[184/289] exec: copy-and-paste the fixes into compat_do_execve() paths

Greg KH
2010-12-08T01:02:38Z

From: Oleg Nesterov <oleg@redhat.com>

commit 114279be2120a916e8a04feeb2ac976a10016f2f upstream.

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 <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/compat.c | 28 +++++++++++++++-------------
fs/exec.c | 8 ++++----
include/linux/binfmts.h | 4 ++++
3 files changed, 23 insertions(+), 17 deletions(-)

--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1378,6 +1378,10 @@ static int compat_count(compat_uptr_t __
argv++;
if (i++ >= max)
return -E2BIG;
+
+ if (fatal_signal_pending(current))
+ return -ERESTARTNOHAND;
+ cond_resched();
}
}
return i;
@@ -1419,6 +1423,12 @@ static int compat_copy_strings(int argc,
while (len > 0) {
int offset, bytes_to_copy;

+ if (fatal_signal_pending(current)) {
+ ret = -ERESTARTNOHAND;
+ goto out;
+ }
+ cond_resched();
+
offset = pos % PAGE_SIZE;
if (offset == 0)
offset = PAGE_SIZE;
@@ -1435,18 +1445,8 @@ static int compat_copy_strings(int argc,
if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
struct page *page;

-#ifdef CONFIG_STACK_GROWSUP
- ret = expand_stack_downwards(bprm->vma, pos);
- if (ret < 0) {
- /* We've exceed the stack rlimit. */
- ret = -E2BIG;
- goto out;
- }
-#endif
- ret = get_user_pages(current, bprm->mm, pos,
- 1, 1, 1, &page, NULL);
- if (ret <= 0) {
- /* We've exceed the stack rlimit. */
+ page = get_arg_page(bprm, pos, 1);
+ if (!page) {
ret = -E2BIG;
goto out;
}
@@ -1567,8 +1567,10 @@ int compat_do_execve(char * filename,
return retval;

out:
- if (bprm->mm)
+ if (bprm->mm) {
+ acct_arg_size(bprm, 0);
mmput(bprm->mm);
+ }

out_file:
if (bprm->file) {
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -157,7 +157,7 @@ out:

#ifdef CONFIG_MMU

-static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
struct mm_struct *mm = current->mm;
long diff = (long)(pages - bprm->vma_pages);
@@ -176,7 +176,7 @@ static void acct_arg_size(struct linux_b
#endif
}

-static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;
@@ -290,11 +290,11 @@ static bool valid_arg_len(struct linux_b

#else

-static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
}

-static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -60,6 +60,10 @@ struct linux_binprm{
unsigned long loader, exec;
};

+extern void acct_arg_size(struct linux_binprm *bprm, unsigned long pages);
+extern struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write);
+
#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
#define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)