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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/***
Copyright © 2013 Intel Corporation
Author: Auke Kok <auke-jan.h.kok@intel.com>
***/
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/xattr.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "log.h"
#include "macro.h"
#include "path-util.h"
#include "process-util.h"
#include "smack-util.h"
#include "stdio-util.h"
#include "string-table.h"
#include "xattr-util.h"
#if ENABLE_SMACK
bool mac_smack_use(void) {
static int cached_use = -1;
if (cached_use < 0)
cached_use = access("/sys/fs/smackfs/", F_OK) >= 0;
return cached_use;
}
static const char* const smack_attr_table[_SMACK_ATTR_MAX] = {
[SMACK_ATTR_ACCESS] = "security.SMACK64",
[SMACK_ATTR_EXEC] = "security.SMACK64EXEC",
[SMACK_ATTR_MMAP] = "security.SMACK64MMAP",
[SMACK_ATTR_TRANSMUTE] = "security.SMACK64TRANSMUTE",
[SMACK_ATTR_IPIN] = "security.SMACK64IPIN",
[SMACK_ATTR_IPOUT] = "security.SMACK64IPOUT",
};
DEFINE_STRING_TABLE_LOOKUP(smack_attr, SmackAttr);
int mac_smack_read(const char *path, SmackAttr attr, char **label) {
assert(path);
assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
assert(label);
if (!mac_smack_use())
return 0;
return getxattr_malloc(path, smack_attr_to_string(attr), label, true);
}
int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
assert(fd >= 0);
assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
assert(label);
if (!mac_smack_use())
return 0;
return fgetxattr_malloc(fd, smack_attr_to_string(attr), label);
}
int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
int r;
assert(path);
assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
if (!mac_smack_use())
return 0;
if (label)
r = lsetxattr(path, smack_attr_to_string(attr), label, strlen(label), 0);
else
r = lremovexattr(path, smack_attr_to_string(attr));
if (r < 0)
return -errno;
return 0;
}
int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
int r;
assert(fd >= 0);
assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
if (!mac_smack_use())
return 0;
if (label)
r = fsetxattr(fd, smack_attr_to_string(attr), label, strlen(label), 0);
else
r = fremovexattr(fd, smack_attr_to_string(attr));
if (r < 0)
return -errno;
return 0;
}
int mac_smack_apply_pid(pid_t pid, const char *label) {
const char *p;
int r;
assert(label);
if (!mac_smack_use())
return 0;
p = procfs_file_alloca(pid, "attr/current");
r = write_string_file(p, label, WRITE_STRING_FILE_DISABLE_BUFFER);
if (r < 0)
return r;
return r;
}
static int smack_fix_fd(int fd , const char *abspath, LabelFixFlags flags) {
char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
const char *label;
struct stat st;
int r;
/* The caller should have done the sanity checks. */
assert(abspath);
assert(path_is_absolute(abspath));
/* Path must be in /dev. */
if (!path_startswith(abspath, "/dev"))
return 0;
if (fstat(fd, &st) < 0)
return -errno;
/*
* Label directories and character devices "*".
* Label symlinks "_".
* Don't change anything else.
*/
if (S_ISDIR(st.st_mode))
label = SMACK_STAR_LABEL;
else if (S_ISLNK(st.st_mode))
label = SMACK_FLOOR_LABEL;
else if (S_ISCHR(st.st_mode))
label = SMACK_STAR_LABEL;
else
return 0;
xsprintf(procfs_path, "/proc/self/fd/%i", fd);
if (setxattr(procfs_path, "security.SMACK64", label, strlen(label), 0) < 0) {
_cleanup_free_ char *old_label = NULL;
r = -errno;
/* If the FS doesn't support labels, then exit without warning */
if (r == -EOPNOTSUPP)
return 0;
/* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
if (r == -EROFS && (flags & LABEL_IGNORE_EROFS))
return 0;
/* If the old label is identical to the new one, suppress any kind of error */
if (getxattr_malloc(procfs_path, "security.SMACK64", &old_label, false) >= 0 &&
streq(old_label, label))
return 0;
return log_debug_errno(r, "Unable to fix SMACK label of %s: %m", abspath);
}
return 0;
}
int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
_cleanup_free_ char *p = NULL;
_cleanup_close_ int fd = -1;
int r;
assert(path);
if (!mac_smack_use())
return 0;
fd = openat(dirfd, path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
if (fd < 0) {
if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
return 0;
return -errno;
}
if (!path_is_absolute(path)) {
r = fd_get_path(fd, &p);
if (r < 0)
return r;
path = p;
}
return smack_fix_fd(fd, path, flags);
}
int mac_smack_fix_container(const char *path, const char *inside_path, LabelFixFlags flags) {
_cleanup_free_ char *abspath = NULL;
_cleanup_close_ int fd = -1;
int r;
assert(path);
if (!mac_smack_use())
return 0;
r = path_make_absolute_cwd(path, &abspath);
if (r < 0)
return r;
fd = open(abspath, O_NOFOLLOW|O_CLOEXEC|O_PATH);
if (fd < 0) {
if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
return 0;
return -errno;
}
return smack_fix_fd(fd, inside_path, flags);
}
int mac_smack_copy(const char *dest, const char *src) {
int r;
_cleanup_free_ char *label = NULL;
assert(dest);
assert(src);
r = mac_smack_read(src, SMACK_ATTR_ACCESS, &label);
if (r < 0)
return r;
r = mac_smack_apply(dest, SMACK_ATTR_ACCESS, label);
if (r < 0)
return r;
return r;
}
#else
bool mac_smack_use(void) {
return false;
}
int mac_smack_read(const char *path, SmackAttr attr, char **label) {
return -EOPNOTSUPP;
}
int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
return -EOPNOTSUPP;
}
int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
return 0;
}
int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
return 0;
}
int mac_smack_apply_pid(pid_t pid, const char *label) {
return 0;
}
int mac_smack_fix_container(const char *path, const char *inside_path, LabelFixFlags flags) {
return 0;
}
int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
return 0;
}
int mac_smack_copy(const char *dest, const char *src) {
return 0;
}
#endif
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