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authorPeter Jones <pjones@redhat.com>2016-02-08 22:48:15 +0300
committerMatt Fleming <matt@codeblueprint.co.uk>2016-02-10 19:25:52 +0300
commited8b0de5a33d2a2557dce7f9429dca8cb5bc5879 (patch)
tree1dcd2e49cc432ae312677ec47453ec3abc18f1d2 /fs/efivarfs
parent8282f5d9c17fe15a9e658c06e3f343efae1a2a2f (diff)
downloadlinux-ed8b0de5a33d2a2557dce7f9429dca8cb5bc5879.tar.xz
efi: Make efivarfs entries immutable by default
"rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by: Peter Jones <pjones@redhat.com> Tested-by: Lee, Chun-Yi <jlee@suse.com> Acked-by: Matthew Garrett <mjg59@coreos.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Diffstat (limited to 'fs/efivarfs')
-rw-r--r--fs/efivarfs/file.c70
-rw-r--r--fs/efivarfs/inode.c30
-rw-r--r--fs/efivarfs/internal.h3
-rw-r--r--fs/efivarfs/super.c9
4 files changed, 98 insertions, 14 deletions
diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index c424e4813ec8..d48e0d261d78 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -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 @@ out_free:
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,
};
diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 3381b9da9ee6..e2ab6d0497f2 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -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];
@@ -138,7 +145,8 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
out:
if (err) {
kfree(var);
- iput(inode);
+ if (inode)
+ iput(inode);
}
return err;
}
diff --git a/fs/efivarfs/internal.h b/fs/efivarfs/internal.h
index b5ff16addb7c..b4505188e799 100644
--- a/fs/efivarfs/internal.h
+++ b/fs/efivarfs/internal.h
@@ -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;
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 8651ac28ec0d..dd029d13ea61 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -120,6 +120,7 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
char *name;
int len;
int err = -ENOMEM;
+ bool is_removable = false;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
@@ -137,13 +138,17 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
ucs2_as_utf8(name, entry->var.VariableName, len);
+ if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
+ is_removable = true;
+
name[len] = '-';
efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
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;
@@ -199,7 +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;