----- On May 21, 2019, at 2:01 PM, Gabriel-Andrew Pollo-Guilbert gabriel.pollo-guilb...@efficios.com wrote:
> In case of a per-UID buffers, events following a setuid() call should be a per-UID buffers -> per-UID buffer > fowarded to buffers of the new UID. In order to do so, we add a wrapper around fowarded -> forwarded (you should setup a spell checker for your commit msg) > setuid() that unregister and re-register the application from the session > daemon. > > Signed-off-by: Gabriel-Andrew Pollo-Guilbert > <gabriel.pollo-guilb...@efficios.com> > --- > 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(); fct() in C means fct(...) (variable arguments) (unlike C++). You really mean fct(void) here. > > #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 <lttng/ust-dlfcn.h> > +#include <unistd.h> > +#include <errno.h> > +#include <stdio.h> > + > +#include <lttng/ust.h> If possible, move all lttng specific includes at the end of the include list. We only have a newline before including "local" headers (between ""), and there are none here, so newline not needed. > + > +int setuid(uid_t uid) { Run this patch through the Linux kernel checkpatch.pl script please. > + 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() () -> (void) > +{ > + /* > + * 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. > + */ We can remove this todo. We can document this in a comment at the top of the file. That's how it works, and I don't see much point in trying to optimize for this use-case. The comment could look like: /* * Re-register the application when changing user ID. This is especially * important for per-UID buffers. It is not strictly needed for per-PID * buffers, but a slight extra overhead when changing user ID is considered * harmless for a relatively infrequent operation. */ > + > + DBG("Unregistering the process"); > + lttng_ust_fixup_tls(); > + lttng_ust_exit(); > + > + sem_count = 2; Since we use it in code, we need to define (locally) e.g. #define LTTNG_UST_INIT_SEM_COUNT 2 Just above the sem_count definition and use it. We try hard to never hardcode any constant. > + lttng_ust_comm_should_quit = 0; > + initialized = 0; 0 is fine though. Thanks, Mathieu > + > + 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 > > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev