1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * For architectures where we want to allow direct access to the PCI config
4  * stuff - it would probably be preferable on PCs too, but there people
5  * just do it by hand with the magic northbridge registers.
6  */
7 
8 #include <linux/errno.h>
9 #include <linux/pci.h>
10 #include <linux/security.h>
11 #include <linux/syscalls.h>
12 #include <linux/uaccess.h>
13 #include "pci.h"
14 
SYSCALL_DEFINE5(pciconfig_read,unsigned long,bus,unsigned long,dfn,unsigned long,off,unsigned long,len,void __user *,buf)15 SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,
16 		unsigned long, off, unsigned long, len, void __user *, buf)
17 {
18 	struct pci_dev *dev;
19 	u8 byte;
20 	u16 word;
21 	u32 dword;
22 	int err, cfg_ret;
23 
24 	err = -EPERM;
25 	dev = NULL;
26 	if (!capable(CAP_SYS_ADMIN))
27 		goto error;
28 
29 	err = -ENODEV;
30 	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
31 	if (!dev)
32 		goto error;
33 
34 	switch (len) {
35 	case 1:
36 		cfg_ret = pci_user_read_config_byte(dev, off, &byte);
37 		break;
38 	case 2:
39 		cfg_ret = pci_user_read_config_word(dev, off, &word);
40 		break;
41 	case 4:
42 		cfg_ret = pci_user_read_config_dword(dev, off, &dword);
43 		break;
44 	default:
45 		err = -EINVAL;
46 		goto error;
47 	}
48 
49 	err = -EIO;
50 	if (cfg_ret)
51 		goto error;
52 
53 	switch (len) {
54 	case 1:
55 		err = put_user(byte, (unsigned char __user *)buf);
56 		break;
57 	case 2:
58 		err = put_user(word, (unsigned short __user *)buf);
59 		break;
60 	case 4:
61 		err = put_user(dword, (unsigned int __user *)buf);
62 		break;
63 	}
64 	pci_dev_put(dev);
65 	return err;
66 
67 error:
68 	/* ??? XFree86 doesn't even check the return value.  They
69 	   just look for 0xffffffff in the output, since that's what
70 	   they get instead of a machine check on x86.  */
71 	switch (len) {
72 	case 1:
73 		put_user(-1, (unsigned char __user *)buf);
74 		break;
75 	case 2:
76 		put_user(-1, (unsigned short __user *)buf);
77 		break;
78 	case 4:
79 		put_user(-1, (unsigned int __user *)buf);
80 		break;
81 	}
82 	pci_dev_put(dev);
83 	return err;
84 }
85 
SYSCALL_DEFINE5(pciconfig_write,unsigned long,bus,unsigned long,dfn,unsigned long,off,unsigned long,len,void __user *,buf)86 SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
87 		unsigned long, off, unsigned long, len, void __user *, buf)
88 {
89 	struct pci_dev *dev;
90 	u8 byte;
91 	u16 word;
92 	u32 dword;
93 	int err = 0;
94 
95 	if (!capable(CAP_SYS_ADMIN) ||
96 	    security_locked_down(LOCKDOWN_PCI_ACCESS))
97 		return -EPERM;
98 
99 	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
100 	if (!dev)
101 		return -ENODEV;
102 
103 	switch (len) {
104 	case 1:
105 		err = get_user(byte, (u8 __user *)buf);
106 		if (err)
107 			break;
108 		err = pci_user_write_config_byte(dev, off, byte);
109 		if (err)
110 			err = -EIO;
111 		break;
112 
113 	case 2:
114 		err = get_user(word, (u16 __user *)buf);
115 		if (err)
116 			break;
117 		err = pci_user_write_config_word(dev, off, word);
118 		if (err)
119 			err = -EIO;
120 		break;
121 
122 	case 4:
123 		err = get_user(dword, (u32 __user *)buf);
124 		if (err)
125 			break;
126 		err = pci_user_write_config_dword(dev, off, dword);
127 		if (err)
128 			err = -EIO;
129 		break;
130 
131 	default:
132 		err = -EINVAL;
133 		break;
134 	}
135 	pci_dev_put(dev);
136 	return err;
137 }
138