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/* PipeWire
* Copyright (C) 2018 Wim Taymans <wim.taymans@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "config.h"
#include "pipewire/core.h"
#include "pipewire/interfaces.h"
#include "pipewire/link.h"
#include "pipewire/log.h"
#include "pipewire/module.h"
#include "pipewire/properties.h"
#include "pipewire/utils.h"
static const struct spa_dict_item module_props[] = {
{ PW_MODULE_PROP_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
{ PW_MODULE_PROP_DESCRIPTION, "Perform access check" },
{ PW_MODULE_PROP_VERSION, PACKAGE_VERSION },
};
struct impl {
struct pw_core *core;
struct pw_properties *properties;
struct spa_hook core_listener;
struct spa_hook module_listener;
};
static int check_cmdline(struct pw_client *client, const struct ucred *ucred, const char *str)
{
char path[2048];
int fd;
sprintf(path, "/proc/%u/cmdline", ucred->pid);
fd = open(path, O_RDONLY);
if (fd < 0)
return -errno;
if (read(fd, path, 1024) <= 0)
return -EIO;
if (strcmp(path, str) == 0)
return 1;
return 0;
}
static int check_flatpak(struct pw_client *client, const struct ucred *ucred)
{
char root_path[2048];
int root_fd, info_fd, res;
struct stat stat_buf;
sprintf(root_path, "/proc/%u/root", ucred->pid);
root_fd = openat (AT_FDCWD, root_path, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY);
if (root_fd == -1) {
/* Not able to open the root dir shouldn't happen. Probably the app died and
* we're failing due to /proc/$pid not existing. In that case fail instead
* of treating this as privileged. */
res = -errno;
pw_log_error("failed to open \"%s\": %m", root_path);
return res;
}
info_fd = openat (root_fd, ".flatpak-info", O_RDONLY | O_CLOEXEC | O_NOCTTY);
close (root_fd);
if (info_fd == -1) {
if (errno == ENOENT) {
pw_log_debug("no .flatpak-info, client on the host");
/* No file => on the host */
return 0;
}
res = -errno;
pw_log_error("error opening .flatpak-info: %m");
return res;
}
if (fstat (info_fd, &stat_buf) != 0 || !S_ISREG (stat_buf.st_mode)) {
/* Some weird fd => failure, assume sandboxed */
close(info_fd);
pw_log_error("error fstat .flatpak-info: %m");
}
return 1;
}
static void
core_check_access(void *data, struct pw_client *client)
{
struct impl *impl = data;
const struct ucred *ucred;
struct spa_dict_item items[2];
const char *str;
int res;
ucred = pw_client_get_ucred(client);
if (!ucred) {
pw_log_info("no trusted pid found, assuming not sandboxed\n");
goto granted;
} else {
pw_log_info("client has trusted pid %d", ucred->pid);
}
if (impl->properties && (str = pw_properties_get(impl->properties, "blacklisted")) != NULL) {
res = check_cmdline(client, ucred, str);
if (res == 0)
goto granted;
if (res > 0)
res = EACCES;
goto blacklisted;
}
if (impl->properties && (str = pw_properties_get(impl->properties, "restricted")) != NULL) {
res = check_cmdline(client, ucred, str);
if (res == 0)
goto granted;
if (res < 0) {
pw_log_warn("module %p: client %p restricted check failed: %s",
impl, client, spa_strerror(res));
}
else if (res > 0) {
pw_log_debug("module %p: restricted client %p added", impl, client);
}
items[0] = SPA_DICT_ITEM_INIT("pipewire.access", "restricted");
goto wait_permissions;
}
res = check_flatpak(client, ucred);
if (res != 0) {
if (res < 0) {
pw_log_warn("module %p: client %p sandbox check failed: %s",
impl, client, spa_strerror(res));
}
else if (res > 0) {
pw_log_debug("module %p: sandboxed client %p added", impl, client);
}
items[0] = SPA_DICT_ITEM_INIT("pipewire.access", "flatpak");
goto wait_permissions;
}
granted:
pw_log_debug("module %p: client %p access granted", impl, client);
pw_client_set_permissions(client, PW_PERM_RWX);
return;
wait_permissions:
pw_log_debug("module %p: client %p wait for permissions", impl, client);
pw_client_update_properties(client, &SPA_DICT_INIT(items, 1));
pw_client_set_busy(client, true);
return;
blacklisted:
items[0] = SPA_DICT_ITEM_INIT("pipewire.access", "blacklisted");
pw_resource_error(pw_client_get_core_resource(client), 0, res, "blacklisted");
pw_client_update_properties(client, &SPA_DICT_INIT(items, 1));
return;
}
static const struct pw_core_events core_events = {
PW_VERSION_CORE_EVENTS,
.check_access = core_check_access,
};
static void module_destroy(void *data)
{
struct impl *impl = data;
spa_hook_remove(&impl->core_listener);
spa_hook_remove(&impl->module_listener);
if (impl->properties)
pw_properties_free(impl->properties);
free(impl);
}
static const struct pw_module_events module_events = {
PW_VERSION_MODULE_EVENTS,
.destroy = module_destroy,
};
int pipewire__module_init(struct pw_module *module, const char *args)
{
struct pw_core *core = pw_module_get_core(module);
struct pw_properties *props;
struct impl *impl;
impl = calloc(1, sizeof(struct impl));
if (impl == NULL)
return -ENOMEM;
pw_log_debug("module %p: new %s", impl, args);
if (args)
props = pw_properties_new_string(args);
else
props = NULL;
impl->core = core;
impl->properties = props;
pw_core_add_listener(core, &impl->core_listener, &core_events, impl);
pw_module_add_listener(module, &impl->module_listener, &module_events, impl);
pw_module_update_properties(module, &SPA_DICT_INIT_ARRAY(module_props));
return 0;
}
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