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Systemd/src/core/smack-setup.c
Lennart Poettering 0d53667334 tree-wide: use __fsetlocking() instead of fxyz_unlocked() 
Let's replace usage of fputc_unlocked() and friends by __fsetlocking(f,
FSETLOCKING_BYCALLER). This turns off locking for the entire FILE*,
instead of doing individual per-call decision whether to use normal
calls or _unlocked() calls.

This has various benefits:

1. It's easier to read and easier not to forget

2. It's more comprehensive, as fprintf() and friends are covered too
   (as these functions have no _unlocked() counterpart)

3. Philosophically, it's a bit more correct, because it's more a
   property of the file handle really whether we ever pass it on to another
   thread, not of the operations we then apply to it.

This patch reworks all pieces of codes that so far used fxyz_unlocked()
calls to use __fsetlocking() instead. It also reworks all places that
use open_memstream(), i.e. use stdio FILE* for string manipulations.

Note that this in some way a revert of 4b61c87511.
2017-12-14 10:42:25 +01:00

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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright (C) 2013 Intel Corporation
Authors:
Nathaniel Chen <nathaniel.chen@intel.com>
systemd 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; either version 2.1 of the License,
or (at your option) any later version.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include "alloc-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "log.h"
#include "macro.h"
#include "smack-setup.h"
#include "string-util.h"
#include "util.h"
#if ENABLE_SMACK
static int write_access2_rules(const char* srcdir) {
_cleanup_close_ int load2_fd = -1, change_fd = -1;
_cleanup_closedir_ DIR *dir = NULL;
struct dirent *entry;
char buf[NAME_MAX];
int dfd = -1;
int r = 0;
load2_fd = open("/sys/fs/smackfs/load2", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (load2_fd < 0) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/load2': %m");
return -errno; /* negative error */
}
change_fd = open("/sys/fs/smackfs/change-rule", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (change_fd < 0) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/change-rule': %m");
return -errno; /* negative error */
}
/* write rules to load2 or change-rule from every file in the directory */
dir = opendir(srcdir);
if (!dir) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to opendir '%s': %m", srcdir);
return errno; /* positive on purpose */
}
dfd = dirfd(dir);
assert(dfd >= 0);
FOREACH_DIRENT(entry, dir, return 0) {
int fd;
_cleanup_fclose_ FILE *policy = NULL;
if (!dirent_is_file(entry))
continue;
fd = openat(dfd, entry->d_name, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
if (r == 0)
r = -errno;
log_warning_errno(errno, "Failed to open '%s': %m", entry->d_name);
continue;
}
policy = fdopen(fd, "re");
if (!policy) {
if (r == 0)
r = -errno;
safe_close(fd);
log_error_errno(errno, "Failed to open '%s': %m", entry->d_name);
continue;
}
/* load2 write rules in the kernel require a line buffered stream */
FOREACH_LINE(buf, policy,
log_error_errno(errno, "Failed to read line from '%s': %m",
entry->d_name)) {
_cleanup_free_ char *sbj = NULL, *obj = NULL, *acc1 = NULL, *acc2 = NULL;
if (isempty(truncate_nl(buf)) || strchr(COMMENTS, *buf))
continue;
/* if 3 args -> load rule : subject object access1 */
/* if 4 args -> change rule : subject object access1 access2 */
if (sscanf(buf, "%ms %ms %ms %ms", &sbj, &obj, &acc1, &acc2) < 3) {
log_error_errno(errno, "Failed to parse rule '%s' in '%s', ignoring.", buf, entry->d_name);
continue;
}
if (write(isempty(acc2) ? load2_fd : change_fd, buf, strlen(buf)) < 0) {
if (r == 0)
r = -errno;
log_error_errno(errno, "Failed to write '%s' to '%s' in '%s'",
buf, isempty(acc2) ? "/sys/fs/smackfs/load2" : "/sys/fs/smackfs/change-rule", entry->d_name);
}
}
}
return r;
}
static int write_cipso2_rules(const char* srcdir) {
_cleanup_close_ int cipso2_fd = -1;
_cleanup_closedir_ DIR *dir = NULL;
struct dirent *entry;
char buf[NAME_MAX];
int dfd = -1;
int r = 0;
cipso2_fd = open("/sys/fs/smackfs/cipso2", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (cipso2_fd < 0) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/cipso2': %m");
return -errno; /* negative error */
}
/* write rules to cipso2 from every file in the directory */
dir = opendir(srcdir);
if (!dir) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to opendir '%s': %m", srcdir);
return errno; /* positive on purpose */
}
dfd = dirfd(dir);
assert(dfd >= 0);
FOREACH_DIRENT(entry, dir, return 0) {
int fd;
_cleanup_fclose_ FILE *policy = NULL;
if (!dirent_is_file(entry))
continue;
fd = openat(dfd, entry->d_name, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
if (r == 0)
r = -errno;
log_error_errno(errno, "Failed to open '%s': %m", entry->d_name);
continue;
}
policy = fdopen(fd, "re");
if (!policy) {
if (r == 0)
r = -errno;
safe_close(fd);
log_error_errno(errno, "Failed to open '%s': %m", entry->d_name);
continue;
}
/* cipso2 write rules in the kernel require a line buffered stream */
FOREACH_LINE(buf, policy,
log_error_errno(errno, "Failed to read line from '%s': %m",
entry->d_name)) {
if (isempty(truncate_nl(buf)) || strchr(COMMENTS, *buf))
continue;
if (write(cipso2_fd, buf, strlen(buf)) < 0) {
if (r == 0)
r = -errno;
log_error_errno(errno, "Failed to write '%s' to '/sys/fs/smackfs/cipso2' in '%s'",
buf, entry->d_name);
break;
}
}
}
return r;
}
static int write_netlabel_rules(const char* srcdir) {
_cleanup_fclose_ FILE *dst = NULL;
_cleanup_closedir_ DIR *dir = NULL;
struct dirent *entry;
char buf[NAME_MAX];
int dfd = -1;
int r = 0;
dst = fopen("/sys/fs/smackfs/netlabel", "we");
if (!dst) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to open /sys/fs/smackfs/netlabel: %m");
return -errno; /* negative error */
}
/* write rules to dst from every file in the directory */
dir = opendir(srcdir);
if (!dir) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to opendir %s: %m", srcdir);
return errno; /* positive on purpose */
}
dfd = dirfd(dir);
assert(dfd >= 0);
FOREACH_DIRENT(entry, dir, return 0) {
int fd;
_cleanup_fclose_ FILE *policy = NULL;
fd = openat(dfd, entry->d_name, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
if (r == 0)
r = -errno;
log_warning_errno(errno, "Failed to open %s: %m", entry->d_name);
continue;
}
policy = fdopen(fd, "re");
if (!policy) {
if (r == 0)
r = -errno;
safe_close(fd);
log_error_errno(errno, "Failed to open %s: %m", entry->d_name);
continue;
}
(void) __fsetlocking(policy, FSETLOCKING_BYCALLER);
/* load2 write rules in the kernel require a line buffered stream */
FOREACH_LINE(buf, policy,
log_error_errno(errno, "Failed to read line from %s: %m", entry->d_name)) {
int q;
if (!fputs(buf, dst)) {
if (r == 0)
r = -EINVAL;
log_error_errno(errno, "Failed to write line to /sys/fs/smackfs/netlabel");
break;
}
q = fflush_and_check(dst);
if (q < 0) {
if (r == 0)
r = q;
log_error_errno(q, "Failed to flush writes to /sys/fs/smackfs/netlabel: %m");
break;
}
}
}
return r;
}
static int write_onlycap_list(void) {
_cleanup_close_ int onlycap_fd = -1;
_cleanup_free_ char *list = NULL;
_cleanup_fclose_ FILE *f = NULL;
size_t len = 0, allocated = 0;
char buf[LINE_MAX];
int r;
f = fopen("/etc/smack/onlycap", "re");
if (!f) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to read '/etc/smack/onlycap'");
return errno == ENOENT ? ENOENT : -errno;
}
FOREACH_LINE(buf, f, return -errno) {
size_t l;
if (isempty(truncate_nl(buf)) || strchr(COMMENTS, *buf))
continue;
l = strlen(buf);
if (!GREEDY_REALLOC(list, allocated, len + l + 1))
return log_oom();
stpcpy(list + len, buf)[0] = ' ';
len += l + 1;
}
if (!len)
return 0;
list[len - 1] = 0;
onlycap_fd = open("/sys/fs/smackfs/onlycap", O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (onlycap_fd < 0) {
if (errno != ENOENT)
log_warning_errno(errno, "Failed to open '/sys/fs/smackfs/onlycap'");
return -errno; /* negative error */
}
r = write(onlycap_fd, list, len);
if (r < 0)
return log_error_errno(errno, "Failed to write onlycap list(%s) to '/sys/fs/smackfs/onlycap'", list);
return 0;
}
#endif
int mac_smack_setup(bool *loaded_policy) {
#if ENABLE_SMACK
int r;
assert(loaded_policy);
r = write_access2_rules("/etc/smack/accesses.d/");
switch(r) {
case -ENOENT:
log_debug("Smack is not enabled in the kernel.");
return 0;
case ENOENT:
log_debug("Smack access rules directory '/etc/smack/accesses.d/' not found");
return 0;
case 0:
log_info("Successfully loaded Smack policies.");
break;
default:
log_warning_errno(r, "Failed to load Smack access rules, ignoring: %m");
return 0;
}
#ifdef SMACK_RUN_LABEL
r = write_string_file("/proc/self/attr/current", SMACK_RUN_LABEL, 0);
if (r < 0)
log_warning_errno(r, "Failed to set SMACK label \"" SMACK_RUN_LABEL "\" on self: %m");
r = write_string_file("/sys/fs/smackfs/ambient", SMACK_RUN_LABEL, 0);
if (r < 0)
log_warning_errno(r, "Failed to set SMACK ambient label \"" SMACK_RUN_LABEL "\": %m");
r = write_string_file("/sys/fs/smackfs/netlabel",
"0.0.0.0/0 " SMACK_RUN_LABEL, 0);
if (r < 0)
log_warning_errno(r, "Failed to set SMACK netlabel rule \"0.0.0.0/0 " SMACK_RUN_LABEL "\": %m");
r = write_string_file("/sys/fs/smackfs/netlabel", "127.0.0.1 -CIPSO", 0);
if (r < 0)
log_warning_errno(r, "Failed to set SMACK netlabel rule \"127.0.0.1 -CIPSO\": %m");
#endif
r = write_cipso2_rules("/etc/smack/cipso.d/");
switch(r) {
case -ENOENT:
log_debug("Smack/CIPSO is not enabled in the kernel.");
return 0;
case ENOENT:
log_debug("Smack/CIPSO access rules directory '/etc/smack/cipso.d/' not found");
break;
case 0:
log_info("Successfully loaded Smack/CIPSO policies.");
break;
default:
log_warning_errno(r, "Failed to load Smack/CIPSO access rules, ignoring: %m");
break;
}
r = write_netlabel_rules("/etc/smack/netlabel.d/");
switch(r) {
case -ENOENT:
log_debug("Smack/CIPSO is not enabled in the kernel.");
return 0;
case ENOENT:
log_debug("Smack network host rules directory '/etc/smack/netlabel.d/' not found");
break;
case 0:
log_info("Successfully loaded Smack network host rules.");
break;
default:
log_warning_errno(r, "Failed to load Smack network host rules: %m, ignoring.");
break;
}
r = write_onlycap_list();
switch(r) {
case -ENOENT:
log_debug("Smack is not enabled in the kernel.");
break;
case ENOENT:
log_debug("Smack onlycap list file '/etc/smack/onlycap' not found");
break;
case 0:
log_info("Successfully wrote Smack onlycap list.");
break;
default:
log_emergency_errno(r, "Failed to write Smack onlycap list.");
return r;
}
*loaded_policy = true;
#endif
return 0;
}
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