[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH 02/29] tools: add a new xen logging daemon
Add "xenlogd", a new logging daemon meant to support infrastructure domains (e.g. xenstore-stubdom) to write log files in dom0. For now only add the code needed for starting the daemon and registering it with Xenstore via a new "/tool/xenlog/state" node by writing the "running" state to it. Signed-off-by: Juergen Gross <jgross@xxxxxxxx> --- tools/Makefile | 1 + tools/xenlogd/.gitignore | 1 + tools/xenlogd/Makefile | 38 ++++++++++ tools/xenlogd/xenlogd.c | 145 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 185 insertions(+) create mode 100644 tools/xenlogd/.gitignore create mode 100644 tools/xenlogd/Makefile create mode 100644 tools/xenlogd/xenlogd.c diff --git a/tools/Makefile b/tools/Makefile index 3a510663a0..0225020416 100644 --- a/tools/Makefile +++ b/tools/Makefile @@ -32,6 +32,7 @@ SUBDIRS-y += xenpmd SUBDIRS-$(CONFIG_GOLANG) += golang SUBDIRS-y += xl SUBDIRS-y += helpers +SUBDIRS-y += xenlogd SUBDIRS-$(CONFIG_X86) += xenpaging SUBDIRS-$(CONFIG_X86) += debugger SUBDIRS-$(CONFIG_TESTS) += tests diff --git a/tools/xenlogd/.gitignore b/tools/xenlogd/.gitignore new file mode 100644 index 0000000000..a0305ae096 --- /dev/null +++ b/tools/xenlogd/.gitignore @@ -0,0 +1 @@ +/xenlogd diff --git a/tools/xenlogd/Makefile b/tools/xenlogd/Makefile new file mode 100644 index 0000000000..550e914f59 --- /dev/null +++ b/tools/xenlogd/Makefile @@ -0,0 +1,38 @@ +# +# tools/helpers/Makefile +# + +XEN_ROOT = $(CURDIR)/../.. +include $(XEN_ROOT)/tools/Rules.mk + +CFLAGS += $(PTHREAD_CFLAGS) +LDFLAGS += $(PTHREAD_LDFLAGS) + +TARGETS := xenlogd + +XENLOGD_OBJS = xenlogd.o +$(XENLOGD_OBJS): CFLAGS += $(CFLAGS_libxenstore) +$(XENLOGD_OBJS): CFLAGS += $(CFLAGS_libxenevtchn) +$(XENLOGD_OBJS): CFLAGS += $(CFLAGS_libxengnttab) +xenlogd: LDLIBS += $(call xenlibs-ldlibs,store evtchn gnttab) + +.PHONY: all +all: $(TARGETS) + +xenlogd: $(XENLOGD_OBJS) + $(CC) $(LDFLAGS) -o $@ $(XENLOGD_OBJS) $(LDLIBS) $(APPEND_LDFLAGS) + +.PHONY: install +install: all + $(INSTALL_DIR) $(DESTDIR)$(LIBEXEC_BIN) + for i in $(TARGETS); do $(INSTALL_PROG) $$i $(DESTDIR)$(LIBEXEC_BIN); done + +.PHONY: uninstall +uninstall: + for i in $(TARGETS); do rm -f $(DESTDIR)$(LIBEXEC_BIN)/$$i; done + +.PHONY: clean +clean: + $(RM) *.o $(TARGETS) $(DEPS_RM) + +distclean: clean diff --git a/tools/xenlogd/xenlogd.c b/tools/xenlogd/xenlogd.c new file mode 100644 index 0000000000..792d1026a3 --- /dev/null +++ b/tools/xenlogd/xenlogd.c @@ -0,0 +1,145 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * xenlogd - Xen logging daemon + * + * Copyright (C) 2023 Juergen Gross <jgross@xxxxxxxx> + * + * Daemon to enable guests to access a directory of the dom0 file system. + * Access is made via the 9pfs protocol (xenlogd acts as a PV 9pfs backend). + * + * Usage: xenlogd + * + * xenlogd does NOT support writing any links (neither soft links nor hard + * links), and it is accepting only canonicalized file paths in order to + * avoid the possibility to "escape" from the guest specific directory. + * + * The backend device string is "xen_9pfs", the tag used for mounting the + * 9pfs device is "Xen". + * + * As an additional security measure the maximum file space used by the guest + * can be limited by the backend Xenstore node "max-size" specifying the size + * in MBytes. This size includes the size of the root directory of the guest. + */ + +#include <err.h> +#include <errno.h> +#include <signal.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <unistd.h> +#include <xenevtchn.h> +#include <xengnttab.h> +#include <xenstore.h> + +static bool stop_me; +static bool daemon_running; +static struct xs_handle *xs; +static xengnttab_handle *xg; +static xenevtchn_handle *xe; + +static void handle_stop(int sig) +{ + stop_me = true; +} + +static void close_all(void) +{ + if ( daemon_running ) + xs_rm(xs, XBT_NULL, "/tool/xenlog"); + if ( xe ) + xenevtchn_close(xe); + if ( xg ) + xengnttab_close(xg); + if ( xs ) + xs_close(xs); + closelog(); +} + +static void do_err(const char *msg) +{ + syslog(LOG_ALERT, "%s, errno = %d", msg, errno); + close_all(); + exit(1); +} + +static void xen_connect(void) +{ + xs_transaction_t t; + char *val; + unsigned int len; + + xs = xs_open(0); + if ( xs == NULL ) + do_err("xs_open() failed"); + + xg = xengnttab_open(NULL, 0); + if ( xg == NULL ) + do_err("xengnttab_open() failed"); + + xe = xenevtchn_open(NULL, 0); + if ( xe == NULL ) + do_err("xenevtchn_open() failed"); + + while ( true ) + { + t = xs_transaction_start(xs); + if ( t == XBT_NULL ) + do_err("xs_transaction_start() failed"); + + val = xs_read(xs, t, "/tool/xenlog/state", &len); + if ( val ) + { + free(val); + xs_transaction_end(xs, t, true); + do_err("daemon already running"); + } + + if ( !xs_write(xs, t, "/tool/xenlog/state", "running", + strlen("running")) ) + { + xs_transaction_end(xs, t, true); + do_err("xs_write() failed writing state"); + } + + if ( xs_transaction_end(xs, t, false) ) + break; + if ( errno != EAGAIN ) + do_err("xs_transaction_end() failed"); + } + + daemon_running = true; +} + +int main(int argc, char *argv[]) +{ + struct sigaction act = { .sa_handler = handle_stop, }; + int syslog_mask = LOG_MASK(LOG_WARNING) | LOG_MASK(LOG_ERR) | + LOG_MASK(LOG_CRIT) | LOG_MASK(LOG_ALERT) | + LOG_MASK(LOG_EMERG); + + umask(027); + if ( getenv("XENLOGD_VERBOSE") ) + syslog_mask |= LOG_MASK(LOG_NOTICE) | LOG_MASK(LOG_INFO); + openlog("xenlogd", LOG_CONS, LOG_DAEMON); + setlogmask(syslog_mask); + + sigemptyset(&act.sa_mask); + sigaction(SIGHUP, &act, NULL); + + xen_connect(); + + while ( !stop_me ) + { + sleep(60); + } + + close_all(); + + return 0; +} -- 2.35.3
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