Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Pull execve updates from Eric Biederman:
"This set of changes ultimately fixes the interaction of posix file
lock and exec. Fundamentally most of the change is just moving where
unshare_files is called during exec, and tweaking the users of
files_struct so that the count of files_struct is not unnecessarily
played with.
Along the way fcheck and related helpers were renamed to more
accurately reflect what they do.
There were also many other small changes that fell out, as this is the
first time in a long time much of this code has been touched.
Benchmarks haven't turned up any practical issues but Al Viro has
observed a possibility for a lot of pounding on task_lock. So I have
some changes in progress to convert put_files_struct to always rcu
free files_struct. That wasn't ready for the merge window so that will
have to wait until next time"
* 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
exec: Move io_uring_task_cancel after the point of no return
coredump: Document coredump code exclusively used by cell spufs
file: Remove get_files_struct
file: Rename __close_fd_get_file close_fd_get_file
file: Replace ksys_close with close_fd
file: Rename __close_fd to close_fd and remove the files parameter
file: Merge __alloc_fd into alloc_fd
file: In f_dupfd read RLIMIT_NOFILE once.
file: Merge __fd_install into fd_install
proc/fd: In fdinfo seq_show don't use get_files_struct
bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu
file: Implement task_lookup_next_fd_rcu
kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
proc/fd: In tid_fd_mode use task_lookup_fd_rcu
file: Implement task_lookup_fd_rcu
file: Rename fcheck lookup_fd_rcu
file: Replace fcheck_files with files_lookup_fd_rcu
file: Factor files_lookup_fd_locked out of fcheck_files
file: Rename __fcheck_files to files_lookup_fd_raw
...
The function close_fd_get_file is explicitly a variant of
__close_fd[1]. Now that __close_fd has been renamed close_fd, rename
close_fd_get_file to be consistent with close_fd.
When __alloc_fd, __close_fd and __fd_install were introduced the
double underscore indicated that the function took a struct
files_struct parameter. The function __close_fd_get_file never has so
the naming has always been inconsistent. This just cleans things up
so there are not any lingering mentions or references __close_fd left
in the code.
[1] 80cd795630 ("binder: fix use-after-free due to ksys_close() during fdget()")
Link: https://lkml.kernel.org/r/20201120231441.29911-23-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Add a per-transaction flag to indicate that the buffer
must be cleared when the transaction is complete to
prevent copies of sensitive data from being preserved
in memory.
Signed-off-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20201120233743.3617529-1-tkjos@google.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since the original trace_binder_transaction_received cannot
precisely present the real finished time of transaction, adding a
trace_binder_txn_latency_free at the point of free transaction
may be more close to it.
Signed-off-by: Frankie.Chang <Frankie.Chang@mediatek.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/1605063764-12930-3-git-send-email-Frankie.Chang@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Moving all structs to header file makes module more
extendable, and makes all these structs to be defined
in the same file.
Signed-off-by: Frankie.Chang <Frankie.Chang@mediatek.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/1605063764-12930-2-git-send-email-Frankie.Chang@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Depending on the context, the error return value
here (extra_buffers_size < added_size) should be
negative.
Acked-by: Martijn Coenen <maco@android.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Link: https://lore.kernel.org/r/20201026110314.135481-1-zhangqilong3@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A previous commit changed the notification mode from true/false to an
int, allowing notify-no, notify-yes, or signal-notify. This was
backwards compatible in the sense that any existing true/false user
would translate to either 0 (on notification sent) or 1, the latter
which mapped to TWA_RESUME. TWA_SIGNAL was assigned a value of 2.
Clean this up properly, and define a proper enum for the notification
mode. Now we have:
- TWA_NONE. This is 0, same as before the original change, meaning no
notification requested.
- TWA_RESUME. This is 1, same as before the original change, meaning
that we use TIF_NOTIFY_RESUME.
- TWA_SIGNAL. This uses TIF_SIGPENDING/JOBCTL_TASK_WORK for the
notification.
Clean up all the callers, switching their 0/1/false/true to using the
appropriate TWA_* mode for notifications.
Fixes: e91b481623 ("task_work: teach task_work_add() to do signal_wake_up()")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When releasing a thread todo list when tearing down
a binder_proc, the following race was possible which
could result in a use-after-free:
1. Thread 1: enter binder_release_work from binder_thread_release
2. Thread 2: binder_update_ref_for_handle() -> binder_dec_node_ilocked()
3. Thread 2: dec nodeA --> 0 (will free node)
4. Thread 1: ACQ inner_proc_lock
5. Thread 2: block on inner_proc_lock
6. Thread 1: dequeue work (BINDER_WORK_NODE, part of nodeA)
7. Thread 1: REL inner_proc_lock
8. Thread 2: ACQ inner_proc_lock
9. Thread 2: todo list cleanup, but work was already dequeued
10. Thread 2: free node
11. Thread 2: REL inner_proc_lock
12. Thread 1: deref w->type (UAF)
The problem was that for a BINDER_WORK_NODE, the binder_work element
must not be accessed after releasing the inner_proc_lock while
processing the todo list elements since another thread might be
handling a deref on the node containing the binder_work element
leading to the node being freed.
Signed-off-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20201009232455.4054810-1-tkjos@google.com
Cc: <stable@vger.kernel.org> # 4.14, 4.19, 5.4, 5.8
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The pointer n is being initialized with a value that is
never read and it is being updated later with a new value. The
initialization is redundant and can be removed.
Acked-by: Todd Kjos <tkjos@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20200910151221.751464-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The most common cause of the binder transaction buffer filling up is a
client rapidly firing oneway transactions into a process, before it has
a chance to handle them. Yet the root cause of this is often hard to
debug, because either the system or the app will stop, and by that time
binder debug information we dump in bugreports is no longer relevant.
This change warns as soon as a process dips below 80% of its oneway
space (less than 100kB available in the configuration), when any one
process is responsible for either more than 50 transactions, or more
than 50% of the oneway space.
Signed-off-by: Martijn Coenen <maco@android.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20200821122544.1277051-1-maco@android.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The sparse tool complains as follows:
drivers/android/binderfs.c:66:32: warning:
symbol 'binderfs_fs_parameters' was not declared. Should it be static?
This variable is not used outside of binderfs.c, so this commit
marks it static.
Fixes: 095cf502b3 ("binderfs: port to new mount api")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200818112245.43891-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
While binder transactions with the same binder_proc as sender and recipient
are forbidden, transactions with the same task_struct as sender and
recipient are possible (even though currently there is a weird check in
binder_transaction() that rejects them in the target==0 case).
Therefore, task_struct identities can't be used to distinguish whether
the caller is running in the context of the sender or the recipient.
Since I see no easy way to make this WARN_ON() useful and correct, let's
just remove it.
Fixes: 44d8047f1d ("binder: use standard functions to allocate fds")
Reported-by: syzbot+e113a0b970b7b3f394ba@syzkaller.appspotmail.com
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20200806165359.2381483-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
C source files should have `//` as SPDX comment and not `/**/`. Fix this
by running checkpatch on the file.
Signed-off-by: Mrinal Pandey <mrinalmni@gmail.com>
Link: https://lore.kernel.org/r/20200724131449.zvjutbemg3vqhrzh@mrinalpandey
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Binder is designed such that a binder_proc never has references to
itself. If this rule is violated, memory corruption can occur when a
process sends a transaction to itself; see e.g.
<https://syzkaller.appspot.com/bug?extid=09e05aba06723a94d43d>.
There is a remaining edgecase through which such a transaction-to-self
can still occur from the context of a task with BINDER_SET_CONTEXT_MGR
access:
- task A opens /dev/binder twice, creating binder_proc instances P1
and P2
- P1 becomes context manager
- P2 calls ACQUIRE on the magic handle 0, allocating index 0 in its
handle table
- P1 dies (by closing the /dev/binder fd and waiting a bit)
- P2 becomes context manager
- P2 calls ACQUIRE on the magic handle 0, allocating index 1 in its
handle table
[this triggers a warning: "binder: 1974:1974 tried to acquire
reference to desc 0, got 1 instead"]
- task B opens /dev/binder once, creating binder_proc instance P3
- P3 calls P2 (via magic handle 0) with (void*)1 as argument (two-way
transaction)
- P2 receives the handle and uses it to call P3 (two-way transaction)
- P3 calls P2 (via magic handle 0) (two-way transaction)
- P2 calls P2 (via handle 1) (two-way transaction)
And then, if P2 does *NOT* accept the incoming transaction work, but
instead closes the binder fd, we get a crash.
Solve it by preventing the context manager from using ACQUIRE on ref 0.
There shouldn't be any legitimate reason for the context manager to do
that.
Additionally, print a warning if someone manages to find another way to
trigger a transaction-to-self bug in the future.
Cc: stable@vger.kernel.org
Fixes: 457b9a6f09 ("Staging: android: add binder driver")
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Martijn Coenen <maco@android.com>
Link: https://lore.kernel.org/r/20200727120424.1627555-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
syzbot is reporting that mmput() from shrinker function has a risk of
deadlock [1], for delayed_uprobe_add() from update_ref_ctr() calls
kzalloc(GFP_KERNEL) with delayed_uprobe_lock held, and
uprobe_clear_state() from __mmput() also holds delayed_uprobe_lock.
Commit a1b2289cef ("android: binder: drop lru lock in isolate
callback") replaced mmput() with mmput_async() in order to avoid sleeping
with spinlock held. But this patch replaces mmput() with mmput_async() in
order not to start __mmput() from shrinker context.
[1] https://syzkaller.appspot.com/bug?id=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45
Reported-by: syzbot <syzbot+1068f09c44d151250c33@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Acked-by: Todd Kjos <tkjos@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/4ba9adb2-43f5-2de0-22de-f6075c1fab50@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The binder driver makes the assumption proc->context pointer is invariant after
initialization (as documented in the kerneldoc header for struct proc).
However, in commit f0fe2c0f05 ("binder: prevent UAF for binderfs devices II")
proc->context is set to NULL during binder_deferred_release().
Another proc was in the middle of setting up a transaction to the dying
process and crashed on a NULL pointer deref on "context" which is a local
set to &proc->context:
new_ref->data.desc = (node == context->binder_context_mgr_node) ? 0 : 1;
Here's the stack:
[ 5237.855435] Call trace:
[ 5237.855441] binder_get_ref_for_node_olocked+0x100/0x2ec
[ 5237.855446] binder_inc_ref_for_node+0x140/0x280
[ 5237.855451] binder_translate_binder+0x1d0/0x388
[ 5237.855456] binder_transaction+0x2228/0x3730
[ 5237.855461] binder_thread_write+0x640/0x25bc
[ 5237.855466] binder_ioctl_write_read+0xb0/0x464
[ 5237.855471] binder_ioctl+0x30c/0x96c
[ 5237.855477] do_vfs_ioctl+0x3e0/0x700
[ 5237.855482] __arm64_sys_ioctl+0x78/0xa4
[ 5237.855488] el0_svc_common+0xb4/0x194
[ 5237.855493] el0_svc_handler+0x74/0x98
[ 5237.855497] el0_svc+0x8/0xc
The fix is to move the kfree of the binder_device to binder_free_proc()
so the binder_device is freed when we know there are no references
remaining on the binder_proc.
Fixes: f0fe2c0f05 ("binder: prevent UAF for binderfs devices II")
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200622200715.114382-1-tkjos@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit 84af7a6194 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.
This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.
There are a variety of indentation styles found.
a) 4 spaces + '---help---'
b) 7 spaces + '---help---'
c) 8 spaces + '---help---'
d) 1 space + 1 tab + '---help---'
e) 1 tab + '---help---' (correct indentation)
f) 1 tab + 1 space + '---help---'
g) 1 tab + 2 spaces + '---help---'
In order to convert all of them to 1 tab + 'help', I ran the
following commend:
$ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The pointer ctx is being initialized with a value that is never read
and it is being updated later with a new value. The initialization
is redundant and can be removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200402105000.506296-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When I first wrote binderfs the new mount api had not yet landed. Now
that it has been around for a little while and a bunch of filesystems
have already been ported we should do so too. When Al sent his
mount-api-conversion pr he requested that binderfs (and a few others) be
ported separately. It's time we port binderfs. We can make use of the
new option parser, get nicer infrastructure and it will be easier if we
ever add any new mount options.
This survives testing with the binderfs selftests:
for i in `seq 1 1000`; do ./binderfs_test; done
including the new stress tests I sent out for review today:
TAP version 13
1..1
# selftests: filesystems/binderfs: binderfs_test
# [==========] Running 3 tests from 1 test cases.
# [ RUN ] global.binderfs_stress
# [ XFAIL! ] Tests are not run as root. Skipping privileged tests
# [==========] Running 3 tests from 1 test cases.
# [ RUN ] global.binderfs_stress
# [ OK ] global.binderfs_stress
# [ RUN ] global.binderfs_test_privileged
# [ OK ] global.binderfs_test_privileged
# [ RUN ] global.binderfs_test_unprivileged
# # Allocated new binder device with major 243, minor 4, and name my-binder
# # Detected binder version: 8
# [==========] Running 3 tests from 1 test cases.
# [ RUN ] global.binderfs_stress
# [ OK ] global.binderfs_stress
# [ RUN ] global.binderfs_test_privileged
# [ OK ] global.binderfs_test_privileged
# [ RUN ] global.binderfs_test_unprivileged
# [ OK ] global.binderfs_test_unprivileged
# [==========] 3 / 3 tests passed.
# [ PASSED ]
ok 1 selftests: filesystems/binderfs: binderfs_test
Cc: Todd Kjos <tkjos@google.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200313153427.141789-1-christian.brauner@ubuntu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Binderfs binder-control devices are cleaned up via binderfs_evict_inode
too() which will use refcount_dec_and_test(). However, we missed to set
the refcount for binderfs binder-control devices and so we underflowed
when the binderfs instance got unmounted. Pretty obvious oversight and
should have been part of the more general UAF fix. The good news is that
having test cases (suprisingly) helps.
Technically, we could detect that we're about to cleanup the
binder-control dentry in binderfs_evict_inode() and then simply clean it
up. But that makes the assumption that the binder driver itself will
never make use of a binderfs binder-control device after the binderfs
instance it belongs to has been unmounted and the superblock for it been
destroyed. While it is unlikely to ever come to this let's be on the
safe side. Performance-wise this also really doesn't matter since the
binder-control device is only every really when creating the binderfs
filesystem or creating additional binder devices. Both operations are
pretty rare.
Fixes: f0fe2c0f05 ("binder: prevent UAF for binderfs devices II")
Link: https://lore.kernel.org/r/CA+G9fYusdfg7PMfC9Xce-xLT7NiyKSbgojpK35GOm=Pf9jXXrA@mail.gmail.com
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20200311105309.1742827-1-christian.brauner@ubuntu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a necessary follow up to the first fix I proposed and we merged
in 2669b8b0c7 ("binder: prevent UAF for binderfs devices"). I have been
overly optimistic that the simple fix I proposed would work. But alas,
ihold() + iput() won't work since the inodes won't survive the
destruction of the superblock.
So all we get with my prior fix is a different race with a tinier
race-window but it doesn't solve the issue. Fwiw, the problem lies with
generic_shutdown_super(). It even has this cozy Al-style comment:
if (!list_empty(&sb->s_inodes)) {
printk("VFS: Busy inodes after unmount of %s. "
"Self-destruct in 5 seconds. Have a nice day...\n",
sb->s_id);
}
On binder_release(), binder_defer_work(proc, BINDER_DEFERRED_RELEASE) is
called which punts the actual cleanup operation to a workqueue. At some
point, binder_deferred_func() will be called which will end up calling
binder_deferred_release() which will retrieve and cleanup the
binder_context attach to this struct binder_proc.
If we trace back where this binder_context is attached to binder_proc we
see that it is set in binder_open() and is taken from the struct
binder_device it is associated with. This obviously assumes that the
struct binder_device that context is attached to is _never_ freed. While
that might be true for devtmpfs binder devices it is most certainly
wrong for binderfs binder devices.
So, assume binder_open() is called on a binderfs binder devices. We now
stash away the struct binder_context associated with that struct
binder_devices:
proc->context = &binder_dev->context;
/* binderfs stashes devices in i_private */
if (is_binderfs_device(nodp)) {
binder_dev = nodp->i_private;
info = nodp->i_sb->s_fs_info;
binder_binderfs_dir_entry_proc = info->proc_log_dir;
} else {
.
.
.
proc->context = &binder_dev->context;
Now let's assume that the binderfs instance for that binder devices is
shutdown via umount() and/or the mount namespace associated with it goes
away. As long as there is still an fd open for that binderfs binder
device things are fine. But let's assume we now close the last fd for
that binderfs binder device. Now binder_release() is called and punts to
the workqueue. Assume that the workqueue has quite a bit of stuff to do
and doesn't get to cleaning up the struct binder_proc and the associated
struct binder_context with it for that binderfs binder device right
away. In the meantime, the VFS is killing the super block and is
ultimately calling sb->evict_inode() which means it will call
binderfs_evict_inode() which does:
static void binderfs_evict_inode(struct inode *inode)
{
struct binder_device *device = inode->i_private;
struct binderfs_info *info = BINDERFS_I(inode);
clear_inode(inode);
if (!S_ISCHR(inode->i_mode) || !device)
return;
mutex_lock(&binderfs_minors_mutex);
--info->device_count;
ida_free(&binderfs_minors, device->miscdev.minor);
mutex_unlock(&binderfs_minors_mutex);
kfree(device->context.name);
kfree(device);
}
thereby freeing the struct binder_device including struct
binder_context.
Now the workqueue finally has time to get around to cleaning up struct
binder_proc and is now trying to access the associate struct
binder_context. Since it's already freed it will OOPs.
Fix this by introducing a refounct on binder devices.
This is an alternative fix to 51d8a7eca6 ("binder: prevent UAF read in
print_binder_transaction_log_entry()").
Fixes: 3ad20fe393 ("binder: implement binderfs")
Fixes: 2669b8b0c7 ("binder: prevent UAF for binderfs devices")
Fixes: 03e2e07e38 ("binder: Make transaction_log available in binderfs")
Related : 51d8a7eca6 ("binder: prevent UAF read in print_binder_transaction_log_entry()")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Todd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20200303164340.670054-1-christian.brauner@ubuntu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On binder_release(), binder_defer_work(proc, BINDER_DEFERRED_RELEASE) is
called which punts the actual cleanup operation to a workqueue. At some
point, binder_deferred_func() will be called which will end up calling
binder_deferred_release() which will retrieve and cleanup the
binder_context attach to this struct binder_proc.
If we trace back where this binder_context is attached to binder_proc we
see that it is set in binder_open() and is taken from the struct
binder_device it is associated with. This obviously assumes that the
struct binder_device that context is attached to is _never_ freed. While
that might be true for devtmpfs binder devices it is most certainly
wrong for binderfs binder devices.
So, assume binder_open() is called on a binderfs binder devices. We now
stash away the struct binder_context associated with that struct
binder_devices:
proc->context = &binder_dev->context;
/* binderfs stashes devices in i_private */
if (is_binderfs_device(nodp)) {
binder_dev = nodp->i_private;
info = nodp->i_sb->s_fs_info;
binder_binderfs_dir_entry_proc = info->proc_log_dir;
} else {
.
.
.
proc->context = &binder_dev->context;
Now let's assume that the binderfs instance for that binder devices is
shutdown via umount() and/or the mount namespace associated with it goes
away. As long as there is still an fd open for that binderfs binder
device things are fine. But let's assume we now close the last fd for
that binderfs binder device. Now binder_release() is called and punts to
the workqueue. Assume that the workqueue has quite a bit of stuff to do
and doesn't get to cleaning up the struct binder_proc and the associated
struct binder_context with it for that binderfs binder device right
away. In the meantime, the VFS is killing the super block and is
ultimately calling sb->evict_inode() which means it will call
binderfs_evict_inode() which does:
static void binderfs_evict_inode(struct inode *inode)
{
struct binder_device *device = inode->i_private;
struct binderfs_info *info = BINDERFS_I(inode);
clear_inode(inode);
if (!S_ISCHR(inode->i_mode) || !device)
return;
mutex_lock(&binderfs_minors_mutex);
--info->device_count;
ida_free(&binderfs_minors, device->miscdev.minor);
mutex_unlock(&binderfs_minors_mutex);
kfree(device->context.name);
kfree(device);
}
thereby freeing the struct binder_device including struct
binder_context.
Now the workqueue finally has time to get around to cleaning up struct
binder_proc and is now trying to access the associate struct
binder_context. Since it's already freed it will OOPs.
Fix this by holding an additional reference to the inode that is only
released once the workqueue is done cleaning up struct binder_proc. This
is an easy alternative to introducing separate refcounting on struct
binder_device which we can always do later if it becomes necessary.
This is an alternative fix to 51d8a7eca6 ("binder: prevent UAF read in
print_binder_transaction_log_entry()").
Fixes: 3ad20fe393 ("binder: implement binderfs")
Fixes: 03e2e07e38 ("binder: Make transaction_log available in binderfs")
Related : 51d8a7eca6 ("binder: prevent UAF read in print_binder_transaction_log_entry()")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'for-5.6/io_uring-vfs-2020-01-29' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe:
- Support for various new opcodes (fallocate, openat, close, statx,
fadvise, madvise, openat2, non-vectored read/write, send/recv, and
epoll_ctl)
- Faster ring quiesce for fileset updates
- Optimizations for overflow condition checking
- Support for max-sized clamping
- Support for probing what opcodes are supported
- Support for io-wq backend sharing between "sibling" rings
- Support for registering personalities
- Lots of little fixes and improvements
* tag 'for-5.6/io_uring-vfs-2020-01-29' of git://git.kernel.dk/linux-block: (64 commits)
io_uring: add support for epoll_ctl(2)
eventpoll: support non-blocking do_epoll_ctl() calls
eventpoll: abstract out epoll_ctl() handler
io_uring: fix linked command file table usage
io_uring: support using a registered personality for commands
io_uring: allow registering credentials
io_uring: add io-wq workqueue sharing
io-wq: allow grabbing existing io-wq
io_uring/io-wq: don't use static creds/mm assignments
io-wq: make the io_wq ref counted
io_uring: fix refcounting with batched allocations at OOM
io_uring: add comment for drain_next
io_uring: don't attempt to copy iovec for READ/WRITE
io_uring: honor IOSQE_ASYNC for linked reqs
io_uring: prep req when do IOSQE_ASYNC
io_uring: use labeled array init in io_op_defs
io_uring: optimise sqe-to-req flags translation
io_uring: remove REQ_F_IO_DRAINED
io_uring: file switch work needs to get flushed on exit
io_uring: hide uring_fd in ctx
...
Since commit 43e23b6c0b ("debugfs: log errors when something goes wrong")
debugfs logs attempts to create existing files.
However binder attempts to create multiple debugfs files with
the same name when a single PID has multiple contexts, this leads
to log spamming during an Android boot (17 such messages during
boot on my system).
Fix this by checking if we already know the PID and only create
the debugfs entry for the first context per PID.
Do the same thing for binderfs for symmetry.
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Acked-by: Todd Kjos <tkjos@google.com>
Fixes: 43e23b6c0b ("debugfs: log errors when something goes wrong")
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1578671054-5982-1-git-send-email-martin.fuzzey@flowbird.group
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Just one caller of this, and just use filp_close() there manually.
This is important to allow async close/removal of the fd.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For BINDER_TYPE_PTR and BINDER_TYPE_FDA transactions, the
num_valid local was calculated incorrectly causing the
range check in binder_validate_ptr() to miss out-of-bounds
offsets.
Fixes: bde4a19fc0 ("binder: use userspace pointer as base of buffer space")
Signed-off-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191213202531.55010-1-tkjos@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As part of the cleanup of some remaining y2038 issues, I came to
fs/compat_ioctl.c, which still has a couple of commands that need support
for time64_t.
In completely unrelated work, I spent time on cleaning up parts of this
file in the past, moving things out into drivers instead.
After Al Viro reviewed an earlier version of this series and did a lot
more of that cleanup, I decided to try to completely eliminate the rest
of it and move it all into drivers.
This series incorporates some of Al's work and many patches of my own,
but in the end stops short of actually removing the last part, which is
the scsi ioctl handlers. I have patches for those as well, but they need
more testing or possibly a rewrite.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Merge tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground
Pull removal of most of fs/compat_ioctl.c from Arnd Bergmann:
"As part of the cleanup of some remaining y2038 issues, I came to
fs/compat_ioctl.c, which still has a couple of commands that need
support for time64_t.
In completely unrelated work, I spent time on cleaning up parts of
this file in the past, moving things out into drivers instead.
After Al Viro reviewed an earlier version of this series and did a lot
more of that cleanup, I decided to try to completely eliminate the
rest of it and move it all into drivers.
This series incorporates some of Al's work and many patches of my own,
but in the end stops short of actually removing the last part, which
is the scsi ioctl handlers. I have patches for those as well, but they
need more testing or possibly a rewrite"
* tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (42 commits)
scsi: sd: enable compat ioctls for sed-opal
pktcdvd: add compat_ioctl handler
compat_ioctl: move SG_GET_REQUEST_TABLE handling
compat_ioctl: ppp: move simple commands into ppp_generic.c
compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t
compat_ioctl: move PPPIOCSCOMPRESS to ppp_generic
compat_ioctl: unify copy-in of ppp filters
tty: handle compat PPP ioctls
compat_ioctl: move SIOCOUTQ out of compat_ioctl.c
compat_ioctl: handle SIOCOUTQNSD
af_unix: add compat_ioctl support
compat_ioctl: reimplement SG_IO handling
compat_ioctl: move WDIOC handling into wdt drivers
fs: compat_ioctl: move FITRIM emulation into file systems
gfs2: add compat_ioctl support
compat_ioctl: remove unused convert_in_user macro
compat_ioctl: remove last RAID handling code
compat_ioctl: remove /dev/raw ioctl translation
compat_ioctl: remove PCI ioctl translation
compat_ioctl: remove joystick ioctl translation
...
The old loop wouldn't stop when reaching `start` if `start==NULL`, instead
continuing backwards to index -1 and crashing.
Luckily you need to be highly privileged to map things at NULL, so it's not
a big problem.
Fix it by adjusting the loop so that the loop variable is always in bounds.
This patch is deliberately minimal to simplify backporting, but IMO this
function could use a refactor. The jump labels in the second loop body are
horrible (the error gotos should be jumping to free_range instead), and
both loops would look nicer if they just iterated upwards through indices.
And the up_read()+mmput() shouldn't be duplicated like that.
Cc: stable@vger.kernel.org
Fixes: 457b9a6f09 ("Staging: android: add binder driver")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191018205631.248274-3-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
binder_alloc_mmap_handler() attempts to detect the use of ->mmap() on a
binder_proc whose binder_alloc has already been initialized by checking
whether alloc->buffer is non-zero.
Before commit 880211667b ("binder: remove kernel vm_area for buffer
space"), alloc->buffer was a kernel mapping address, which is always
non-zero, but since that commit, it is a userspace mapping address.
A sufficiently privileged user can map /dev/binder at NULL, tricking
binder_alloc_mmap_handler() into assuming that the binder_proc has not been
mapped yet. This leads to memory unsafety.
Luckily, no context on Android has such privileges, and on a typical Linux
desktop system, you need to be root to do that.
Fix it by using the mapping size instead of the mapping address to
distinguish the mapped case. A valid VMA can't have size zero.
Fixes: 880211667b ("binder: remove kernel vm_area for buffer space")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191018205631.248274-2-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
binder_alloc_print_pages() iterates over
alloc->pages[0..alloc->buffer_size-1] under alloc->mutex.
binder_alloc_mmap_handler() writes alloc->pages and alloc->buffer_size
without holding that lock, and even writes them before the last bailout
point.
Unfortunately we can't take the alloc->mutex in the ->mmap() handler
because mmap_sem can be taken while alloc->mutex is held.
So instead, we have to locklessly check whether the binder_alloc has been
fully initialized with binder_alloc_get_vma(), like in
binder_alloc_new_buf_locked().
Fixes: 8ef4665aa1 ("android: binder: Add page usage in binder stats")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191018205631.248274-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We want the binder fix in here as well for testing and to work on top
of.
Also handles a merge issue in binder.c to help linux-next out
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The .ioctl and .compat_ioctl file operations have the same prototype so
they can both point to the same function, which works great almost all
the time when all the commands are compatible.
One exception is the s390 architecture, where a compat pointer is only
31 bit wide, and converting it into a 64-bit pointer requires calling
compat_ptr(). Most drivers here will never run in s390, but since we now
have a generic helper for it, it's easy enough to use it consistently.
I double-checked all these drivers to ensure that all ioctl arguments
are used as pointers or are ignored, but are not interpreted as integer
values.
Acked-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Darren Hart (VMware) <dvhart@infradead.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
vm_insert_page() does increment the page refcount, and just to be sure,
I've confirmed it by printing page_count(page[0].page_ptr) before and after
vm_insert_page(). It's 1 before, 2 afterwards, as expected.
Fixes: a145dd411e ("VM: add "vm_insert_page()" function")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191018153946.128584-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SZ_1K has been defined in include/linux/sizes.h since v3.6. Get rid of the
duplicate definition.
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191016150119.154756-2-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
binder_mmap() tries to prevent the creation of overly big binder mappings
by silently truncating the size of the VMA to 4MiB. However, this violates
the API contract of mmap(). If userspace attempts to create a large binder
VMA, and later attempts to unmap that VMA, it will call munmap() on a range
beyond the end of the VMA, which may have been allocated to another VMA in
the meantime. This can lead to userspace memory corruption.
The following sequence of calls leads to a segfault without this commit:
int main(void) {
int binder_fd = open("/dev/binder", O_RDWR);
if (binder_fd == -1) err(1, "open binder");
void *binder_mapping = mmap(NULL, 0x800000UL, PROT_READ, MAP_SHARED,
binder_fd, 0);
if (binder_mapping == MAP_FAILED) err(1, "mmap binder");
void *data_mapping = mmap(NULL, 0x400000UL, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (data_mapping == MAP_FAILED) err(1, "mmap data");
munmap(binder_mapping, 0x800000UL);
*(char*)data_mapping = 1;
return 0;
}
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Todd Kjos <tkjos@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191016150119.154756-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
binder_alloc_buffer_lookup() doesn't exist and is named
"binder_alloc_prepare_to_free()". Correct the code comments to reflect
this.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20190930201250.139554-1-joel@joelfernandes.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a binder transaction is initiated on a binder device coming from a
binderfs instance, a pointer to the name of the binder device is stashed
in the binder_transaction_log_entry's context_name member. Later on it
is used to print the name in print_binder_transaction_log_entry(). By
the time print_binder_transaction_log_entry() accesses context_name
binderfs_evict_inode() might have already freed the associated memory
thereby causing a UAF. Do the simple thing and prevent this by copying
the name of the binder device instead of stashing a pointer to it.
Reported-by: Jann Horn <jannh@google.com>
Fixes: 03e2e07e38 ("binder: Make transaction_log available in binderfs")
Link: https://lore.kernel.org/r/CAG48ez14Q0-F8LqsvcNbyR2o6gPW8SHXsm4u5jmD9MpsteM2Tw@mail.gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Todd Kjos <tkjos@google.com>
Reviewed-by: Hridya Valsaraju <hridya@google.com>
Link: https://lore.kernel.org/r/20191008130159.10161-1-christian.brauner@ubuntu.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently /sys/kernel/debug/binder/proc contains
the debug data for every binder_proc instance.
This patch makes this information also available
in a binderfs instance mounted with a mount option
"stats=global" in addition to debugfs. The patch does
not affect the presence of the file in debugfs.
If a binderfs instance is mounted at path /dev/binderfs,
this file would be present at /dev/binderfs/binder_logs/proc.
This change provides an alternate way to access this file when debugfs
is not mounted.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Hridya Valsaraju <hridya@google.com>
Link: https://lore.kernel.org/r/20190903161655.107408-5-hridya@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Christian Brauner
Linus Torvalds
Eric W. Biederman
Todd Kjos
Frankie.Chang
Zhang Qilong
Andrew Bridges
Jens Axboe
Liu Shixin
Colin Ian King
Martijn Coenen
Wei Yongjun
YangHui
Jann Horn
Mrinal Pandey
Tetsuo Handa
Masahiro Yamada
Michel Lespinasse
Tang Bin
Greg Kroah-Hartman
Martin Fuzzey
Todd Kjos
Arnd Bergmann
Joel Fernandes (Google)
Hridya Valsaraju