We need information about exports when crossing mountpoints during
lookup or NFSv4 readdir.  If we don't already have that information
cached, we may have to ask (and wait for) rpc.mountd.

In both cases we currently hold the i_mutex on the parent of the
directory we're asking rpc.mountd about.  We've seen situations where
rpc.mountd performs some operation on that directory that tries to take
the i_mutex again, resulting in deadlock.

With some care, we may be able to avoid that in rpc.mountd.  But it
seems better just to avoid holding a mutex while waiting on userspace.

It appears that lookup_one_len is pretty much the only operation that
needs the i_mutex.  So we could just drop the i_mutex elsewhere and do
something like

	mutex_lock()
	lookup_one_len()
	mutex_unlock()

In many cases though the lookup would have been cached and not required
the i_mutex, so it's more efficient to create a lookup_one_len() variant
that only takes the i_mutex when necessary.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The affs code uses "time_t" and "get_seconds()". This will cause
problems on 32-bit architectures in 2038 when time_t overflows.
This patch replaces them with "time64_t" and
"ktime_get_real_seconds()". This patch introduces expensive 64-bit
divsion in "secs_to_datestamp()", considering this function is not
called so often, the cost should be acceptable.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: DengChao <chao.deng@linaro.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

We may sleep inside a the lock, so use a mutex rather than spinlock.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

User can pass an arbitrary large buffer to getdents().

It is typically a 32KB buffer used by libc scandir() implementation.

When scanning /proc/{pid}/fd, we can hold cpu way too long,
so add a cond_resched() to be kind with other tasks.

We've seen latencies of more than 50ms on real workloads.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The logfs_block_ops structures are never modified, so declare them as
const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

With packetized mode for pipes, it's not possible to set O_DIRECT on pipe file
via sys_fcntl, because of unsupported sanity checks.
Ability to set this flag will be used by CRIU to migrate packetized pipes.

v2:
Fixed typos and mode variable to check.

Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

During testing, I discovered that __generic_file_splice_read() returns
0 (EOF) when aops->readpage fails with AOP_TRUNCATED_PAGE on the first
page of a single/multi-page splice read operation. This EOF return code
causes the userspace test to (correctly) report a zero-length read error
when it was expecting otherwise.

The current strategy of returning a partial non-zero read when ->readpage
returns AOP_TRUNCATED_PAGE works only when the failed page is not the
first of the lot being processed.

This patch attempts to retry lookup and call ->readpage again on pages
that had previously failed with AOP_TRUNCATED_PAGE. With this patch, my
tests pass and I haven't noticed any unwanted side effects.

This version removes the thrice-retry loop and instead indefinitely
retries lookups on AOP_TRUNCATED_PAGE errors from ->readpage. This
behavior is now similar to do_generic_file_read().

Signed-off-by: Abhi Das <adas@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... instead of open coding it.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

This replaces all code in fs/compat_ioctl.c that translated
ioctl arguments into a in-kernel structure, then performed
do_ioctl under set_fs(KERNEL_DS), with code that allocates
data on the user stack and can call the VFS ioctl handler
under USER_DS.

This is done as a hardening measure because the caller
does not know what kind of ioctl handler will be invoked,
only that no corresponding compat_ioctl handler exists and
what the ioctl command number is. The accidental
invocation of an unlocked_ioctl handler that unexpectedly
calls copy_to_user could be a severe security issue.

Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In code in fs/compat_ioctl.c that translates ioctl arguments
into a in-kernel structure, then performs sys_ioctl, possibly
under set_fs(KERNEL_DS), this commit changes the sys_ioctl
calls to do_ioctl calls. do_ioctl is a new function that does
the same thing as sys_ioctl, but doesn't look up the fd again.

This change is made to avoid (potential) security issues
because of ioctl handlers that accept one of the ioctl
commands I2C_FUNCS, VIDEO_GET_EVENT, MTIOCPOS, MTIOCGET,
TIOCGSERIAL, TIOCSSERIAL, RTC_IRQP_READ, RTC_EPOCH_READ.
This can happen for multiple reasons:

 - The ioctl command number could be reused.
 - The ioctl handler might not check the full ioctl
   command. This is e.g. true for drm_ioctl.
 - The ioctl handler is very special, e.g. cuse_file_ioctl

The real issue is that set_fs(KERNEL_DS) is used here,
but that's fixed in a separate commit
"compat_ioctl: don't call do_ioctl under set_fs(KERNEL_DS)".

This change mitigates potential security issues by
preventing a race that permits invocation of
unlocked_ioctl handlers under KERNEL_DS through compat
code even if a corresponding compat_ioctl handler exists.

So far, no way has been identified to use this to damage
kernel memory without having CAP_SYS_ADMIN in the init ns
(with the capability, doing reads/writes at arbitrary
kernel addresses should be easy through CUSE's ioctl
handler with FUSE_IOCTL_UNRESTRICTED set).

[AV: two missed sys_ioctl() taken care of]

Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

This allow to directly print block_device name.
Currently one should use bdevname() with temporal char buffer.
This is very ineffective because bloat stack usage for deep IO call-traces

Example:
	%pg  ->    sda, sda1 or loop0p1

[AV: fixed a minor braino - position updates should not be dependent
upon having reached the of buffer]

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

gendisk with part==0 is obviously gendisk->disk_name.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Number of fds is already known based on passed list.

No functional changes.

Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

[folded a fix by Dan Carpenter]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... rather than play with __get_free_pages() (and figuring out the
allocation order, etc.)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

get_zeroed_page does alloc_page and returns page_address of the result;
subsequent virt_to_page will recover the page, but since the caller
needs both page and its page_address() anyway, why bother going through
that wrapper at all?

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... so virt_to_phys(p) & (PAGE_SIZE - 1) is a very odd way to
spell offset_in_page(p).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

let it just return NULL, pointer to kernel copy or ERR_PTR().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

When __get_user64() had been removed, its helper (__get_user64_nocheck)
got missed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

they hadn't been used in last 15 years...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

all we do to buffer is strncmp()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

again, it only parses the contents of the copied buffer, so
get_zeroed_page() might as well had been kmalloc(), which makes
it open-coded memdup_user_nul()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>