diff options
Diffstat (limited to 'fs/overlayfs/file.c')
| -rw-r--r-- | fs/overlayfs/file.c | 178 |
1 files changed, 148 insertions, 30 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 84dd957efa24..e235a635d9ec 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -1,9 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2017 Red Hat, 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 <linux/cred.h> @@ -11,6 +8,7 @@ #include <linux/mount.h> #include <linux/xattr.h> #include <linux/uio.h> +#include <linux/uaccess.h> #include "overlayfs.h" static char ovl_whatisit(struct inode *inode, struct inode *realinode) @@ -29,10 +27,11 @@ static struct file *ovl_open_realfile(const struct file *file, struct inode *inode = file_inode(file); struct file *realfile; const struct cred *old_cred; + int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY; old_cred = ovl_override_creds(inode->i_sb); - realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME, - realinode, current_cred()); + realfile = open_with_fake_path(&file->f_path, flags, realinode, + current_cred()); revert_creds(old_cred); pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n", @@ -50,7 +49,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags) int err; /* No atime modificaton on underlying */ - flags |= O_NOATIME; + flags |= O_NOATIME | FMODE_NONOTIFY; /* If some flag changed that cannot be changed then something's amiss */ if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK)) @@ -116,11 +115,10 @@ static int ovl_real_fdget(const struct file *file, struct fd *real) static int ovl_open(struct inode *inode, struct file *file) { - struct dentry *dentry = file_dentry(file); struct file *realfile; int err; - err = ovl_open_maybe_copy_up(dentry, file->f_flags); + err = ovl_maybe_copy_up(file_dentry(file), file->f_flags); if (err) return err; @@ -145,11 +143,47 @@ static int ovl_release(struct inode *inode, struct file *file) static loff_t ovl_llseek(struct file *file, loff_t offset, int whence) { - struct inode *realinode = ovl_inode_real(file_inode(file)); + struct inode *inode = file_inode(file); + struct fd real; + const struct cred *old_cred; + ssize_t ret; + + /* + * The two special cases below do not need to involve real fs, + * so we can optimizing concurrent callers. + */ + if (offset == 0) { + if (whence == SEEK_CUR) + return file->f_pos; + + if (whence == SEEK_SET) + return vfs_setpos(file, 0, 0); + } + + ret = ovl_real_fdget(file, &real); + if (ret) + return ret; + + /* + * Overlay file f_pos is the master copy that is preserved + * through copy up and modified on read/write, but only real + * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose + * limitations that are more strict than ->s_maxbytes for specific + * files, so we use the real file to perform seeks. + */ + inode_lock(inode); + real.file->f_pos = file->f_pos; - return generic_file_llseek_size(file, offset, whence, - realinode->i_sb->s_maxbytes, - i_size_read(realinode)); + old_cred = ovl_override_creds(inode->i_sb); + ret = vfs_llseek(real.file, offset, whence); + revert_creds(old_cred); + + file->f_pos = real.file->f_pos; + inode_unlock(inode); + + fdput(real); + + return ret; } static void ovl_file_accessed(struct file *file) @@ -372,34 +406,118 @@ static long ovl_real_ioctl(struct file *file, unsigned int cmd, return ret; } -static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd, + unsigned long arg, unsigned int iflags) { long ret; struct inode *inode = file_inode(file); + unsigned int old_iflags; + + if (!inode_owner_or_capable(inode)) + return -EACCES; + + ret = mnt_want_write_file(file); + if (ret) + return ret; + + inode_lock(inode); + + /* Check the capability before cred override */ + ret = -EPERM; + old_iflags = READ_ONCE(inode->i_flags); + if (((iflags ^ old_iflags) & (S_APPEND | S_IMMUTABLE)) && + !capable(CAP_LINUX_IMMUTABLE)) + goto unlock; + + ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY); + if (ret) + goto unlock; + + ret = ovl_real_ioctl(file, cmd, arg); + + ovl_copyflags(ovl_inode_real(inode), inode); +unlock: + inode_unlock(inode); + + mnt_drop_write_file(file); + + return ret; + +} + +static unsigned int ovl_fsflags_to_iflags(unsigned int flags) +{ + unsigned int iflags = 0; + + if (flags & FS_SYNC_FL) + iflags |= S_SYNC; + if (flags & FS_APPEND_FL) + iflags |= S_APPEND; + if (flags & FS_IMMUTABLE_FL) + iflags |= S_IMMUTABLE; + if (flags & FS_NOATIME_FL) + iflags |= S_NOATIME; + + return iflags; +} + +static long ovl_ioctl_set_fsflags(struct file *file, unsigned int cmd, + unsigned long arg) +{ + unsigned int flags; + + if (get_user(flags, (int __user *) arg)) + return -EFAULT; + + return ovl_ioctl_set_flags(file, cmd, arg, + ovl_fsflags_to_iflags(flags)); +} + +static unsigned int ovl_fsxflags_to_iflags(unsigned int xflags) +{ + unsigned int iflags = 0; + + if (xflags & FS_XFLAG_SYNC) + iflags |= S_SYNC; + if (xflags & FS_XFLAG_APPEND) + iflags |= S_APPEND; + if (xflags & FS_XFLAG_IMMUTABLE) + iflags |= S_IMMUTABLE; + if (xflags & FS_XFLAG_NOATIME) + iflags |= S_NOATIME; + + return iflags; +} + +static long ovl_ioctl_set_fsxflags(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct fsxattr fa; + + memset(&fa, 0, sizeof(fa)); + if (copy_from_user(&fa, (void __user *) arg, sizeof(fa))) + return -EFAULT; + + return ovl_ioctl_set_flags(file, cmd, arg, + ovl_fsxflags_to_iflags(fa.fsx_xflags)); +} + +static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + long ret; switch (cmd) { case FS_IOC_GETFLAGS: + case FS_IOC_FSGETXATTR: ret = ovl_real_ioctl(file, cmd, arg); break; case FS_IOC_SETFLAGS: - if (!inode_owner_or_capable(inode)) - return -EACCES; - - ret = mnt_want_write_file(file); - if (ret) - return ret; - - ret = ovl_copy_up_with_data(file_dentry(file)); - if (!ret) { - ret = ovl_real_ioctl(file, cmd, arg); - - inode_lock(inode); - ovl_copyflags(ovl_inode_real(inode), inode); - inode_unlock(inode); - } + ret = ovl_ioctl_set_fsflags(file, cmd, arg); + break; - mnt_drop_write_file(file); + case FS_IOC_FSSETXATTR: + ret = ovl_ioctl_set_fsxflags(file, cmd, arg); break; default: |