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exec: unify do_execve/compat_do_execve code

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Add the appropriate members into struct user_arg_ptr and teach
get_user_arg_ptr() to handle is_compat = T case correctly.

This allows us to remove the compat_do_execve() code from fs/compat.c
and reimplement compat_do_execve() as the trivial wrapper on top of
do_execve_common(is_compat => true).

In fact, this fixes another (minor) bug. "compat_uptr_t str" can
overflow after "str += len" in compat_copy_strings() if a 64bit
application execs via sys32_execve().

Unexport acct_arg_size() and get_arg_page(), fs/compat.c doesn't
need them any longer.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
This commit is contained in:
Oleg Nesterov
2011-03-06 18:02:54 +01:00
parent ba2d01629d
commit 0e028465d1
3 changed files with 50 additions and 251 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
fs/exec.c
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@@ -55,6 +55,7 @@
#include <linux/fs_struct.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
#include <linux/compat.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
@@ -167,7 +168,7 @@ out:
#ifdef CONFIG_MMU
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
struct mm_struct *mm = current->mm;
long diff = (long)(pages - bprm->vma_pages);
@@ -186,7 +187,7 @@ void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
#endif
}
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;
@@ -305,11 +306,11 @@ static bool valid_arg_len(struct linux_binprm *bprm, long len)
#else
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
}
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;
@@ -399,17 +400,36 @@ err:
}
struct user_arg_ptr {
const char __user *const __user *native;
#ifdef CONFIG_COMPAT
bool is_compat;
#endif
union {
const char __user *const __user *native;
#ifdef CONFIG_COMPAT
compat_uptr_t __user *compat;
#endif
} ptr;
};
static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
{
const char __user *ptr;
const char __user *native;
if (get_user(ptr, argv.native + nr))
#ifdef CONFIG_COMPAT
if (unlikely(argv.is_compat)) {
compat_uptr_t compat;
if (get_user(compat, argv.ptr.compat + nr))
return ERR_PTR(-EFAULT);
return compat_ptr(compat);
}
#endif
if (get_user(native, argv.ptr.native + nr))
return ERR_PTR(-EFAULT);
return ptr;
return native;
}
/*
@@ -419,7 +439,7 @@ static int count(struct user_arg_ptr argv, int max)
{
int i = 0;
if (argv.native != NULL) {
if (argv.ptr.native != NULL) {
for (;;) {
const char __user *p = get_user_arg_ptr(argv, i);
@@ -542,7 +562,7 @@ int copy_strings_kernel(int argc, const char *const *__argv,
int r;
mm_segment_t oldfs = get_fs();
struct user_arg_ptr argv = {
.native = (const char __user *const __user *)__argv,
.ptr.native = (const char __user *const __user *)__argv,
};
set_fs(KERNEL_DS);
@@ -1516,11 +1536,29 @@ int do_execve(const char *filename,
const char __user *const __user *__envp,
struct pt_regs *regs)
{
struct user_arg_ptr argv = { .native = __argv };
struct user_arg_ptr envp = { .native = __envp };
struct user_arg_ptr argv = { .ptr.native = __argv };
struct user_arg_ptr envp = { .ptr.native = __envp };
return do_execve_common(filename, argv, envp, regs);
}
#ifdef CONFIG_COMPAT
int compat_do_execve(char *filename,
compat_uptr_t __user *__argv,
compat_uptr_t __user *__envp,
struct pt_regs *regs)
{
struct user_arg_ptr argv = {
.is_compat = true,
.ptr.compat = __argv,
};
struct user_arg_ptr envp = {
.is_compat = true,
.ptr.compat = __envp,
};
return do_execve_common(filename, argv, envp, regs);
}
#endif
void set_binfmt(struct linux_binfmt *new)
{
struct mm_struct *mm = current->mm;