To ensure that load_misc_binary() can't use the partially destroyed
Node, see also the next patch.

The current logic looks wrong in any case, once we close interp_file it
doesn't make any sense to delay kfree(inode->i_private), this Node is no
longer valid.  Even if the MISC_FMT_OPEN_FILE/interp_file checks were
not racy (they are), load_misc_binary() should not try to reopen
->interpreter if MISC_FMT_OPEN_FILE is set but ->interp_file is NULL.

And I can't understand why do we use filp_close(), not fput().

Link: http://lkml.kernel.org/r/20170922143644.GA17216@redhat.comSigned-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ben Woodard <woodard@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jim Foraker <foraker1@llnl.gov>
Cc: <tdhooge@llnl.gov>
Cc: Travis Gummels <tgummels@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kill_node() nullifies/checks Node->dentry to avoid double free.  This
complicates the next changes and this is very confusing:

 - we do not need to check dentry != NULL under entries_lock,
   kill_node() is always called under inode_lock(d_inode(root)) and we
   rely on this inode_lock() anyway, without this lock the
   MISC_FMT_OPEN_FILE cleanup could race with itself.

 - if kill_inode() was already called and ->dentry == NULL we should not
   even try to close e->interp_file.

We can change bm_entry_write() to simply check !list_empty(list) before
kill_node.  Again, we rely on inode_lock(), in particular it saves us
from the race with bm_status_write(), another caller of kill_node().

Link: http://lkml.kernel.org/r/20170922143641.GA17210@redhat.comSigned-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ben Woodard <woodard@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jim Foraker <foraker1@llnl.gov>
Cc: <tdhooge@llnl.gov>
Cc: Travis Gummels <tgummels@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use proper ssize_t and size_t types for the return value and count
argument, move the offset last and make it an in/out argument like
all other read/write helpers, and make the buf argument a void pointer
to get rid of lots of casts in the callers.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

simple_fill_super() is passed an array of tree_descr structures which
describe the files to create in the filesystem's root directory.  Since
these arrays are never modified intentionally, they should be 'const' so
that they are placed in .rodata and benefit from memory protection.
This patch updates the function signature and all users, and also
constifies tree_descr.name.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Update code that relied on sched.h including various MM types for them.

This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

current_fs_time() uses struct super_block* as an argument.
As per Linus's suggestion, this is changed to take struct
inode* as a parameter instead. This is because the function
is primarily meant for vfs inode timestamps.
Also the function was renamed as per Arnd's suggestion.

Change all calls to current_fs_time() to use the new
current_time() function instead. current_fs_time() will be
deleted.
Signed-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... no need to dget/dput it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This patch adds a new flag 'F' to the binfmt handlers.  If you pass in
'F' the binary that runs the emulation will be opened immediately and
in future, will be cloned from the open file.

The net effect is that the handler survives both changeroots and mount
namespace changes, making it easy to work with foreign architecture
containers without contaminating the container image with the
emulator.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

sprintf() reliably returns the number of characters printed, so we don't
need to ask strlen() where we are.  Also replace calling sprintf("%02x")
in a loop with the much simpler bin2hex().

[akpm@linux-foundation.org: it's odd to include kernel.h after everything else]
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

scanarg(s, del) never returns s; the empty field results in s + 1.
Restore the correct checks, and move NUL-termination into scanarg(),
while we are at it.

Incidentally, mixing "coding style cleanups" (for small values of cleanup)
with functional changes is a Bad Idea(tm)...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This patchset adds execveat(2) for x86, and is derived from Meredydd
Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528).

The primary aim of adding an execveat syscall is to allow an
implementation of fexecve(3) that does not rely on the /proc filesystem,
at least for executables (rather than scripts).  The current glibc version
of fexecve(3) is implemented via /proc, which causes problems in sandboxed
or otherwise restricted environments.

Given the desire for a /proc-free fexecve() implementation, HPA suggested
(https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be
an appropriate generalization.

Also, having a new syscall means that it can take a flags argument without
back-compatibility concerns.  The current implementation just defines the
AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be
added in future -- for example, flags for new namespaces (as suggested at
https://lkml.org/lkml/2006/7/11/474).

Related history:
 - https://lkml.org/lkml/2006/12/27/123 is an example of someone
   realizing that fexecve() is likely to fail in a chroot environment.
 - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered
   documenting the /proc requirement of fexecve(3) in its manpage, to
   "prevent other people from wasting their time".
 - https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a
   problem where a process that did setuid() could not fexecve()
   because it no longer had access to /proc/self/fd; this has since
   been fixed.

This patch (of 4):

Add a new execveat(2) system call.  execveat() is to execve() as openat()
is to open(): it takes a file descriptor that refers to a directory, and
resolves the filename relative to that.

In addition, if the filename is empty and AT_EMPTY_PATH is specified,
execveat() executes the file to which the file descriptor refers.  This
replicates the functionality of fexecve(), which is a system call in other
UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/<fd>" (and
so relies on /proc being mounted).

The filename fed to the executed program as argv[0] (or the name of the
script fed to a script interpreter) will be of the form "/dev/fd/<fd>"
(for an empty filename) or "/dev/fd/<fd>/<filename>", effectively
reflecting how the executable was found.  This does however mean that
execution of a script in a /proc-less environment won't work; also, script
execution via an O_CLOEXEC file descriptor fails (as the file will not be
accessible after exec).

Based on patches by Meredydd Luff.
Signed-off-by: NDavid Drysdale <drysdale@google.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@aerifal.cx>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

GFP_USER means "honour cpuset nodes-allowed beancounting".  These are
regular old kernel objects and there seems no reason to give them this
treatment.
Acked-by: NMike Frysinger <vapier@gentoo.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clean up various coding style issues that checkpatch complains about.
No functional changes here.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When trying to develop a custom format handler, the errors returned all
effectively get bucketed as EINVAL with no kernel messages.  The other
errors (ENOMEM/EFAULT) are internal/obvious and basic.  Thus any time a
bad handler is rejected, the developer has to walk the dense code and
try to guess where it went wrong.  Needing to dive into kernel code is
itself a fairly high barrier for a lot of people.

To improve this situation, let's deploy extensive pr_debug markers at
logical parse points, and add comments to the dense parsing logic.  It
let's you see exactly where the parsing aborts, the string the kernel
received (useful when dealing with shell code), how it translated the
buffers to binary data, and how it will apply the mask at runtime.

Some example output:
  $ echo ':qemu-foo:M::\x7fELF\xAD\xAD\x01\x00:\xff\xff\xff\xff\xff\x00\xff\x00:/usr/bin/qemu-foo:POC' > register
  $ dmesg
  binfmt_misc: register: received 92 bytes
  binfmt_misc: register: delim: 0x3a {:}
  binfmt_misc: register: name: {qemu-foo}
  binfmt_misc: register: type: M (magic)
  binfmt_misc: register: offset: 0x0
  binfmt_misc: register: magic[raw]: 5c 78 37 66 45 4c 46 5c 78 41 44 5c 78 41 44 5c  \x7fELF\xAD\xAD\
  binfmt_misc: register: magic[raw]: 78 30 31 5c 78 30 30 00                          x01\x00.
  binfmt_misc: register:  mask[raw]: 5c 78 66 66 5c 78 66 66 5c 78 66 66 5c 78 66 66  \xff\xff\xff\xff
  binfmt_misc: register:  mask[raw]: 5c 78 66 66 5c 78 30 30 5c 78 66 66 5c 78 30 30  \xff\x00\xff\x00
  binfmt_misc: register:  mask[raw]: 00                                               .
  binfmt_misc: register: magic/mask length: 8
  binfmt_misc: register: magic[decoded]: 7f 45 4c 46 ad ad 01 00                          .ELF....
  binfmt_misc: register:  mask[decoded]: ff ff ff ff ff 00 ff 00                          ........
  binfmt_misc: register:  magic[masked]: 7f 45 4c 46 ad 00 01 00                          .ELF....
  binfmt_misc: register: interpreter: {/usr/bin/qemu-foo}
  binfmt_misc: register: flag: P (preserve argv0)
  binfmt_misc: register: flag: O (open binary)
  binfmt_misc: register: flag: C (preserve creds)

The [raw] lines show us exactly what was received from userspace.  The
lines after that show us how the kernel has decoded things.
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch replaces calls to get_unused_fd() with equivalent call to
get_unused_fd_flags(0) to preserve current behavor for existing code.

In a further patch, get_unused_fd() will be removed so that new code start
using get_unused_fd_flags(), with the hope O_CLOEXEC could be used, either
by default or choosen by userspace.
Signed-off-by: NYann Droneaud <ydroneaud@opteya.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

gcc-4.9 on ARM gives us a mysterious warning about the binfmt_misc
parse_command function:

  fs/binfmt_misc.c: In function 'parse_command.part.3':
  fs/binfmt_misc.c:405:7: warning: array subscript is above array bounds [-Warray-bounds]

I've managed to trace this back to the ARM implementation of memset,
which is called from copy_from_user in case of a fault and which does

 #define memset(p,v,n)                                                  \
        ({                                                              \
                void *__p = (p); size_t __n = n;                        \
                if ((__n) != 0) {                                       \
                        if (__builtin_constant_p((v)) && (v) == 0)      \
                                __memzero((__p),(__n));                 \
                        else                                            \
                                memset((__p),(v),(__n));                \
                }                                                       \
                (__p);                                                  \
        })

Apparently gcc gets confused by the check for "size != 0" and believes
that the size might be zero when it gets to the line that does "if
(s[count-1] == '\n')", so it would access data outside of the array.

gcc is clearly wrong here, since this condition was already checked
earlier in the function and the 'size' value can not change in the
meantime.

Fortunately, we can work around it and get rid of the warning by
rearranging the function to check for zero size after doing the
copy_from_user.  It is still safe to pass a zero size into
copy_from_user, so it does not cause any side effects.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current code places a 256 byte limit on the registration format.
This ends up being fairly limited when you try to do matching against a
binary format like ELF:

 - the magic & mask formats cannot have any embedded NUL chars
   (string_unescape_inplace halts at the first NUL)
 - each escape sequence quadruples the size: \x00 is needed for NUL
 - trying to match bytes at the start of the file as well as further
   on leads to a lot of \x00 sequences in the mask
 - magic & mask have to be the same length (when decoded)
 - still need bytes for the other fields
 - impossible!

Let's look at a concrete (and common) example: using QEMU to run MIPS
ELFs.  The name field uses 11 bytes "qemu-mipsel".  The interp uses 20
bytes "/usr/bin/qemu-mipsel".  The type & flags takes up 4 bytes.  We
need 7 bytes for the delimiter (usually ":").  We can skip offset.  So
already we're down to 107 bytes to use with the magic/mask instead of
the real limit of 128 (BINPRM_BUF_SIZE).  If people use shell code to
register (which they do the majority of the time), they're down to ~26
possible bytes since the escape sequence must be \x##.

The ELF format looks like (both 32 & 64 bit):

	e_ident: 16 bytes
	e_type: 2 bytes
	e_machine: 2 bytes

Those 20 bytes are enough for most architectures because they have so few
formats in the first place, thus they can be uniquely identified.  That
also means for shell users, since 20 is smaller than 26, they can sanely
register a handler.

But for some targets (like MIPS), we need to poke further.  The ELF fields
continue on:

	e_entry: 4 or 8 bytes
	e_phoff: 4 or 8 bytes
	e_shoff: 4 or 8 bytes
	e_flags: 4 bytes

We only care about e_flags here as that includes the bits to identify
whether the ELF is O32/N32/N64.  But now we have to consume another 16
bytes (for 32 bit ELFs) or 28 bytes (for 64 bit ELFs) just to match the
flags.  If every byte is escaped, we send 288 more bytes to the kernel
((20 {e_ident,e_type,e_machine} + 12 {e_entry,e_phoff,e_shoff} + 4
{e_flags}) * 2 {mask,magic} * 4 {escape}) and we've clearly blown our
budget.

Even if we try to be clever and do the decoding ourselves (rather than
relying on the kernel to process \x##), we still can't hit the mark --
string_unescape_inplace treats mask & magic as C strings so NUL cannot
be embedded.  That leaves us with having to pass \x00 for the 12/24
entry/phoff/shoff bytes (as those will be completely random addresses),
and that is a minimum requirement of 48/96 bytes for the mask alone.
Add up the rest and we blow through it (this is for 64 bit ELFs):
magic: 20 {e_ident,e_type,e_machine} + 24 {e_entry,e_phoff,e_shoff} +
       4 {e_flags} = 48              # ^^ See note below.
mask: 20 {e_ident,e_type,e_machine} + 96 {e_entry,e_phoff,e_shoff} +
       4 {e_flags} = 120
Remember above we had 107 left over, and now we're at 168.  This is of
course the *best* case scenario -- you'll also want to have NUL bytes
in the magic & mask too to match literal zeros.

Note: the reason we can use 24 in the magic is that we can work off of the
fact that for bytes the mask would clobber, we can stuff any value into
magic that we want.  So when mask is \x00, we don't need the magic to also
be \x00, it can be an unescaped raw byte like '!'.  This lets us handle
more formats (barely) under the current 256 limit, but that's a pretty
tall hoop to force people to jump through.

With all that said, let's bump the limit from 256 bytes to 1920.  This way
we support escaping every byte of the mask & magic field (which is 1024
bytes by themselves -- 128 * 4 * 2), and we leave plenty of room for other
fields.  Like long paths to the interpreter (when you have source in your
/really/long/homedir/qemu/foo).  Since the current code stuffs more than
one structure into the same buffer, we leave a bit of space to easily
round up to 2k.  1920 is just as arbitrary as 256 ;).
Signed-off-by: NMike Frysinger <vapier@gentoo.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A missing 'break' statement in bm_status_write() results in a user program
receiving '3' when doing the following:

  write(fd, "-1", 2);
Signed-off-by: NLuis Henriques <luis.henriques@canonical.com>
Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is string_unescape_inplace() function which decodes strings in generic
way. Let's use it.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Modify the request_module to prefix the file system type with "fs-"
and add aliases to all of the filesystems that can be built as modules
to match.

A common practice is to build all of the kernel code and leave code
that is not commonly needed as modules, with the result that many
users are exposed to any bug anywhere in the kernel.

Looking for filesystems with a fs- prefix limits the pool of possible
modules that can be loaded by mount to just filesystems trivially
making things safer with no real cost.

Using aliases means user space can control the policy of which
filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
with blacklist and alias directives.  Allowing simple, safe,
well understood work-arounds to known problematic software.

This also addresses a rare but unfortunate problem where the filesystem
name is not the same as it's module name and module auto-loading
would not work.  While writing this patch I saw a handful of such
cases.  The most significant being autofs that lives in the module
autofs4.

This is relevant to user namespaces because we can reach the request
module in get_fs_type() without having any special permissions, and
people get uncomfortable when a user specified string (in this case
the filesystem type) goes all of the way to request_module.

After having looked at this issue I don't think there is any
particular reason to perform any filtering or permission checks beyond
making it clear in the module request that we want a filesystem
module.  The common pattern in the kernel is to call request_module()
without regards to the users permissions.  In general all a filesystem
module does once loaded is call register_filesystem() and go to sleep.
Which means there is not much attack surface exposed by loading a
filesytem module unless the filesystem is mounted.  In a user
namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
which most filesystems do not set today.
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Acked-by: NKees Cook <keescook@chromium.org>
Reported-by: NKees Cook <keescook@google.com>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

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

If a series of scripts are executed, each triggering module loading via
unprintable bytes in the script header, kernel stack contents can leak
into the command line.

Normally execution of binfmt_script and binfmt_misc happens recursively.
However, when modules are enabled, and unprintable bytes exist in the
bprm->buf, execution will restart after attempting to load matching
binfmt modules.  Unfortunately, the logic in binfmt_script and
binfmt_misc does not expect to get restarted.  They leave bprm->interp
pointing to their local stack.  This means on restart bprm->interp is
left pointing into unused stack memory which can then be copied into the
userspace argv areas.

After additional study, it seems that both recursion and restart remains
the desirable way to handle exec with scripts, misc, and modules.  As
such, we need to protect the changes to interp.

This changes the logic to require allocation for any changes to the
bprm->interp.  To avoid adding a new kmalloc to every exec, the default
value is left as-is.  Only when passing through binfmt_script or
binfmt_misc does an allocation take place.

For a proof of concept, see DoTest.sh from:

   http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: halfdog <me@halfdog.net>
Cc: P J P <ppandit@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To avoid an explosion of request_module calls on a chain of abusive
scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon
as maximum recursion depth is hit, the error will fail all the way back
up the chain, aborting immediately.

This also has the side-effect of stopping the user's shell from attempting
to reexecute the top-level file as a shell script. As seen in the
dash source:

        if (cmd != path_bshell && errno == ENOEXEC) {
                *argv-- = cmd;
                *argv = cmd = path_bshell;
                goto repeat;
        }

The above logic was designed for running scripts automatically that lacked
the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC,
things continue to behave as the shell expects.

Additionally, when tracking recursion, the binfmt handlers should not be
involved. The recursion being tracked is the depth of calls through
search_binary_handler(), so that function should be exclusively responsible
for tracking the depth.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: halfdog <me@halfdog.net>
Cc: P J P <ppandit@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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

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

After we moved inode_sync_wait() from end_writeback() it doesn't make sense
to call the function end_writeback() anymore. Rename it to clear_inode()
which well says what the function really does - set I_CLEAR flag.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>

- Move open-coded filesystem magic numbers into magic.h

- Rearrange magic.h so that the filesystem-related constants are grouped
  together.
Signed-off-by: NMuthukumar R <muthur@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just don't pass NULL to it - nobody does, anyway.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

new helper: would_dump(bprm, file).  Checks if we are allowed to
read the file and if we are not - sets ENFORCE_NODUMP.  Exported,
used in places that previously open-coded the same logics.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

Instead of always assigning an increasing inode number in new_inode
move the call to assign it into those callers that actually need it.
For now callers that need it is estimated conservatively, that is
the call is added to all filesystems that do not assign an i_ino
by themselves.  For a few more filesystems we can avoid assigning
any inode number given that they aren't user visible, and for others
it could be done lazily when an inode number is actually needed,
but that's left for later patches.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>

Commit 74641f58 ("alpha: binfmt_aout fix") (May 2009) introduced a
regression - binfmt_misc is now consulted after binfmt_elf, which will
unfortunately break ia32el.  ia32 ELF binaries on ia64 used to be matched
using binfmt_misc and executed using wrapper.  As 32bit binaries are now
matched by binfmt_elf before bindmt_misc kicks in, the wrapper is ignored.

The fix increases precedence of binfmt_misc to the original state.
Signed-off-by: NJan Sembera <jsembera@suse.cz>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Richard Henderson <rth@twiddle.net
Cc: <stable@kernel.org>		[2.6.everything.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:

arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type

This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to.  This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel().  A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().

do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.

Further kernel_execve() and sys_execve() need to be changed to match.

This has been test built on x86_64, frv, arm and mips.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Tested-by: NRalf Baechle <ralf@linux-mips.org>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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

The following is what it looks like before patching.
It is not much readable.

user@ubuntu:/proc/sys/fs/binfmt_misc$ cat status
enableduser@ubuntu:/proc/sys/fs/binfmt_misc$
Signed-off-by: NQinghuang Feng <qhfeng.kernel@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>