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21cb47be6f
The inode_owner_or_capable() helper determines whether the caller is the owner of the inode or is capable with respect to that inode. Allow it to handle idmapped mounts. If the inode is accessed through an idmapped mount it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Similarly, allow the inode_init_owner() helper to handle idmapped mounts. It initializes a new inode on idmapped mounts by mapping the fsuid and fsgid of the caller from the mount's user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
192 lines
4.0 KiB
C
192 lines
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2012 Red Hat, Inc.
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* Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
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*/
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#include <linux/efi.h>
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#include <linux/delay.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/mount.h>
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#include "internal.h"
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static ssize_t efivarfs_file_write(struct file *file,
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const char __user *userbuf, size_t count, loff_t *ppos)
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{
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struct efivar_entry *var = file->private_data;
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void *data;
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u32 attributes;
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struct inode *inode = file->f_mapping->host;
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unsigned long datasize = count - sizeof(attributes);
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ssize_t bytes;
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bool set = false;
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if (count < sizeof(attributes))
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return -EINVAL;
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if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
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return -EFAULT;
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if (attributes & ~(EFI_VARIABLE_MASK))
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return -EINVAL;
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data = memdup_user(userbuf + sizeof(attributes), datasize);
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if (IS_ERR(data))
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return PTR_ERR(data);
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bytes = efivar_entry_set_get_size(var, attributes, &datasize,
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data, &set);
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if (!set && bytes) {
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if (bytes == -ENOENT)
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bytes = -EIO;
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goto out;
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}
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if (bytes == -ENOENT) {
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drop_nlink(inode);
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d_delete(file->f_path.dentry);
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dput(file->f_path.dentry);
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} else {
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inode_lock(inode);
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i_size_write(inode, datasize + sizeof(attributes));
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inode->i_mtime = current_time(inode);
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inode_unlock(inode);
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}
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bytes = count;
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out:
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kfree(data);
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return bytes;
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}
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static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
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size_t count, loff_t *ppos)
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{
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struct efivar_entry *var = file->private_data;
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unsigned long datasize = 0;
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u32 attributes;
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void *data;
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ssize_t size = 0;
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int err;
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while (!__ratelimit(&file->f_cred->user->ratelimit))
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msleep(50);
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err = efivar_entry_size(var, &datasize);
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/*
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* efivarfs represents uncommitted variables with
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* zero-length files. Reading them should return EOF.
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*/
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if (err == -ENOENT)
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return 0;
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else if (err)
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return err;
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data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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size = efivar_entry_get(var, &attributes, &datasize,
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data + sizeof(attributes));
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if (size)
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goto out_free;
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memcpy(data, &attributes, sizeof(attributes));
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size = simple_read_from_buffer(userbuf, count, ppos,
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data, datasize + sizeof(attributes));
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out_free:
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kfree(data);
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return size;
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}
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static inline unsigned int efivarfs_getflags(struct inode *inode)
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{
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unsigned int i_flags;
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unsigned int flags = 0;
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i_flags = inode->i_flags;
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if (i_flags & S_IMMUTABLE)
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flags |= FS_IMMUTABLE_FL;
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return flags;
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}
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static int
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efivarfs_ioc_getxflags(struct file *file, void __user *arg)
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{
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struct inode *inode = file->f_mapping->host;
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unsigned int flags = efivarfs_getflags(inode);
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if (copy_to_user(arg, &flags, sizeof(flags)))
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return -EFAULT;
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return 0;
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}
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static int
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efivarfs_ioc_setxflags(struct file *file, void __user *arg)
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{
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struct inode *inode = file->f_mapping->host;
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unsigned int flags;
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unsigned int i_flags = 0;
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unsigned int oldflags = efivarfs_getflags(inode);
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int error;
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if (!inode_owner_or_capable(&init_user_ns, inode))
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return -EACCES;
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if (copy_from_user(&flags, arg, sizeof(flags)))
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return -EFAULT;
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if (flags & ~FS_IMMUTABLE_FL)
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return -EOPNOTSUPP;
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if (flags & FS_IMMUTABLE_FL)
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i_flags |= S_IMMUTABLE;
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error = mnt_want_write_file(file);
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if (error)
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return error;
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inode_lock(inode);
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error = vfs_ioc_setflags_prepare(inode, oldflags, flags);
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if (error)
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goto out;
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inode_set_flags(inode, i_flags, S_IMMUTABLE);
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out:
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inode_unlock(inode);
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mnt_drop_write_file(file);
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return error;
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}
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static long
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efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p)
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{
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void __user *arg = (void __user *)p;
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switch (cmd) {
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case FS_IOC_GETFLAGS:
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return efivarfs_ioc_getxflags(file, arg);
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case FS_IOC_SETFLAGS:
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return efivarfs_ioc_setxflags(file, arg);
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}
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return -ENOTTY;
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}
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const struct file_operations efivarfs_file_operations = {
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.open = simple_open,
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.read = efivarfs_file_read,
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.write = efivarfs_file_write,
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.llseek = no_llseek,
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.unlocked_ioctl = efivarfs_file_ioctl,
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};
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