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b4b2ff4f61
With FAN_DENY response, user trying to perform the filesystem operation gets an error with errno set to EPERM. It is useful for hierarchical storage management (HSM) service to be able to deny access for reasons more diverse than EPERM, for example EAGAIN, if HSM could retry the operation later. Allow fanotify groups with priority FAN_CLASSS_PRE_CONTENT to responsd to permission events with the response value FAN_DENY_ERRNO(errno), instead of FAN_DENY to return a custom error. Limit custom error values to errors expected on read(2)/write(2) and open(2) of regular files. This list could be extended in the future. Userspace can test for legitimate values of FAN_DENY_ERRNO(errno) by writing a response to an fanotify group fd with a value of FAN_NOFD in the fd field of the response. The change in fanotify_response is backward compatible, because errno is written in the high 8 bits of the 32bit response field and old kernels reject respose value with high bits set. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/1e5fb6af84b69ca96b5c849fa5f10bdf4d1dc414.1731684329.git.josef@toxicpanda.com
148 lines
5.0 KiB
C
148 lines
5.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_FANOTIFY_H
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#define _LINUX_FANOTIFY_H
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#include <linux/sysctl.h>
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#include <uapi/linux/fanotify.h>
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#define FAN_GROUP_FLAG(group, flag) \
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((group)->fanotify_data.flags & (flag))
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/*
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* Flags allowed to be passed from/to userspace.
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*
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* We intentionally do not add new bits to the old FAN_ALL_* constants, because
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* they are uapi exposed constants. If there are programs out there using
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* these constant, the programs may break if re-compiled with new uapi headers
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* and then run on an old kernel.
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*/
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/* Group classes where permission events are allowed */
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#define FANOTIFY_PERM_CLASSES (FAN_CLASS_CONTENT | \
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FAN_CLASS_PRE_CONTENT)
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#define FANOTIFY_CLASS_BITS (FAN_CLASS_NOTIF | FANOTIFY_PERM_CLASSES)
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#define FANOTIFY_FID_BITS (FAN_REPORT_DFID_NAME_TARGET)
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#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS | FAN_REPORT_PIDFD)
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/*
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* fanotify_init() flags that require CAP_SYS_ADMIN.
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* We do not allow unprivileged groups to request permission events.
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* We do not allow unprivileged groups to get other process pid in events.
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* We do not allow unprivileged groups to use unlimited resources.
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*/
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#define FANOTIFY_ADMIN_INIT_FLAGS (FANOTIFY_PERM_CLASSES | \
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FAN_REPORT_TID | \
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FAN_REPORT_PIDFD | \
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FAN_REPORT_FD_ERROR | \
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FAN_UNLIMITED_QUEUE | \
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FAN_UNLIMITED_MARKS)
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/*
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* fanotify_init() flags that are allowed for user without CAP_SYS_ADMIN.
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* FAN_CLASS_NOTIF is the only class we allow for unprivileged group.
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* We do not allow unprivileged groups to get file descriptors in events,
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* so one of the flags for reporting file handles is required.
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*/
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#define FANOTIFY_USER_INIT_FLAGS (FAN_CLASS_NOTIF | \
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FANOTIFY_FID_BITS | \
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FAN_CLOEXEC | FAN_NONBLOCK)
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#define FANOTIFY_INIT_FLAGS (FANOTIFY_ADMIN_INIT_FLAGS | \
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FANOTIFY_USER_INIT_FLAGS)
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/* Internal group flags */
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#define FANOTIFY_UNPRIV 0x80000000
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#define FANOTIFY_INTERNAL_GROUP_FLAGS (FANOTIFY_UNPRIV)
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#define FANOTIFY_MARK_TYPE_BITS (FAN_MARK_INODE | FAN_MARK_MOUNT | \
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FAN_MARK_FILESYSTEM)
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#define FANOTIFY_MARK_CMD_BITS (FAN_MARK_ADD | FAN_MARK_REMOVE | \
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FAN_MARK_FLUSH)
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#define FANOTIFY_MARK_IGNORE_BITS (FAN_MARK_IGNORED_MASK | \
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FAN_MARK_IGNORE)
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#define FANOTIFY_MARK_FLAGS (FANOTIFY_MARK_TYPE_BITS | \
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FANOTIFY_MARK_CMD_BITS | \
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FANOTIFY_MARK_IGNORE_BITS | \
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FAN_MARK_DONT_FOLLOW | \
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FAN_MARK_ONLYDIR | \
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FAN_MARK_IGNORED_SURV_MODIFY | \
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FAN_MARK_EVICTABLE)
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/*
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* Events that can be reported with data type FSNOTIFY_EVENT_PATH.
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* Note that FAN_MODIFY can also be reported with data type
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* FSNOTIFY_EVENT_INODE.
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*/
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#define FANOTIFY_PATH_EVENTS (FAN_ACCESS | FAN_MODIFY | \
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FAN_CLOSE | FAN_OPEN | FAN_OPEN_EXEC)
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/*
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* Directory entry modification events - reported only to directory
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* where entry is modified and not to a watching parent.
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*/
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#define FANOTIFY_DIRENT_EVENTS (FAN_MOVE | FAN_CREATE | FAN_DELETE | \
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FAN_RENAME)
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/* Content events can be used to inspect file content */
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#define FANOTIFY_CONTENT_PERM_EVENTS (FAN_OPEN_PERM | FAN_OPEN_EXEC_PERM | \
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FAN_ACCESS_PERM)
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/* Pre-content events can be used to fill file content */
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#define FANOTIFY_PRE_CONTENT_EVENTS (FAN_PRE_ACCESS)
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/* Events that require a permission response from user */
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#define FANOTIFY_PERM_EVENTS (FANOTIFY_CONTENT_PERM_EVENTS | \
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FANOTIFY_PRE_CONTENT_EVENTS)
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/* Events that can be reported with event->fd */
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#define FANOTIFY_FD_EVENTS (FANOTIFY_PATH_EVENTS | FANOTIFY_PERM_EVENTS)
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/* Events that can only be reported with data type FSNOTIFY_EVENT_INODE */
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#define FANOTIFY_INODE_EVENTS (FANOTIFY_DIRENT_EVENTS | \
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FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
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/* Events that can only be reported with data type FSNOTIFY_EVENT_ERROR */
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#define FANOTIFY_ERROR_EVENTS (FAN_FS_ERROR)
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/* Events that user can request to be notified on */
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#define FANOTIFY_EVENTS (FANOTIFY_PATH_EVENTS | \
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FANOTIFY_INODE_EVENTS | \
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FANOTIFY_ERROR_EVENTS)
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/* Extra flags that may be reported with event or control handling of events */
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#define FANOTIFY_EVENT_FLAGS (FAN_EVENT_ON_CHILD | FAN_ONDIR)
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/* Events that may be reported to user */
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#define FANOTIFY_OUTGOING_EVENTS (FANOTIFY_EVENTS | \
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FANOTIFY_PERM_EVENTS | \
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FAN_Q_OVERFLOW | FAN_ONDIR)
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/* Events and flags relevant only for directories */
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#define FANOTIFY_DIRONLY_EVENT_BITS (FANOTIFY_DIRENT_EVENTS | \
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FAN_EVENT_ON_CHILD | FAN_ONDIR)
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#define ALL_FANOTIFY_EVENT_BITS (FANOTIFY_OUTGOING_EVENTS | \
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FANOTIFY_EVENT_FLAGS)
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/* These masks check for invalid bits in permission responses. */
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#define FANOTIFY_RESPONSE_ACCESS (FAN_ALLOW | FAN_DENY)
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#define FANOTIFY_RESPONSE_FLAGS (FAN_AUDIT | FAN_INFO)
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#define FANOTIFY_RESPONSE_VALID_MASK \
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(FANOTIFY_RESPONSE_ACCESS | FANOTIFY_RESPONSE_FLAGS | \
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(FAN_ERRNO_MASK << FAN_ERRNO_SHIFT))
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/* Do not use these old uapi constants internally */
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#undef FAN_ALL_CLASS_BITS
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#undef FAN_ALL_INIT_FLAGS
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#undef FAN_ALL_MARK_FLAGS
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#undef FAN_ALL_EVENTS
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#undef FAN_ALL_PERM_EVENTS
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#undef FAN_ALL_OUTGOING_EVENTS
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#endif /* _LINUX_FANOTIFY_H */
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