__io_fixed_fd_install() returns 0 on success for non-alloc mode
(specific slot), not the slot index. io_pipe_fixed() used this return
value directly as the slot index in fds[], which can cause the reported
values returned via copy_to_user() to be incorrect, or the error path
operating on the incorrect direct descriptor.
Fix by computing the actual 0-based slot index (slot - 1) for specific
slot mode, while preserving the existing behavior for auto-alloc mode
where __io_fixed_fd_install() already returns the allocated index.
Cc: stable@vger.kernel.org
Fixes: 53db8a71ec ("io_uring: add support for IORING_OP_PIPE")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'io_uring-bpf-restrictions.4-20260206' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux
Pull io_uring bpf filters from Jens Axboe:
"This adds support for both cBPF filters for io_uring, as well as task
inherited restrictions and filters.
seccomp and io_uring don't play along nicely, as most of the
interesting data to filter on resides somewhat out-of-band, in the
submission queue ring.
As a result, things like containers and systemd that apply seccomp
filters, can't filter io_uring operations.
That leaves them with just one choice if filtering is critical -
filter the actual io_uring_setup(2) system call to simply disallow
io_uring. That's rather unfortunate, and has limited us because of it.
io_uring already has some filtering support. It requires the ring to
be setup in a disabled state, and then a filter set can be applied.
This filter set is completely bi-modal - an opcode is either enabled
or it's not. Once a filter set is registered, the ring can be enabled.
This is very restrictive, and it's not useful at all to systemd or
containers which really want both broader and more specific control.
This first adds support for cBPF filters for opcodes, which enables
tighter control over what exactly a specific opcode may do. As
examples, specific support is added for IORING_OP_OPENAT/OPENAT2,
allowing filtering on resolve flags. And another example is added for
IORING_OP_SOCKET, allowing filtering on domain/type/protocol. These
are both common use cases. cBPF was chosen rather than eBPF, because
the latter is often restricted in containers as well.
These filters are run post the init phase of the request, which allows
filters to even dip into data that is being passed in struct in user
memory, as the init side of requests make that data stable by bringing
it into the kernel. This allows filtering without needing to copy this
data twice, or have filters etc know about the exact layout of the
user data. The filters get the already copied and sanitized data
passed.
On top of that support is added for per-task filters, meaning that any
ring created with a task that has a per-task filter will get those
filters applied when it's created. These filters are inherited across
fork as well. Once a filter has been registered, any further added
filters may only further restrict what operations are permitted.
Filters cannot change the return value of an operation, they can only
permit or deny it based on the contents"
* tag 'io_uring-bpf-restrictions.4-20260206' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
io_uring: allow registration of per-task restrictions
io_uring: add task fork hook
io_uring/bpf_filter: add ref counts to struct io_bpf_filter
io_uring/bpf_filter: cache lookup table in ctx->bpf_filters
io_uring/bpf_filter: allow filtering on contents of struct open_how
io_uring/net: allow filtering on IORING_OP_SOCKET data
io_uring: add support for BPF filtering for opcode restrictions
This adds custom filtering for IORING_OP_OPENAT and IORING_OP_OPENAT2,
where the open_how flags, mode, and resolve can be checked by filters.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
"filp" thing never made sense; seeing that there are exactly 4 callers
in the entire tree (and it's neither exported nor even declared in
linux/*/*.h), there's no point keeping that ugliness.
FWIW, the 'filp' thing did originate in OSD&I; for some reason Tanenbaum
decided to call the object representing an opened file 'struct filp',
the last letter standing for 'position'. In all Unices, Linux included,
the corresponding object had always been 'struct file'...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are two filename-related problems in io_uring and its
interplay with audit.
Filenames are imported when request is submitted and used when
it is processed. Unfortunately, the latter may very well
happen in a different thread. In that case the reference to
filename is put into the wrong audit_context - that of submitting
thread, not the processing one. Audit logics is called by
the latter, and it really wants to be able to find the names
in audit_context current (== processing) thread.
Another related problem is the headache with refcounts -
normally all references to given struct filename are visible
only to one thread (the one that uses that struct filename).
io_uring violates that - an extra reference is stashed in
audit_context of submitter. It gets dropped when submitter
returns to userland, which can happen simultaneously with
processing thread deciding to drop the reference it got.
We paper over that by making refcount atomic, but that means
pointless headache for everyone.
Solution: the notion of partially imported filenames. Namely,
already copied from userland, but *not* exposed to audit yet.
io_uring can create that in submitter thread, and complete the
import (obtaining the usual reference to struct filename) in
processing thread.
Object: struct delayed_filename.
Primitives for working with it:
delayed_getname(&delayed_filename, user_string) - copies the name from
userland, returning 0 and stashing the address of (still incomplete)
struct filename in delayed_filename on success and returning -E... on
error.
delayed_getname_uflags(&delayed_filename, user_string, atflags) -
similar, in the same relation to delayed_getname() as getname_uflags()
is to getname()
complete_getname(&delayed_filename) - completes the import of filename
stashed in delayed_filename and returns struct filename to caller,
emptying delayed_filename.
CLASS(filename_complete_delayed, name)(&delayed_filename) - variant of
CLASS(filename) with complete_getname() for constructor.
dismiss_delayed_filename(&delayed_filename) - destructor; drops whatever
might be stashed in delayed_filename, emptying it.
putname_to_delayed(&delayed_filename, name) - if name is shared, stashes
its copy into delayed_filename and drops the reference to name, otherwise
stashes the name itself in there.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
__io_openat_prep() allocates a struct filename using getname(). However,
for the condition of the file being installed in the fixed file table as
well as having O_CLOEXEC flag set, the function returns early. At that
point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
the memory for the newly allocated struct filename is not cleaned up,
causing a memory leak.
Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
successful getname() call, so that when the request is torn down, the
filename will be cleaned up, along with other resources needing cleanup.
Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
Fixes: b9445598d8 ("io_uring: openat directly into fixed fd table")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring/io_uring.h doesn't use anything declared in
io_uring/filetable.h, so drop the unnecessary #include. Add filetable.h
includes in .c files previously relying on the transitive include from
io_uring.h.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than have the caller set the FMODE_NOWAIT flags for both output
files, move it to create_pipe_files() where other f_mode flags are set
anyway with stream_open(). With that, both __do_pipe_flags() and
io_pipe() can remove the manual setting of the NOWAIT flags.
No intended functional changes, just a code cleanup.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/1f0473f8-69f3-4eb1-aa77-3334c6a71d24@kernel.dk
Signed-off-by: Christian Brauner <brauner@kernel.org>
IOU_COMPLETE is more descriptive, in that it explicitly says that the
return value means "please post a completion for this request". This
patch completes the transition from IOU_OK to IOU_COMPLETE, replacing
existing IOU_OK users.
This is a purely mechanical change.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This works just like pipe2(2), except it also supports fixed file
descriptors. Used in a similar fashion as for other fd instantiating
opcodes (like accept, socket, open, etc), where sqe->file_slot is set
appropriately if two direct descriptors are desired rather than a set
of normal file descriptors.
sqe->addr must be set to a pointer to an array of 2 integers, which
is where the fixed/normal file descriptors are copied to.
sqe->pipe_flags contains flags, same as what is allowed for pipe2(2).
Future expansion of per-op private flags can go in sqe->ioprio,
like we do for other opcodes that take both a "syscall" flag set and
an io_uring opcode specific flag set.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need to correct some aspects of the IORING_OP_FIXED_FD_INSTALL
command to take into account the security implications of making an
io_uring-private file descriptor generally accessible to a userspace
task.
The first change in this patch is to enable auditing of the FD_INSTALL
operation as installing a file descriptor into a task's file descriptor
table is a security relevant operation and something that admins/users
may want to audit.
The second change is to disable the io_uring credential override
functionality, also known as io_uring "personalities", in the
FD_INSTALL command. The credential override in FD_INSTALL is
particularly problematic as it affects the credentials used in the
security_file_receive() LSM hook. If a task were to request a
credential override via REQ_F_CREDS on a FD_INSTALL operation, the LSM
would incorrectly check to see if the overridden credentials of the
io_uring were able to "receive" the file as opposed to the task's
credentials. After discussions upstream, it's difficult to imagine a
use case where we would want to allow a credential override on a
FD_INSTALL operation so we are simply going to block REQ_F_CREDS on
IORING_OP_FIXED_FD_INSTALL operations.
Fixes: dc18b89ab1 ("io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL")
Signed-off-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20240123215501.289566-2-paul@paul-moore.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring can currently open/close regular files or fixed/direct
descriptors. Or you can instantiate a fixed descriptor from a regular
one, and then close the regular descriptor. But you currently can't turn
a purely fixed/direct descriptor into a regular file descriptor.
IORING_OP_FIXED_FD_INSTALL adds support for installing a direct
descriptor into the normal file table, just like receiving a file
descriptor or opening a new file would do. This is all nicely abstracted
into receive_fd(), and hence adding support for this is truly trivial.
Since direct descriptors are only usable within io_uring itself, it can
be useful to turn them into real file descriptors if they ever need to
be accessed via normal syscalls. This can either be a transitory thing,
or just a permanent transition for a given direct descriptor.
By default, new fds are installed with O_CLOEXEC set. The application
can disable O_CLOEXEC by setting IORING_FIXED_FD_NO_CLOEXEC in the
sqe->install_fd_flags member.
Suggested-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Only io_uring uses __close_fd_get_file(). All it does is hide
current->files but io_uring accesses files_struct directly right now
anyway so it's a bit pointless. Just rename pick_file() to
file_close_fd_locked() and let io_uring use it. Add a lockdep assert in
there that we expect the caller to hold file_lock while we're at it.
Link: https://lore.kernel.org/r/20231130-vfs-files-fixes-v1-2-e73ca6f4ea83@kernel.org
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
While valid we don't need to open-code rcu dereferences if we're
acquiring file_lock anyway.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20231010030615.GO800259@ZenIV
Signed-off-by: Christian Brauner <brauner@kernel.org>
O_TMPFILE is actually __O_TMPFILE|O_DIRECTORY. This means that the old
check for whether RESOLVE_CACHED can be used would incorrectly think
that O_DIRECTORY could not be used with RESOLVE_CACHED.
Cc: stable@vger.kernel.org # v5.12+
Fixes: 3a81fd0204 ("io_uring: enable LOOKUP_CACHED path resolution for filename lookups")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/r/20230807-resolve_cached-o_tmpfile-v3-1-e49323e1ef6f@cyphar.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
fsnotify_open() hook is called only from high level system calls
context and not called for the very many helpers to open files.
This may makes sense for many of the special file open cases, but it is
inconsistent with fsnotify_close() hook that is called for every last
fput() of on a file object with FMODE_OPENED.
As a result, it is possible to observe ACCESS, MODIFY and CLOSE events
without ever observing an OPEN event.
Fix this inconsistency by replacing all the fsnotify_open() hooks with
a single hook inside do_dentry_open().
If there are special cases that would like to opt-out of the possible
overhead of fsnotify() call in fsnotify_open(), they would probably also
want to avoid the overhead of fsnotify() call in the rest of the fsnotify
hooks, so they should be opening that file with the __FMODE_NONOTIFY flag.
However, in the majority of those cases, the s_fsnotify_connectors
optimization in fsnotify_parent() would be sufficient to avoid the
overhead of fsnotify() call anyway.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230611122429.1499617-1-amir73il@gmail.com>
Put it with the filetable code, which is where it belongs. While doing
so, have the helpers take a ctx rather than an io_kiocb. It doesn't make
sense to use a request, as it's not an operation on the request itself.
It applies to the ring itself.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
