| /* |
| * Copyright (c) 1998-2014 Erez Zadok |
| * Copyright (c) 2009 Shrikar Archak |
| * Copyright (c) 2003-2014 Stony Brook University |
| * Copyright (c) 2003-2014 The Research Foundation of SUNY |
| * Copyright (C) 2013-2014, 2016 Motorola Mobility, LLC |
| * Copyright (C) 2017 Google, Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include "esdfs.h" |
| |
| static ssize_t esdfs_read(struct file *file, char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| int err; |
| struct file *lower_file; |
| struct dentry *dentry = file->f_path.dentry; |
| const struct cred *creds = |
| esdfs_override_creds(ESDFS_SB(dentry->d_sb), |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| err = vfs_read(lower_file, buf, count, ppos); |
| /* update our inode atime upon a successful lower read */ |
| if (err >= 0) |
| fsstack_copy_attr_atime(dentry->d_inode, |
| file_inode(lower_file)); |
| |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static ssize_t esdfs_write(struct file *file, const char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| int err; |
| |
| struct file *lower_file; |
| struct dentry *dentry = file->f_path.dentry; |
| const struct cred *creds = |
| esdfs_override_creds(ESDFS_SB(dentry->d_sb), |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| err = vfs_write(lower_file, buf, count, ppos); |
| /* update our inode times+sizes upon a successful lower write */ |
| if (err >= 0) { |
| fsstack_copy_inode_size(dentry->d_inode, |
| file_inode(lower_file)); |
| esdfs_copy_attr(dentry->d_inode, |
| file_inode(lower_file)); |
| } |
| |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static int esdfs_readdir(struct file *file, struct dir_context *ctx) |
| { |
| int err; |
| struct file *lower_file = NULL; |
| struct dentry *dentry = file->f_path.dentry; |
| const struct cred *creds = |
| esdfs_override_creds(ESDFS_SB(dentry->d_sb), |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| err = iterate_dir(lower_file, ctx); |
| file->f_pos = lower_file->f_pos; |
| if (err >= 0) /* copy the atime */ |
| fsstack_copy_attr_atime(dentry->d_inode, |
| file_inode(lower_file)); |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static long esdfs_unlocked_ioctl(struct file *file, unsigned int cmd, |
| unsigned long arg) |
| { |
| long err = -ENOTTY; |
| struct file *lower_file; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| if (cmd == ESDFS_IOC_DIS_ACCESS) { |
| if (!capable(CAP_SYS_ADMIN)) { |
| err = -EPERM; |
| goto out; |
| } |
| set_opt(sbi, ACCESS_DISABLE); |
| err = 0; |
| goto out; |
| } |
| |
| lower_file = esdfs_lower_file(file); |
| |
| /* XXX: use vfs_ioctl if/when VFS exports it */ |
| if (!lower_file || !lower_file->f_op) |
| goto out; |
| if (lower_file->f_op->unlocked_ioctl) |
| err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); |
| |
| /* some ioctls can change inode attributes (EXT2_IOC_SETFLAGS) */ |
| if (!err) |
| esdfs_copy_attr(file->f_path.dentry->d_inode, |
| file_inode(lower_file)); |
| out: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| #ifdef CONFIG_COMPAT |
| static long esdfs_compat_ioctl(struct file *file, unsigned int cmd, |
| unsigned long arg) |
| { |
| long err = -ENOTTY; |
| struct file *lower_file; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| |
| /* XXX: use vfs_ioctl if/when VFS exports it */ |
| if (!lower_file || !lower_file->f_op) |
| goto out; |
| if (lower_file->f_op->compat_ioctl) |
| err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); |
| |
| out: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| #endif |
| |
| static int esdfs_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| int err = 0; |
| bool willwrite; |
| struct file *lower_file; |
| const struct vm_operations_struct *saved_vm_ops = NULL; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| /* this might be deferred to mmap's writepage */ |
| willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags); |
| |
| /* |
| * File systems which do not implement ->writepage may use |
| * generic_file_readonly_mmap as their ->mmap op. If you call |
| * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL. |
| * But we cannot call the lower ->mmap op, so we can't tell that |
| * writeable mappings won't work. Therefore, our only choice is to |
| * check if the lower file system supports the ->writepage, and if |
| * not, return EINVAL (the same error that |
| * generic_file_readonly_mmap returns in that case). |
| */ |
| lower_file = esdfs_lower_file(file); |
| if (willwrite && !lower_file->f_mapping->a_ops->writepage) { |
| err = -EINVAL; |
| esdfs_msg(file->f_mapping->host->i_sb, KERN_INFO, |
| "lower file system does not support writeable mmap\n"); |
| goto out; |
| } |
| |
| /* |
| * find and save lower vm_ops. |
| * |
| * XXX: the VFS should have a cleaner way of finding the lower vm_ops |
| */ |
| if (!ESDFS_F(file)->lower_vm_ops) { |
| err = lower_file->f_op->mmap(lower_file, vma); |
| if (err) { |
| esdfs_msg(file->f_mapping->host->i_sb, KERN_ERR, |
| "lower mmap failed %d\n", err); |
| goto out; |
| } |
| saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */ |
| } |
| |
| /* |
| * Next 3 lines are all I need from generic_file_mmap. I definitely |
| * don't want its test for ->readpage which returns -ENOEXEC. |
| */ |
| file_accessed(file); |
| vma->vm_ops = &esdfs_vm_ops; |
| |
| file->f_mapping->a_ops = &esdfs_aops; /* set our aops */ |
| if (!ESDFS_F(file)->lower_vm_ops) /* save for our ->fault */ |
| ESDFS_F(file)->lower_vm_ops = saved_vm_ops; |
| |
| vma->vm_private_data = file; |
| get_file(lower_file); |
| vma->vm_file = lower_file; |
| out: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static int esdfs_open(struct inode *inode, struct file *file) |
| { |
| int err = 0; |
| struct file *lower_file = NULL; |
| struct path lower_path; |
| struct esdfs_sb_info *sbi = ESDFS_SB(inode->i_sb); |
| const struct cred *creds = |
| esdfs_override_creds(ESDFS_SB(inode->i_sb), |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| if (test_opt(sbi, ACCESS_DISABLE)) { |
| esdfs_revert_creds(creds, NULL); |
| return -ENOENT; |
| } |
| |
| /* don't open unhashed/deleted files */ |
| if (d_unhashed(file->f_path.dentry)) { |
| err = -ENOENT; |
| goto out_err; |
| } |
| |
| file->private_data = |
| kzalloc(sizeof(struct esdfs_file_info), GFP_KERNEL); |
| if (!ESDFS_F(file)) { |
| err = -ENOMEM; |
| goto out_err; |
| } |
| |
| /* open lower object and link esdfs's file struct to lower's */ |
| esdfs_get_lower_path(file->f_path.dentry, &lower_path); |
| lower_file = dentry_open(&lower_path, file->f_flags, current_cred()); |
| path_put(&lower_path); |
| if (IS_ERR(lower_file)) { |
| err = PTR_ERR(lower_file); |
| lower_file = esdfs_lower_file(file); |
| if (lower_file) { |
| esdfs_set_lower_file(file, NULL); |
| fput(lower_file); /* fput calls dput for lower_dentry */ |
| } |
| } else { |
| esdfs_set_lower_file(file, lower_file); |
| } |
| |
| if (err) |
| kfree(ESDFS_F(file)); |
| else |
| esdfs_copy_attr(inode, esdfs_lower_inode(inode)); |
| out_err: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static int esdfs_flush(struct file *file, fl_owner_t id) |
| { |
| int err = 0; |
| struct file *lower_file = NULL; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| if (lower_file && lower_file->f_op && lower_file->f_op->flush) { |
| filemap_write_and_wait(file->f_mapping); |
| err = lower_file->f_op->flush(lower_file, id); |
| } |
| |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| /* release all lower object references & free the file info structure */ |
| static int esdfs_file_release(struct inode *inode, struct file *file) |
| { |
| struct file *lower_file; |
| |
| lower_file = esdfs_lower_file(file); |
| if (lower_file) { |
| esdfs_set_lower_file(file, NULL); |
| fput(lower_file); |
| } |
| |
| kfree(ESDFS_F(file)); |
| return 0; |
| } |
| |
| static int esdfs_fsync(struct file *file, loff_t start, loff_t end, |
| int datasync) |
| { |
| int err; |
| struct file *lower_file; |
| struct path lower_path; |
| struct dentry *dentry = file->f_path.dentry; |
| const struct cred *creds = |
| esdfs_override_creds(ESDFS_SB(dentry->d_sb), |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| err = __generic_file_fsync(file, start, end, datasync); |
| if (err) |
| goto out; |
| lower_file = esdfs_lower_file(file); |
| esdfs_get_lower_path(dentry, &lower_path); |
| err = vfs_fsync_range(lower_file, start, end, datasync); |
| esdfs_put_lower_path(dentry, &lower_path); |
| out: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| static int esdfs_fasync(int fd, struct file *file, int flag) |
| { |
| int err = 0; |
| struct file *lower_file = NULL; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| lower_file = esdfs_lower_file(file); |
| if (lower_file->f_op && lower_file->f_op->fasync) |
| err = lower_file->f_op->fasync(fd, lower_file, flag); |
| |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| /* |
| * Wrapfs cannot use generic_file_llseek as ->llseek, because it would |
| * only set the offset of the upper file. So we have to implement our |
| * own method to set both the upper and lower file offsets |
| * consistently. |
| */ |
| static loff_t esdfs_file_llseek(struct file *file, loff_t offset, int whence) |
| { |
| int err; |
| struct file *lower_file; |
| struct esdfs_sb_info *sbi = ESDFS_SB(file->f_path.dentry->d_sb); |
| const struct cred *creds = esdfs_override_creds(sbi, |
| ESDFS_I(file->f_inode), NULL); |
| if (!creds) |
| return -ENOMEM; |
| |
| err = generic_file_llseek(file, offset, whence); |
| if (err < 0) |
| goto out; |
| |
| lower_file = esdfs_lower_file(file); |
| err = generic_file_llseek(lower_file, offset, whence); |
| |
| out: |
| esdfs_revert_creds(creds, NULL); |
| return err; |
| } |
| |
| /* |
| * Wrapfs read_iter, redirect modified iocb to lower read_iter |
| */ |
| ssize_t |
| esdfs_read_iter(struct kiocb *iocb, struct iov_iter *iter) |
| { |
| int err; |
| struct file *file = iocb->ki_filp, *lower_file; |
| |
| lower_file = esdfs_lower_file(file); |
| if (!lower_file->f_op->read_iter) { |
| err = -EINVAL; |
| goto out; |
| } |
| |
| get_file(lower_file); /* prevent lower_file from being released */ |
| iocb->ki_filp = lower_file; |
| err = lower_file->f_op->read_iter(iocb, iter); |
| iocb->ki_filp = file; |
| fput(lower_file); |
| /* update upper inode atime as needed */ |
| if (err >= 0 || err == -EIOCBQUEUED) |
| fsstack_copy_attr_atime(file->f_path.dentry->d_inode, |
| file_inode(lower_file)); |
| out: |
| return err; |
| } |
| |
| /* |
| * Wrapfs write_iter, redirect modified iocb to lower write_iter |
| */ |
| ssize_t |
| esdfs_write_iter(struct kiocb *iocb, struct iov_iter *iter) |
| { |
| int err; |
| struct file *file = iocb->ki_filp, *lower_file; |
| |
| lower_file = esdfs_lower_file(file); |
| if (!lower_file->f_op->write_iter) { |
| err = -EINVAL; |
| goto out; |
| } |
| |
| get_file(lower_file); /* prevent lower_file from being released */ |
| iocb->ki_filp = lower_file; |
| err = lower_file->f_op->write_iter(iocb, iter); |
| iocb->ki_filp = file; |
| fput(lower_file); |
| /* update upper inode times/sizes as needed */ |
| if (err >= 0 || err == -EIOCBQUEUED) { |
| fsstack_copy_inode_size(file->f_path.dentry->d_inode, |
| file_inode(lower_file)); |
| fsstack_copy_attr_times(file->f_path.dentry->d_inode, |
| file_inode(lower_file)); |
| } |
| out: |
| return err; |
| } |
| |
| const struct file_operations esdfs_main_fops = { |
| .llseek = generic_file_llseek, |
| .read = esdfs_read, |
| .write = esdfs_write, |
| .unlocked_ioctl = esdfs_unlocked_ioctl, |
| #ifdef CONFIG_COMPAT |
| .compat_ioctl = esdfs_compat_ioctl, |
| #endif |
| .mmap = esdfs_mmap, |
| .open = esdfs_open, |
| .flush = esdfs_flush, |
| .release = esdfs_file_release, |
| .fsync = esdfs_fsync, |
| .fasync = esdfs_fasync, |
| .read_iter = esdfs_read_iter, |
| .write_iter = esdfs_write_iter, |
| }; |
| |
| /* trimmed directory options */ |
| const struct file_operations esdfs_dir_fops = { |
| .llseek = esdfs_file_llseek, |
| .read = generic_read_dir, |
| .iterate = esdfs_readdir, |
| .unlocked_ioctl = esdfs_unlocked_ioctl, |
| #ifdef CONFIG_COMPAT |
| .compat_ioctl = esdfs_compat_ioctl, |
| #endif |
| .open = esdfs_open, |
| .release = esdfs_file_release, |
| .flush = esdfs_flush, |
| .fsync = esdfs_fsync, |
| .fasync = esdfs_fasync, |
| }; |