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SubjectRe: BUG? atleast >=2.6.19-rc5, x86 chroot on x86_64
Date
Chuck Ebbert <76306.1226@compuserve.com> wrote:

> Here is a patch to reverse that. Kasper, can you test it?
> (Your filesystem is on a FAT/VFAT volume, I assume.)

Please don't revert that patch. If you do, you'll break CONFIG_BLOCK=n.

Can you compile and run the attached program as both 32-bit and 64-bit?

On my x86_64 test box, I did:

[root@andromeda ~]# mkfs.vfat /dev/sda5
[root@andromeda ~]# mount /dev/sda5 /mnt
[root@andromeda ~]# mkdir /mnt/a
[root@andromeda ~]# /tmp/ioctl /mnt/a # 32-bit
268 : 82187201, 82187202
268 : 82187201, 82187202
Calling VFAT_IOCTL_READDIR_BOTH32
Calling VFAT_IOCTL_READDIR_BOTH
[root@andromeda ~]# /tmp/ioctl /mnt/a # 64-bit
280 : 82307201, 82307202
268 : 82187201, 82187202
Calling VFAT_IOCTL_READDIR_BOTH32
ioctl: Inappropriate ioctl for device
Calling VFAT_IOCTL_READDIR_BOTH

Which is what I'd expect (the 64-bit ioctl does not support the 32-bit
function). Tracing the 64-bit version shows that the right numbers are being
given to the syscall, though strace decodes them as the same symbol if not in
raw mode:

[root@andromeda ~]# strace -eioctl -eraw=ioctl /tmp/ioctl /mnt/a
280 : 82307201, 82307202
268 : 82187201, 82187202
Calling VFAT_IOCTL_READDIR_BOTH32
ioctl(0x3, 0x82187201, 0x7fff9cec36c0) = -1 (errno 25)
ioctl: Inappropriate ioctl for device
Calling VFAT_IOCTL_READDIR_BOTH
ioctl(0x3, 0x82307201, 0x7fff9cec3490) = 0x1
Process 3410 detached

Applying the attached patch to the kernel produces the following elements in
the log for the 32-bit compilation:

==> fat_compat_dir_ioctl(82187201,ffa803b8)
==> fat_dir_ioctl(82307201,ffff810036a97ca8)
<== fat_dir_ioctl() = 1
<== fat_compat_dir_ioctl() = 1
==> fat_compat_dir_ioctl(82187201,ffa801a0)
==> fat_dir_ioctl(82307201,ffff810036a97ca8)
<== fat_dir_ioctl() = 1
<== fat_compat_dir_ioctl() = 1

and this for the 64-bit compilation:

==> fat_dir_ioctl(82187201,7fff031f69f0)
call fat_generic_ioctl()
<== fat_dir_ioctl() = -25
==> fat_dir_ioctl(82307201,7fff031f67c0)
<== fat_dir_ioctl() = 1

Which is entirely what I'd expect.

However, it's possible that the 64-bit kernel interface used to allow the
32-bit calls. If that's the case could you be running a 64-bit program
somewhere in your 32-bit chroot?

| i have only tested with >=rc5, thw folling, as an example, appears in
| dmesg:
| ioctl32(regedit.exe:11801): Unknown cmd fd(9) cmd(82187201){02}
| arg(00221000) on /home/redeeman
| ioctl32(regedit.exe:11801): Unknown cmd fd(9) cmd(82187201){02}
| arg(00221000) on /home/redeeman/.wine/drive_c/windows/system32
| ioctl32(regedit.exe:11801): Unknown cmd fd(9) cmd(82187201){02}
| arg(00221000) on /home/redeeman/.wine/drive_c/windows/system

How do you get that? I don't see anything like that. I've tried:

echo 1 >/proc/sys/kernel/compat-log

But that doesn't seem to do anything.

David

#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>

#define _IOC_NRBITS 8
#define _IOC_TYPEBITS 8
#define _IOC_SIZEBITS 14
#define _IOC_DIRBITS 2

#define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
#define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
#define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
#define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)

#define _IOC_NRSHIFT 0
#define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
#define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
#define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)

#define _IOC_NONE 0U
#define _IOC_WRITE 1U
#define _IOC_READ 2U

#define _IOC(dir,type,nr,size) \
(((dir) << _IOC_DIRSHIFT) | \
((type) << _IOC_TYPESHIFT) | \
((nr) << _IOC_NRSHIFT) | \
((size) << _IOC_SIZESHIFT))

extern unsigned int __invalid_size_argument_for_IOC;
#define _IOC_TYPECHECK(t) \
((sizeof(t) == sizeof(t[1]) && \
sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
sizeof(t) : __invalid_size_argument_for_IOC)

#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
#define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
#define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
#define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))

#define VFAT_IOCTL_READDIR_BOTH32 _IOR('r', 1, struct compat_dirent[2])
#define VFAT_IOCTL_READDIR_SHORT32 _IOR('r', 2, struct compat_dirent[2])
#define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2])
#define VFAT_IOCTL_READDIR_SHORT _IOR('r', 2, struct dirent [2])

typedef unsigned short u16;
typedef signed int s32;
typedef unsigned int u32;
typedef long __kernel_off_t;
typedef s32 compat_off_t;

struct compat_dirent {
u32 d_ino;
compat_off_t d_off;
u16 d_reclen;
char d_name[256];
};

struct dirent {
long d_ino;
__kernel_off_t d_off;
unsigned short d_reclen;
char d_name[256]; /* We must not include limits.h! */
};

#define O_DIRECTORY 00200000 /* must be a directory */

int main(int argc, char *argv[])
{
struct compat_dirent cdire[2];
struct dirent dire[2];
int fd;

printf("%zu : %lx, %lx\n",
sizeof(struct dirent),
(unsigned long) VFAT_IOCTL_READDIR_BOTH,
(unsigned long) VFAT_IOCTL_READDIR_SHORT);
printf("%zu : %lx, %lx\n",
sizeof(struct compat_dirent),
(unsigned long) VFAT_IOCTL_READDIR_BOTH32,
(unsigned long) VFAT_IOCTL_READDIR_SHORT32);

for (argv++; *argv; argv++) {
fd = open(*argv, O_DIRECTORY | O_RDONLY);
if (fd < 0) {
perror(*argv);
exit(1);
}

printf("Calling VFAT_IOCTL_READDIR_BOTH32\n");
if (ioctl(fd, VFAT_IOCTL_READDIR_BOTH32, cdire) < 0)
perror("ioctl");
printf("Calling VFAT_IOCTL_READDIR_BOTH\n");
if (ioctl(fd, VFAT_IOCTL_READDIR_BOTH, dire) < 0)
perror("ioctl");
close(fd);
}

return 0;
}
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 69c439f..eadaef1 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -704,6 +704,8 @@ static int fat_dir_ioctl(struct inode *
struct dirent __user *d1;
int ret, short_only, both;

+ printk("==> fat_dir_ioctl(%x,%lx)\n", cmd, arg);
+
switch (cmd) {
case VFAT_IOCTL_READDIR_SHORT:
short_only = 1;
@@ -714,7 +716,9 @@ static int fat_dir_ioctl(struct inode *
both = 1;
break;
default:
- return fat_generic_ioctl(inode, filp, cmd, arg);
+ printk("call fat_generic_ioctl()\n");
+ ret = fat_generic_ioctl(inode, filp, cmd, arg);
+ goto out;
}

d1 = (struct dirent __user *)arg;
@@ -739,6 +743,8 @@ static int fat_dir_ioctl(struct inode *
mutex_unlock(&inode->i_mutex);
if (ret >= 0)
ret = buf.result;
+out:
+ printk("<== fat_dir_ioctl() = %d\n", ret);
return ret;
}

@@ -769,6 +775,8 @@ static long fat_compat_dir_ioctl(struct
mm_segment_t oldfs = get_fs();
struct dirent d[2];

+ printk("==> fat_compat_dir_ioctl(%x,%lx)\n", cmd, arg);
+
switch (cmd) {
case VFAT_IOCTL_READDIR_BOTH32:
cmd = VFAT_IOCTL_READDIR_BOTH;
@@ -790,6 +798,7 @@ static long fat_compat_dir_ioctl(struct
ret |= fat_compat_put_dirent32(&d[0], p);
ret |= fat_compat_put_dirent32(&d[1], p + 1);
}
+ printk("<== fat_compat_dir_ioctl() = %d\n", ret);
return ret;
}
#endif /* CONFIG_COMPAT */
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