![David Howells](/assets/img/avatar_default.png)
Add a system call to make extended file information available, including file creation and some attribute flags where available through the underlying filesystem. The getattr inode operation is altered to take two additional arguments: a u32 request_mask and an unsigned int flags that indicate the synchronisation mode. This change is propagated to the vfs_getattr*() function. Functions like vfs_stat() are now inline wrappers around new functions vfs_statx() and vfs_statx_fd() to reduce stack usage. ======== OVERVIEW ======== The idea was initially proposed as a set of xattrs that could be retrieved with getxattr(), but the general preference proved to be for a new syscall with an extended stat structure. A number of requests were gathered for features to be included. The following have been included: (1) Make the fields a consistent size on all arches and make them large. (2) Spare space, request flags and information flags are provided for future expansion. (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an __s64). (4) Creation time: The SMB protocol carries the creation time, which could be exported by Samba, which will in turn help CIFS make use of FS-Cache as that can be used for coherency data (stx_btime). This is also specified in NFSv4 as a recommended attribute and could be exported by NFSD [Steve French]. (5) Lightweight stat: Ask for just those details of interest, and allow a netfs (such as NFS) to approximate anything not of interest, possibly without going to the server [Trond Myklebust, Ulrich Drepper, Andreas Dilger] (AT_STATX_DONT_SYNC). (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks its cached attributes are up to date [Trond Myklebust] (AT_STATX_FORCE_SYNC). And the following have been left out for future extension: (7) Data version number: Could be used by userspace NFS servers [Aneesh Kumar]. Can also be used to modify fill_post_wcc() in NFSD which retrieves i_version directly, but has just called vfs_getattr(). It could get it from the kstat struct if it used vfs_xgetattr() instead. (There's disagreement on the exact semantics of a single field, since not all filesystems do this the same way). (8) BSD stat compatibility: Including more fields from the BSD stat such as creation time (st_btime) and inode generation number (st_gen) [Jeremy Allison, Bernd Schubert]. (9) Inode generation number: Useful for FUSE and userspace NFS servers [Bernd Schubert]. (This was asked for but later deemed unnecessary with the open-by-handle capability available and caused disagreement as to whether it's a security hole or not). (10) Extra coherency data may be useful in making backups [Andreas Dilger]. (No particular data were offered, but things like last backup timestamp, the data version number and the DOS archive bit would come into this category). (11) Allow the filesystem to indicate what it can/cannot provide: A filesystem can now say it doesn't support a standard stat feature if that isn't available, so if, for instance, inode numbers or UIDs don't exist or are fabricated locally... (This requires a separate system call - I have an fsinfo() call idea for this). (12) Store a 16-byte volume ID in the superblock that can be returned in struct xstat [Steve French]. (Deferred to fsinfo). (13) Include granularity fields in the time data to indicate the granularity of each of the times (NFSv4 time_delta) [Steve French]. (Deferred to fsinfo). (14) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags. Note that the Linux IOC flags are a mess and filesystems such as Ext4 define flags that aren't in linux/fs.h, so translation in the kernel may be a necessity (or, possibly, we provide the filesystem type too). (Some attributes are made available in stx_attributes, but the general feeling was that the IOC flags were to ext[234]-specific and shouldn't be exposed through statx this way). (15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer, Michael Kerrisk]. (Deferred, probably to fsinfo. Finding out if there's an ACL or seclabal might require extra filesystem operations). (16) Femtosecond-resolution timestamps [Dave Chinner]. (A __reserved field has been left in the statx_timestamp struct for this - if there proves to be a need). (17) A set multiple attributes syscall to go with this. =============== NEW SYSTEM CALL =============== The new system call is: int ret = statx(int dfd, const char *filename, unsigned int flags, unsigned int mask, struct statx *buffer); The dfd, filename and flags parameters indicate the file to query, in a similar way to fstatat(). There is no equivalent of lstat() as that can be emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as that can be emulated by passing a NULL filename to statx() with the fd of interest in dfd. Whether or not statx() synchronises the attributes with the backing store can be controlled by OR'ing a value into the flags argument (this typically only affects network filesystems): (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this respect. (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise its attributes with the server - which might require data writeback to occur to get the timestamps correct. (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a network filesystem. The resulting values should be considered approximate. mask is a bitmask indicating the fields in struct statx that are of interest to the caller. The user should set this to STATX_BASIC_STATS to get the basic set returned by stat(). It should be noted that asking for more information may entail extra I/O operations. buffer points to the destination for the data. This must be 256 bytes in size. ====================== MAIN ATTRIBUTES RECORD ====================== The following structures are defined in which to return the main attribute set: struct statx_timestamp { __s64 tv_sec; __s32 tv_nsec; __s32 __reserved; }; struct statx { __u32 stx_mask; __u32 stx_blksize; __u64 stx_attributes; __u32 stx_nlink; __u32 stx_uid; __u32 stx_gid; __u16 stx_mode; __u16 __spare0[1]; __u64 stx_ino; __u64 stx_size; __u64 stx_blocks; __u64 __spare1[1]; struct statx_timestamp stx_atime; struct statx_timestamp stx_btime; struct statx_timestamp stx_ctime; struct statx_timestamp stx_mtime; __u32 stx_rdev_major; __u32 stx_rdev_minor; __u32 stx_dev_major; __u32 stx_dev_minor; __u64 __spare2[14]; }; The defined bits in request_mask and stx_mask are: STATX_TYPE Want/got stx_mode & S_IFMT STATX_MODE Want/got stx_mode & ~S_IFMT STATX_NLINK Want/got stx_nlink STATX_UID Want/got stx_uid STATX_GID Want/got stx_gid STATX_ATIME Want/got stx_atime{,_ns} STATX_MTIME Want/got stx_mtime{,_ns} STATX_CTIME Want/got stx_ctime{,_ns} STATX_INO Want/got stx_ino STATX_SIZE Want/got stx_size STATX_BLOCKS Want/got stx_blocks STATX_BASIC_STATS [The stuff in the normal stat struct] STATX_BTIME Want/got stx_btime{,_ns} STATX_ALL [All currently available stuff] stx_btime is the file creation time, stx_mask is a bitmask indicating the data provided and __spares*[] are where as-yet undefined fields can be placed. Time fields are structures with separate seconds and nanoseconds fields plus a reserved field in case we want to add even finer resolution. Note that times will be negative if before 1970; in such a case, the nanosecond fields will also be negative if not zero. The bits defined in the stx_attributes field convey information about a file, how it is accessed, where it is and what it does. The following attributes map to FS_*_FL flags and are the same numerical value: STATX_ATTR_COMPRESSED File is compressed by the fs STATX_ATTR_IMMUTABLE File is marked immutable STATX_ATTR_APPEND File is append-only STATX_ATTR_NODUMP File is not to be dumped STATX_ATTR_ENCRYPTED File requires key to decrypt in fs Within the kernel, the supported flags are listed by: KSTAT_ATTR_FS_IOC_FLAGS [Are any other IOC flags of sufficient general interest to be exposed through this interface?] New flags include: STATX_ATTR_AUTOMOUNT Object is an automount trigger These are for the use of GUI tools that might want to mark files specially, depending on what they are. Fields in struct statx come in a number of classes: (0) stx_dev_*, stx_blksize. These are local system information and are always available. (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino, stx_size, stx_blocks. These will be returned whether the caller asks for them or not. The corresponding bits in stx_mask will be set to indicate whether they actually have valid values. If the caller didn't ask for them, then they may be approximated. For example, NFS won't waste any time updating them from the server, unless as a byproduct of updating something requested. If the values don't actually exist for the underlying object (such as UID or GID on a DOS file), then the bit won't be set in the stx_mask, even if the caller asked for the value. In such a case, the returned value will be a fabrication. Note that there are instances where the type might not be valid, for instance Windows reparse points. (2) stx_rdev_*. This will be set only if stx_mode indicates we're looking at a blockdev or a chardev, otherwise will be 0. (3) stx_btime. Similar to (1), except this will be set to 0 if it doesn't exist. ======= TESTING ======= The following test program can be used to test the statx system call: samples/statx/test-statx.c Just compile and run, passing it paths to the files you want to examine. The file is built automatically if CONFIG_SAMPLES is enabled. Here's some example output. Firstly, an NFS directory that crosses to another FSID. Note that the AUTOMOUNT attribute is set because transiting this directory will cause d_automount to be invoked by the VFS. [root@andromeda ~]# /tmp/test-statx -A /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:26 Inode: 1703937 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------) Secondly, the result of automounting on that directory. [root@andromeda ~]# /tmp/test-statx /warthog/data statx(/warthog/data) = 0 results=7ff Size: 4096 Blocks: 8 IO Block: 1048576 directory Device: 00:27 Inode: 2 Links: 125 Access: (3777/drwxrwxrwx) Uid: 0 Gid: 4041 Access: 2016-11-24 09:02:12.219699527+0000 Modify: 2016-11-17 10:44:36.225653653+0000 Change: 2016-11-17 10:44:36.225653653+0000 Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1078 lines
24 KiB
C
1078 lines
24 KiB
C
/*
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*
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* Copyright (C) 2011 Novell Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/xattr.h>
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#include <linux/security.h>
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#include <linux/cred.h>
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#include <linux/module.h>
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#include <linux/posix_acl.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/atomic.h>
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#include <linux/ratelimit.h>
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#include "overlayfs.h"
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static unsigned short ovl_redirect_max = 256;
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module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
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MODULE_PARM_DESC(ovl_redirect_max,
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"Maximum length of absolute redirect xattr value");
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void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
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{
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int err;
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dget(wdentry);
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if (d_is_dir(wdentry))
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err = ovl_do_rmdir(wdir, wdentry);
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else
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err = ovl_do_unlink(wdir, wdentry);
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dput(wdentry);
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if (err) {
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pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
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wdentry, err);
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}
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}
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struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry)
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{
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struct dentry *temp;
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char name[20];
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static atomic_t temp_id = ATOMIC_INIT(0);
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/* counter is allowed to wrap, since temp dentries are ephemeral */
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snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
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temp = lookup_one_len(name, workdir, strlen(name));
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if (!IS_ERR(temp) && temp->d_inode) {
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pr_err("overlayfs: workdir/%s already exists\n", name);
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dput(temp);
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temp = ERR_PTR(-EIO);
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}
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return temp;
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}
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/* caller holds i_mutex on workdir */
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static struct dentry *ovl_whiteout(struct dentry *workdir,
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struct dentry *dentry)
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{
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int err;
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struct dentry *whiteout;
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struct inode *wdir = workdir->d_inode;
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whiteout = ovl_lookup_temp(workdir, dentry);
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if (IS_ERR(whiteout))
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return whiteout;
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err = ovl_do_whiteout(wdir, whiteout);
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if (err) {
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dput(whiteout);
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whiteout = ERR_PTR(err);
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}
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return whiteout;
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}
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int ovl_create_real(struct inode *dir, struct dentry *newdentry,
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struct cattr *attr, struct dentry *hardlink, bool debug)
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{
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int err;
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if (newdentry->d_inode)
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return -ESTALE;
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if (hardlink) {
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err = ovl_do_link(hardlink, dir, newdentry, debug);
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} else {
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switch (attr->mode & S_IFMT) {
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case S_IFREG:
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err = ovl_do_create(dir, newdentry, attr->mode, debug);
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break;
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case S_IFDIR:
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err = ovl_do_mkdir(dir, newdentry, attr->mode, debug);
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break;
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case S_IFCHR:
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case S_IFBLK:
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case S_IFIFO:
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case S_IFSOCK:
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err = ovl_do_mknod(dir, newdentry,
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attr->mode, attr->rdev, debug);
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break;
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case S_IFLNK:
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err = ovl_do_symlink(dir, newdentry, attr->link, debug);
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break;
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default:
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err = -EPERM;
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}
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}
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if (!err && WARN_ON(!newdentry->d_inode)) {
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/*
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* Not quite sure if non-instantiated dentry is legal or not.
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* VFS doesn't seem to care so check and warn here.
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*/
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err = -ENOENT;
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}
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return err;
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}
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static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
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{
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int err;
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err = ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
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if (!err)
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ovl_dentry_set_opaque(dentry);
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return err;
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}
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static int ovl_dir_getattr(const struct path *path, struct kstat *stat,
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u32 request_mask, unsigned int flags)
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{
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struct dentry *dentry = path->dentry;
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int err;
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enum ovl_path_type type;
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struct path realpath;
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const struct cred *old_cred;
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type = ovl_path_real(dentry, &realpath);
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old_cred = ovl_override_creds(dentry->d_sb);
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err = vfs_getattr(&realpath, stat, request_mask, flags);
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revert_creds(old_cred);
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if (err)
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return err;
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stat->dev = dentry->d_sb->s_dev;
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stat->ino = dentry->d_inode->i_ino;
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/*
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* It's probably not worth it to count subdirs to get the
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* correct link count. nlink=1 seems to pacify 'find' and
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* other utilities.
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*/
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if (OVL_TYPE_MERGE(type))
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stat->nlink = 1;
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return 0;
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}
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/* Common operations required to be done after creation of file on upper */
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static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
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struct dentry *newdentry, bool hardlink)
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{
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ovl_dentry_version_inc(dentry->d_parent);
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ovl_dentry_update(dentry, newdentry);
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if (!hardlink) {
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ovl_inode_update(inode, d_inode(newdentry));
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ovl_copyattr(newdentry->d_inode, inode);
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} else {
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WARN_ON(ovl_inode_real(inode, NULL) != d_inode(newdentry));
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inc_nlink(inode);
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}
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d_instantiate(dentry, inode);
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}
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static bool ovl_type_merge(struct dentry *dentry)
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{
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return OVL_TYPE_MERGE(ovl_path_type(dentry));
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}
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static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
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struct cattr *attr, struct dentry *hardlink)
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{
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struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
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struct inode *udir = upperdir->d_inode;
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struct dentry *newdentry;
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int err;
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if (!hardlink && !IS_POSIXACL(udir))
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attr->mode &= ~current_umask();
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inode_lock_nested(udir, I_MUTEX_PARENT);
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newdentry = lookup_one_len(dentry->d_name.name, upperdir,
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dentry->d_name.len);
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err = PTR_ERR(newdentry);
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if (IS_ERR(newdentry))
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goto out_unlock;
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err = ovl_create_real(udir, newdentry, attr, hardlink, false);
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if (err)
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goto out_dput;
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if (ovl_type_merge(dentry->d_parent)) {
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/* Setting opaque here is just an optimization, allow to fail */
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ovl_set_opaque(dentry, newdentry);
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}
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ovl_instantiate(dentry, inode, newdentry, !!hardlink);
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newdentry = NULL;
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out_dput:
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dput(newdentry);
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out_unlock:
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inode_unlock(udir);
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return err;
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}
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static int ovl_lock_rename_workdir(struct dentry *workdir,
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struct dentry *upperdir)
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{
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/* Workdir should not be the same as upperdir */
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if (workdir == upperdir)
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goto err;
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/* Workdir should not be subdir of upperdir and vice versa */
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if (lock_rename(workdir, upperdir) != NULL)
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goto err_unlock;
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return 0;
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err_unlock:
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unlock_rename(workdir, upperdir);
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err:
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pr_err("overlayfs: failed to lock workdir+upperdir\n");
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return -EIO;
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}
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static struct dentry *ovl_clear_empty(struct dentry *dentry,
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struct list_head *list)
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{
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struct dentry *workdir = ovl_workdir(dentry);
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struct inode *wdir = workdir->d_inode;
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struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
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struct inode *udir = upperdir->d_inode;
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struct path upperpath;
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struct dentry *upper;
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struct dentry *opaquedir;
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struct kstat stat;
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int err;
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if (WARN_ON(!workdir))
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return ERR_PTR(-EROFS);
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err = ovl_lock_rename_workdir(workdir, upperdir);
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if (err)
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goto out;
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ovl_path_upper(dentry, &upperpath);
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err = vfs_getattr(&upperpath, &stat,
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STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
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if (err)
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goto out_unlock;
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err = -ESTALE;
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if (!S_ISDIR(stat.mode))
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goto out_unlock;
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upper = upperpath.dentry;
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if (upper->d_parent->d_inode != udir)
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goto out_unlock;
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opaquedir = ovl_lookup_temp(workdir, dentry);
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err = PTR_ERR(opaquedir);
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if (IS_ERR(opaquedir))
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goto out_unlock;
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err = ovl_create_real(wdir, opaquedir,
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&(struct cattr){.mode = stat.mode}, NULL, true);
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if (err)
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goto out_dput;
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err = ovl_copy_xattr(upper, opaquedir);
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if (err)
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goto out_cleanup;
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err = ovl_set_opaque(dentry, opaquedir);
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if (err)
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goto out_cleanup;
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inode_lock(opaquedir->d_inode);
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err = ovl_set_attr(opaquedir, &stat);
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inode_unlock(opaquedir->d_inode);
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if (err)
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goto out_cleanup;
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err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
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if (err)
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goto out_cleanup;
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ovl_cleanup_whiteouts(upper, list);
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ovl_cleanup(wdir, upper);
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unlock_rename(workdir, upperdir);
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/* dentry's upper doesn't match now, get rid of it */
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d_drop(dentry);
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return opaquedir;
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out_cleanup:
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ovl_cleanup(wdir, opaquedir);
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out_dput:
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dput(opaquedir);
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out_unlock:
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unlock_rename(workdir, upperdir);
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out:
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return ERR_PTR(err);
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}
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static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
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{
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int err;
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struct dentry *ret = NULL;
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enum ovl_path_type type = ovl_path_type(dentry);
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LIST_HEAD(list);
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err = ovl_check_empty_dir(dentry, &list);
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if (err) {
|
|
ret = ERR_PTR(err);
|
|
goto out_free;
|
|
}
|
|
|
|
/*
|
|
* When removing an empty opaque directory, then it makes no sense to
|
|
* replace it with an exact replica of itself.
|
|
*
|
|
* If no upperdentry then skip clearing whiteouts.
|
|
*
|
|
* Can race with copy-up, since we don't hold the upperdir mutex.
|
|
* Doesn't matter, since copy-up can't create a non-empty directory
|
|
* from an empty one.
|
|
*/
|
|
if (OVL_TYPE_UPPER(type) && OVL_TYPE_MERGE(type))
|
|
ret = ovl_clear_empty(dentry, &list);
|
|
|
|
out_free:
|
|
ovl_cache_free(&list);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
|
|
const struct posix_acl *acl)
|
|
{
|
|
void *buffer;
|
|
size_t size;
|
|
int err;
|
|
|
|
if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
|
|
return 0;
|
|
|
|
size = posix_acl_to_xattr(NULL, acl, NULL, 0);
|
|
buffer = kmalloc(size, GFP_KERNEL);
|
|
if (!buffer)
|
|
return -ENOMEM;
|
|
|
|
size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
|
|
err = size;
|
|
if (err < 0)
|
|
goto out_free;
|
|
|
|
err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
|
|
out_free:
|
|
kfree(buffer);
|
|
return err;
|
|
}
|
|
|
|
static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
|
|
struct cattr *cattr,
|
|
struct dentry *hardlink)
|
|
{
|
|
struct dentry *workdir = ovl_workdir(dentry);
|
|
struct inode *wdir = workdir->d_inode;
|
|
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
struct inode *udir = upperdir->d_inode;
|
|
struct dentry *upper;
|
|
struct dentry *newdentry;
|
|
int err;
|
|
struct posix_acl *acl, *default_acl;
|
|
|
|
if (WARN_ON(!workdir))
|
|
return -EROFS;
|
|
|
|
if (!hardlink) {
|
|
err = posix_acl_create(dentry->d_parent->d_inode,
|
|
&cattr->mode, &default_acl, &acl);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = ovl_lock_rename_workdir(workdir, upperdir);
|
|
if (err)
|
|
goto out;
|
|
|
|
newdentry = ovl_lookup_temp(workdir, dentry);
|
|
err = PTR_ERR(newdentry);
|
|
if (IS_ERR(newdentry))
|
|
goto out_unlock;
|
|
|
|
upper = lookup_one_len(dentry->d_name.name, upperdir,
|
|
dentry->d_name.len);
|
|
err = PTR_ERR(upper);
|
|
if (IS_ERR(upper))
|
|
goto out_dput;
|
|
|
|
err = ovl_create_real(wdir, newdentry, cattr, hardlink, true);
|
|
if (err)
|
|
goto out_dput2;
|
|
|
|
/*
|
|
* mode could have been mutilated due to umask (e.g. sgid directory)
|
|
*/
|
|
if (!hardlink &&
|
|
!S_ISLNK(cattr->mode) &&
|
|
newdentry->d_inode->i_mode != cattr->mode) {
|
|
struct iattr attr = {
|
|
.ia_valid = ATTR_MODE,
|
|
.ia_mode = cattr->mode,
|
|
};
|
|
inode_lock(newdentry->d_inode);
|
|
err = notify_change(newdentry, &attr, NULL);
|
|
inode_unlock(newdentry->d_inode);
|
|
if (err)
|
|
goto out_cleanup;
|
|
}
|
|
if (!hardlink) {
|
|
err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
|
|
acl);
|
|
if (err)
|
|
goto out_cleanup;
|
|
|
|
err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
|
|
default_acl);
|
|
if (err)
|
|
goto out_cleanup;
|
|
}
|
|
|
|
if (!hardlink && S_ISDIR(cattr->mode)) {
|
|
err = ovl_set_opaque(dentry, newdentry);
|
|
if (err)
|
|
goto out_cleanup;
|
|
|
|
err = ovl_do_rename(wdir, newdentry, udir, upper,
|
|
RENAME_EXCHANGE);
|
|
if (err)
|
|
goto out_cleanup;
|
|
|
|
ovl_cleanup(wdir, upper);
|
|
} else {
|
|
err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
|
|
if (err)
|
|
goto out_cleanup;
|
|
}
|
|
ovl_instantiate(dentry, inode, newdentry, !!hardlink);
|
|
newdentry = NULL;
|
|
out_dput2:
|
|
dput(upper);
|
|
out_dput:
|
|
dput(newdentry);
|
|
out_unlock:
|
|
unlock_rename(workdir, upperdir);
|
|
out:
|
|
if (!hardlink) {
|
|
posix_acl_release(acl);
|
|
posix_acl_release(default_acl);
|
|
}
|
|
return err;
|
|
|
|
out_cleanup:
|
|
ovl_cleanup(wdir, newdentry);
|
|
goto out_dput2;
|
|
}
|
|
|
|
static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
|
|
struct cattr *attr, struct dentry *hardlink)
|
|
{
|
|
int err;
|
|
const struct cred *old_cred;
|
|
struct cred *override_cred;
|
|
|
|
err = ovl_copy_up(dentry->d_parent);
|
|
if (err)
|
|
return err;
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
err = -ENOMEM;
|
|
override_cred = prepare_creds();
|
|
if (override_cred) {
|
|
override_cred->fsuid = inode->i_uid;
|
|
override_cred->fsgid = inode->i_gid;
|
|
if (!hardlink) {
|
|
err = security_dentry_create_files_as(dentry,
|
|
attr->mode, &dentry->d_name, old_cred,
|
|
override_cred);
|
|
if (err) {
|
|
put_cred(override_cred);
|
|
goto out_revert_creds;
|
|
}
|
|
}
|
|
put_cred(override_creds(override_cred));
|
|
put_cred(override_cred);
|
|
|
|
if (!ovl_dentry_is_whiteout(dentry))
|
|
err = ovl_create_upper(dentry, inode, attr,
|
|
hardlink);
|
|
else
|
|
err = ovl_create_over_whiteout(dentry, inode, attr,
|
|
hardlink);
|
|
}
|
|
out_revert_creds:
|
|
revert_creds(old_cred);
|
|
if (!err) {
|
|
struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
|
|
|
|
WARN_ON(inode->i_mode != realinode->i_mode);
|
|
WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
|
|
WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
|
|
const char *link)
|
|
{
|
|
int err;
|
|
struct inode *inode;
|
|
struct cattr attr = {
|
|
.rdev = rdev,
|
|
.link = link,
|
|
};
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = -ENOMEM;
|
|
inode = ovl_new_inode(dentry->d_sb, mode, rdev);
|
|
if (!inode)
|
|
goto out_drop_write;
|
|
|
|
inode_init_owner(inode, dentry->d_parent->d_inode, mode);
|
|
attr.mode = inode->i_mode;
|
|
|
|
err = ovl_create_or_link(dentry, inode, &attr, NULL);
|
|
if (err)
|
|
iput(inode);
|
|
|
|
out_drop_write:
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
bool excl)
|
|
{
|
|
return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
|
|
}
|
|
|
|
static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
|
|
{
|
|
return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
|
|
}
|
|
|
|
static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
|
|
dev_t rdev)
|
|
{
|
|
/* Don't allow creation of "whiteout" on overlay */
|
|
if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
|
|
return -EPERM;
|
|
|
|
return ovl_create_object(dentry, mode, rdev, NULL);
|
|
}
|
|
|
|
static int ovl_symlink(struct inode *dir, struct dentry *dentry,
|
|
const char *link)
|
|
{
|
|
return ovl_create_object(dentry, S_IFLNK, 0, link);
|
|
}
|
|
|
|
static int ovl_link(struct dentry *old, struct inode *newdir,
|
|
struct dentry *new)
|
|
{
|
|
int err;
|
|
struct inode *inode;
|
|
|
|
err = ovl_want_write(old);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = ovl_copy_up(old);
|
|
if (err)
|
|
goto out_drop_write;
|
|
|
|
inode = d_inode(old);
|
|
ihold(inode);
|
|
|
|
err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old));
|
|
if (err)
|
|
iput(inode);
|
|
|
|
out_drop_write:
|
|
ovl_drop_write(old);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
|
|
{
|
|
struct dentry *workdir = ovl_workdir(dentry);
|
|
struct inode *wdir = workdir->d_inode;
|
|
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
struct inode *udir = upperdir->d_inode;
|
|
struct dentry *whiteout;
|
|
struct dentry *upper;
|
|
struct dentry *opaquedir = NULL;
|
|
int err;
|
|
int flags = 0;
|
|
|
|
if (WARN_ON(!workdir))
|
|
return -EROFS;
|
|
|
|
if (is_dir) {
|
|
opaquedir = ovl_check_empty_and_clear(dentry);
|
|
err = PTR_ERR(opaquedir);
|
|
if (IS_ERR(opaquedir))
|
|
goto out;
|
|
}
|
|
|
|
err = ovl_lock_rename_workdir(workdir, upperdir);
|
|
if (err)
|
|
goto out_dput;
|
|
|
|
upper = lookup_one_len(dentry->d_name.name, upperdir,
|
|
dentry->d_name.len);
|
|
err = PTR_ERR(upper);
|
|
if (IS_ERR(upper))
|
|
goto out_unlock;
|
|
|
|
err = -ESTALE;
|
|
if ((opaquedir && upper != opaquedir) ||
|
|
(!opaquedir && ovl_dentry_upper(dentry) &&
|
|
upper != ovl_dentry_upper(dentry))) {
|
|
goto out_dput_upper;
|
|
}
|
|
|
|
whiteout = ovl_whiteout(workdir, dentry);
|
|
err = PTR_ERR(whiteout);
|
|
if (IS_ERR(whiteout))
|
|
goto out_dput_upper;
|
|
|
|
if (d_is_dir(upper))
|
|
flags = RENAME_EXCHANGE;
|
|
|
|
err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
|
|
if (err)
|
|
goto kill_whiteout;
|
|
if (flags)
|
|
ovl_cleanup(wdir, upper);
|
|
|
|
ovl_dentry_version_inc(dentry->d_parent);
|
|
out_d_drop:
|
|
d_drop(dentry);
|
|
dput(whiteout);
|
|
out_dput_upper:
|
|
dput(upper);
|
|
out_unlock:
|
|
unlock_rename(workdir, upperdir);
|
|
out_dput:
|
|
dput(opaquedir);
|
|
out:
|
|
return err;
|
|
|
|
kill_whiteout:
|
|
ovl_cleanup(wdir, whiteout);
|
|
goto out_d_drop;
|
|
}
|
|
|
|
static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
|
|
{
|
|
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
|
|
struct inode *dir = upperdir->d_inode;
|
|
struct dentry *upper;
|
|
struct dentry *opaquedir = NULL;
|
|
int err;
|
|
|
|
/* Redirect dir can be !ovl_lower_positive && OVL_TYPE_MERGE */
|
|
if (is_dir && ovl_dentry_get_redirect(dentry)) {
|
|
opaquedir = ovl_check_empty_and_clear(dentry);
|
|
err = PTR_ERR(opaquedir);
|
|
if (IS_ERR(opaquedir))
|
|
goto out;
|
|
}
|
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
upper = lookup_one_len(dentry->d_name.name, upperdir,
|
|
dentry->d_name.len);
|
|
err = PTR_ERR(upper);
|
|
if (IS_ERR(upper))
|
|
goto out_unlock;
|
|
|
|
err = -ESTALE;
|
|
if ((opaquedir && upper != opaquedir) ||
|
|
(!opaquedir && upper != ovl_dentry_upper(dentry)))
|
|
goto out_dput_upper;
|
|
|
|
if (is_dir)
|
|
err = vfs_rmdir(dir, upper);
|
|
else
|
|
err = vfs_unlink(dir, upper, NULL);
|
|
ovl_dentry_version_inc(dentry->d_parent);
|
|
|
|
/*
|
|
* Keeping this dentry hashed would mean having to release
|
|
* upperpath/lowerpath, which could only be done if we are the
|
|
* sole user of this dentry. Too tricky... Just unhash for
|
|
* now.
|
|
*/
|
|
if (!err)
|
|
d_drop(dentry);
|
|
out_dput_upper:
|
|
dput(upper);
|
|
out_unlock:
|
|
inode_unlock(dir);
|
|
dput(opaquedir);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_do_remove(struct dentry *dentry, bool is_dir)
|
|
{
|
|
enum ovl_path_type type;
|
|
int err;
|
|
const struct cred *old_cred;
|
|
|
|
err = ovl_want_write(dentry);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = ovl_copy_up(dentry->d_parent);
|
|
if (err)
|
|
goto out_drop_write;
|
|
|
|
type = ovl_path_type(dentry);
|
|
|
|
old_cred = ovl_override_creds(dentry->d_sb);
|
|
if (!ovl_lower_positive(dentry))
|
|
err = ovl_remove_upper(dentry, is_dir);
|
|
else
|
|
err = ovl_remove_and_whiteout(dentry, is_dir);
|
|
revert_creds(old_cred);
|
|
if (!err) {
|
|
if (is_dir)
|
|
clear_nlink(dentry->d_inode);
|
|
else
|
|
drop_nlink(dentry->d_inode);
|
|
}
|
|
out_drop_write:
|
|
ovl_drop_write(dentry);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
static int ovl_unlink(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
return ovl_do_remove(dentry, false);
|
|
}
|
|
|
|
static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
return ovl_do_remove(dentry, true);
|
|
}
|
|
|
|
static bool ovl_type_merge_or_lower(struct dentry *dentry)
|
|
{
|
|
enum ovl_path_type type = ovl_path_type(dentry);
|
|
|
|
return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
|
|
}
|
|
|
|
static bool ovl_can_move(struct dentry *dentry)
|
|
{
|
|
return ovl_redirect_dir(dentry->d_sb) ||
|
|
!d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
|
|
}
|
|
|
|
static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
|
|
{
|
|
char *buf, *ret;
|
|
struct dentry *d, *tmp;
|
|
int buflen = ovl_redirect_max + 1;
|
|
|
|
if (samedir) {
|
|
ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
|
|
GFP_KERNEL);
|
|
goto out;
|
|
}
|
|
|
|
buf = ret = kmalloc(buflen, GFP_TEMPORARY);
|
|
if (!buf)
|
|
goto out;
|
|
|
|
buflen--;
|
|
buf[buflen] = '\0';
|
|
for (d = dget(dentry); !IS_ROOT(d);) {
|
|
const char *name;
|
|
int thislen;
|
|
|
|
spin_lock(&d->d_lock);
|
|
name = ovl_dentry_get_redirect(d);
|
|
if (name) {
|
|
thislen = strlen(name);
|
|
} else {
|
|
name = d->d_name.name;
|
|
thislen = d->d_name.len;
|
|
}
|
|
|
|
/* If path is too long, fall back to userspace move */
|
|
if (thislen + (name[0] != '/') > buflen) {
|
|
ret = ERR_PTR(-EXDEV);
|
|
spin_unlock(&d->d_lock);
|
|
goto out_put;
|
|
}
|
|
|
|
buflen -= thislen;
|
|
memcpy(&buf[buflen], name, thislen);
|
|
tmp = dget_dlock(d->d_parent);
|
|
spin_unlock(&d->d_lock);
|
|
|
|
dput(d);
|
|
d = tmp;
|
|
|
|
/* Absolute redirect: finished */
|
|
if (buf[buflen] == '/')
|
|
break;
|
|
buflen--;
|
|
buf[buflen] = '/';
|
|
}
|
|
ret = kstrdup(&buf[buflen], GFP_KERNEL);
|
|
out_put:
|
|
dput(d);
|
|
kfree(buf);
|
|
out:
|
|
return ret ? ret : ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
static int ovl_set_redirect(struct dentry *dentry, bool samedir)
|
|
{
|
|
int err;
|
|
const char *redirect = ovl_dentry_get_redirect(dentry);
|
|
|
|
if (redirect && (samedir || redirect[0] == '/'))
|
|
return 0;
|
|
|
|
redirect = ovl_get_redirect(dentry, samedir);
|
|
if (IS_ERR(redirect))
|
|
return PTR_ERR(redirect);
|
|
|
|
err = ovl_do_setxattr(ovl_dentry_upper(dentry), OVL_XATTR_REDIRECT,
|
|
redirect, strlen(redirect), 0);
|
|
if (!err) {
|
|
spin_lock(&dentry->d_lock);
|
|
ovl_dentry_set_redirect(dentry, redirect);
|
|
spin_unlock(&dentry->d_lock);
|
|
} else {
|
|
kfree(redirect);
|
|
if (err == -EOPNOTSUPP)
|
|
ovl_clear_redirect_dir(dentry->d_sb);
|
|
else
|
|
pr_warn_ratelimited("overlay: failed to set redirect (%i)\n", err);
|
|
/* Fall back to userspace copy-up */
|
|
err = -EXDEV;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int ovl_rename(struct inode *olddir, struct dentry *old,
|
|
struct inode *newdir, struct dentry *new,
|
|
unsigned int flags)
|
|
{
|
|
int err;
|
|
struct dentry *old_upperdir;
|
|
struct dentry *new_upperdir;
|
|
struct dentry *olddentry;
|
|
struct dentry *newdentry;
|
|
struct dentry *trap;
|
|
bool old_opaque;
|
|
bool new_opaque;
|
|
bool cleanup_whiteout = false;
|
|
bool overwrite = !(flags & RENAME_EXCHANGE);
|
|
bool is_dir = d_is_dir(old);
|
|
bool new_is_dir = d_is_dir(new);
|
|
bool samedir = olddir == newdir;
|
|
struct dentry *opaquedir = NULL;
|
|
const struct cred *old_cred = NULL;
|
|
|
|
err = -EINVAL;
|
|
if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
|
|
goto out;
|
|
|
|
flags &= ~RENAME_NOREPLACE;
|
|
|
|
/* Don't copy up directory trees */
|
|
err = -EXDEV;
|
|
if (!ovl_can_move(old))
|
|
goto out;
|
|
if (!overwrite && !ovl_can_move(new))
|
|
goto out;
|
|
|
|
err = ovl_want_write(old);
|
|
if (err)
|
|
goto out;
|
|
|
|
err = ovl_copy_up(old);
|
|
if (err)
|
|
goto out_drop_write;
|
|
|
|
err = ovl_copy_up(new->d_parent);
|
|
if (err)
|
|
goto out_drop_write;
|
|
if (!overwrite) {
|
|
err = ovl_copy_up(new);
|
|
if (err)
|
|
goto out_drop_write;
|
|
}
|
|
|
|
old_cred = ovl_override_creds(old->d_sb);
|
|
|
|
if (overwrite && new_is_dir && ovl_type_merge_or_lower(new)) {
|
|
opaquedir = ovl_check_empty_and_clear(new);
|
|
err = PTR_ERR(opaquedir);
|
|
if (IS_ERR(opaquedir)) {
|
|
opaquedir = NULL;
|
|
goto out_revert_creds;
|
|
}
|
|
}
|
|
|
|
if (overwrite) {
|
|
if (ovl_lower_positive(old)) {
|
|
if (!ovl_dentry_is_whiteout(new)) {
|
|
/* Whiteout source */
|
|
flags |= RENAME_WHITEOUT;
|
|
} else {
|
|
/* Switch whiteouts */
|
|
flags |= RENAME_EXCHANGE;
|
|
}
|
|
} else if (is_dir && ovl_dentry_is_whiteout(new)) {
|
|
flags |= RENAME_EXCHANGE;
|
|
cleanup_whiteout = true;
|
|
}
|
|
}
|
|
|
|
old_upperdir = ovl_dentry_upper(old->d_parent);
|
|
new_upperdir = ovl_dentry_upper(new->d_parent);
|
|
|
|
trap = lock_rename(new_upperdir, old_upperdir);
|
|
|
|
olddentry = lookup_one_len(old->d_name.name, old_upperdir,
|
|
old->d_name.len);
|
|
err = PTR_ERR(olddentry);
|
|
if (IS_ERR(olddentry))
|
|
goto out_unlock;
|
|
|
|
err = -ESTALE;
|
|
if (olddentry != ovl_dentry_upper(old))
|
|
goto out_dput_old;
|
|
|
|
newdentry = lookup_one_len(new->d_name.name, new_upperdir,
|
|
new->d_name.len);
|
|
err = PTR_ERR(newdentry);
|
|
if (IS_ERR(newdentry))
|
|
goto out_dput_old;
|
|
|
|
old_opaque = ovl_dentry_is_opaque(old);
|
|
new_opaque = ovl_dentry_is_opaque(new);
|
|
|
|
err = -ESTALE;
|
|
if (ovl_dentry_upper(new)) {
|
|
if (opaquedir) {
|
|
if (newdentry != opaquedir)
|
|
goto out_dput;
|
|
} else {
|
|
if (newdentry != ovl_dentry_upper(new))
|
|
goto out_dput;
|
|
}
|
|
} else {
|
|
if (!d_is_negative(newdentry) &&
|
|
(!new_opaque || !ovl_is_whiteout(newdentry)))
|
|
goto out_dput;
|
|
}
|
|
|
|
if (olddentry == trap)
|
|
goto out_dput;
|
|
if (newdentry == trap)
|
|
goto out_dput;
|
|
|
|
if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
|
|
goto out_dput;
|
|
|
|
err = 0;
|
|
if (is_dir) {
|
|
if (ovl_type_merge_or_lower(old))
|
|
err = ovl_set_redirect(old, samedir);
|
|
else if (!old_opaque && ovl_type_merge(new->d_parent))
|
|
err = ovl_set_opaque(old, olddentry);
|
|
if (err)
|
|
goto out_dput;
|
|
}
|
|
if (!overwrite && new_is_dir) {
|
|
if (ovl_type_merge_or_lower(new))
|
|
err = ovl_set_redirect(new, samedir);
|
|
else if (!new_opaque && ovl_type_merge(old->d_parent))
|
|
err = ovl_set_opaque(new, newdentry);
|
|
if (err)
|
|
goto out_dput;
|
|
}
|
|
|
|
err = ovl_do_rename(old_upperdir->d_inode, olddentry,
|
|
new_upperdir->d_inode, newdentry, flags);
|
|
if (err)
|
|
goto out_dput;
|
|
|
|
if (cleanup_whiteout)
|
|
ovl_cleanup(old_upperdir->d_inode, newdentry);
|
|
|
|
ovl_dentry_version_inc(old->d_parent);
|
|
ovl_dentry_version_inc(new->d_parent);
|
|
|
|
out_dput:
|
|
dput(newdentry);
|
|
out_dput_old:
|
|
dput(olddentry);
|
|
out_unlock:
|
|
unlock_rename(new_upperdir, old_upperdir);
|
|
out_revert_creds:
|
|
revert_creds(old_cred);
|
|
out_drop_write:
|
|
ovl_drop_write(old);
|
|
out:
|
|
dput(opaquedir);
|
|
return err;
|
|
}
|
|
|
|
const struct inode_operations ovl_dir_inode_operations = {
|
|
.lookup = ovl_lookup,
|
|
.mkdir = ovl_mkdir,
|
|
.symlink = ovl_symlink,
|
|
.unlink = ovl_unlink,
|
|
.rmdir = ovl_rmdir,
|
|
.rename = ovl_rename,
|
|
.link = ovl_link,
|
|
.setattr = ovl_setattr,
|
|
.create = ovl_create,
|
|
.mknod = ovl_mknod,
|
|
.permission = ovl_permission,
|
|
.getattr = ovl_dir_getattr,
|
|
.listxattr = ovl_listxattr,
|
|
.get_acl = ovl_get_acl,
|
|
.update_time = ovl_update_time,
|
|
};
|