linux-toradex.git/include/linux/binfmts.h, branch v2.6.39-rc7

binfmt_elf: cleanups

2011-01-13T16:03:12+00:00

This cleans up a few bits in binfmt_elf.c and binfmts.h:

- the hasvdso field in struct linux_binfmt is unused, so remove it and
  the only initialization of it

- the elf_map CPP symbol is not defined anywhere in the kernel, so
  remove an unnecessary #ifndef elf_map

- reduce excessive indentation in elf_format's initializer

- add missing spaces, remove extraneous spaces

No functional changes, but tested on x86 (32 and 64 bit), powerpc (32 and
64 bit), sparc64, arm, and alpha.

Signed-off-by: Mikael Pettersson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

exec: copy-and-paste the fixes into compat_do_execve() paths

2010-12-01T01:56:38+00:00

Note: this patch targets 2.6.37 and tries to be as simple as possible.
That is why it adds more copy-and-paste horror into fs/compat.c and
uglifies fs/exec.c, this will be cleanuped later.

compat_copy_strings() plays with bprm->vma/mm directly and thus has
two problems: it lacks the RLIMIT_STACK check and argv/envp memory
is not visible to oom killer.

Export acct_arg_size() and get_arg_page(), change compat_copy_strings()
to use get_arg_page(), change compat_do_execve() to do acct_arg_size(0)
as do_execve() does.

Add the fatal_signal_pending/cond_resched checks into compat_count() and
compat_copy_strings(), this matches the code in fs/exec.c and certainly
makes sense.

Signed-off-by: Oleg Nesterov 
Cc: KOSAKI Motohiro 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

exec: make argv/envp memory visible to oom-killer

2010-12-01T01:56:37+00:00

Brad Spengler published a local memory-allocation DoS that
evades the OOM-killer (though not the virtual memory RLIMIT):
http://www.grsecurity.net/~spender/64bit_dos.c

execve()->copy_strings() can allocate a lot of memory, but
this is not visible to oom-killer, nobody can see the nascent
bprm->mm and take it into account.

With this patch get_arg_page() increments current's MM_ANONPAGES
counter every time we allocate the new page for argv/envp. When
do_execve() succeds or fails, we change this counter back.

Technically this is not 100% correct, we can't know if the new
page is swapped out and turn MM_ANONPAGES into MM_SWAPENTS, but
I don't think this really matters and everything becomes correct
once exec changes ->mm or fails.

Reported-by: Brad Spengler 
Reviewed-and-discussed-by: KOSAKI Motohiro 
Signed-off-by: Oleg Nesterov 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

Make do_execve() take a const filename pointer

2010-08-18T01:07:43+00:00

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: David Howells 
Tested-by: Ralf Baechle 
Acked-by: Russell King 
Signed-off-by: Linus Torvalds

coredump: pass mm->flags as a coredump parameter for consistency

2010-03-06T19:26:46+00:00

Pass mm->flags as a coredump parameter for consistency.

 ---
1787         if (mm->core_state || !get_dumpable(mm)) {  <- (1)
1788                 up_write(&mm->mmap_sem);
1789                 put_cred(cred);
1790                 goto fail;
1791         }
1792
[...]
1798         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */ <-(2)
1799                 flag = O_EXCL;          /* Stop rewrite attacks */
1800                 cred->fsuid = 0;        /* Dump root private */
1801         }
 ---

Since dumpable bits are not protected by lock, there is a chance to change
these bits between (1) and (2).

To solve this issue, this patch copies mm->flags to
coredump_params.mm_flags at the beginning of do_coredump() and uses it
instead of get_dumpable() while dumping core.

This copy is also passed to binfmt->core_dump, since elf*_core_dump() uses
dump_filter bits in mm->flags.

[akpm@linux-foundation.org: fix merge]
Signed-off-by: Masami Hiramatsu 
Acked-by: Roland McGrath 
Cc: Hidehiro Kawai 
Cc: Oleg Nesterov 
Cc: Ingo Molnar 
Reviewed-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Split 'flush_old_exec' into two functions

2010-01-29T16:22:01+00:00

'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 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

mm: introduce coredump parameter structure

2009-12-17T23:45:31+00:00

Introduce coredump parameter data structure (struct coredump_params) to
simplify binfmt->core_dump() arguments.

Signed-off-by: Masami Hiramatsu 
Suggested-by: Ingo Molnar 
Cc: Hidehiro Kawai 
Cc: Oleg Nesterov 
Cc: Roland McGrath 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

exec: fix set_binfmt() vs sys_delete_module() race

2009-09-24T14:21:01+00:00

sys_delete_module() can set MODULE_STATE_GOING after
search_binary_handler() does try_module_get().  In this case
set_binfmt()->try_module_get() fails but since none of the callers
check the returned error, the task will run with the wrong old
->binfmt.

The proper fix should change all ->load_binary() methods, but we can
rely on fact that the caller must hold a reference to binfmt->module
and use __module_get() which never fails.

Signed-off-by: Oleg Nesterov 
Acked-by: Rusty Russell 
Cc: Hiroshi Shimamoto 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

exec: do not sleep in TASK_TRACED under ->cred_guard_mutex

2009-09-05T18:30:42+00:00

Tom Horsley reports that his debugger hangs when it tries to read
/proc/pid_of_tracee/maps, this happens since

	"mm_for_maps: take ->cred_guard_mutex to fix the race with exec"
	04b836cbf19e885f8366bccb2e4b0474346c02d

commit in 2.6.31.

But the root of the problem lies in the fact that do_execve() path calls
tracehook_report_exec() which can stop if the tracer sets PT_TRACE_EXEC.

The tracee must not sleep in TASK_TRACED holding this mutex.  Even if we
remove ->cred_guard_mutex from mm_for_maps() and proc_pid_attr_write(),
another task doing PTRACE_ATTACH should not hang until it is killed or the
tracee resumes.

With this patch do_execve() does not use ->cred_guard_mutex directly and
we do not hold it throughout, instead:

	- introduce prepare_bprm_creds() helper, it locks the mutex
	  and calls prepare_exec_creds() to initialize bprm->cred.

	- install_exec_creds() drops the mutex after commit_creds(),
	  and thus before tracehook_report_exec()->ptrace_stop().

	  or, if exec fails,

	  free_bprm() drops this mutex when bprm->cred != NULL which
	  indicates install_exec_creds() was not called.

Reported-by: Tom Horsley 
Signed-off-by: Oleg Nesterov 
Acked-by: David Howells 
Cc: Roland McGrath 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

alpha: binfmt_aout fix

2009-05-02T22:36:10+00:00

This fixes the problem introduced by commit 3bfacef412 (get rid of
special-casing the /sbin/loader on alpha): osf/1 ecoff binary segfaults
when binfmt_aout built as module.  That happens because aout binary
handler gets on the top of the binfmt list due to late registration, and
kernel attempts to execute the binary without preparatory work that must
be done by binfmt_loader.

Fixed by changing the registration order of the default binfmt handlers
using list_add_tail() and introducing insert_binfmt() function which
places new handler on the top of the binfmt list.  This might be generally
useful for installing arch-specific frontends for default handlers or just
for overriding them.

Signed-off-by: Ivan Kokshaysky 
Cc: Al Viro 
Cc: Richard Henderson 
Signed-off-by: Linus Torvalds