From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriel-Andrew Pollo-Guilbert Subject: [lttng-ust RFC] Add setuid wrapper for per-UID buffers Date: Tue, 21 May 2019 14:01:11 -0400 Message-ID: <20190521180111.29677-1-gabriel.pollo-guilbert__47822.5782908098$1558461784$gmane$org@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.efficios.com (mail.efficios.com [167.114.142.138]) by lists.lttng.org (Postfix) with ESMTPS id 457kBT6BDCz10M0 for ; Tue, 21 May 2019 14:02:41 -0400 (EDT) List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" To: lttng-dev@lists.lttng.org List-Id: lttng-dev@lists.lttng.org In case of a per-UID buffers, events following a setuid() call should be fowarded to buffers of the new UID. In order to do so, we add a wrapper around setuid() that unregister and re-register the application from the session daemon. Signed-off-by: Gabriel-Andrew Pollo-Guilbert --- Makefile.am | 1 + configure.ac | 1 + include/lttng/ust.h | 1 + liblttng-ust-setuid/Makefile.am | 10 +++++++ liblttng-ust-setuid/ustsetuid.c | 48 +++++++++++++++++++++++++++++++++ liblttng-ust/lttng-ust-comm.c | 23 ++++++++++++++++ 6 files changed, 84 insertions(+) create mode 100644 liblttng-ust-setuid/Makefile.am create mode 100644 liblttng-ust-setuid/ustsetuid.c diff --git a/Makefile.am b/Makefile.am index 810761ca..e8812e59 100644 --- a/Makefile.am +++ b/Makefile.am @@ -5,6 +5,7 @@ SUBDIRS = . include snprintf libringbuffer liblttng-ust-comm \ liblttng-ust-ctl \ liblttng-ust-fd \ liblttng-ust-fork \ + liblttng-ust-setuid \ liblttng-ust-libc-wrapper \ liblttng-ust-cyg-profile \ tools diff --git a/configure.ac b/configure.ac index 52fc3f68..95780dba 100644 --- a/configure.ac +++ b/configure.ac @@ -522,6 +522,7 @@ AC_CONFIG_FILES([ liblttng-ust/Makefile liblttng-ust-ctl/Makefile liblttng-ust-fork/Makefile + liblttng-ust-setuid/Makefile liblttng-ust-dl/Makefile liblttng-ust-fd/Makefile liblttng-ust-java/Makefile diff --git a/include/lttng/ust.h b/include/lttng/ust.h index 2779d7a7..37f15520 100644 --- a/include/lttng/ust.h +++ b/include/lttng/ust.h @@ -32,6 +32,7 @@ extern "C" { extern void ust_before_fork(sigset_t *save_sigset); extern void ust_after_fork_parent(sigset_t *restore_sigset); extern void ust_after_fork_child(sigset_t *restore_sigset); +extern void ust_after_setuid(); #ifdef __cplusplus } diff --git a/liblttng-ust-setuid/Makefile.am b/liblttng-ust-setuid/Makefile.am new file mode 100644 index 00000000..df3cd622 --- /dev/null +++ b/liblttng-ust-setuid/Makefile.am @@ -0,0 +1,10 @@ +AM_CPPFLAGS = -I$(top_srcdir)/include +AM_CFLAGS += -fno-strict-aliasing + +lib_LTLIBRARIES = liblttng-ust-setuid.la +liblttng_ust_setuid_la_SOURCES = ustsetuid.c +liblttng_ust_setuid_la_LIBADD = \ + $(top_builddir)/liblttng-ust/liblttng-ust.la \ + $(DL_LIBS) + +liblttng_ust_setuid_la_CFLAGS = -DUST_COMPONENT=liblttng-ust-setuid $(AM_CFLAGS) diff --git a/liblttng-ust-setuid/ustsetuid.c b/liblttng-ust-setuid/ustsetuid.c new file mode 100644 index 00000000..f95e1896 --- /dev/null +++ b/liblttng-ust-setuid/ustsetuid.c @@ -0,0 +1,48 @@ +/* + * Copyright (C) 2019 Gabriel-Andrew Pollo-Guilbert + * + * 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; version 2.1 of + * the License. + * + * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#define _GNU_SOURCE +#include +#include +#include +#include + +#include + +int setuid(uid_t uid) { + static int (*plibc_func)(uid_t) = NULL; + int retval; + + if (plibc_func == NULL) { + plibc_func = dlsym(RTLD_NEXT, "setuid"); + if (plibc_func == NULL) { + fprintf(stderr, "libustsetuid: unable to find \"setuid\" symbol\n"); + errno = ENOSYS; + return -1; + } + } + + retval = plibc_func(uid); + if(retval < 0) { + return retval; + } + + ust_after_setuid(); + + return retval; +} diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c index 61dbb41b..5e55466e 100644 --- a/liblttng-ust/lttng-ust-comm.c +++ b/liblttng-ust/lttng-ust-comm.c @@ -2072,3 +2072,26 @@ void lttng_ust_sockinfo_session_enabled(void *owner) struct sock_info *sock_info = owner; sock_info->statedump_pending = 1; } + +void ust_after_setuid() +{ + /* + * TODO: Don't re-register the application if in per-PID mode. That + * said, LTTng-UST isn't aware of the buffer types configured by + * LTTng-Tools. + */ + + DBG("Unregistering the process"); + lttng_ust_fixup_tls(); + lttng_ust_exit(); + + sem_count = 2; + lttng_ust_comm_should_quit = 0; + initialized = 0; + + global_apps.wait_shm_mmap = NULL; + local_apps.wait_shm_mmap = NULL; + + DBG("Registering the process under new UID=%u", getuid()); + lttng_ust_init(); +} -- 2.21.0