linux-toradex.git/fs/binfmt_flat.c, branch v2.6.32.31

Split 'flush_old_exec' into two functions

2010-02-09T12:50:49+00:00

commit 221af7f87b97431e3ee21ce4b0e77d5411cf1549 upstream.

'flush_old_exec()' is the point of no return when doing an execve(), and
it is pretty badly misnamed.  It doesn't just flush the old executable
environment, it also starts up the new one.

Which is very inconvenient for things like setting up the new
personality, because we want the new personality to affect the starting
of the new environment, but at the same time we do _not_ want the new
personality to take effect if flushing the old one fails.

As a result, the x86-64 '32-bit' personality is actually done using this
insane "I'm going to change the ABI, but I haven't done it yet" bit
(TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the
personality, but just the "pending" bit, so that "flush_thread()" can do
the actual personality magic.

This patch in no way changes any of that insanity, but it does split the
'flush_old_exec()' function up into a preparatory part that can fail
(still called flush_old_exec()), and a new part that will actually set
up the new exec environment (setup_new_exec()).  All callers are changed
to trivially comply with the new world order.

Signed-off-by: H. Peter Anvin 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

flat: use IS_ERR_VALUE() helper macro

2009-09-24T14:21:03+00:00

There is a common macro now for testing mixed pointer/errno values, so use
that rather than handling the casts ourself.

Signed-off-by: Mike Frysinger 
Acked-by: David McCullough 
Acked-by: Greg Ungerer 
Cc: David Howells 
Cc: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

flat: fix uninitialized ptr with shared libs

2009-08-07T17:39:57+00:00

The new credentials code broke load_flat_shared_library() as it now uses
an uninitialized cred pointer.

Reported-by: Bernd Schmidt 
Tested-by: Bernd Schmidt 
Cc: Mike Frysinger 
Cc: David Howells 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

flat: fix data sections alignment

2009-05-29T15:40:02+00:00

The flat loader uses an architecture's flat_stack_align() to align the
stack but assumes word-alignment is enough for the data sections.

However, on the Xtensa S6000 we have registers up to 128bit width
which can be used from userspace and therefor need userspace stack and
data-section alignment of at least this size.

This patch drops flat_stack_align() and uses the same alignment that
is required for slab caches, ARCH_SLAB_MINALIGN, or wordsize if it's
not defined by the architecture.

It also fixes m32r which was obviously kaput, aligning an
uninitialized stack entry instead of the stack pointer.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oskar Schirmer 
Cc: David Howells 
Cc: Russell King 
Cc: Bryan Wu 
Cc: Geert Uytterhoeven 
Acked-by: Paul Mundt 
Cc: Greg Ungerer 
Signed-off-by: Johannes Weiner 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

FLAT: Don't attempt to expand the userspace stack to fill the space allocated

2009-01-08T12:04:47+00:00

Stop the FLAT binfmt from attempting to expand the userspace stack and brk
segments to fill the space actually allocated for it.  The space allocated may
be rounded up by mmap(), and may be wasted.

However, finding out how much space we actually obtained uses the contentious
kobjsize() function which we'd like to get rid of as it doesn't necessarily
work for all slab allocators.

Signed-off-by: David Howells 
Tested-by: Mike Frysinger 
Acked-by: Paul Mundt

CRED: Make execve() take advantage of copy-on-write credentials

2008-11-13T23:39:24+00:00

Make execve() take advantage of copy-on-write credentials, allowing it to set
up the credentials in advance, and then commit the whole lot after the point
of no return.

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     The credential bits from struct linux_binprm are, for the most part,
     replaced with a single credentials pointer (bprm->cred).  This means that
     all the creds can be calculated in advance and then applied at the point
     of no return with no possibility of failure.

     I would like to replace bprm->cap_effective with:

	cap_isclear(bprm->cap_effective)

     but this seems impossible due to special behaviour for processes of pid 1
     (they always retain their parent's capability masks where normally they'd
     be changed - see cap_bprm_set_creds()).

     The following sequence of events now happens:

     (a) At the start of do_execve, the current task's cred_exec_mutex is
     	 locked to prevent PTRACE_ATTACH from obsoleting the calculation of
     	 creds that we make.

     (a) prepare_exec_creds() is then called to make a copy of the current
     	 task's credentials and prepare it.  This copy is then assigned to
     	 bprm->cred.

  	 This renders security_bprm_alloc() and security_bprm_free()
     	 unnecessary, and so they've been removed.

     (b) The determination of unsafe execution is now performed immediately
     	 after (a) rather than later on in the code.  The result is stored in
     	 bprm->unsafe for future reference.

     (c) prepare_binprm() is called, possibly multiple times.

     	 (i) This applies the result of set[ug]id binaries to the new creds
     	     attached to bprm->cred.  Personality bit clearance is recorded,
     	     but now deferred on the basis that the exec procedure may yet
     	     fail.

         (ii) This then calls the new security_bprm_set_creds().  This should
	     calculate the new LSM and capability credentials into *bprm->cred.

	     This folds together security_bprm_set() and parts of
	     security_bprm_apply_creds() (these two have been removed).
	     Anything that might fail must be done at this point.

         (iii) bprm->cred_prepared is set to 1.

	     bprm->cred_prepared is 0 on the first pass of the security
	     calculations, and 1 on all subsequent passes.  This allows SELinux
	     in (ii) to base its calculations only on the initial script and
	     not on the interpreter.

     (d) flush_old_exec() is called to commit the task to execution.  This
     	 performs the following steps with regard to credentials:

	 (i) Clear pdeath_signal and set dumpable on certain circumstances that
	     may not be covered by commit_creds().

         (ii) Clear any bits in current->personality that were deferred from
             (c.i).

     (e) install_exec_creds() [compute_creds() as was] is called to install the
     	 new credentials.  This performs the following steps with regard to
     	 credentials:

         (i) Calls security_bprm_committing_creds() to apply any security
             requirements, such as flushing unauthorised files in SELinux, that
             must be done before the credentials are changed.

	     This is made up of bits of security_bprm_apply_creds() and
	     security_bprm_post_apply_creds(), both of which have been removed.
	     This function is not allowed to fail; anything that might fail
	     must have been done in (c.ii).

         (ii) Calls commit_creds() to apply the new credentials in a single
             assignment (more or less).  Possibly pdeath_signal and dumpable
             should be part of struct creds.

	 (iii) Unlocks the task's cred_replace_mutex, thus allowing
	     PTRACE_ATTACH to take place.

         (iv) Clears The bprm->cred pointer as the credentials it was holding
             are now immutable.

         (v) Calls security_bprm_committed_creds() to apply any security
             alterations that must be done after the creds have been changed.
             SELinux uses this to flush signals and signal handlers.

     (f) If an error occurs before (d.i), bprm_free() will call abort_creds()
     	 to destroy the proposed new credentials and will then unlock
     	 cred_replace_mutex.  No changes to the credentials will have been
     	 made.

 (2) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_bprm_alloc(), ->bprm_alloc_security()
     (*) security_bprm_free(), ->bprm_free_security()

     	 Removed in favour of preparing new credentials and modifying those.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()
     (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds()

     	 Removed; split between security_bprm_set_creds(),
     	 security_bprm_committing_creds() and security_bprm_committed_creds().

     (*) security_bprm_set(), ->bprm_set_security()

     	 Removed; folded into security_bprm_set_creds().

     (*) security_bprm_set_creds(), ->bprm_set_creds()

     	 New.  The new credentials in bprm->creds should be checked and set up
     	 as appropriate.  bprm->cred_prepared is 0 on the first call, 1 on the
     	 second and subsequent calls.

     (*) security_bprm_committing_creds(), ->bprm_committing_creds()
     (*) security_bprm_committed_creds(), ->bprm_committed_creds()

     	 New.  Apply the security effects of the new credentials.  This
     	 includes closing unauthorised files in SELinux.  This function may not
     	 fail.  When the former is called, the creds haven't yet been applied
     	 to the process; when the latter is called, they have.

 	 The former may access bprm->cred, the latter may not.

 (3) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) The bprm_security_struct struct has been removed in favour of using
     	 the credentials-under-construction approach.

     (c) flush_unauthorized_files() now takes a cred pointer and passes it on
     	 to inode_has_perm(), file_has_perm() and dentry_open().

Signed-off-by: David Howells 
Acked-by: James Morris 
Acked-by: Serge Hallyn 
Signed-off-by: James Morris

uclinux: fix gzip header parsing in binfmt_flat.c

2008-10-16T18:21:29+00:00

There are off-by-one errors in decompress_exec() when calculating the length of
optional "original file name" and "comment" fields: the "ret" index is not
incremented when terminating '\0' character is reached. The check of the buffer
overflow (after an "extra-field" length was taken into account) is also fixed.

I've encountered this off-by-one error when tried to reuse
gzip-header-parsing part of the decompress_exec() function.  There was an
"original file name" field in the payload (with miscalculated length) and
zlib_inflate() returned Z_DATA_ERROR.  But after the fix similar to this
one all worked fine.

Signed-off-by: Volodymyr G Lukiianyk 
Acked-by: Greg Ungerer 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

binfmt_flat: Stub in a FLAT_PLAT_INIT().

2008-08-11T11:17:55+00:00

This provides a FLAT_PLAT_INIT() arch hook for platforms that need to set
up specific register state prior to calling in to the process, as per
ELF_PLAT_INIT().

Signed-off-by: Takashi YOSHII 
Signed-off-by: Paul Mundt

tracehook: exec

2008-07-26T19:00:08+00:00

This moves all the ptrace hooks related to exec into tracehook.h inlines.

This also lifts the calls for tracing out of the binfmt load_binary hooks
into search_binary_handler() after it calls into the binfmt module.  This
change has no effect, since all the binfmt modules' load_binary functions
did the call at the end on success, and now search_binary_handler() does
it immediately after return if successful.  We consolidate the repeated
code, and binfmt modules no longer need to import ptrace_notify().

Signed-off-by: Roland McGrath 
Cc: Oleg Nesterov 
Reviewed-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

nommu: fix ksize() abuse

2008-06-06T18:29:13+00:00

The nommu binfmt code uses ksize() for pointers returned from do_mmap()
which is wrong.  This converts the call-sites to use the nommu specific
kobjsize() function which works as expected.

Cc: Christoph Lameter 
Cc: Matt Mackall 
Acked-by: Paul Mundt 
Acked-by: David Howells 
Signed-off-by: Pekka Enberg 
Acked-by: Greg Ungerer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds