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  1. 09 10月, 2012 1 次提交
  3. 27 9月, 2012 4 次提交
  5. 31 7月, 2012 1 次提交
  7. 30 5月, 2012 1 次提交
  9. 03 5月, 2012 1 次提交
  11. 20 2月, 2012 1 次提交
    • D
      Wrap accesses to the fd_sets in struct fdtable · 1dce27c5
      由 David Howells 提交于 
      Wrap accesses to the fd_sets in struct fdtable (for recording open files and
close-on-exec flags) so that we can move away from using fd_sets since we
abuse the fd_set structs by not allocating the full-sized structure under
normal circumstances and by non-core code looking at the internals of the
fd_sets.

The first abuse means that use of FD_ZERO() on these fd_sets is not permitted,
since that cannot be told about their abnormal lengths.

This introduces six wrapper functions for setting, clearing and testing
close-on-exec flags and fd-is-open flags:

	void __set_close_on_exec(int fd, struct fdtable *fdt);
	void __clear_close_on_exec(int fd, struct fdtable *fdt);
	bool close_on_exec(int fd, const struct fdtable *fdt);
	void __set_open_fd(int fd, struct fdtable *fdt);
	void __clear_open_fd(int fd, struct fdtable *fdt);
	bool fd_is_open(int fd, const struct fdtable *fdt);

Note that I've prepended '__' to the names of the set/clear functions because
they require the caller to hold a lock to use them.

Note also that I haven't added wrappers for looking behind the scenes at the
the array.  Possibly that should exist too.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174942.23314.1364.stgit@warthog.procyon.org.ukSigned-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
      1dce27c5
  13. 24 3月, 2011 1 次提交
  15. 15 3月, 2011 1 次提交
    • A
      New kind of open files - "location only". · 1abf0c71
      由 Al Viro 提交于 
      New flag for open(2) - O_PATH.  Semantics:
	* pathname is resolved, but the file itself is _NOT_ opened
as far as filesystem is concerned.
	* almost all operations on the resulting descriptors shall
fail with -EBADF.  Exceptions are:
	1) operations on descriptors themselves (i.e.
		close(), dup(), dup2(), dup3(), fcntl(fd, F_DUPFD),
		fcntl(fd, F_DUPFD_CLOEXEC, ...), fcntl(fd, F_GETFD),
		fcntl(fd, F_SETFD, ...))
	2) fcntl(fd, F_GETFL), for a common non-destructive way to
		check if descriptor is open
	3) "dfd" arguments of ...at(2) syscalls, i.e. the starting
		points of pathname resolution
	* closing such descriptor does *NOT* affect dnotify or
posix locks.
	* permissions are checked as usual along the way to file;
no permission checks are applied to the file itself.  Of course,
giving such thing to syscall will result in permission checks (at
the moment it means checking that starting point of ....at() is
a directory and caller has exec permissions on it).

fget() and fget_light() return NULL on such descriptors; use of
fget_raw() and fget_raw_light() is needed to get them.  That protects
existing code from dealing with those things.

There are two things still missing (they come in the next commits):
one is handling of symlinks (right now we refuse to open them that
way; see the next commit for semantics related to those) and another
is descriptor passing via SCM_RIGHTS datagrams.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      1abf0c71
  17. 03 2月, 2011 1 次提交
  19. 28 10月, 2010 2 次提交
    • L
      fasync: Fix placement of FASYNC flag comment · 55f335a8
      由 Linus Torvalds 提交于 
      In commit f7347ce4 ("fasync: re-organize fasync entry insertion to
allow it under a spinlock") Arnd took an earlier patch of mine that had
the comment about the FASYNC flag above the wrong function.

When the fasync_add_entry() function was split to introduce the new
fasync_insert_entry() helper function, the code that actually cares
about the FASYNC bit moved to that new helper.

So just move the comment to the right point.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      55f335a8
    • L
      fasync: re-organize fasync entry insertion to allow it under a spinlock · f7347ce4
      由 Linus Torvalds 提交于 
      You currently cannot use "fasync_helper()" in an atomic environment to
insert a new fasync entry, because it will need to allocate the new
"struct fasync_struct".

Yet fcntl_setlease() wants to call this under lock_flocks(), which is in
the process of being converted from the BKL to a spinlock.

In order to fix this, this abstracts out the actual fasync list
insertion and the fasync allocations into functions of their own, and
teaches fs/locks.c to pre-allocate the fasync_struct entry.  That way
the actual list insertion can happen while holding the required
spinlock.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
[bfields@redhat.com: rebase on top of my changes to Arnd's patch]
Tested-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
      f7347ce4
  21. 10 9月, 2010 1 次提交
  23. 11 8月, 2010 1 次提交
  25. 30 6月, 2010 1 次提交
  27. 05 6月, 2010 1 次提交
  29. 22 5月, 2010 1 次提交
  31. 22 4月, 2010 1 次提交
    • E
      fasync: RCU and fine grained locking · 989a2979
      由 Eric Dumazet 提交于 
      kill_fasync() uses a central rwlock, candidate for RCU conversion, to
avoid cache line ping pongs on SMP.

fasync_remove_entry() and fasync_add_entry() can disable IRQS on a short
section instead during whole list scan.

Use a spinlock per fasync_struct to synchronize kill_fasync_rcu() and
fasync_{remove|add}_entry(). This spinlock is IRQ safe, so sock_fasync()
doesnt need its own implementation and can use fasync_helper(), to
reduce code size and complexity.

We can remove __kill_fasync() direct use in net/socket.c, and rename it
to kill_fasync_rcu().
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      989a2979
  33. 07 3月, 2010 1 次提交
  35. 08 2月, 2010 1 次提交
    • L
      Fix race in tty_fasync() properly · 80e1e823
      由 Linus Torvalds 提交于 
      This reverts commit 70362511 ("tty: fix race in tty_fasync") and
commit b04da8bf ("fnctl: f_modown should call write_lock_irqsave/
restore") that tried to fix up some of the fallout but was incomplete.

It turns out that we really cannot hold 'tty->ctrl_lock' over calling
__f_setown, because not only did that cause problems with interrupt
disables (which the second commit fixed), it also causes a potential
ABBA deadlock due to lock ordering.

Thanks to Tetsuo Handa for following up on the issue, and running
lockdep to show the problem.  It goes roughly like this:

 - f_getown gets filp->f_owner.lock for reading without interrupts
   disabled, so an interrupt that happens while that lock is held can
   cause a lockdep chain from f_owner.lock -> sighand->siglock.

 - at the same time, the tty->ctrl_lock -> f_owner.lock chain that
   commit 70362511 introduced, together with the pre-existing
   sighand->siglock -> tty->ctrl_lock chain means that we have a lock
   dependency the other way too.

So instead of extending tty->ctrl_lock over the whole __f_setown() call,
we now just take a reference to the 'pid' structure while holding the
lock, and then release it after having done the __f_setown.  That still
guarantees that 'struct pid' won't go away from under us, which is all
we really ever needed.
Reported-and-tested-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Acked-by: NAmérico Wang <xiyou.wangcong@gmail.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      80e1e823
  37. 27 1月, 2010 1 次提交
  39. 17 12月, 2009 1 次提交
    • L
      fasync: split 'fasync_helper()' into separate add/remove functions · 53281b6d
      由 Linus Torvalds 提交于 
      Yes, the add and remove cases do share the same basic loop and the
locking, but the compiler can inline and then CSE some of the end result
anyway.  And splitting it up makes the code way easier to follow,
and makes it clearer exactly what the semantics are.

In particular, we must make sure that the FASYNC flag in file->f_flags
exactly matches the state of "is this file on any fasync list", since
not only is that flag visible to user space (F_GETFL), but we also use
that flag to check whether we need to remove any fasync entries on file
close.

We got that wrong for the case of a mixed use of file locking (which
tries to remove any fasync entries for file leases) and fasync.

Splitting the function up also makes it possible to do some future
optimizations without making the function even messier.  In particular,
since the FASYNC flag has to match the state of "is this on a list", we
can do the following future optimizations:

 - on remove, we don't even need to get the locks and traverse the list
   if FASYNC isn't set, since we can know a priori that there is no
   point (this is effectively the same optimization that we already do
   in __fput() wrt removing fasync on file close)

 - on add, we can use the FASYNC flag to decide whether we are changing
   an existing entry or need to allocate a new one.

but this is just the cleanup + fix for the FASYNC flag.
Acked-by: NAl Viro <viro@ZenIV.linux.org.uk>
Tested-by: NTavis Ormandy <taviso@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      53281b6d
  41. 18 11月, 2009 1 次提交
  43. 24 9月, 2009 2 次提交
    • P
      fcntl: add F_[SG]ETOWN_EX · ba0a6c9f
      由 Peter Zijlstra 提交于 
      In order to direct the SIGIO signal to a particular thread of a
multi-threaded application we cannot, like suggested by the manpage, put a
TID into the regular fcntl(F_SETOWN) call.  It will still be send to the
whole process of which that thread is part.

Since people do want to properly direct SIGIO we introduce F_SETOWN_EX.

The need to direct SIGIO comes from self-monitoring profiling such as with
perf-counters.  Perf-counters uses SIGIO to notify that new sample data is
available.  If the signal is delivered to the same task that generated the
new sample it can augment that data by inspecting the task's user-space
state right after it returns from the kernel.  This is esp.  convenient
for interpreted or virtual machine driven environments.

Both F_SETOWN_EX and F_GETOWN_EX take a pointer to a struct f_owner_ex
as argument:

struct f_owner_ex {
	int   type;
	pid_t pid;
};

Where type is one of F_OWNER_TID, F_OWNER_PID or F_OWNER_GID.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Tested-by: Nstephane eranian <eranian@googlemail.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ba0a6c9f
    • O
      signals: send_sigio: use do_send_sig_info() to avoid check_kill_permission() · 06f1631a
      由 Oleg Nesterov 提交于 
      group_send_sig_info()->check_kill_permission() assumes that current is the
sender and uses current_cred().

This is not true in send_sigio_to_task() case.  From the security pov the
sender is not current, but the task which did fcntl(F_SETOWN), that is why
we have sigio_perm() which uses the right creds to check.

Fortunately, send_sigio() always sends either SEND_SIG_PRIV or
SI_FROMKERNEL() signal, so check_kill_permission() does nothing.  But
still it would be tidier to avoid this bogus security check and save a
couple of cycles.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      06f1631a
  45. 13 7月, 2009 1 次提交
  47. 17 6月, 2009 2 次提交
  49. 12 5月, 2009 1 次提交
  51. 30 3月, 2009 1 次提交
  53. 16 3月, 2009 3 次提交
    • J
      Rationalize fasync return values · 60aa4924
      由 Jonathan Corbet 提交于 
      Most fasync implementations do something like:

     return fasync_helper(...);

But fasync_helper() will return a positive value at times - a feature used
in at least one place.  Thus, a number of other drivers do:

     err = fasync_helper(...);
     if (err < 0)
             return err;
     return 0;

In the interests of consistency and more concise code, it makes sense to
map positive return values onto zero where ->fasync() is called.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
      60aa4924
    • J
      Move FASYNC bit handling to f_op->fasync() · 76398425
      由 Jonathan Corbet 提交于 
      Removing the BKL from FASYNC handling ran into the challenge of keeping the
setting of the FASYNC bit in filp->f_flags atomic with regard to calls to
the underlying fasync() function.  Andi Kleen suggested moving the handling
of that bit into fasync(); this patch does exactly that.  As a result, we
have a couple of internal API changes: fasync() must now manage the FASYNC
bit, and it will be called without the BKL held.

As it happens, every fasync() implementation in the kernel with one
exception calls fasync_helper().  So, if we make fasync_helper() set the
FASYNC bit, we can avoid making any changes to the other fasync()
functions - as long as those functions, themselves, have proper locking.
Most fasync() implementations do nothing but call fasync_helper() - which
has its own lock - so they are easily verified as correct.  The BKL had
already been pushed down into the rest.

The networking code has its own version of fasync_helper(), so that code
has been augmented with explicit FASYNC bit handling.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Miller <davem@davemloft.net>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
      76398425
    • J
      Use f_lock to protect f_flags · db1dd4d3
      由 Jonathan Corbet 提交于 
      Traditionally, changes to struct file->f_flags have been done under BKL
protection, or with no protection at all.  This patch causes all f_flags
changes after file open/creation time to be done under protection of
f_lock.  This allows the removal of some BKL usage and fixes a number of
longstanding (if microscopic) races.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
      db1dd4d3
  55. 14 1月, 2009 1 次提交
  57. 06 12月, 2008 1 次提交
  59. 14 11月, 2008 3 次提交