linux.git/fs/notify, branch v5.15

fsnotify: fix sb_connectors leak

2021-09-10T16:46:48+00:00

Fix a leak in s_fsnotify_connectors counter in case of a race between
concurrent add of new fsnotify mark to an object.

The task that lost the race fails to drop the counter before freeing
the unused connector.

Following umount() hangs in fsnotify_sb_delete()/wait_var_event(),
because s_fsnotify_connectors never drops to zero.

Fixes: ec44610fe2b8 ("fsnotify: count all objects with attached connectors")
Reported-by: Murphy Zhou 
Link: https://lore.kernel.org/linux-fsdevel/20210907063338.ycaw6wvhzrfsfdlp@xzhoux.usersys.redhat.com/
Signed-off-by: Amir Goldstein 
Signed-off-by: Linus Torvalds

Merge tag 'fsnotify_for_v5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2021-08-30T17:04:31+00:00

Pull fsnotify updates from Jan Kara:
 "fsnotify speedups when notification actually isn't used and support
  for identifying processes which caused fanotify events through pidfd
  instead of normal pid"

* tag 'fsnotify_for_v5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: optimize the case of no marks of any type
  fsnotify: count all objects with attached connectors
  fsnotify: count s_fsnotify_inode_refs for attached connectors
  fsnotify: replace igrab() with ihold() on attach connector
  fanotify: add pidfd support to the fanotify API
  fanotify: introduce a generic info record copying helper
  fanotify: minor cosmetic adjustments to fid labels
  kernel/pid.c: implement additional checks upon pidfd_create() parameters
  kernel/pid.c: remove static qualifier from pidfd_create()

fsnotify: count all objects with attached connectors

2021-08-11T11:50:48+00:00

Rename s_fsnotify_inode_refs to s_fsnotify_connectors and count all
objects with attached connectors, not only inodes with attached
connectors.

This will be used to optimize fsnotify() calls on sb without any
type of marks.

Link: https://lore.kernel.org/r/20210810151220.285179-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Reviewed-by: Matthew Bobrowski 
Signed-off-by: Jan Kara

fsnotify: count s_fsnotify_inode_refs for attached connectors

2021-08-11T11:50:42+00:00

Instead of incrementing s_fsnotify_inode_refs when detaching connector
from inode, increment it earlier when attaching connector to inode.
Next patch is going to use s_fsnotify_inode_refs to count all objects
with attached connectors.

Link: https://lore.kernel.org/r/20210810151220.285179-3-amir73il@gmail.com
Reviewed-by: Matthew Bobrowski 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: replace igrab() with ihold() on attach connector

2021-08-11T11:50:28+00:00

We must have a reference on inode, so ihold is cheaper.

Link: https://lore.kernel.org/r/20210810151220.285179-2-amir73il@gmail.com
Reviewed-by: Matthew Bobrowski 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fanotify: add pidfd support to the fanotify API

2021-08-10T11:08:49+00:00

Introduce a new flag FAN_REPORT_PIDFD for fanotify_init(2) which
allows userspace applications to control whether a pidfd information
record containing a pidfd is to be returned alongside the generic
event metadata for each event.

If FAN_REPORT_PIDFD is enabled for a notification group, an additional
struct fanotify_event_info_pidfd object type will be supplied
alongside the generic struct fanotify_event_metadata for a single
event. This functionality is analogous to that of FAN_REPORT_FID in
terms of how the event structure is supplied to a userspace
application. Usage of FAN_REPORT_PIDFD with
FAN_REPORT_FID/FAN_REPORT_DFID_NAME is permitted, and in this case a
struct fanotify_event_info_pidfd object will likely follow any struct
fanotify_event_info_fid object.

Currently, the usage of the FAN_REPORT_TID flag is not permitted along
with FAN_REPORT_PIDFD as the pidfd API currently only supports the
creation of pidfds for thread-group leaders. Additionally, usage of
the FAN_REPORT_PIDFD flag is limited to privileged processes only
i.e. event listeners that are running with the CAP_SYS_ADMIN
capability. Attempting to supply the FAN_REPORT_TID initialization
flags with FAN_REPORT_PIDFD or creating a notification group without
CAP_SYS_ADMIN will result with -EINVAL being returned to the caller.

In the event of a pidfd creation error, there are two types of error
values that can be reported back to the listener. There is
FAN_NOPIDFD, which will be reported in cases where the process
responsible for generating the event has terminated prior to the event
listener being able to read the event. Then there is FAN_EPIDFD, which
will be reported when a more generic pidfd creation error has occurred
when fanotify calls pidfd_create().

Link: https://lore.kernel.org/r/5f9e09cff7ed62bfaa51c1369e0f7ea5f16a91aa.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski 
Signed-off-by: Jan Kara

fanotify: introduce a generic info record copying helper

2021-08-10T10:55:37+00:00

The copy_info_records_to_user() helper allows for the separation of
info record copying routines/conditionals from copy_event_to_user(),
which reduces the overall clutter within this function. This becomes
especially true as we start introducing additional info records in the
future i.e. struct fanotify_event_info_pidfd. On success, this helper
returns the total amount of bytes that have been copied into the user
supplied buffer and on error, a negative value is returned to the
caller.

The newly defined macro FANOTIFY_INFO_MODES can be used to obtain info
record types that have been enabled for a specific notification
group. This macro becomes useful in the subsequent patch when the
FAN_REPORT_PIDFD initialization flag is introduced.

Link: https://lore.kernel.org/r/8872947dfe12ce8ae6e9a7f2d49ea29bc8006af0.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

fanotify: minor cosmetic adjustments to fid labels

2021-08-10T10:53:09+00:00

With the idea to support additional info record types in the future
i.e. fanotify_event_info_pidfd, it's a good idea to rename some of the
labels assigned to some of the existing fid related functions,
parameters, etc which more accurately represent the intent behind
their usage.

For example, copy_info_to_user() was defined with a generic function
label, which arguably reads as being supportive of different info
record types, however the parameter list for this function is
explicitly tailored towards the creation and copying of the
fanotify_event_info_fid records. This same point applies to the macro
defined as FANOTIFY_INFO_HDR_LEN.

With fanotify_event_info_len(), we change the parameter label so that
the function implies that it can be extended to calculate the length
for additional info record types.

Link: https://lore.kernel.org/r/7c3ec33f3c718dac40764305d4d494d858f59c51.1628398044.git.repnop@google.com
Signed-off-by: Matthew Bobrowski 
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara

ucounts: add missing data type changes

2021-08-09T20:45:02+00:00

commit f9c82a4ea89c3 ("Increase size of ucounts to atomic_long_t")
changed the data type of ucounts/ucounts_max to long, but missed to
adjust a few other places. This is noticeable on big endian platforms
from user space because the /proc/sys/user/max_*_names files all
contain 0.

v4 - Made the min and max constants long so the sysctl values
     are actually settable on little endian machines.
     -- EWB

Fixes: f9c82a4ea89c ("Increase size of ucounts to atomic_long_t")
Signed-off-by: Sven Schnelle 
Tested-by: Nathan Chancellor 
Tested-by: Linux Kernel Functional Testing 
Acked-by: Alexey Gladkov 
v1: https://lkml.kernel.org/r/20210721115800.910778-1-svens@linux.ibm.com
v2: https://lkml.kernel.org/r/20210721125233.1041429-1-svens@linux.ibm.com
v3: https://lkml.kernel.org/r/20210730062854.3601635-1-svens@linux.ibm.com
Link: https://lkml.kernel.org/r/8735rijqlv.fsf_-_@disp2133
Signed-off-by: Eric W. Biederman

fanotify: fix copy_event_to_user() fid error clean up

2021-06-14T10:16:37+00:00

Ensure that clean up is performed on the allocated file descriptor and
struct file object in the event that an error is encountered while copying
fid info objects. Currently, we return directly to the caller when an error
is experienced in the fid info copying helper, which isn't ideal given that
the listener process could be left with a dangling file descriptor in their
fdtable.

Fixes: 5e469c830fdb ("fanotify: copy event fid info to user")
Fixes: 44d705b0370b ("fanotify: report name info for FAN_DIR_MODIFY event")
Link: https://lore.kernel.org/linux-fsdevel/YMKv1U7tNPK955ho@google.com/T/#m15361cd6399dad4396aad650de25dbf6b312288e
Link: https://lore.kernel.org/r/1ef8ae9100101eb1a91763c516c2e9a3a3b112bd.1623376346.git.repnop@google.com
Signed-off-by: Matthew Bobrowski 
Signed-off-by: Jan Kara