Commit 4682c211 authored by Ingo Molnar's avatar Ingo Molnar

Merge tag 'efi-urgent' of...

Merge tag 'efi-urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into x86/urgent

Pull EFI fixes from Matt Fleming:

 * Prevent accidental deletion of EFI variables through efivarfs that
   may brick machines. We use a whitelist of known-safe variables to
   allow things like installing distributions to work out of the box, and
   instead restrict vendor-specific variable deletion by making
   non-whitelist variables immutable (Peter Jones)
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parents 1926e54f ed8b0de5
......@@ -14,3 +14,10 @@ filesystem.
efivarfs is typically mounted like this,
mount -t efivarfs none /sys/firmware/efi/efivars
Due to the presence of numerous firmware bugs where removing non-standard
UEFI variables causes the system firmware to fail to POST, efivarfs
files that are not well-known standardized variables are created
as immutable files. This doesn't prevent removal - "chattr -i" will work -
but it does prevent this kind of failure from being accomplished
accidentally.
......@@ -221,7 +221,7 @@ sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
}
if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
efivar_validate(name, data, size) == false) {
efivar_validate(vendor, name, data, size) == false) {
printk(KERN_ERR "efivars: Malformed variable content\n");
return -EINVAL;
}
......@@ -447,7 +447,8 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
}
if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
efivar_validate(name, data, size) == false) {
efivar_validate(new_var->VendorGuid, name, data,
size) == false) {
printk(KERN_ERR "efivars: Malformed variable content\n");
return -EINVAL;
}
......@@ -540,38 +541,30 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
static int
efivar_create_sysfs_entry(struct efivar_entry *new_var)
{
int i, short_name_size;
int short_name_size;
char *short_name;
unsigned long variable_name_size;
efi_char16_t *variable_name;
unsigned long utf8_name_size;
efi_char16_t *variable_name = new_var->var.VariableName;
int ret;
variable_name = new_var->var.VariableName;
variable_name_size = ucs2_strlen(variable_name) * sizeof(efi_char16_t);
/*
* Length of the variable bytes in ASCII, plus the '-' separator,
* Length of the variable bytes in UTF8, plus the '-' separator,
* plus the GUID, plus trailing NUL
*/
short_name_size = variable_name_size / sizeof(efi_char16_t)
+ 1 + EFI_VARIABLE_GUID_LEN + 1;
short_name = kzalloc(short_name_size, GFP_KERNEL);
utf8_name_size = ucs2_utf8size(variable_name);
short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;
short_name = kmalloc(short_name_size, GFP_KERNEL);
if (!short_name)
return -ENOMEM;
/* Convert Unicode to normal chars (assume top bits are 0),
ala UTF-8 */
for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
short_name[i] = variable_name[i] & 0xFF;
}
ucs2_as_utf8(short_name, variable_name, short_name_size);
/* This is ugly, but necessary to separate one vendor's
private variables from another's. */
*(short_name + strlen(short_name)) = '-';
short_name[utf8_name_size] = '-';
efi_guid_to_str(&new_var->var.VendorGuid,
short_name + strlen(short_name));
short_name + utf8_name_size + 1);
new_var->kobj.kset = efivars_kset;
......
......@@ -165,66 +165,131 @@ validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
}
struct variable_validate {
efi_guid_t vendor;
char *name;
bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
unsigned long len);
};
/*
* This is the list of variables we need to validate, as well as the
* whitelist for what we think is safe not to default to immutable.
*
* If it has a validate() method that's not NULL, it'll go into the
* validation routine. If not, it is assumed valid, but still used for
* whitelisting.
*
* Note that it's sorted by {vendor,name}, but globbed names must come after
* any other name with the same prefix.
*/
static const struct variable_validate variable_validate[] = {
{ "BootNext", validate_uint16 },
{ "BootOrder", validate_boot_order },
{ "DriverOrder", validate_boot_order },
{ "Boot*", validate_load_option },
{ "Driver*", validate_load_option },
{ "ConIn", validate_device_path },
{ "ConInDev", validate_device_path },
{ "ConOut", validate_device_path },
{ "ConOutDev", validate_device_path },
{ "ErrOut", validate_device_path },
{ "ErrOutDev", validate_device_path },
{ "Timeout", validate_uint16 },
{ "Lang", validate_ascii_string },
{ "PlatformLang", validate_ascii_string },
{ "", NULL },
{ EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
{ EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
{ EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
{ EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
{ EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
{ EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
{ EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
{ EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
{ EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
{ EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
{ NULL_GUID, "", NULL },
};
static bool
variable_matches(const char *var_name, size_t len, const char *match_name,
int *match)
{
for (*match = 0; ; (*match)++) {
char c = match_name[*match];
char u = var_name[*match];
/* Wildcard in the matching name means we've matched */
if (c == '*')
return true;
/* Case sensitive match */
if (!c && *match == len)
return true;
if (c != u)
return false;
if (!c)
return true;
}
return true;
}
bool
efivar_validate(efi_char16_t *var_name, u8 *data, unsigned long len)
efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
unsigned long data_size)
{
int i;
u16 *unicode_name = var_name;
unsigned long utf8_size;
u8 *utf8_name;
utf8_size = ucs2_utf8size(var_name);
utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
if (!utf8_name)
return false;
for (i = 0; variable_validate[i].validate != NULL; i++) {
ucs2_as_utf8(utf8_name, var_name, utf8_size);
utf8_name[utf8_size] = '\0';
for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
const char *name = variable_validate[i].name;
int match;
int match = 0;
for (match = 0; ; match++) {
char c = name[match];
u16 u = unicode_name[match];
if (efi_guidcmp(vendor, variable_validate[i].vendor))
continue;
/* All special variables are plain ascii */
if (u > 127)
if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
if (variable_validate[i].validate == NULL)
break;
kfree(utf8_name);
return variable_validate[i].validate(var_name, match,
data, data_size);
}
}
kfree(utf8_name);
return true;
}
EXPORT_SYMBOL_GPL(efivar_validate);
/* Wildcard in the matching name means we've matched */
if (c == '*')
return variable_validate[i].validate(var_name,
match, data, len);
bool
efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
size_t len)
{
int i;
bool found = false;
int match = 0;
/* Case sensitive match */
if (c != u)
break;
/*
* Check if our variable is in the validated variables list
*/
for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
if (efi_guidcmp(variable_validate[i].vendor, vendor))
continue;
/* Reached the end of the string while matching */
if (!c)
return variable_validate[i].validate(var_name,
match, data, len);
if (variable_matches(var_name, len,
variable_validate[i].name, &match)) {
found = true;
break;
}
}
return true;
/*
* If it's in our list, it is removable.
*/
return found;
}
EXPORT_SYMBOL_GPL(efivar_validate);
EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
static efi_status_t
check_var_size(u32 attributes, unsigned long size)
......@@ -852,7 +917,7 @@ int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
*set = false;
if (efivar_validate(name, data, *size) == false)
if (efivar_validate(*vendor, name, data, *size) == false)
return -EINVAL;
/*
......
......@@ -10,6 +10,7 @@
#include <linux/efi.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include "internal.h"
......@@ -103,9 +104,78 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
return size;
}
static int
efivarfs_ioc_getxflags(struct file *file, void __user *arg)
{
struct inode *inode = file->f_mapping->host;
unsigned int i_flags;
unsigned int flags = 0;
i_flags = inode->i_flags;
if (i_flags & S_IMMUTABLE)
flags |= FS_IMMUTABLE_FL;
if (copy_to_user(arg, &flags, sizeof(flags)))
return -EFAULT;
return 0;
}
static int
efivarfs_ioc_setxflags(struct file *file, void __user *arg)
{
struct inode *inode = file->f_mapping->host;
unsigned int flags;
unsigned int i_flags = 0;
int error;
if (!inode_owner_or_capable(inode))
return -EACCES;
if (copy_from_user(&flags, arg, sizeof(flags)))
return -EFAULT;
if (flags & ~FS_IMMUTABLE_FL)
return -EOPNOTSUPP;
if (!capable(CAP_LINUX_IMMUTABLE))
return -EPERM;
if (flags & FS_IMMUTABLE_FL)
i_flags |= S_IMMUTABLE;
error = mnt_want_write_file(file);
if (error)
return error;
inode_lock(inode);
inode_set_flags(inode, i_flags, S_IMMUTABLE);
inode_unlock(inode);
mnt_drop_write_file(file);
return 0;
}
long
efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p)
{
void __user *arg = (void __user *)p;
switch (cmd) {
case FS_IOC_GETFLAGS:
return efivarfs_ioc_getxflags(file, arg);
case FS_IOC_SETFLAGS:
return efivarfs_ioc_setxflags(file, arg);
}
return -ENOTTY;
}
const struct file_operations efivarfs_file_operations = {
.open = simple_open,
.read = efivarfs_file_read,
.write = efivarfs_file_write,
.llseek = no_llseek,
.unlocked_ioctl = efivarfs_file_ioctl,
};
......@@ -15,7 +15,8 @@
#include "internal.h"
struct inode *efivarfs_get_inode(struct super_block *sb,
const struct inode *dir, int mode, dev_t dev)
const struct inode *dir, int mode,
dev_t dev, bool is_removable)
{
struct inode *inode = new_inode(sb);
......@@ -23,6 +24,7 @@ struct inode *efivarfs_get_inode(struct super_block *sb,
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_flags = is_removable ? 0 : S_IMMUTABLE;
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_fop = &efivarfs_file_operations;
......@@ -102,22 +104,17 @@ static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
static int efivarfs_create(struct inode *dir, struct dentry *dentry,
umode_t mode, bool excl)
{
struct inode *inode;
struct inode *inode = NULL;
struct efivar_entry *var;
int namelen, i = 0, err = 0;
bool is_removable = false;
if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
return -EINVAL;
inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
if (!inode)
return -ENOMEM;
var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
if (!var) {
err = -ENOMEM;
goto out;
}
if (!var)
return -ENOMEM;
/* length of the variable name itself: remove GUID and separator */
namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
......@@ -125,6 +122,16 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
&var->var.VendorGuid);
if (efivar_variable_is_removable(var->var.VendorGuid,
dentry->d_name.name, namelen))
is_removable = true;
inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0, is_removable);
if (!inode) {
err = -ENOMEM;
goto out;
}
for (i = 0; i < namelen; i++)
var->var.VariableName[i] = dentry->d_name.name[i];
......@@ -138,6 +145,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
out:
if (err) {
kfree(var);
if (inode)
iput(inode);
}
return err;
......
......@@ -15,7 +15,8 @@ extern const struct file_operations efivarfs_file_operations;
extern const struct inode_operations efivarfs_dir_inode_operations;
extern bool efivarfs_valid_name(const char *str, int len);
extern struct inode *efivarfs_get_inode(struct super_block *sb,
const struct inode *dir, int mode, dev_t dev);
const struct inode *dir, int mode, dev_t dev,
bool is_removable);
extern struct list_head efivarfs_list;
......
......@@ -118,8 +118,9 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
struct dentry *dentry, *root = sb->s_root;
unsigned long size = 0;
char *name;
int len, i;
int len;
int err = -ENOMEM;
bool is_removable = false;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
......@@ -128,15 +129,17 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
memcpy(entry->var.VariableName, name16, name_size);
memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
len = ucs2_strlen(entry->var.VariableName);
len = ucs2_utf8size(entry->var.VariableName);
/* name, plus '-', plus GUID, plus NUL*/
name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
if (!name)
goto fail;
for (i = 0; i < len; i++)
name[i] = entry->var.VariableName[i] & 0xFF;
ucs2_as_utf8(name, entry->var.VariableName, len);
if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
is_removable = true;
name[len] = '-';
......@@ -144,7 +147,8 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0);
inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
is_removable);
if (!inode)
goto fail_name;
......@@ -200,7 +204,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_d_op = &efivarfs_d_ops;
sb->s_time_gran = 1;
inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
if (!inode)
return -ENOMEM;
inode->i_op = &efivarfs_dir_inode_operations;
......
......@@ -1199,7 +1199,10 @@ int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
struct list_head *head, bool remove);
bool efivar_validate(efi_char16_t *var_name, u8 *data, unsigned long len);
bool efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
unsigned long data_size);
bool efivar_variable_is_removable(efi_guid_t vendor, const char *name,
size_t len);
extern struct work_struct efivar_work;
void efivar_run_worker(void);
......
......@@ -11,4 +11,8 @@ unsigned long ucs2_strlen(const ucs2_char_t *s);
unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);
unsigned long ucs2_utf8size(const ucs2_char_t *src);
unsigned long ucs2_as_utf8(u8 *dest, const ucs2_char_t *src,
unsigned long maxlength);
#endif /* _LINUX_UCS2_STRING_H_ */
......@@ -49,3 +49,65 @@ ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
}
}
EXPORT_SYMBOL(ucs2_strncmp);
unsigned long
ucs2_utf8size(const ucs2_char_t *src)
{
unsigned long i;
unsigned long j = 0;
for (i = 0; i < ucs2_strlen(src); i++) {
u16 c = src[i];
if (c > 0x800)
j += 3;
else if (c > 0x80)
j += 2;
else
j += 1;
}
return j;
}
EXPORT_SYMBOL(ucs2_utf8size);
/*
* copy at most maxlength bytes of whole utf8 characters to dest from the
* ucs2 string src.
*
* The return value is the number of characters copied, not including the
* final NUL character.
*/
unsigned long
ucs2_as_utf8(u8 *dest, const ucs2_char_t *src, unsigned long maxlength)
{
unsigned int i;
unsigned long j = 0;
unsigned long limit = ucs2_strnlen(src, maxlength);
for (i = 0; maxlength && i < limit; i++) {
u16 c = src[i];
if (c > 0x800) {
if (maxlength < 3)
break;
maxlength -= 3;
dest[j++] = 0xe0 | (c & 0xf000) >> 12;
dest[j++] = 0x80 | (c & 0x0fc0) >> 8;
dest[j++] = 0x80 | (c & 0x003f);
} else if (c > 0x80) {
if (maxlength < 2)
break;
maxlength -= 2;
dest[j++] = 0xc0 | (c & 0xfe0) >> 5;
dest[j++] = 0x80 | (c & 0x01f);
} else {
maxlength -= 1;
dest[j++] = c & 0x7f;
}
}
if (maxlength)
dest[j] = '\0';
return j;
}
EXPORT_SYMBOL(ucs2_as_utf8);
......@@ -88,7 +88,11 @@ test_delete()
exit 1
fi
rm $file 2>/dev/null
if [ $? -ne 0 ]; then
chattr -i $file
rm $file
fi
if [ -e $file ]; then
echo "$file couldn't be deleted" >&2
......@@ -111,6 +115,7 @@ test_zero_size_delete()
exit 1
fi
chattr -i $file
printf "$attrs" > $file
if [ -e $file ]; then
......@@ -141,8 +146,12 @@ test_valid_filenames()
echo "$file could not be created" >&2
ret=1
else
rm $file 2>/dev/null
if [ $? -ne 0 ]; then
chattr -i $file
rm $file
fi
fi
done
exit $ret
......@@ -174,7 +183,11 @@ test_invalid_filenames()
if [ -e $file ]; then
echo "Creating $file should have failed" >&2
rm $file 2>/dev/null
if [ $? -ne 0 ]; then
chattr -i $file
rm $file
fi
ret=1
fi
done
......
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/fs.h>
static int set_immutable(const char *path, int immutable)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
if (immutable)
flags |= FS_IMMUTABLE_FL;
else
flags &= ~FS_IMMUTABLE_FL;
rc = ioctl(fd, FS_IOC_SETFLAGS, &flags);
error = errno;
close(fd);
errno = error;
return rc;
}
static int get_immutable(const char *path)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
close(fd);
if (flags & FS_IMMUTABLE_FL)
return 1;
return 0;
}
int main(int argc, char **argv)
{
......@@ -27,7 +85,7 @@ int main(int argc, char **argv)
buf[4] = 0;
/* create a test variable */
fd = open(path, O_WRONLY | O_CREAT);
fd = open(path, O_WRONLY | O_CREAT, 0600);
if (fd < 0) {
perror("open(O_WRONLY)");
return EXIT_FAILURE;
......@@ -41,6 +99,18 @@ int main(int argc, char **argv)
close(fd);
rc = get_immutable(path);
if (rc < 0) {
perror("ioctl(FS_IOC_GETFLAGS)");
return EXIT_FAILURE;
} else if (rc) {
rc = set_immutable(path, 0);
if (rc < 0) {
perror("ioctl(FS_IOC_SETFLAGS)");
return EXIT_FAILURE;
}
}
fd = open(path, O_RDONLY);
if (fd < 0) {
perror("open");
......
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