forked from luck/tmp_suning_uos_patched
2eebf582c9
When an fanotify listener is closing it may cause a deadlock between the listener and the original task doing an fs operation. If the original task is waiting for a permissions response it will be holding the srcu lock. The listener cannot clean up and exit until after that srcu lock is syncronized. Thus deadlock. The fix introduced here is to stop accepting new permissions events when a listener is shutting down and to grant permission for all outstanding events. Thus the original task will eventually release the srcu lock and the listener can complete shutdown. Reported-by: Andreas Gruenbacher <agruen@suse.de> Cc: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Eric Paris <eparis@redhat.com>
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
#ifndef _LINUX_FANOTIFY_H
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#define _LINUX_FANOTIFY_H
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#include <linux/types.h>
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/* the following events that user-space can register for */
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#define FAN_ACCESS 0x00000001 /* File was accessed */
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#define FAN_MODIFY 0x00000002 /* File was modified */
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#define FAN_CLOSE_WRITE 0x00000008 /* Unwrittable file closed */
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#define FAN_CLOSE_NOWRITE 0x00000010 /* Writtable file closed */
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#define FAN_OPEN 0x00000020 /* File was opened */
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#define FAN_EVENT_ON_CHILD 0x08000000 /* interested in child events */
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/* FIXME currently Q's have no limit.... */
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#define FAN_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
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#define FAN_OPEN_PERM 0x00010000 /* File open in perm check */
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#define FAN_ACCESS_PERM 0x00020000 /* File accessed in perm check */
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/* helper events */
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#define FAN_CLOSE (FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE) /* close */
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/* flags used for fanotify_init() */
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#define FAN_CLOEXEC 0x00000001
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#define FAN_NONBLOCK 0x00000002
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#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK)
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/* flags used for fanotify_modify_mark() */
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#define FAN_MARK_ADD 0x00000001
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#define FAN_MARK_REMOVE 0x00000002
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#define FAN_MARK_DONT_FOLLOW 0x00000004
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#define FAN_MARK_ONLYDIR 0x00000008
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#define FAN_MARK_MOUNT 0x00000010
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#define FAN_MARK_IGNORED_MASK 0x00000020
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#define FAN_MARK_IGNORED_SURV_MODIFY 0x00000040
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#define FAN_MARK_FLUSH 0x00000080
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#define FAN_ALL_MARK_FLAGS (FAN_MARK_ADD |\
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FAN_MARK_REMOVE |\
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FAN_MARK_DONT_FOLLOW |\
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FAN_MARK_ONLYDIR |\
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FAN_MARK_MOUNT |\
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FAN_MARK_IGNORED_MASK |\
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FAN_MARK_IGNORED_SURV_MODIFY)
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/*
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* All of the events - we build the list by hand so that we can add flags in
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* the future and not break backward compatibility. Apps will get only the
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* events that they originally wanted. Be sure to add new events here!
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*/
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#define FAN_ALL_EVENTS (FAN_ACCESS |\
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FAN_MODIFY |\
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FAN_CLOSE |\
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FAN_OPEN)
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/*
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* All events which require a permission response from userspace
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*/
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#define FAN_ALL_PERM_EVENTS (FAN_OPEN_PERM |\
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FAN_ACCESS_PERM)
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#define FAN_ALL_OUTGOING_EVENTS (FAN_ALL_EVENTS |\
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FAN_ALL_PERM_EVENTS |\
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FAN_Q_OVERFLOW)
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#define FANOTIFY_METADATA_VERSION 1
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struct fanotify_event_metadata {
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__u32 event_len;
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__u32 vers;
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__s32 fd;
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__u64 mask;
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__s64 pid;
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} __attribute__ ((packed));
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struct fanotify_response {
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__s32 fd;
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__u32 response;
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} __attribute__ ((packed));
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/* Legit userspace responses to a _PERM event */
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#define FAN_ALLOW 0x01
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#define FAN_DENY 0x02
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/* Helper functions to deal with fanotify_event_metadata buffers */
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#define FAN_EVENT_METADATA_LEN (sizeof(struct fanotify_event_metadata))
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#define FAN_EVENT_NEXT(meta, len) ((len) -= (meta)->event_len, \
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(struct fanotify_event_metadata*)(((char *)(meta)) + \
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(meta)->event_len))
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#define FAN_EVENT_OK(meta, len) ((long)(len) >= (long)FAN_EVENT_METADATA_LEN && \
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(long)(meta)->event_len >= (long)FAN_EVENT_METADATA_LEN && \
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(long)(meta)->event_len <= (long)(len))
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#endif /* _LINUX_FANOTIFY_H */
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