linux-stable/drivers/pci/syscall.c
Heiner Kallweit ef9e4005cb PCI: Align checking of syscall user config accessors
After 34e3207205 ("PCI: handle positive error codes"),
pci_user_read_config_*() and pci_user_write_config_*() return 0 or negative
errno values, not PCIBIOS_* values like PCIBIOS_SUCCESSFUL or
PCIBIOS_BAD_REGISTER_NUMBER.

Remove comparisons with PCIBIOS_SUCCESSFUL and check only for non-zero.  It
happens that PCIBIOS_SUCCESSFUL is zero, so this is not a functional
change, but it aligns this code with the user accessors.

[bhelgaas: commit log]
Fixes: 34e3207205 ("PCI: handle positive error codes")
Link: https://lore.kernel.org/r/f1220314-e518-1e18-bf94-8e6f8c703758@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2021-01-27 10:41:59 -06:00

136 lines
2.7 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* For architectures where we want to allow direct access to the PCI config
* stuff - it would probably be preferable on PCs too, but there people
* just do it by hand with the magic northbridge registers.
*/
#include <linux/errno.h>
#include <linux/pci.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include "pci.h"
SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
unsigned long, off, unsigned long, len, void __user *, buf)
{
struct pci_dev *dev;
u8 byte;
u16 word;
u32 dword;
long err;
int cfg_ret;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = -ENODEV;
dev = pci_get_domain_bus_and_slot(0, bus, dfn);
if (!dev)
goto error;
switch (len) {
case 1:
cfg_ret = pci_user_read_config_byte(dev, off, &byte);
break;
case 2:
cfg_ret = pci_user_read_config_word(dev, off, &word);
break;
case 4:
cfg_ret = pci_user_read_config_dword(dev, off, &dword);
break;
default:
err = -EINVAL;
goto error;
}
err = -EIO;
if (cfg_ret)
goto error;
switch (len) {
case 1:
err = put_user(byte, (unsigned char __user *)buf);
break;
case 2:
err = put_user(word, (unsigned short __user *)buf);
break;
case 4:
err = put_user(dword, (unsigned int __user *)buf);
break;
}
pci_dev_put(dev);
return err;
error:
/* ??? XFree86 doesn't even check the return value. They
just look for 0xffffffff in the output, since that's what
they get instead of a machine check on x86. */
switch (len) {
case 1:
put_user(-1, (unsigned char __user *)buf);
break;
case 2:
put_user(-1, (unsigned short __user *)buf);
break;
case 4:
put_user(-1, (unsigned int __user *)buf);
break;
}
pci_dev_put(dev);
return err;
}
SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
unsigned long, off, unsigned long, len, void __user *, buf)
{
struct pci_dev *dev;
u8 byte;
u16 word;
u32 dword;
int err = 0;
if (!capable(CAP_SYS_ADMIN) ||
security_locked_down(LOCKDOWN_PCI_ACCESS))
return -EPERM;
dev = pci_get_domain_bus_and_slot(0, bus, dfn);
if (!dev)
return -ENODEV;
switch (len) {
case 1:
err = get_user(byte, (u8 __user *)buf);
if (err)
break;
err = pci_user_write_config_byte(dev, off, byte);
if (err)
err = -EIO;
break;
case 2:
err = get_user(word, (u16 __user *)buf);
if (err)
break;
err = pci_user_write_config_word(dev, off, word);
if (err)
err = -EIO;
break;
case 4:
err = get_user(dword, (u32 __user *)buf);
if (err)
break;
err = pci_user_write_config_dword(dev, off, dword);
if (err)
err = -EIO;
break;
default:
err = -EINVAL;
break;
}
pci_dev_put(dev);
return err;
}