ext4: disklayout: inode impl.
PiperOrigin-RevId: 257010414
This commit is contained in:
Ayush Ranjan
gVisor bot
parent
67f2cefce0
commit
8f9b1ca8e7
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@ -8,7 +8,10 @@ go_library(
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"block_group.go",
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"block_group_32.go",
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"block_group_64.go",
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"disklayout.go",
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"inode.go",
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"inode_new.go",
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"inode_old.go",
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"superblock.go",
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"superblock_32.go",
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"superblock_64.go",
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@ -29,7 +32,9 @@ go_test(
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size = "small",
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srcs = [
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"block_group_test.go",
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"inode_test.go",
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"superblock_test.go",
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],
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embed = [":disklayout"],
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deps = ["//pkg/sentry/kernel/time"],
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)
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@ -17,12 +17,6 @@ package disklayout
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// BlockGroup32Bit emulates the first half of struct ext4_group_desc in
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// fs/ext4/ext4.h. It is the block group descriptor struct for ext2, ext3 and
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// 32-bit ext4 filesystems. It implements BlockGroup interface.
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//
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// The suffix `Lo` here stands for lower bits because this is also used in the
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// 64-bit version where these fields represent the lower half of the fields.
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// The suffix `Raw` has been added to indicate that the field does not have a
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// counterpart in the 64-bit version and to resolve name collision with the
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// interface.
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type BlockGroup32Bit struct {
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BlockBitmapLo uint32
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InodeBitmapLo uint32
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@ -38,6 +32,9 @@ type BlockGroup32Bit struct {
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ChecksumRaw uint16
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}
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// Compiles only if BlockGroup32Bit implements BlockGroup.
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var _ BlockGroup = (*BlockGroup32Bit)(nil)
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// InodeTable implements BlockGroup.InodeTable.
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func (bg *BlockGroup32Bit) InodeTable() uint64 { return uint64(bg.InodeTableLo) }
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@ -18,9 +18,6 @@ package disklayout
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// It is the block group descriptor struct for 64-bit ext4 filesystems.
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// It implements BlockGroup interface. It is an extension of the 32-bit
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// version of BlockGroup.
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//
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// The suffix `Hi` here stands for upper bits because they represent the upper
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// half of the fields.
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type BlockGroup64Bit struct {
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// We embed the 32-bit struct here because 64-bit version is just an extension
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// of the 32-bit version.
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@ -40,6 +37,9 @@ type BlockGroup64Bit struct {
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_ uint32 // Padding to 64 bytes.
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}
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// Compiles only if BlockGroup64Bit implements BlockGroup.
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var _ BlockGroup = (*BlockGroup64Bit)(nil)
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// Methods to override. Checksum() and Flags() are not overridden.
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// InodeTable implements BlockGroup.InodeTable.
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@ -0,0 +1,50 @@
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// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package disklayout provides Linux ext file system's disk level structures
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// which can be directly read into from the underlying device. Structs aim to
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// emulate structures `exactly` how they are layed out on disk.
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//
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// This library aims to be compatible with all ext(2/3/4) systems so it
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// provides a generic interface for all major structures and various
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// implementations (for different versions). The user code is responsible for
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// using appropriate implementations based on the underlying device.
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//
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// Interfacing all major structures here serves a few purposes:
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// - Abstracts away the complexity of the underlying structure from client
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// code. The client only has to figure out versioning on set up and then
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// can use these as black boxes and pass it higher up the stack.
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// - Having pointer receivers forces the user to use pointers to these
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// heavy structs. Hence, prevents the client code from unintentionally
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// copying these by value while passing the interface around.
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// - Version-based implementation selection is resolved on set up hence
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// avoiding per call overhead of choosing implementation.
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// - All interface methods are pretty light weight (do not take in any
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// parameters by design). Passing pointer arguments to interface methods
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// can lead to heap allocation as the compiler won't be able to perform
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// escape analysis on an unknown implementation at compile time.
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//
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// Notes:
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// - All fields in these structs are exported because binary.Read would
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// panic otherwise.
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// - All structures on disk are in little-endian order. Only jbd2 (journal)
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// structures are in big-endian order.
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// - All OS dependent fields in these structures will be interpretted using
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// the Linux version of that field.
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// - The suffix `Lo` in field names stands for lower bits of that field.
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// - The suffix `Hi` in field names stands for upper bits of that field.
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// - The suffix `Raw` has been added to indicate that the field is not split
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// into Lo and Hi fields and also to resolve name collision with the
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// respective interface.
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package disklayout
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@ -0,0 +1,96 @@
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// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package disklayout
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import "gvisor.dev/gvisor/pkg/sentry/kernel/time"
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// InodeNew represents ext4 inode structure which can be bigger than
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// OldInodeSize. The actual size of this struct should be determined using
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// inode.ExtraInodeSize. Accessing any field here should be verified with the
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// actual size. The extra space between the end of the inode struct and end of
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// the inode record can be used to store extended attr.
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//
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// If the TimeExtra fields are in scope, the lower 2 bits of those are used
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// to extend their counter part to be 34 bits wide; the rest (upper) 30 bits
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// are used to provide nanoscond precision. Hence, these timestamps will now
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// overflow in May 2446.
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// See https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#inode-timestamps.
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type InodeNew struct {
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InodeOld
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ExtraInodeSize uint16
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ChecksumHi uint16
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ChangeTimeExtra uint32
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ModificationTimeExtra uint32
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AccessTimeExtra uint32
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CreationTime uint32
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CreationTimeExtra uint32
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VersionHi uint32
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ProjectID uint32
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}
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// Compiles only if InodeNew implements Inode.
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var _ Inode = (*InodeNew)(nil)
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// fromExtraTime decodes the extra time and constructs the kernel time struct
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// with nanosecond precision.
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func fromExtraTime(lo int32, extra uint32) time.Time {
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// See description above InodeNew for format.
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seconds := (int64(extra&0x3) << 32) + int64(lo)
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nanoseconds := int64(extra >> 2)
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return time.FromUnix(seconds, nanoseconds)
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}
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// Only override methods which change due to ext4 specific fields.
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// Size implements Inode.Size.
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func (in *InodeNew) Size() uint64 {
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return (uint64(in.SizeHi) << 32) | uint64(in.SizeLo)
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}
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// InodeSize implements Inode.InodeSize.
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func (in *InodeNew) InodeSize() uint16 {
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return oldInodeSize + in.ExtraInodeSize
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}
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// ChangeTime implements Inode.ChangeTime.
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func (in *InodeNew) ChangeTime() time.Time {
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// Apply new timestamp logic if inode.ChangeTimeExtra is in scope.
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if in.ExtraInodeSize >= 8 {
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return fromExtraTime(in.ChangeTimeRaw, in.ChangeTimeExtra)
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}
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return in.InodeOld.ChangeTime()
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}
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// ModificationTime implements Inode.ModificationTime.
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func (in *InodeNew) ModificationTime() time.Time {
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// Apply new timestamp logic if inode.ModificationTimeExtra is in scope.
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if in.ExtraInodeSize >= 12 {
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return fromExtraTime(in.ModificationTimeRaw, in.ModificationTimeExtra)
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}
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return in.InodeOld.ModificationTime()
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}
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// AccessTime implements Inode.AccessTime.
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func (in *InodeNew) AccessTime() time.Time {
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// Apply new timestamp logic if inode.AccessTimeExtra is in scope.
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if in.ExtraInodeSize >= 16 {
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return fromExtraTime(in.AccessTimeRaw, in.AccessTimeExtra)
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}
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return in.InodeOld.AccessTime()
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}
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@ -0,0 +1,117 @@
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// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package disklayout
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
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"gvisor.dev/gvisor/pkg/sentry/kernel/time"
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)
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const (
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// oldInodeSize is the inode size in ext2/ext3.
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oldInodeSize = 128
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)
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// InodeOld implements Inode interface. It emulates ext2/ext3 inode struct.
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// Inode struct size and record size are both 128 bytes for this.
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//
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// All fields representing time are in seconds since the epoch. Which means that
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// they will overflow in January 2038.
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type InodeOld struct {
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ModeRaw uint16
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UIDLo uint16
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SizeLo uint32
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// The time fields are signed integers because they could be negative to
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// represent time before the epoch.
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AccessTimeRaw int32
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ChangeTimeRaw int32
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ModificationTimeRaw int32
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DeletionTimeRaw int32
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GIDLo uint16
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LinksCountRaw uint16
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BlocksCountLo uint32
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FlagsRaw uint32
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VersionLo uint32 // This is OS dependent.
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BlocksRaw [60]byte
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Generation uint32
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FileACLLo uint32
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SizeHi uint32
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ObsoFaddr uint32
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// OS dependent fields have been inlined here.
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BlocksCountHi uint16
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FileACLHi uint16
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UIDHi uint16
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GIDHi uint16
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ChecksumLo uint16
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_ uint16
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}
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// Compiles only if InodeOld implements Inode.
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var _ Inode = (*InodeOld)(nil)
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// Mode implements Inode.Mode.
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func (in *InodeOld) Mode() linux.FileMode { return linux.FileMode(in.ModeRaw) }
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// UID implements Inode.UID.
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func (in *InodeOld) UID() auth.KUID {
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return auth.KUID((uint32(in.UIDHi) << 16) | uint32(in.UIDLo))
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}
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// GID implements Inode.GID.
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func (in *InodeOld) GID() auth.KGID {
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return auth.KGID((uint32(in.GIDHi) << 16) | uint32(in.GIDLo))
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}
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// Size implements Inode.Size.
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func (in *InodeOld) Size() uint64 {
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// In ext2/ext3, in.SizeHi did not exist, it was instead named in.DirACL.
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return uint64(in.SizeLo)
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}
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// InodeSize implements Inode.InodeSize.
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func (in *InodeOld) InodeSize() uint16 { return oldInodeSize }
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// AccessTime implements Inode.AccessTime.
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func (in *InodeOld) AccessTime() time.Time {
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return time.FromUnix(int64(in.AccessTimeRaw), 0)
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}
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// ChangeTime implements Inode.ChangeTime.
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func (in *InodeOld) ChangeTime() time.Time {
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return time.FromUnix(int64(in.ChangeTimeRaw), 0)
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}
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// ModificationTime implements Inode.ModificationTime.
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func (in *InodeOld) ModificationTime() time.Time {
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return time.FromUnix(int64(in.ModificationTimeRaw), 0)
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}
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// DeletionTime implements Inode.DeletionTime.
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func (in *InodeOld) DeletionTime() time.Time {
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return time.FromUnix(int64(in.DeletionTimeRaw), 0)
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}
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// LinksCount implements Inode.LinksCount.
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func (in *InodeOld) LinksCount() uint16 { return in.LinksCountRaw }
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// Flags implements Inode.Flags.
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func (in *InodeOld) Flags() InodeFlags { return InodeFlagsFromInt(in.FlagsRaw) }
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// Blocks implements Inode.Blocks.
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func (in *InodeOld) Blocks() [60]byte { return in.BlocksRaw }
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@ -0,0 +1,222 @@
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// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package disklayout
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import (
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"fmt"
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"strconv"
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"testing"
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"gvisor.dev/gvisor/pkg/sentry/kernel/time"
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)
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// TestInodeSize tests that the inode structs are of the correct size.
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func TestInodeSize(t *testing.T) {
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assertSize(t, InodeOld{}, oldInodeSize)
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// This was updated from 156 bytes to 160 bytes in Oct 2015.
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assertSize(t, InodeNew{}, 160)
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}
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// TestTimestampSeconds tests that the seconds part of [a/c/m] timestamps in
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// ext4 inode structs are decoded correctly.
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//
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// These tests are derived from the table under https://www.kernel.org/doc/html/latest/filesystems/ext4/dynamic.html#inode-timestamps.
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func TestTimestampSeconds(t *testing.T) {
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type timestampTest struct {
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// msbSet tells if the most significant bit of InodeOld.[X]TimeRaw is set.
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// If this is set then the 32-bit time is negative.
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msbSet bool
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// lowerBound tells if we should take the lowest possible value of
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// InodeOld.[X]TimeRaw while satisfying test.msbSet condition. If set to
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// false it tells to take the highest possible value.
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lowerBound bool
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// extraBits is InodeNew.[X]TimeExtra.
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extraBits uint32
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// want is the kernel time struct that is expected.
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want time.Time
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}
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tests := []timestampTest{
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// 1901-12-13
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{
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msbSet: true,
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lowerBound: true,
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extraBits: 0,
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want: time.FromUnix(int64(-0x80000000), 0),
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},
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// 1969-12-31
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{
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msbSet: true,
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lowerBound: false,
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extraBits: 0,
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want: time.FromUnix(int64(-1), 0),
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},
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// 1970-01-01
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{
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msbSet: false,
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lowerBound: true,
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extraBits: 0,
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want: time.FromUnix(int64(0), 0),
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},
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// 2038-01-19
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{
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msbSet: false,
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lowerBound: false,
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extraBits: 0,
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want: time.FromUnix(int64(0x7fffffff), 0),
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},
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// 2038-01-19
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{
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msbSet: true,
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lowerBound: true,
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extraBits: 1,
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want: time.FromUnix(int64(0x80000000), 0),
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},
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// 2106-02-07
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{
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msbSet: true,
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lowerBound: false,
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extraBits: 1,
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want: time.FromUnix(int64(0xffffffff), 0),
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},
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// 2106-02-07
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{
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msbSet: false,
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lowerBound: true,
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extraBits: 1,
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want: time.FromUnix(int64(0x100000000), 0),
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},
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// 2174-02-25
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{
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msbSet: false,
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lowerBound: false,
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extraBits: 1,
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want: time.FromUnix(int64(0x17fffffff), 0),
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},
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// 2174-02-25
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{
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msbSet: true,
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lowerBound: true,
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extraBits: 2,
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want: time.FromUnix(int64(0x180000000), 0),
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},
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// 2242-03-16
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{
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msbSet: true,
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lowerBound: false,
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extraBits: 2,
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want: time.FromUnix(int64(0x1ffffffff), 0),
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},
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// 2242-03-16
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{
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msbSet: false,
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lowerBound: true,
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extraBits: 2,
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||||
want: time.FromUnix(int64(0x200000000), 0),
|
||||
},
|
||||
|
||||
// 2310-04-04
|
||||
{
|
||||
msbSet: false,
|
||||
lowerBound: false,
|
||||
extraBits: 2,
|
||||
want: time.FromUnix(int64(0x27fffffff), 0),
|
||||
},
|
||||
|
||||
// 2310-04-04
|
||||
{
|
||||
msbSet: true,
|
||||
lowerBound: true,
|
||||
extraBits: 3,
|
||||
want: time.FromUnix(int64(0x280000000), 0),
|
||||
},
|
||||
|
||||
// 2378-04-22
|
||||
{
|
||||
msbSet: true,
|
||||
lowerBound: false,
|
||||
extraBits: 3,
|
||||
want: time.FromUnix(int64(0x2ffffffff), 0),
|
||||
},
|
||||
|
||||
// 2378-04-22
|
||||
{
|
||||
msbSet: false,
|
||||
lowerBound: true,
|
||||
extraBits: 3,
|
||||
want: time.FromUnix(int64(0x300000000), 0),
|
||||
},
|
||||
|
||||
// 2446-05-10
|
||||
{
|
||||
msbSet: false,
|
||||
lowerBound: false,
|
||||
extraBits: 3,
|
||||
want: time.FromUnix(int64(0x37fffffff), 0),
|
||||
},
|
||||
}
|
||||
|
||||
lowerMSB0 := int32(0) // binary: 00000000 00000000 00000000 00000000
|
||||
upperMSB0 := int32(0x7fffffff) // binary: 01111111 11111111 11111111 11111111
|
||||
lowerMSB1 := int32(-0x80000000) // binary: 10000000 00000000 00000000 00000000
|
||||
upperMSB1 := int32(-1) // binary: 11111111 11111111 11111111 11111111
|
||||
|
||||
get32BitTime := func(test timestampTest) int32 {
|
||||
if test.msbSet {
|
||||
if test.lowerBound {
|
||||
return lowerMSB1
|
||||
}
|
||||
|
||||
return upperMSB1
|
||||
}
|
||||
|
||||
if test.lowerBound {
|
||||
return lowerMSB0
|
||||
}
|
||||
|
||||
return upperMSB0
|
||||
}
|
||||
|
||||
getTestName := func(test timestampTest) string {
|
||||
return fmt.Sprintf(
|
||||
"Tests time decoding with epoch bits 0b%s and 32-bit raw time: MSB set=%t, lower bound=%t",
|
||||
strconv.FormatInt(int64(test.extraBits), 2),
|
||||
test.msbSet,
|
||||
test.lowerBound,
|
||||
)
|
||||
}
|
||||
|
||||
for _, test := range tests {
|
||||
t.Run(getTestName(test), func(t *testing.T) {
|
||||
if got := fromExtraTime(get32BitTime(test), test.extraBits); got != test.want {
|
||||
t.Errorf("Expected: %v, Got: %v", test.want, got)
|
||||
}
|
||||
})
|
||||
}
|
||||
}
|
||||
|
|
@ -12,22 +12,6 @@
|
|||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
// Package disklayout provides Linux ext file system's disk level structures
|
||||
// which can be directly read into from the underlying device. All structures
|
||||
// on disk are in little-endian order. Only jbd2 (journal) structures are in
|
||||
// big-endian order. Structs aim to emulate structures `exactly` how they are
|
||||
// layed out on disk.
|
||||
//
|
||||
// This library aims to be compatible with all ext(2/3/4) systems so it
|
||||
// provides a generic interface for all major structures and various
|
||||
// implementations (for different versions). The user code is responsible for
|
||||
// using appropriate implementations based on the underlying device.
|
||||
//
|
||||
// Notes:
|
||||
// - All fields in these structs are exported because binary.Read would
|
||||
// panic otherwise.
|
||||
// - All OS dependent fields in these structures will be interpretted using
|
||||
// the Linux version of that field.
|
||||
package disklayout
|
||||
|
||||
// SuperBlock should be implemented by structs representing the ext superblock.
|
||||
|
|
@ -109,7 +93,7 @@ type SuperBlock interface {
|
|||
// - Inode disk record size = sb.s_inode_size (function return value).
|
||||
// = 256 (default)
|
||||
// - Inode struct size = 128 + inode.i_extra_isize.
|
||||
// = 128 + 28 = 156 (default)
|
||||
// = 128 + 32 = 160 (default)
|
||||
InodeSize() uint16
|
||||
|
||||
// InodesPerGroup returns the number of inodes in a block group.
|
||||
|
|
|
|||
|
|
@ -16,10 +16,6 @@ package disklayout
|
|||
|
||||
// SuperBlock32Bit implements SuperBlock and represents the 32-bit version of
|
||||
// the ext4_super_block struct in fs/ext4/ext4.h.
|
||||
//
|
||||
// The suffix `Raw` has been added to indicate that the field does not have a
|
||||
// counterpart in the 64-bit version and to resolve name collision with the
|
||||
// interface.
|
||||
type SuperBlock32Bit struct {
|
||||
// We embed the old superblock struct here because the 32-bit version is just
|
||||
// an extension of the old version.
|
||||
|
|
@ -52,6 +48,9 @@ type SuperBlock32Bit struct {
|
|||
JnlBlocks [17]uint32
|
||||
}
|
||||
|
||||
// Compiles only if SuperBlock32Bit implements SuperBlock.
|
||||
var _ SuperBlock = (*SuperBlock32Bit)(nil)
|
||||
|
||||
// Only override methods which change based on the additional fields above.
|
||||
// Not overriding SuperBlock.BgDescSize because it would still return 32 here.
|
||||
|
||||
|
|
|
|||
|
|
@ -18,9 +18,6 @@ package disklayout
|
|||
// the ext4_super_block struct in fs/ext4/ext4.h. This sums up to be exactly
|
||||
// 1024 bytes (smallest possible block size) and hence the superblock always
|
||||
// fits in no more than one data block.
|
||||
//
|
||||
// The suffix `Hi` here stands for upper bits because they represent the upper
|
||||
// half of the fields.
|
||||
type SuperBlock64Bit struct {
|
||||
// We embed the 32-bit struct here because 64-bit version is just an extension
|
||||
// of the 32-bit version.
|
||||
|
|
@ -78,6 +75,9 @@ type SuperBlock64Bit struct {
|
|||
Checksum uint32
|
||||
}
|
||||
|
||||
// Compiles only if SuperBlock64Bit implements SuperBlock.
|
||||
var _ SuperBlock = (*SuperBlock64Bit)(nil)
|
||||
|
||||
// Only override methods which change based on the 64-bit feature.
|
||||
|
||||
// BlocksCount implements SuperBlock.BlocksCount.
|
||||
|
|
|
|||
|
|
@ -16,12 +16,6 @@ package disklayout
|
|||
|
||||
// SuperBlockOld implements SuperBlock and represents the old version of the
|
||||
// superblock struct in ext2 and ext3 systems.
|
||||
//
|
||||
// The suffix `Lo` here stands for lower bits because this is also used in the
|
||||
// 64-bit version where these fields represent the lower half of the fields.
|
||||
// The suffix `Raw` has been added to indicate that the field does not have a
|
||||
// counterpart in the 64-bit version and to resolve name collision with the
|
||||
// interface.
|
||||
type SuperBlockOld struct {
|
||||
InodesCountRaw uint32
|
||||
BlocksCountLo uint32
|
||||
|
|
@ -84,7 +78,7 @@ func (sb *SuperBlockOld) ClusterSize() uint64 { return 1 << (10 + sb.LogClusterS
|
|||
func (sb *SuperBlockOld) ClustersPerGroup() uint32 { return sb.ClustersPerGroupRaw }
|
||||
|
||||
// InodeSize implements SuperBlock.InodeSize.
|
||||
func (sb *SuperBlockOld) InodeSize() uint16 { return 128 }
|
||||
func (sb *SuperBlockOld) InodeSize() uint16 { return oldInodeSize }
|
||||
|
||||
// InodesPerGroup implements SuperBlock.InodesPerGroup.
|
||||
func (sb *SuperBlockOld) InodesPerGroup() uint32 { return sb.InodesPerGroupRaw }
|
||||
|
|
|
|||
Loading…
Reference in New Issue