqlite_remove_client(blob, len);
+
+ return ret ? -EREMOTEIO : ret;
+}
+
+static int
+cltrack_check(const char *id)
+{
+ int ret;
+ ssize_t len;
+
+ xlog(D_GENERAL, "%s: check client record", __func__);
+
+ ret = sqlite_prepare_dbh(storagedir);
+ if (ret)
+ return ret;
+
+ len = hex_str_to_bin(id, blob, sizeof(blob));
+ if (len < 0)
+ return (int)len;
+
+ ret = sqlite_check_client(blob, len);
+
+ return ret ? -EPERM : ret;
+}
+
+static int
+cltrack_gracedone(const char *timestr)
+{
+ int ret;
+ char *tail;
+ time_t gracetime;
+
+
+ ret = sqlite_prepare_dbh(storagedir);
+ if (ret)
+ return ret;
+
+ errno = 0;
+ gracetime = strtol(timestr, &tail, 0);
+
+ /* did the resulting value overflow? (Probably -ERANGE here) */
+ if (errno)
+ return -errno;
+
+ /* string wasn't fully converted */
+ if (*tail)
+ return -EINVAL;
+
+ xlog(D_GENERAL, "%s: grace done. gracetime=%ld", __func__, gracetime);
+
+ ret = sqlite_remove_unreclaimed(gracetime);
+
+ return ret ? -EREMOTEIO : ret;
+}
+
+static struct cltrack_cmd *
+find_cmd(char *cmdname)
+{
+ struct cltrack_cmd *current = &commands[0];
+
+ while (current->name) {
+ if (!strcmp(cmdname, current->name))
+ return current;
+ ++current;
+ }
+
+ xlog(L_ERROR, "%s: '%s' doesn't match any known command",
+ __func__, cmdname);
+ return NULL;
+}
+
+int
+main(int argc, char **argv)
+{
+ char arg;
+ int rc = 0;
+ char *progname, *cmdarg = NULL;
+ struct cltrack_cmd *cmd;
+
+ progname = strdup(basename(argv[0]));
+ if (!progname) {
+ fprintf(stderr, "%s: unable to allocate memory.\n", argv[0]);
+ return 1;
+ }
+
+ xlog_syslog(1);
+ xlog_stderr(0);
+
+ /* process command-line options */
+ while ((arg = getopt_long(argc, argv, "hdfs:", longopts,
+ NULL)) != EOF) {
+ switch (arg) {
+ case 'd':
+ xlog_config(D_ALL, 1);
+ case 'f':
+ xlog_syslog(0);
+ xlog_stderr(1);
+ break;
+ case 's':
+ storagedir = optarg;
+ break;
+ default:
+ usage(progname);
+ return 0;
+ }
+ }
+
+ xlog_open(progname);
+
+ /* we expect a command, at least */
+ if (optind >= argc) {
+ xlog(L_ERROR, "Missing command name\n");
+ rc = -EINVAL;
+ goto out;
+ }
+
+ /* drop all capabilities */
+ rc = cltrack_set_caps();
+ if (rc)
+ goto out;
+
+ cmd = find_cmd(argv[optind]);
+ if (!cmd) {
+ /*
+ * In the event that we get a command that we don't understand
+ * then return a distinct error. The kernel can use this to
+ * determine a new kernel/old userspace situation and cope
+ * with it.
+ */
+ rc = -ENOSYS;
+ goto out;
+ }
+
+ /* populate arg var if command needs it */
+ if (cmd->needs_arg) {
+ if (optind + 1 >= argc) {
+ xlog(L_ERROR, "Command %s requires an argument\n",
+ cmd->name);
+ rc = -EINVAL;
+ goto out;
+ }
+ cmdarg = argv[optind + 1];
+ }
+ rc = cmd->func(cmdarg);
+out:
+ free(progname);
+ return rc;
+}
--
1.7.11.7
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