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gvisor/pkg/abi/linux/file.go
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Tiwei Bie eca83ac68c Add initial support for EROFS 
This patch adds initial support for EROFS [1]. Below is a brief
summary of the supported features.

Both inode formats are supported:

- compact format (32 bytes);
- extended format (64 bytes);

Below data layouts are supported:

- flat file data without data inline (no extent);
- flat file data with tail packing data inline (no extent);

Below file types are supported:

- directory;
- regular file;
- symlink;

Special files (e.g. fifo) can be listed, but cannot be accessed.

With this patch, sentry will be able to mount the EROFS image
created with below command and access the files on it.

 mkfs.erofs -E noinline_data <IMAGE FILE> <SOURCE DIRECTORY>

[1] https://docs.kernel.org/filesystems/erofs.html

Updates #8956

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
2023-10-04 18:15:30 +08:00

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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package linux
import (
"fmt"
"strings"
"gvisor.dev/gvisor/pkg/abi"
)
// Constants for open(2).
const (
O_ACCMODE = 000000003
O_RDONLY = 000000000
O_WRONLY = 000000001
O_RDWR = 000000002
O_CREAT = 000000100
O_EXCL = 000000200
O_NOCTTY = 000000400
O_TRUNC = 000001000
O_APPEND = 000002000
O_NONBLOCK = 000004000
O_DSYNC = 000010000
O_ASYNC = 000020000
O_NOATIME = 001000000
O_CLOEXEC = 002000000
O_SYNC = 004000000 // __O_SYNC in Linux
O_PATH = 010000000
O_TMPFILE = 020000000 // __O_TMPFILE in Linux
)
// Constants for fstatat(2).
const (
AT_SYMLINK_NOFOLLOW = 0x100
)
// Constants for mount(2).
const (
MS_RDONLY = 0x1
MS_NOSUID = 0x2
MS_NODEV = 0x4
MS_NOEXEC = 0x8
MS_SYNCHRONOUS = 0x10
MS_REMOUNT = 0x20
MS_MANDLOCK = 0x40
MS_DIRSYNC = 0x80
MS_NOATIME = 0x400
MS_NODIRATIME = 0x800
MS_BIND = 0x1000
MS_MOVE = 0x2000
MS_REC = 0x4000
MS_POSIXACL = 0x10000
MS_UNBINDABLE = 0x20000
MS_PRIVATE = 0x40000
MS_SLAVE = 0x80000
MS_SHARED = 0x100000
MS_RELATIME = 0x200000
MS_KERNMOUNT = 0x400000
MS_I_VERSION = 0x800000
MS_STRICTATIME = 0x1000000
MS_MGC_VAL = 0xC0ED0000
MS_MGC_MSK = 0xffff0000
)
// Constants for umount2(2).
const (
MNT_FORCE = 0x1
MNT_DETACH = 0x2
MNT_EXPIRE = 0x4
UMOUNT_NOFOLLOW = 0x8
)
// Constants for unlinkat(2).
const (
AT_REMOVEDIR = 0x200
)
// Constants for linkat(2) and fchownat(2).
const (
AT_SYMLINK_FOLLOW = 0x400
AT_EMPTY_PATH = 0x1000
)
// Constants for faccessat2(2).
const (
AT_EACCESS = 0x200
)
// Constants for all file-related ...at(2) syscalls.
const (
AT_FDCWD = -100
)
// Special values for the ns field in utimensat(2).
const (
UTIME_NOW = ((1 << 30) - 1)
UTIME_OMIT = ((1 << 30) - 2)
)
// MaxSymlinkTraversals is the maximum number of links that will be followed by
// the kernel to resolve a symlink.
const MaxSymlinkTraversals = 40
// Constants for flock(2).
const (
LOCK_SH = 1 // shared lock
LOCK_EX = 2 // exclusive lock
LOCK_NB = 4 // or'd with one of the above to prevent blocking
LOCK_UN = 8 // remove lock
)
// Values for mode_t.
const (
S_IFMT = 0170000
S_IFSOCK = 0140000
S_IFLNK = 0120000
S_IFREG = 0100000
S_IFBLK = 060000
S_IFDIR = 040000
S_IFCHR = 020000
S_IFIFO = 010000
FileTypeMask = S_IFMT
ModeSocket = S_IFSOCK
ModeSymlink = S_IFLNK
ModeRegular = S_IFREG
ModeBlockDevice = S_IFBLK
ModeDirectory = S_IFDIR
ModeCharacterDevice = S_IFCHR
ModeNamedPipe = S_IFIFO
S_ISUID = 04000
S_ISGID = 02000
S_ISVTX = 01000
ModeSetUID = S_ISUID
ModeSetGID = S_ISGID
ModeSticky = S_ISVTX
ModeUserAll = 0700
ModeUserRead = 0400
ModeUserWrite = 0200
ModeUserExec = 0100
ModeGroupAll = 0070
ModeGroupRead = 0040
ModeGroupWrite = 0020
ModeGroupExec = 0010
ModeOtherAll = 0007
ModeOtherRead = 0004
ModeOtherWrite = 0002
ModeOtherExec = 0001
PermissionsMask = 0777
)
// Values for linux_dirent64.d_type.
const (
DT_UNKNOWN = 0
DT_FIFO = 1
DT_CHR = 2
DT_DIR = 4
DT_BLK = 6
DT_REG = 8
DT_LNK = 10
DT_SOCK = 12
DT_WHT = 14
)
// DirentType are the friendly strings for linux_dirent64.d_type.
var DirentType = abi.ValueSet{
DT_UNKNOWN: "DT_UNKNOWN",
DT_FIFO: "DT_FIFO",
DT_CHR: "DT_CHR",
DT_DIR: "DT_DIR",
DT_BLK: "DT_BLK",
DT_REG: "DT_REG",
DT_LNK: "DT_LNK",
DT_SOCK: "DT_SOCK",
DT_WHT: "DT_WHT",
}
// Values for fs on-disk file types.
const (
FT_UNKNOWN = 0
FT_REG_FILE = 1
FT_DIR = 2
FT_CHRDEV = 3
FT_BLKDEV = 4
FT_FIFO = 5
FT_SOCK = 6
FT_SYMLINK = 7
FT_MAX = 8
)
// Conversion from fs on-disk file type to dirent type.
var direntTypeByFileType = [FT_MAX]uint8{
FT_UNKNOWN: DT_UNKNOWN,
FT_REG_FILE: DT_REG,
FT_DIR: DT_DIR,
FT_CHRDEV: DT_CHR,
FT_BLKDEV: DT_BLK,
FT_FIFO: DT_FIFO,
FT_SOCK: DT_SOCK,
FT_SYMLINK: DT_LNK,
}
// FileTypeToDirentType converts the on-disk file type (FT_*) to the directory
// entry type (DT_*).
func FileTypeToDirentType(filetype uint8) uint8 {
if filetype >= FT_MAX {
return DT_UNKNOWN
}
return direntTypeByFileType[filetype]
}
// Values for preadv2/pwritev2.
const (
// NOTE(b/120162627): gVisor does not implement the RWF_HIPRI feature, but
// the flag is accepted as a valid flag argument for preadv2/pwritev2 and
// silently ignored.
RWF_HIPRI = 0x00000001
RWF_DSYNC = 0x00000002
RWF_SYNC = 0x00000004
RWF_VALID = RWF_HIPRI | RWF_DSYNC | RWF_SYNC
)
// SizeOfStat is the size of a Stat struct.
var SizeOfStat = (*Stat)(nil).SizeBytes()
// Flags for statx.
const (
AT_NO_AUTOMOUNT = 0x800
AT_STATX_SYNC_TYPE = 0x6000
AT_STATX_SYNC_AS_STAT = 0x0000
AT_STATX_FORCE_SYNC = 0x2000
AT_STATX_DONT_SYNC = 0x4000
)
// Mask values for statx.
const (
STATX_TYPE = 0x00000001
STATX_MODE = 0x00000002
STATX_NLINK = 0x00000004
STATX_UID = 0x00000008
STATX_GID = 0x00000010
STATX_ATIME = 0x00000020
STATX_MTIME = 0x00000040
STATX_CTIME = 0x00000080
STATX_INO = 0x00000100
STATX_SIZE = 0x00000200
STATX_BLOCKS = 0x00000400
STATX_BASIC_STATS = 0x000007ff
STATX_BTIME = 0x00000800
STATX_ALL = 0x00000fff
STATX__RESERVED = 0x80000000
)
// Bitmasks for Statx.Attributes and Statx.AttributesMask, from
// include/uapi/linux/stat.h.
const (
STATX_ATTR_COMPRESSED = 0x00000004
STATX_ATTR_IMMUTABLE = 0x00000010
STATX_ATTR_APPEND = 0x00000020
STATX_ATTR_NODUMP = 0x00000040
STATX_ATTR_ENCRYPTED = 0x00000800
STATX_ATTR_AUTOMOUNT = 0x00001000
)
// Statx represents struct statx.
//
// +marshal boundCheck slice:StatxSlice
type Statx struct {
Mask uint32
Blksize uint32
Attributes uint64
Nlink uint32
UID uint32
GID uint32
Mode uint16
_ uint16
Ino uint64
Size uint64
Blocks uint64
AttributesMask uint64
Atime StatxTimestamp
Btime StatxTimestamp
Ctime StatxTimestamp
Mtime StatxTimestamp
RdevMajor uint32
RdevMinor uint32
DevMajor uint32
DevMinor uint32
}
// String implements fmt.Stringer.String.
func (s *Statx) String() string {
return fmt.Sprintf("Statx{Mask: %#x, Mode: %s, UID: %d, GID: %d, Ino: %d, DevMajor: %d, DevMinor: %d, Size: %d, Blocks: %d, Blksize: %d, Nlink: %d, Atime: %s, Btime: %s, Ctime: %s, Mtime: %s, Attributes: %d, AttributesMask: %d, RdevMajor: %d, RdevMinor: %d}",
s.Mask, FileMode(s.Mode), s.UID, s.GID, s.Ino, s.DevMajor, s.DevMinor, s.Size, s.Blocks, s.Blksize, s.Nlink, s.Atime.ToTime(), s.Btime.ToTime(), s.Ctime.ToTime(), s.Mtime.ToTime(), s.Attributes, s.AttributesMask, s.RdevMajor, s.RdevMinor)
}
// SizeOfStatx is the size of a Statx struct.
var SizeOfStatx = (*Statx)(nil).SizeBytes()
// FileMode represents a mode_t.
//
// +marshal
type FileMode uint16
// Permissions returns just the permission bits.
func (m FileMode) Permissions() FileMode {
return m & PermissionsMask
}
// FileType returns just the file type bits.
func (m FileMode) FileType() FileMode {
return m & FileTypeMask
}
// ExtraBits returns everything but the file type and permission bits.
func (m FileMode) ExtraBits() FileMode {
return m &^ (PermissionsMask | FileTypeMask)
}
// IsDir returns true if file type represents a directory.
func (m FileMode) IsDir() bool {
return m.FileType() == S_IFDIR
}
// String returns a string representation of m.
func (m FileMode) String() string {
var s []string
if ft := m.FileType(); ft != 0 {
s = append(s, fileType.Parse(uint64(ft)))
}
if eb := m.ExtraBits(); eb != 0 {
s = append(s, modeExtraBits.Parse(uint64(eb)))
}
s = append(s, fmt.Sprintf("0o%o", m.Permissions()))
return strings.Join(s, "|")
}
// DirentType maps file types to dirent types appropriate for (struct
// dirent)::d_type.
func (m FileMode) DirentType() uint8 {
switch m.FileType() {
case ModeSocket:
return DT_SOCK
case ModeSymlink:
return DT_LNK
case ModeRegular:
return DT_REG
case ModeBlockDevice:
return DT_BLK
case ModeDirectory:
return DT_DIR
case ModeCharacterDevice:
return DT_CHR
case ModeNamedPipe:
return DT_FIFO
default:
return DT_UNKNOWN
}
}
var modeExtraBits = abi.FlagSet{
{
Flag: ModeSetUID,
Name: "S_ISUID",
},
{
Flag: ModeSetGID,
Name: "S_ISGID",
},
{
Flag: ModeSticky,
Name: "S_ISVTX",
},
}
var fileType = abi.ValueSet{
ModeSocket: "S_IFSOCK",
ModeSymlink: "S_IFLINK",
ModeRegular: "S_IFREG",
ModeBlockDevice: "S_IFBLK",
ModeDirectory: "S_IFDIR",
ModeCharacterDevice: "S_IFCHR",
ModeNamedPipe: "S_IFIFO",
}
// Constants for memfd_create(2). Source: include/uapi/linux/memfd.h
const (
MFD_CLOEXEC = 0x0001
MFD_ALLOW_SEALING = 0x0002
)
// Constants related to file seals. Source: include/uapi/{asm-generic,linux}/fcntl.h
const (
F_LINUX_SPECIFIC_BASE = 1024
F_ADD_SEALS = F_LINUX_SPECIFIC_BASE + 9
F_GET_SEALS = F_LINUX_SPECIFIC_BASE + 10
F_SEAL_SEAL = 0x0001 // Prevent further seals from being set.
F_SEAL_SHRINK = 0x0002 // Prevent file from shrinking.
F_SEAL_GROW = 0x0004 // Prevent file from growing.
F_SEAL_WRITE = 0x0008 // Prevent writes.
)
// Constants related to fallocate(2). Source: include/uapi/linux/falloc.h
const (
FALLOC_FL_KEEP_SIZE = 0x01
FALLOC_FL_PUNCH_HOLE = 0x02
FALLOC_FL_NO_HIDE_STALE = 0x04
FALLOC_FL_COLLAPSE_RANGE = 0x08
FALLOC_FL_ZERO_RANGE = 0x10
FALLOC_FL_INSERT_RANGE = 0x20
FALLOC_FL_UNSHARE_RANGE = 0x40
)
// Constants related to close_range(2). Source: /include/uapi/linux/close_range.h
const (
CLOSE_RANGE_UNSHARE = uint32(1 << 1)
CLOSE_RANGE_CLOEXEC = uint32(1 << 2)
)
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