commit 67d69e9d1a upstream.
AUDIT_TRIM is expected to be idempotent, but multiple executions resulted
in a refcount underflow and use-after-free.
git bisect fingered commit fb041bb7c0 ("locking/refcount: Consolidate
implementations of refcount_t") but this patch with its more thorough
checking that wasn't in the x86 assembly code merely exposed a previously
existing tree refcount imbalance in the case of tree trimming code that
was refactored with prune_one() to remove a tree introduced in
commit 8432c70062 ("audit: Simplify locking around untag_chunk()")
Move the put_tree() to cover only the prune_one() case.
Passes audit-testsuite and 3 passes of "auditctl -t" with at least one
directory watch.
Cc: Jan Kara <jack@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Seiji Nishikawa <snishika@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 8432c70062 ("audit: Simplify locking around untag_chunk()")
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
[PM: reformatted/cleaned-up the commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 950cc0d2be upstream.
The handle_inode_event() interface was added as (quoting comment):
"a simple variant of handle_event() for groups that only have inode
marks and don't have ignore mask".
In other words, all backends except fanotify. The inotify backend
also falls under this category, but because it required extra arguments
it was left out of the initial pass of backends conversion to the
simple interface.
This results in code duplication between the generic helper
fsnotify_handle_event() and the inotify_handle_event() callback
which also happen to be buggy code.
Generalize the handle_inode_event() arguments and add the check for
FS_EXCL_UNLINK flag to the generic helper, so inotify backend could
be converted to use the simple interface.
Link: https://lore.kernel.org/r/20201202120713.702387-2-amir73il@gmail.com
CC: stable@vger.kernel.org
Fixes: b9a1b97725 ("fsnotify: create method handle_inode_event() in fsnotify_operations")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull fsnotify updates from Jan Kara:
- fanotify fix for softlockups when there are many queued events
- performance improvement to reduce fsnotify overhead when not used
- Amir's implementation of fanotify events with names. With these you
can now efficiently monitor whole filesystem, eg to mirror changes to
another machine.
* tag 'fsnotify_for_v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (37 commits)
fanotify: compare fsid when merging name event
fsnotify: create method handle_inode_event() in fsnotify_operations
fanotify: report parent fid + child fid
fanotify: report parent fid + name + child fid
fanotify: add support for FAN_REPORT_NAME
fanotify: report events with parent dir fid to sb/mount/non-dir marks
fanotify: add basic support for FAN_REPORT_DIR_FID
fsnotify: remove check that source dentry is positive
fsnotify: send event with parent/name info to sb/mount/non-dir marks
audit: do not set FS_EVENT_ON_CHILD in audit marks mask
inotify: do not set FS_EVENT_ON_CHILD in non-dir mark mask
fsnotify: pass dir and inode arguments to fsnotify()
fsnotify: create helper fsnotify_inode()
fsnotify: send event to parent and child with single callback
inotify: report both events on parent and child with single callback
dnotify: report both events on parent and child with single callback
fanotify: no external fh buffer in fanotify_name_event
fanotify: use struct fanotify_info to parcel the variable size buffer
fsnotify: add object type "child" to object type iterator
fanotify: use FAN_EVENT_ON_CHILD as implicit flag on sb/mount/non-dir marks
...
The method handle_event() grew a lot of complexity due to the design of
fanotify and merging of ignore masks.
Most backends do not care about this complex functionality, so we can hide
this complexity from them.
Introduce a method handle_inode_event() that serves those backends and
passes a single inode mark and less arguments.
This change converts all backends except fanotify and inotify to use the
simplified handle_inode_event() method. In pricipal, inotify could have
also used the new method, but that would require passing more arguments
on the simple helper (data, data_type, cookie), so we leave it with the
handle_event() method.
Link: https://lore.kernel.org/r/20200722125849.17418-9-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The 'inode' argument to handle_event(), sometimes referred to as
'to_tell' is somewhat obsolete.
It is a remnant from the times when a group could only have an inode mark
associated with an event.
We now pass an iter_info array to the callback, with all marks associated
with an event.
Most backends ignore this argument, with two exceptions:
1. dnotify uses it for sanity check that event is on directory
2. fanotify uses it to report fid of directory on directory entry
modification events
Remove the 'inode' argument and add a 'dir' argument.
The callback function signature is deliberately changed, because
the meaning of the argument has changed and the arguments have
been documented.
The 'dir' argument is set to when 'file_name' is specified and it is
referring to the directory that the 'file_name' entry belongs to.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct audit_chunk {
...
struct node {
struct list_head list;
struct audit_tree *owner;
unsigned index; /* index; upper bit indicates 'will prune' */
} owners[];
};
Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.
So, replace the following form:
offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
with:
struct_size(chunk, owners, count)
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
note that conditions surrounding accesses to dname in audit_watch_handle_event()
and audit_mark_handle_event() guarantee that dname won't have been NULL.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since the context is derived from the task parameter handed to
__audit_free(), hand the context to audit_kill_trees() so it can be used
to associate with a syscall record. This requires adding the context
parameter to kill_rules() rather than using the current audit_context.
The callers of trim_marked() and evict_chunk() still have their context.
The EOE record was being issued prior to the pruning of the killed_tree
list.
Move the kill_trees call before the audit_log_exit call in
__audit_free() and __audit_syscall_exit() so that any pruned trees
CONFIG_CHANGE records are included with the associated syscall event by
the user library due to the EOE record flagging the end of the event.
See: https://github.com/linux-audit/audit-kernel/issues/50
See: https://github.com/linux-audit/audit-kernel/issues/59
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: fixed merge fuzz in kernel/audit_tree.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
There are some cases where we are making multiple audit_log_format()
calls in a row, for no apparent reason. Squash these down to a
single audit_log_format() call whenever possible.
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Variables pointing to fsnotify_mark are sometimes called 'entry' and
sometimes 'mark'. Use 'mark' in all places.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
[PM: minor merge fuzz due to updated patches previously in the series]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Audit tree code currently associates new fsnotify mark with each new
chunk. As chunk attached to an inode is replaced when new tag is added /
removed, we also need to remove old fsnotify mark and add a new one on
such occasion. This is cumbersome and makes locking rules somewhat
difficult to follow.
Fix these problems by allocating fsnotify mark independently of chunk
and keeping it all the time while there is some chunk attached to an
inode. Also add documentation about the locking rules so that things are
easier to follow.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
[PM: minor merge fuzz due to updated patches previously in the series]
Signed-off-by: Paul Moore <paul@paul-moore.com>
untag_chunk() has to be called with hash_lock, it drops it and
reacquires it when returning. The unlocking of hash_lock is thus hidden
from the callers of untag_chunk() with is rather error prone. Reorganize
the code so that untag_chunk() is called without hash_lock, only with
mark reference preventing the chunk from going away.
Since this requires some more code in the caller of untag_chunk() to
assure forward progress, factor out loop pruning tree from all chunks
into a common helper function.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
When deleting chunk from a tree, drop all unused nodes in a chunk
instead of just the one used by the tree. This gets rid of possibly
lingering unused nodes (created due to fallback path in untag_chunk())
and also removes some special cases and will allow us to simplify
locking in untag_chunk().
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
When removing chunk from a tree, we do shrink the chunk. This can fail
for various reasons (due to races, ENOMEM, etc.) and in some cases we
just bail from untag_chunk() relying on someone else to cleanup.
Although this currently works, later we will need to add new failure
situation which would break. Also this simplifies the code and will
allow us to make locking around untag_chunk() less awkward.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Allocate fsnotify mark independently instead of embedding it inside
chunk. This will allow us to just replace chunk attached to mark when
growing / shrinking chunk instead of replacing mark attached to inode
which is a more complex operation.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Provide a helper function audit_mark_put_chunk() for dropping mark's
reference (which has to happen only after RCU grace period expires).
Currently that happens only from a single place but in later patches we
introduce more callers.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
The audit_tree_group->mark_mutex is held all the time while we create
the fsnotify mark, add it to the inode, and insert chunk into the hash.
Hence mark cannot get detached during this time and so the check whether
the mark is attached in insert_hash() is pointless.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Chunk replacement code is very similar for the cases where we grow or
shrink chunk. Factor the code out into a common helper function.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Currently, the audit tree code does not make sure that when a chunk is
inserted into the hash table, it is fully initialized. So in theory a
user of RCU lookup could see uninitialized structure in the hash table
and crash. Add appropriate barriers between initialization of the
structure and its insertion into hash table.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Currently chunk hash key (which is in fact pointer to the inode) is
derived as chunk->mark.conn->obj. It is tricky to make this dereference
reliable for hash table lookups only under RCU as mark can get detached
from the connector and connector gets freed independently of the
running lookup. Thus there is a possible use after free / NULL ptr
dereference issue:
CPU1 CPU2
untag_chunk()
...
audit_tree_lookup()
list_for_each_entry_rcu(p, list, hash) {
list_del_rcu(&chunk->hash);
fsnotify_destroy_mark(entry);
fsnotify_put_mark(entry)
chunk_to_key(p)
if (!chunk->mark.connector)
...
hlist_del_init_rcu(&mark->obj_list);
if (hlist_empty(&conn->list)) {
inode = fsnotify_detach_connector_from_object(conn);
mark->connector = NULL;
...
frees connector from workqueue
chunk->mark.connector->obj
This race is probably impossible to hit in practice as the race window
on CPU1 is very narrow and CPU2 has a lot of code to execute. Still it's
better to have this fixed. Since the inode the chunk is attached to is
constant during chunk's lifetime it is easy to cache the key in the
chunk itself and thus avoid these issues.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Audit tree code is replacing marks attached to inodes in non-atomic way.
Thus fsnotify_find_mark() in tag_chunk() may find a mark that belongs to
a chunk that is no longer valid one and will soon be destroyed. Tags
added to such chunk will be simply lost.
Fix the problem by making sure old mark is marked as going away (through
fsnotify_detach_mark()) before dropping mark_mutex and thus in an atomic
way wrt tag_chunk(). Note that this does not fix the problem completely
as if tag_chunk() finds a mark that is going away, it fails with
-ENOENT. But at least the failure is not silent and currently there's no
way to search for another fsnotify mark attached to the inode. We'll fix
this problem in later patch.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
When an inode is tagged with a tree, tag_chunk() checks whether there is
audit_tree_group mark attached to the inode and adds one if not. However
nothing protects another tag_chunk() to add the mark between we've
checked and try to add the fsnotify mark thus resulting in an error from
fsnotify_add_mark() and consequently an ENOSPC error from tag_chunk().
Fix the problem by holding mark_mutex over the whole check-insert code
sequence.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Currently, audit_tree code uses mark->lock to protect against detaching
of mark from an inode. In most places it however also uses
mark->group->mark_mutex (as we need to atomically replace attached
marks) and this provides protection against mark detaching as well. So
just remove protection with mark->lock from audit tree code and replace
it with mark->group->mark_mutex protection in all the places. It
simplifies the code and gets rid of some ugly catches like calling
fsnotify_add_mark_locked() with mark->lock held (which cannot sleep only
because we hold a reference to another mark attached to the same inode).
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Pull fsnotify updates from Jan Kara:
"fsnotify cleanups from Amir and a small inotify improvement"
* tag 'fsnotify_for_v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
inotify: Add flag IN_MASK_CREATE for inotify_add_watch()
fanotify: factor out helpers to add/remove mark
fsnotify: add helper to get mask from connector
fsnotify: let connector point to an abstract object
fsnotify: pass connp and object type to fsnotify_add_mark()
fsnotify: use typedef fsnotify_connp_t for brevity
