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/****************************************************************************
* bfs *
* Copyright (C) 2019 Tavian Barnes <tavianator@tavianator.com> *
* *
* Permission to use, copy, modify, and/or distribute this software for any *
* purpose with or without fee is hereby granted. *
* *
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF *
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR *
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF *
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
****************************************************************************/
#include "fsade.h"
#include "bftw.h"
#include "dstring.h"
#include "util.h"
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#if BFS_CAN_CHECK_ACL
# include <sys/acl.h>
#endif
#if BFS_CAN_CHECK_CAPABILITIES
# include <sys/capability.h>
#endif
#if BFS_CAN_CHECK_ACL || BFS_CAN_CHECK_CAPABILITIES
/**
* Many of the APIs used here don't have *at() variants, but we can try to
* emulate something similar if /proc/self/fd is available.
*/
static const char *fake_at(const struct BFTW *ftwbuf) {
static bool proc_works = true;
static bool proc_checked = false;
char *path = NULL;
if (!proc_works || ftwbuf->at_fd == AT_FDCWD) {
goto fail;
}
path = dstrprintf("/proc/self/fd/%d/", ftwbuf->at_fd);
if (!path) {
goto fail;
}
if (!proc_checked) {
proc_checked = true;
if (xfaccessat(AT_FDCWD, path, F_OK) != 0) {
proc_works = false;
goto fail;
}
}
if (dstrcat(&path, ftwbuf->at_path) != 0) {
goto fail;
}
return path;
fail:
dstrfree(path);
return ftwbuf->path;
}
static void free_fake_at(const struct BFTW *ftwbuf, const char *path) {
if (path != ftwbuf->path) {
dstrfree((char *)path);
}
}
/**
* Check if an error was caused by the absence of support or data for a feature.
*/
static bool is_absence_error(int error) {
// If the OS doesn't support the feature, it's obviously not enabled for
// any files
if (error == ENOTSUP) {
return true;
}
// On Linux, ACLs and capabilities are implemented in terms of extended
// attributes, which report ENODATA/ENOATTR when missing
#ifdef ENODATA
if (error == ENODATA) {
return true;
}
#endif
#if defined(ENOATTR) && ENOATTR != ENODATA
if (error == ENOATTR) {
return true;
}
#endif
return false;
}
#endif // BFS_CAN_CHECK_ACL || BFS_CAN_CHECK_CAPABILITIES
#if BFS_CAN_CHECK_ACL
/** Check if any ACLs of the given type are non-trivial. */
static int bfs_check_acl_type(const char *path, acl_type_t type) {
acl_t acl = acl_get_file(path, type);
if (!acl) {
if (is_absence_error(errno)) {
return 0;
} else {
return -1;
}
}
int ret = 0;
acl_entry_t entry;
for (int status = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
status > 0;
status = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry)) {
#if defined(ACL_USER_OBJ) && defined(ACL_GROUP_OBJ) && defined(ACL_OTHER)
acl_tag_t tag;
if (acl_get_tag_type(entry, &tag) != 0) {
continue;
}
if (tag != ACL_USER_OBJ && tag != ACL_GROUP_OBJ && tag != ACL_OTHER) {
ret = 1;
break;
}
#else
ret = 1;
break;
#endif
}
acl_free(acl);
return ret;
}
int bfs_check_acl(const struct BFTW *ftwbuf) {
if (ftwbuf->typeflag == BFTW_LNK) {
return 0;
}
const char *path = fake_at(ftwbuf);
int error = 0;
int ret = bfs_check_acl_type(path, ACL_TYPE_ACCESS);
if (ret < 0) {
error = errno;
}
if (ret <= 0 && ftwbuf->typeflag == BFTW_DIR) {
ret = bfs_check_acl_type(path, ACL_TYPE_DEFAULT);
if (ret < 0) {
error = errno;
}
}
#ifdef ACL_TYPE_EXTENDED
if (ret <= 0) {
ret = bfs_check_acl_type(path, ACL_TYPE_EXTENDED);
if (ret < 0) {
error = errno;
}
}
#endif
free_fake_at(ftwbuf, path);
errno = error;
return ret;
}
#else // !BFS_CAN_CHECK_ACL
int bfs_check_acl(const struct BFTW *ftwbuf) {
errno = ENOTSUP;
return -1;
}
#endif
#if BFS_CAN_CHECK_CAPABILITIES
int bfs_check_capabilities(const struct BFTW *ftwbuf) {
if (ftwbuf->typeflag == BFTW_LNK) {
return 0;
}
int ret = -1, error;
const char *path = fake_at(ftwbuf);
cap_t caps = cap_get_file(path);
if (!caps) {
error = errno;
if (is_absence_error(error)) {
ret = 0;
}
goto out_path;
}
// TODO: Any better way to check for a non-empty capability set?
char *text = cap_to_text(caps, NULL);
if (!text) {
error = errno;
goto out_caps;
}
ret = text[0] ? 1 : 0;
error = errno;
cap_free(text);
out_caps:
cap_free(caps);
out_path:
free_fake_at(ftwbuf, path);
errno = error;
return ret;
}
#else // !BFS_CAN_CHECK_CAPABILITIES
int bfs_check_capabilities(const struct BFTW *ftwbuf) {
errno = ENOTSUP;
return -1;
}
#endif
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