From 0c778200aed85ca099d995a082392cb2d49a08b9 Mon Sep 17 00:00:00 2001 From: Christian Kellner Date: Tue, 30 Apr 2019 13:47:47 +0200 Subject: [PATCH 1/2] helpers: add helpers to automatically close fds Add a inline helper function and a helper macro to be able to automatically close file descriptors. Does nothing if the argument is NULL or the pointed to integer is < 0. --- daemon/helpers.c | 41 +++++++++++++++++++++++++++++++++++++++++ daemon/helpers.h | 19 +++++++++++++++++++ daemon/meson.build | 1 + 3 files changed, 61 insertions(+) create mode 100644 daemon/helpers.c diff --git a/daemon/helpers.c b/daemon/helpers.c new file mode 100644 index 0000000..50fde33 --- /dev/null +++ b/daemon/helpers.c @@ -0,0 +1,41 @@ +/* + +Copyright (c) 2017-2019, Feral Interactive +Copyright (c) 2019, Red Hat +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + * Redistributions of source code must retain the above copyright notice, + this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in the + documentation and/or other materials provided with the distribution. + * Neither the name of Feral Interactive nor the names of its contributors + may be used to endorse or promote products derived from this software + without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +POSSIBILITY OF SUCH DAMAGE. + + */ + +#define _GNU_SOURCE +#include "helpers.h" + +/* Starting with C99 we can use "inline" without "static" and thus avoid + * having multiple (local) definitions of the same inline function. One + * consequence of that is that if the compiler decides to *not* inline + * a specific call to the function the linker will expect an definition. + */ +extern inline void cleanup_close(int *fd); diff --git a/daemon/helpers.h b/daemon/helpers.h index eb2b722..8595092 100644 --- a/daemon/helpers.h +++ b/daemon/helpers.h @@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE. #include #include #include +#include /** * Value clamping helper, works like MIN/MAX but constraints a value within the range. @@ -62,3 +63,21 @@ static inline const char *strtail(const char *haystack, const char *needle) return pos; return NULL; } + +/** + * Helper function for autoclosing file-descriptors. Does nothing if the argument + * is NULL or the referenced integer < 0. + */ +inline void cleanup_close(int *fd_ptr) +{ + if (fd_ptr == NULL || *fd_ptr < 0) + return; + + (void)close(*fd_ptr); +} + +/** + * Helper macro for autoclosing file-descriptors: use by prefixing the variable, + * like "autoclose_fd int fd = -1;". + */ +#define autoclose_fd __attribute__((cleanup(cleanup_close))) diff --git a/daemon/meson.build b/daemon/meson.build index 06cb183..d7cd0b5 100644 --- a/daemon/meson.build +++ b/daemon/meson.build @@ -30,6 +30,7 @@ daemon_sources = [ 'daemonize.c', 'dbus_messaging.c', 'daemon_config.c', + 'helpers.c', ] gamemoded_includes = libgamemode_includes From 70e601267b0264a3e6c42656517870cd0b021372 Mon Sep 17 00:00:00 2001 From: Christian Kellner Date: Tue, 30 Apr 2019 18:18:18 +0200 Subject: [PATCH 2/2] daemon: use readlink not realpath to find the exe The realpath(3) will fail if the target does not exist (internally realpath will stat all the components of the link target path). This is a problem in the case of sandbox applications where the exe points to the absolute path *inside* the sandbox, e.g. to /app/bin/ in the case of flatpak. For these cases realpath(3) will then fail. Therefore use readlink(3) instead. --- daemon/gamemode.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/daemon/gamemode.c b/daemon/gamemode.c index 9855fe6..e8fab8b 100644 --- a/daemon/gamemode.c +++ b/daemon/gamemode.c @@ -40,10 +40,14 @@ POSSIBILITY OF SUCH DAMAGE. #include "helpers.h" #include "logging.h" +#include #include #include #include +#include +#include #include +#include /** * The GameModeClient encapsulates the remote connection, providing a list @@ -650,15 +654,31 @@ static char *game_mode_context_find_exe(pid_t pid) { char buffer[PATH_MAX]; char *proc_path = NULL, *wine_exe = NULL; + autoclose_fd int pidfd = -1; + ssize_t r; - if (!(proc_path = buffered_snprintf(buffer, "/proc/%d/exe", pid))) + if (!(proc_path = buffered_snprintf(buffer, "/proc/%d", pid))) goto fail; - /* Allocate the realpath if possible */ - char *exe = realpath(proc_path, NULL); - if (!exe) + /* Translate /proc//exe to the application binary */ + pidfd = openat(AT_FDCWD, proc_path, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY); + if (pidfd == -1) goto fail; + r = readlinkat(pidfd, "exe", buffer, sizeof(buffer)); + + if (r == sizeof(buffer)) { + errno = ENAMETOOLONG; + r = -1; + } + + if (r == -1) + goto fail; + + buffer[r] = '\0'; + + char *exe = strdup(buffer); + /* Detect if the process is a wine loader process */ if (game_mode_detect_wine_preloader(exe)) { LOG_MSG("Detected wine preloader for client %d [%s].\n", pid, exe);