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-rw-r--r--pkg/merkletree/merkletree.go81
-rw-r--r--pkg/merkletree/merkletree_test.go121
-rw-r--r--pkg/sentry/fsimpl/verity/filesystem.go18
-rw-r--r--pkg/sentry/fsimpl/verity/verity.go66
-rw-r--r--pkg/sentry/fsimpl/verity/verity_test.go407
-rw-r--r--pkg/sentry/vfs/vfs.go4
6 files changed, 605 insertions, 92 deletions
diff --git a/pkg/merkletree/merkletree.go b/pkg/merkletree/merkletree.go
index aea7dde38..d7209ace3 100644
--- a/pkg/merkletree/merkletree.go
+++ b/pkg/merkletree/merkletree.go
@@ -147,20 +147,21 @@ func (layout Layout) blockOffset(level int, index int64) int64 {
// root hash, which contains the root hash of the raw content and the file's
// meatadata.
type VerityDescriptor struct {
- Name string
- FileSize int64
- Mode uint32
- UID uint32
- GID uint32
- Children map[string]struct{}
- RootHash []byte
+ Name string
+ FileSize int64
+ Mode uint32
+ UID uint32
+ GID uint32
+ Children map[string]struct{}
+ SymlinkTarget string
+ RootHash []byte
}
func (d *VerityDescriptor) String() string {
b := new(bytes.Buffer)
e := gob.NewEncoder(b)
e.Encode(d.Children)
- return fmt.Sprintf("Name: %s, Size: %d, Mode: %d, UID: %d, GID: %d, Children: %v, RootHash: %v", d.Name, d.FileSize, d.Mode, d.UID, d.GID, b.Bytes(), d.RootHash)
+ return fmt.Sprintf("Name: %s, Size: %d, Mode: %d, UID: %d, GID: %d, Children: %v, Symlink: %s, RootHash: %v", d.Name, d.FileSize, d.Mode, d.UID, d.GID, b.Bytes(), d.SymlinkTarget, d.RootHash)
}
// verify generates a hash from d, and compares it with expected.
@@ -193,7 +194,8 @@ func hashData(data []byte, hashAlgorithms int) ([]byte, error) {
return digest, nil
}
-// GenerateParams contains the parameters used to generate a Merkle tree.
+// GenerateParams contains the parameters used to generate a Merkle tree for a
+// given file.
type GenerateParams struct {
// File is a reader of the file to be hashed.
File io.ReaderAt
@@ -210,6 +212,8 @@ type GenerateParams struct {
// Children is a map of children names for a directory. It should be
// empty for a regular file.
Children map[string]struct{}
+ // SymlinkTarget is the target path of a symlink file, or "" if the file is not a symlink.
+ SymlinkTarget string
// HashAlgorithms is the algorithms used to hash data.
HashAlgorithms int
// TreeReader is a reader for the Merkle tree.
@@ -227,6 +231,20 @@ type GenerateParams struct {
// Generate returns a hash of a VerityDescriptor, which contains the file
// metadata and the hash from file content.
func Generate(params *GenerateParams) ([]byte, error) {
+ descriptor := VerityDescriptor{
+ FileSize: params.Size,
+ Name: params.Name,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ SymlinkTarget: params.SymlinkTarget,
+ }
+
+ // If file is a symlink do not generate root hash for file content.
+ if params.SymlinkTarget != "" {
+ return hashData([]byte(descriptor.String()), params.HashAlgorithms)
+ }
+
layout, err := InitLayout(params.Size, params.HashAlgorithms, params.DataAndTreeInSameFile)
if err != nil {
return nil, err
@@ -296,15 +314,7 @@ func Generate(params *GenerateParams) ([]byte, error) {
}
numBlocks = (numBlocks + layout.hashesPerBlock() - 1) / layout.hashesPerBlock()
}
- descriptor := VerityDescriptor{
- Name: params.Name,
- FileSize: params.Size,
- Mode: params.Mode,
- UID: params.UID,
- GID: params.GID,
- Children: params.Children,
- RootHash: root,
- }
+ descriptor.RootHash = root
return hashData([]byte(descriptor.String()), params.HashAlgorithms)
}
@@ -330,6 +340,8 @@ type VerifyParams struct {
// Children is a map of children names for a directory. It should be
// empty for a regular file.
Children map[string]struct{}
+ // SymlinkTarget is the target path of a symlink file, or "" if the file is not a symlink.
+ SymlinkTarget string
// HashAlgorithms is the algorithms used to hash data.
HashAlgorithms int
// ReadOffset is the offset of the data range to be verified.
@@ -351,21 +363,23 @@ type VerifyParams struct {
// for the raw root hash.
func verifyMetadata(params *VerifyParams, layout *Layout) error {
var root []byte
- // Only read the root hash if we expect that the Merkle tree file is non-empty.
- if params.Size != 0 {
+ // Only read the root hash if we expect that the file is not a symlink and its
+ // Merkle tree file is non-empty.
+ if params.Size != 0 && params.SymlinkTarget == "" {
root = make([]byte, layout.digestSize)
if _, err := params.Tree.ReadAt(root, layout.blockOffset(layout.rootLevel(), 0 /* index */)); err != nil {
return fmt.Errorf("failed to read root hash: %w", err)
}
}
descriptor := VerityDescriptor{
- Name: params.Name,
- FileSize: params.Size,
- Mode: params.Mode,
- UID: params.UID,
- GID: params.GID,
- Children: params.Children,
- RootHash: root,
+ Name: params.Name,
+ FileSize: params.Size,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ Children: params.Children,
+ SymlinkTarget: params.SymlinkTarget,
+ RootHash: root,
}
return descriptor.verify(params.Expected, params.HashAlgorithms)
}
@@ -421,12 +435,13 @@ func Verify(params *VerifyParams) (int64, error) {
}
}
descriptor := VerityDescriptor{
- Name: params.Name,
- FileSize: params.Size,
- Mode: params.Mode,
- UID: params.UID,
- GID: params.GID,
- Children: params.Children,
+ Name: params.Name,
+ FileSize: params.Size,
+ Mode: params.Mode,
+ UID: params.UID,
+ GID: params.GID,
+ SymlinkTarget: params.SymlinkTarget,
+ Children: params.Children,
}
if err := verifyBlock(params.Tree, &descriptor, &layout, buf, i, params.HashAlgorithms, params.Expected); err != nil {
return 0, err
diff --git a/pkg/merkletree/merkletree_test.go b/pkg/merkletree/merkletree_test.go
index 66ddf09e6..e3a88b3a3 100644
--- a/pkg/merkletree/merkletree_test.go
+++ b/pkg/merkletree/merkletree_test.go
@@ -159,10 +159,11 @@ func TestLayout(t *testing.T) {
}
const (
- defaultName = "merkle_test"
- defaultMode = 0644
- defaultUID = 0
- defaultGID = 0
+ defaultName = "merkle_test"
+ defaultMode = 0644
+ defaultUID = 0
+ defaultGID = 0
+ defaultSymlinkPath = "merkle_test_link"
)
// bytesReadWriter is used to read from/write to/seek in a byte array. Unlike
@@ -203,112 +204,112 @@ func TestGenerate(t *testing.T) {
data: bytes.Repeat([]byte{0}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: false,
- expectedHash: []byte{42, 197, 191, 52, 206, 122, 93, 34, 198, 125, 100, 154, 171, 177, 94, 14, 49, 40, 76, 157, 122, 58, 78, 6, 163, 248, 30, 238, 16, 190, 173, 175},
+ expectedHash: []byte{9, 115, 238, 230, 38, 140, 195, 70, 207, 144, 202, 118, 23, 113, 32, 129, 226, 239, 177, 69, 161, 26, 14, 113, 16, 37, 30, 96, 19, 148, 132, 27},
},
{
name: "OnePageZeroesSHA256SameFile",
data: bytes.Repeat([]byte{0}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: true,
- expectedHash: []byte{42, 197, 191, 52, 206, 122, 93, 34, 198, 125, 100, 154, 171, 177, 94, 14, 49, 40, 76, 157, 122, 58, 78, 6, 163, 248, 30, 238, 16, 190, 173, 175},
+ expectedHash: []byte{9, 115, 238, 230, 38, 140, 195, 70, 207, 144, 202, 118, 23, 113, 32, 129, 226, 239, 177, 69, 161, 26, 14, 113, 16, 37, 30, 96, 19, 148, 132, 27},
},
{
name: "OnePageZeroesSHA512SeparateFile",
data: bytes.Repeat([]byte{0}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: false,
- expectedHash: []byte{87, 131, 150, 74, 0, 218, 117, 114, 34, 23, 212, 16, 122, 97, 124, 172, 41, 46, 107, 150, 33, 46, 56, 39, 5, 246, 215, 187, 140, 83, 35, 63, 111, 74, 155, 241, 161, 214, 92, 141, 232, 125, 99, 71, 168, 102, 82, 20, 229, 249, 248, 28, 29, 238, 199, 223, 173, 180, 179, 46, 241, 240, 237, 74},
+ expectedHash: []byte{127, 8, 95, 11, 83, 101, 51, 39, 170, 235, 39, 43, 135, 243, 145, 118, 148, 58, 27, 155, 182, 205, 44, 47, 5, 223, 215, 17, 35, 16, 43, 104, 43, 11, 8, 88, 171, 7, 249, 243, 14, 62, 126, 218, 23, 159, 237, 237, 42, 226, 39, 25, 87, 48, 253, 191, 116, 213, 37, 3, 187, 152, 154, 14},
},
{
name: "OnePageZeroesSHA512SameFile",
data: bytes.Repeat([]byte{0}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: true,
- expectedHash: []byte{87, 131, 150, 74, 0, 218, 117, 114, 34, 23, 212, 16, 122, 97, 124, 172, 41, 46, 107, 150, 33, 46, 56, 39, 5, 246, 215, 187, 140, 83, 35, 63, 111, 74, 155, 241, 161, 214, 92, 141, 232, 125, 99, 71, 168, 102, 82, 20, 229, 249, 248, 28, 29, 238, 199, 223, 173, 180, 179, 46, 241, 240, 237, 74},
+ expectedHash: []byte{127, 8, 95, 11, 83, 101, 51, 39, 170, 235, 39, 43, 135, 243, 145, 118, 148, 58, 27, 155, 182, 205, 44, 47, 5, 223, 215, 17, 35, 16, 43, 104, 43, 11, 8, 88, 171, 7, 249, 243, 14, 62, 126, 218, 23, 159, 237, 237, 42, 226, 39, 25, 87, 48, 253, 191, 116, 213, 37, 3, 187, 152, 154, 14},
},
{
name: "MultiplePageZeroesSHA256SeparateFile",
data: bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: false,
- expectedHash: []byte{115, 151, 35, 147, 223, 91, 17, 6, 162, 145, 237, 81, 88, 53, 120, 49, 128, 70, 188, 28, 254, 241, 19, 233, 30, 243, 71, 225, 57, 58, 61, 38},
+ expectedHash: []byte{247, 158, 42, 215, 180, 106, 0, 28, 77, 64, 132, 162, 74, 65, 250, 161, 243, 66, 129, 44, 197, 8, 145, 14, 94, 206, 156, 184, 145, 145, 20, 185},
},
{
name: "MultiplePageZeroesSHA256SameFile",
data: bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: true,
- expectedHash: []byte{115, 151, 35, 147, 223, 91, 17, 6, 162, 145, 237, 81, 88, 53, 120, 49, 128, 70, 188, 28, 254, 241, 19, 233, 30, 243, 71, 225, 57, 58, 61, 38},
+ expectedHash: []byte{247, 158, 42, 215, 180, 106, 0, 28, 77, 64, 132, 162, 74, 65, 250, 161, 243, 66, 129, 44, 197, 8, 145, 14, 94, 206, 156, 184, 145, 145, 20, 185},
},
{
name: "MultiplePageZeroesSHA512SeparateFile",
data: bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: false,
- expectedHash: []byte{41, 94, 205, 97, 254, 226, 171, 69, 76, 102, 197, 47, 113, 53, 24, 244, 103, 131, 83, 73, 87, 212, 247, 140, 32, 144, 211, 158, 25, 131, 194, 57, 21, 224, 128, 119, 69, 100, 45, 50, 157, 54, 46, 214, 152, 179, 59, 78, 28, 48, 146, 160, 204, 48, 27, 90, 152, 193, 167, 45, 150, 67, 66, 217},
+ expectedHash: []byte{100, 121, 14, 30, 104, 200, 142, 182, 190, 78, 23, 68, 157, 174, 23, 75, 174, 250, 250, 25, 66, 45, 235, 103, 129, 49, 78, 127, 173, 154, 121, 35, 37, 115, 60, 217, 26, 205, 253, 253, 236, 145, 107, 109, 232, 19, 72, 92, 4, 191, 181, 205, 191, 57, 234, 177, 144, 235, 143, 30, 15, 197, 109, 81},
},
{
name: "MultiplePageZeroesSHA512SameFile",
data: bytes.Repeat([]byte{0}, 128*usermem.PageSize+1),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: true,
- expectedHash: []byte{41, 94, 205, 97, 254, 226, 171, 69, 76, 102, 197, 47, 113, 53, 24, 244, 103, 131, 83, 73, 87, 212, 247, 140, 32, 144, 211, 158, 25, 131, 194, 57, 21, 224, 128, 119, 69, 100, 45, 50, 157, 54, 46, 214, 152, 179, 59, 78, 28, 48, 146, 160, 204, 48, 27, 90, 152, 193, 167, 45, 150, 67, 66, 217},
+ expectedHash: []byte{100, 121, 14, 30, 104, 200, 142, 182, 190, 78, 23, 68, 157, 174, 23, 75, 174, 250, 250, 25, 66, 45, 235, 103, 129, 49, 78, 127, 173, 154, 121, 35, 37, 115, 60, 217, 26, 205, 253, 253, 236, 145, 107, 109, 232, 19, 72, 92, 4, 191, 181, 205, 191, 57, 234, 177, 144, 235, 143, 30, 15, 197, 109, 81},
},
{
name: "SingleASHA256SeparateFile",
data: []byte{'a'},
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: false,
- expectedHash: []byte{52, 159, 140, 206, 140, 138, 231, 140, 94, 14, 252, 66, 175, 128, 191, 14, 52, 215, 190, 184, 165, 50, 182, 224, 42, 156, 145, 0, 1, 15, 187, 85},
+ expectedHash: []byte{90, 124, 194, 100, 206, 242, 75, 152, 47, 249, 16, 27, 136, 161, 223, 228, 121, 241, 126, 158, 126, 122, 100, 120, 117, 15, 81, 78, 201, 133, 119, 111},
},
{
name: "SingleASHA256SameFile",
data: []byte{'a'},
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: true,
- expectedHash: []byte{52, 159, 140, 206, 140, 138, 231, 140, 94, 14, 252, 66, 175, 128, 191, 14, 52, 215, 190, 184, 165, 50, 182, 224, 42, 156, 145, 0, 1, 15, 187, 85},
+ expectedHash: []byte{90, 124, 194, 100, 206, 242, 75, 152, 47, 249, 16, 27, 136, 161, 223, 228, 121, 241, 126, 158, 126, 122, 100, 120, 117, 15, 81, 78, 201, 133, 119, 111},
},
{
name: "SingleASHA512SeparateFile",
data: []byte{'a'},
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: false,
- expectedHash: []byte{232, 90, 223, 95, 60, 151, 149, 172, 174, 58, 206, 97, 189, 103, 6, 202, 67, 248, 1, 189, 243, 51, 250, 42, 5, 89, 195, 9, 50, 74, 39, 169, 114, 228, 109, 225, 128, 210, 63, 94, 18, 133, 58, 48, 225, 100, 176, 55, 87, 60, 235, 224, 143, 41, 15, 253, 94, 28, 251, 233, 99, 207, 152, 108},
+ expectedHash: []byte{24, 10, 13, 25, 113, 62, 169, 99, 151, 70, 166, 113, 81, 81, 163, 85, 5, 25, 29, 15, 46, 37, 104, 120, 142, 218, 52, 178, 187, 83, 30, 166, 101, 87, 70, 196, 188, 61, 123, 20, 13, 254, 126, 52, 212, 111, 75, 203, 33, 233, 233, 47, 181, 161, 43, 193, 131, 41, 99, 33, 164, 73, 89, 152},
},
{
name: "SingleASHA512SameFile",
data: []byte{'a'},
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: true,
- expectedHash: []byte{232, 90, 223, 95, 60, 151, 149, 172, 174, 58, 206, 97, 189, 103, 6, 202, 67, 248, 1, 189, 243, 51, 250, 42, 5, 89, 195, 9, 50, 74, 39, 169, 114, 228, 109, 225, 128, 210, 63, 94, 18, 133, 58, 48, 225, 100, 176, 55, 87, 60, 235, 224, 143, 41, 15, 253, 94, 28, 251, 233, 99, 207, 152, 108},
+ expectedHash: []byte{24, 10, 13, 25, 113, 62, 169, 99, 151, 70, 166, 113, 81, 81, 163, 85, 5, 25, 29, 15, 46, 37, 104, 120, 142, 218, 52, 178, 187, 83, 30, 166, 101, 87, 70, 196, 188, 61, 123, 20, 13, 254, 126, 52, 212, 111, 75, 203, 33, 233, 233, 47, 181, 161, 43, 193, 131, 41, 99, 33, 164, 73, 89, 152},
},
{
name: "OnePageASHA256SeparateFile",
data: bytes.Repeat([]byte{'a'}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: false,
- expectedHash: []byte{157, 60, 139, 54, 248, 39, 187, 77, 31, 107, 241, 26, 240, 49, 83, 159, 182, 60, 128, 85, 121, 204, 15, 249, 44, 248, 127, 134, 58, 220, 41, 185},
+ expectedHash: []byte{132, 54, 112, 142, 156, 19, 50, 140, 138, 240, 192, 154, 100, 120, 242, 69, 64, 217, 62, 166, 127, 88, 23, 197, 100, 66, 255, 215, 214, 229, 54, 1},
},
{
name: "OnePageASHA256SameFile",
data: bytes.Repeat([]byte{'a'}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: true,
- expectedHash: []byte{157, 60, 139, 54, 248, 39, 187, 77, 31, 107, 241, 26, 240, 49, 83, 159, 182, 60, 128, 85, 121, 204, 15, 249, 44, 248, 127, 134, 58, 220, 41, 185},
+ expectedHash: []byte{132, 54, 112, 142, 156, 19, 50, 140, 138, 240, 192, 154, 100, 120, 242, 69, 64, 217, 62, 166, 127, 88, 23, 197, 100, 66, 255, 215, 214, 229, 54, 1},
},
{
name: "OnePageASHA512SeparateFile",
data: bytes.Repeat([]byte{'a'}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: false,
- expectedHash: []byte{116, 22, 252, 100, 32, 241, 254, 228, 167, 228, 110, 146, 156, 189, 6, 30, 27, 127, 94, 181, 15, 98, 173, 60, 34, 102, 92, 174, 181, 80, 205, 90, 88, 12, 125, 194, 148, 175, 184, 168, 37, 66, 127, 194, 19, 132, 93, 147, 168, 217, 227, 131, 100, 25, 213, 255, 132, 60, 196, 217, 24, 158, 1, 50},
+ expectedHash: []byte{165, 46, 176, 116, 47, 209, 101, 193, 64, 185, 30, 9, 52, 22, 24, 154, 135, 220, 232, 168, 215, 45, 222, 226, 207, 104, 160, 10, 156, 98, 245, 250, 76, 21, 68, 204, 65, 118, 69, 52, 210, 155, 36, 109, 233, 103, 1, 40, 218, 89, 125, 38, 247, 194, 2, 225, 119, 155, 65, 99, 182, 111, 110, 145},
},
{
name: "OnePageASHA512SameFile",
data: bytes.Repeat([]byte{'a'}, usermem.PageSize),
hashAlgorithms: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: true,
- expectedHash: []byte{116, 22, 252, 100, 32, 241, 254, 228, 167, 228, 110, 146, 156, 189, 6, 30, 27, 127, 94, 181, 15, 98, 173, 60, 34, 102, 92, 174, 181, 80, 205, 90, 88, 12, 125, 194, 148, 175, 184, 168, 37, 66, 127, 194, 19, 132, 93, 147, 168, 217, 227, 131, 100, 25, 213, 255, 132, 60, 196, 217, 24, 158, 1, 50},
+ expectedHash: []byte{165, 46, 176, 116, 47, 209, 101, 193, 64, 185, 30, 9, 52, 22, 24, 154, 135, 220, 232, 168, 215, 45, 222, 226, 207, 104, 160, 10, 156, 98, 245, 250, 76, 21, 68, 204, 65, 118, 69, 52, 210, 155, 36, 109, 233, 103, 1, 40, 218, 89, 125, 38, 247, 194, 2, 225, 119, 155, 65, 99, 182, 111, 110, 145},
},
}
@@ -348,9 +349,9 @@ func TestGenerate(t *testing.T) {
// prepareVerify generates test data and corresponding Merkle tree, and returns
// the prepared VerifyParams.
-// The test data has size dataSize. The data is hashed with hashAlgorithms. The
-// portion to be verified ranges from verifyStart with verifySize.
-func prepareVerify(t *testing.T, dataSize int64, hashAlgorithm int, dataAndTreeInSameFile bool, verifyStart int64, verifySize int64, out io.Writer) ([]byte, VerifyParams) {
+// The test data has size dataSize. The data is hashed with hashAlgorithm. The
+// portion to be verified is the range [verifyStart, verifyStart + verifySize).
+func prepareVerify(t *testing.T, dataSize int64, hashAlgorithm int, dataAndTreeInSameFile, isSymlink bool, verifyStart, verifySize int64, out io.Writer) ([]byte, VerifyParams) {
t.Helper()
data := make([]byte, dataSize)
// Generate random bytes in data.
@@ -377,6 +378,10 @@ func prepareVerify(t *testing.T, dataSize int64, hashAlgorithm int, dataAndTreeI
bytes: data,
}
}
+
+ if isSymlink {
+ genParams.SymlinkTarget = defaultSymlinkPath
+ }
hash, err := Generate(&genParams)
if err != nil {
t.Fatalf("could not generate Merkle tree:%v", err)
@@ -428,7 +433,7 @@ func TestVerifyInvalidRange(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, linux.FS_VERITY_HASH_ALG_SHA256, false /* dataAndTreeInSameFile */, tc.verifyStart, tc.verifySize, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, linux.FS_VERITY_HASH_ALG_SHA256, false /* dataAndTreeInSameFile */, false /* isSymlink */, tc.verifyStart, tc.verifySize, &buf)
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
}
@@ -436,37 +441,46 @@ func TestVerifyInvalidRange(t *testing.T) {
}
}
+// TODO(b/179422935): Cleanup merkletree verify tests.
func TestVerifyUnmodifiedMetadata(t *testing.T) {
testCases := []struct {
name string
hashAlgorithm int
dataAndTreeInSameFile bool
+ isSymlink bool
}{
{
name: "SHA256SeparateFile",
hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: false,
+ isSymlink: true,
},
{
name: "SHA512SeparateFile",
hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: false,
+ isSymlink: false,
},
{
name: "SHA256SameFile",
hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA256,
dataAndTreeInSameFile: true,
+ isSymlink: false,
},
{
name: "SHA512SameFile",
hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA512,
dataAndTreeInSameFile: true,
+ isSymlink: false,
},
}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, tc.isSymlink, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ if tc.isSymlink {
+ params.SymlinkTarget = defaultSymlinkPath
+ }
if _, err := Verify(&params); !errors.Is(err, nil) {
t.Errorf("Verification failed when expected to succeed: %v", err)
}
@@ -504,7 +518,7 @@ func TestVerifyModifiedName(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.Name += "abc"
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -543,7 +557,7 @@ func TestVerifyModifiedSize(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.Size--
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -582,7 +596,7 @@ func TestVerifyModifiedMode(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.Mode++
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -621,7 +635,7 @@ func TestVerifyModifiedUID(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.UID++
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -660,7 +674,7 @@ func TestVerifyModifiedGID(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.GID++
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -699,7 +713,7 @@ func TestVerifyModifiedChildren(t *testing.T) {
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
var buf bytes.Buffer
- _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
params.Children["abc"] = struct{}{}
if _, err := Verify(&params); errors.Is(err, nil) {
t.Errorf("Verification succeeded when expected to fail")
@@ -708,6 +722,45 @@ func TestVerifyModifiedChildren(t *testing.T) {
}
}
+func TestVerifyModifiedSymlink(t *testing.T) {
+ testCases := []struct {
+ name string
+ hashAlgorithm int
+ dataAndTreeInSameFile bool
+ }{
+ {
+ name: "SHA256SeparateFile",
+ hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA256,
+ dataAndTreeInSameFile: false,
+ },
+ {
+ name: "SHA512SeparateFile",
+ hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA512,
+ dataAndTreeInSameFile: false,
+ },
+ {
+ name: "SHA256SameFile",
+ hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA256,
+ dataAndTreeInSameFile: true,
+ },
+ {
+ name: "SHA512SameFile",
+ hashAlgorithm: linux.FS_VERITY_HASH_ALG_SHA512,
+ dataAndTreeInSameFile: true,
+ },
+ }
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ var buf bytes.Buffer
+ _, params := prepareVerify(t, usermem.PageSize /* dataSize */, tc.hashAlgorithm, tc.dataAndTreeInSameFile, true /* isSymlink */, 0 /* verifyStart */, 0 /* verifySize */, &buf)
+ params.SymlinkTarget = "merkle_modified_test_link"
+ if _, err := Verify(&params); err == nil {
+ t.Errorf("Verification succeeded when expected to fail")
+ }
+ })
+ }
+}
+
func TestModifyOutsideVerifyRange(t *testing.T) {
testCases := []struct {
name string
@@ -772,7 +825,7 @@ func TestModifyOutsideVerifyRange(t *testing.T) {
verifySize := int64(usermem.PageSize)
var buf bytes.Buffer
// Modified byte is outside verify range. Verify should succeed.
- data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, verifyStart, verifySize, &buf)
+ data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, verifyStart, verifySize, &buf)
// Flip a bit in data and checks Verify results.
data[tc.modifyByte] ^= 1
n, err := Verify(&params)
@@ -1015,7 +1068,7 @@ func TestModifyInsideVerifyRange(t *testing.T) {
t.Run(tc.name, func(t *testing.T) {
dataSize := int64(8 * usermem.PageSize)
var buf bytes.Buffer
- data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, tc.verifyStart, tc.verifySize, &buf)
+ data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, tc.verifyStart, tc.verifySize, &buf)
// Flip a bit in data and checks Verify results.
data[tc.modifyByte] ^= 1
if _, err := Verify(&params); errors.Is(err, nil) {
@@ -1064,7 +1117,7 @@ func TestVerifyRandom(t *testing.T) {
size := rand.Int63n(dataSize) + 1
var buf bytes.Buffer
- data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, start, size, &buf)
+ data, params := prepareVerify(t, dataSize, tc.hashAlgorithm, tc.dataAndTreeInSameFile, false /* isSymlink */, start, size, &buf)
// Checks that the random portion of data from the original data is
// verified successfully.
diff --git a/pkg/sentry/fsimpl/verity/filesystem.go b/pkg/sentry/fsimpl/verity/filesystem.go
index a4ad625bb..9057d2b4e 100644
--- a/pkg/sentry/fsimpl/verity/filesystem.go
+++ b/pkg/sentry/fsimpl/verity/filesystem.go
@@ -426,6 +426,17 @@ func (fs *filesystem) verifyStatAndChildrenLocked(ctx context.Context, d *dentry
params.DataAndTreeInSameFile = true
}
+ if d.isSymlink() {
+ target, err := vfsObj.ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.lowerVD,
+ Start: d.lowerVD,
+ })
+ if err != nil {
+ return err
+ }
+ params.SymlinkTarget = target
+ }
+
if _, err := merkletree.Verify(params); err != nil && err != io.EOF {
return alertIntegrityViolation(fmt.Sprintf("Verification stat for %s failed: %v", childPath, err))
}
@@ -433,6 +444,7 @@ func (fs *filesystem) verifyStatAndChildrenLocked(ctx context.Context, d *dentry
d.uid = stat.UID
d.gid = stat.GID
d.size = uint32(size)
+ d.symlinkTarget = params.SymlinkTarget
return nil
}
@@ -934,11 +946,7 @@ func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (st
if err != nil {
return "", err
}
- //TODO(b/162787271): Provide integrity check for ReadlinkAt.
- return fs.vfsfs.VirtualFilesystem().ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{
- Root: d.lowerVD,
- Start: d.lowerVD,
- })
+ return d.readlink(ctx)
}
// RenameAt implements vfs.FilesystemImpl.RenameAt.
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index 8645078a0..374f71568 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -332,6 +332,11 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
d.hash = make([]byte, len(iopts.RootHash))
d.childrenNames = make(map[string]struct{})
+ if !d.isDir() {
+ ctx.Warningf("verity root must be a directory")
+ return nil, nil, syserror.EINVAL
+ }
+
if !fs.allowRuntimeEnable {
// Get children names from the underlying file system.
offString, err := vfsObj.GetXattrAt(ctx, creds, &vfs.PathOperation{
@@ -461,6 +466,9 @@ type dentry struct {
// initialized.
lowerMerkleVD vfs.VirtualDentry
+ // symlinkTarget is the target path of a symlink file in the underlying filesystem.
+ symlinkTarget string
+
// hash is the calculated hash for the current file or directory. hash
// is protected by hashMu.
hashMu sync.RWMutex `state:"nosave"`
@@ -645,6 +653,23 @@ func (d *dentry) getLowerAt(ctx context.Context, vfsObj *vfs.VirtualFilesystem,
}
func (d *dentry) readlink(ctx context.Context) (string, error) {
+ vfsObj := d.fs.vfsfs.VirtualFilesystem()
+ if d.verityEnabled() {
+ stat, err := vfsObj.StatAt(ctx, d.fs.creds, &vfs.PathOperation{
+ Root: d.lowerVD,
+ Start: d.lowerVD,
+ }, &vfs.StatOptions{})
+ if err != nil {
+ return "", err
+ }
+ d.dirMu.Lock()
+ defer d.dirMu.Unlock()
+ if err := d.fs.verifyStatAndChildrenLocked(ctx, d, stat); err != nil {
+ return "", err
+ }
+ return d.symlinkTarget, nil
+ }
+
return d.fs.vfsfs.VirtualFilesystem().ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{
Root: d.lowerVD,
Start: d.lowerVD,
@@ -756,7 +781,8 @@ func (fd *fileDescription) Seek(ctx context.Context, offset int64, whence int32)
// hash of the generated Merkle tree and the data size is returned. If fd
// points to a regular file, the data is the content of the file. If fd points
// to a directory, the data is all hashes of its children, written to the Merkle
-// tree file.
+// tree file. If fd represents a symlink, the data is empty and nothing is written
+// to the Merkle tree file.
//
// Preconditions: fd.d.fs.verityMu must be locked.
func (fd *fileDescription) generateMerkleLocked(ctx context.Context) ([]byte, uint64, error) {
@@ -772,30 +798,30 @@ func (fd *fileDescription) generateMerkleLocked(ctx context.Context) ([]byte, ui
FD: fd.merkleWriter,
Ctx: ctx,
}
+
+ stat, err := fd.lowerFD.Stat(ctx, vfs.StatOptions{})
+ if err != nil {
+ return nil, 0, err
+ }
+
params := &merkletree.GenerateParams{
TreeReader: &merkleReader,
TreeWriter: &merkleWriter,
Children: fd.d.childrenNames,
//TODO(b/156980949): Support passing other hash algorithms.
HashAlgorithms: fd.d.fs.alg.toLinuxHashAlg(),
+ Name: fd.d.name,
+ Mode: uint32(stat.Mode),
+ UID: stat.UID,
+ GID: stat.GID,
}
switch atomic.LoadUint32(&fd.d.mode) & linux.S_IFMT {
case linux.S_IFREG:
// For a regular file, generate a Merkle tree based on its
// content.
- var err error
- stat, err := fd.lowerFD.Stat(ctx, vfs.StatOptions{})
- if err != nil {
- return nil, 0, err
- }
-
params.File = &fdReader
params.Size = int64(stat.Size)
- params.Name = fd.d.name
- params.Mode = uint32(stat.Mode)
- params.UID = stat.UID
- params.GID = stat.GID
params.DataAndTreeInSameFile = false
case linux.S_IFDIR:
// For a directory, generate a Merkle tree based on the hashes
@@ -807,18 +833,20 @@ func (fd *fileDescription) generateMerkleLocked(ctx context.Context) ([]byte, ui
}
params.Size = int64(merkleStat.Size)
-
- stat, err := fd.lowerFD.Stat(ctx, vfs.StatOptions{})
+ params.File = &merkleReader
+ params.DataAndTreeInSameFile = true
+ case linux.S_IFLNK:
+ // For a symlink, generate a Merkle tree file but do not write the root hash
+ // of the target file content to it. Return a hash of a VerityDescriptor object
+ // which includes the symlink target name.
+ target, err := fd.d.readlink(ctx)
if err != nil {
return nil, 0, err
}
- params.File = &merkleReader
- params.Name = fd.d.name
- params.Mode = uint32(stat.Mode)
- params.UID = stat.UID
- params.GID = stat.GID
- params.DataAndTreeInSameFile = true
+ params.Size = int64(stat.Size)
+ params.DataAndTreeInSameFile = false
+ params.SymlinkTarget = target
default:
// TODO(b/167728857): Investigate whether and how we should
// enable other types of file.
diff --git a/pkg/sentry/fsimpl/verity/verity_test.go b/pkg/sentry/fsimpl/verity/verity_test.go
index 798d6a9bd..57bd65202 100644
--- a/pkg/sentry/fsimpl/verity/verity_test.go
+++ b/pkg/sentry/fsimpl/verity/verity_test.go
@@ -163,6 +163,17 @@ func (d *dentry) openLowerMerkleAt(ctx context.Context, vfsObj *vfs.VirtualFiles
})
}
+// mkdirLowerAt creates a directory in the underlying file system.
+func (d *dentry) mkdirLowerAt(ctx context.Context, vfsObj *vfs.VirtualFilesystem, path string, mode linux.FileMode) error {
+ return vfsObj.MkdirAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: d.lowerVD,
+ Start: d.lowerVD,
+ Path: fspath.Parse(path),
+ }, &vfs.MkdirOptions{
+ Mode: mode,
+ })
+}
+
// unlinkLowerAt deletes the file in the underlying file system.
func (d *dentry) unlinkLowerAt(ctx context.Context, vfsObj *vfs.VirtualFilesystem, path string) error {
return vfsObj.UnlinkAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
@@ -208,6 +219,16 @@ func (d *dentry) renameLowerMerkleAt(ctx context.Context, vfsObj *vfs.VirtualFil
}, &vfs.RenameOptions{})
}
+// symlinkLowerAt creates a symbolic link at symlink referring to the given target
+// in the underlying filesystem.
+func (d *dentry) symlinkLowerAt(ctx context.Context, vfsObj *vfs.VirtualFilesystem, target, symlink string) error {
+ return vfsObj.SymlinkAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: d.lowerVD,
+ Start: d.lowerVD,
+ Path: fspath.Parse(symlink),
+ }, target)
+}
+
// newFileFD creates a new file in the verity mount, and returns the FD. The FD
// points to a file that has random data generated.
func newFileFD(ctx context.Context, t *testing.T, vfsObj *vfs.VirtualFilesystem, root vfs.VirtualDentry, filePath string, mode linux.FileMode) (*vfs.FileDescription, int, error) {
@@ -239,6 +260,18 @@ func newFileFD(ctx context.Context, t *testing.T, vfsObj *vfs.VirtualFilesystem,
return fd, dataSize, err
}
+// newDirFD creates a new directory in the verity mount, and returns the FD.
+func newDirFD(ctx context.Context, t *testing.T, vfsObj *vfs.VirtualFilesystem, root vfs.VirtualDentry, dirPath string, mode linux.FileMode) (*vfs.FileDescription, error) {
+ // Create the directory in the underlying file system.
+ if err := dentryFromVD(t, root).mkdirLowerAt(ctx, vfsObj, dirPath, linux.ModeRegular|mode); err != nil {
+ return nil, err
+ }
+ if _, err := dentryFromVD(t, root).openLowerAt(ctx, vfsObj, dirPath, linux.O_RDONLY|linux.O_DIRECTORY, linux.ModeRegular|mode); err != nil {
+ return nil, err
+ }
+ return openVerityAt(ctx, vfsObj, root, dirPath, linux.O_RDONLY|linux.O_DIRECTORY, mode)
+}
+
// newEmptyFileFD creates a new empty file in the verity mount, and returns the FD.
func newEmptyFileFD(ctx context.Context, t *testing.T, vfsObj *vfs.VirtualFilesystem, root vfs.VirtualDentry, filePath string, mode linux.FileMode) (*vfs.FileDescription, error) {
// Create the file in the underlying file system.
@@ -801,3 +834,377 @@ func TestOpenRenamedFileFails(t *testing.T) {
})
}
}
+
+// TestUnmodifiedSymlinkFileReadSucceeds ensures that readlink() for an
+// unmodified verity enabled symlink succeeds.
+func TestUnmodifiedSymlinkFileReadSucceeds(t *testing.T) {
+ testCases := []struct {
+ name string
+ // The symlink target is a directory.
+ hasDirectoryTarget bool
+ // The symlink target is a directory and contains a regular file which will be
+ // used to test walking a symlink.
+ testWalk bool
+ }{
+ {
+ name: "RegularFileTarget",
+ hasDirectoryTarget: false,
+ testWalk: false,
+ },
+ {
+ name: "DirectoryTarget",
+ hasDirectoryTarget: true,
+ testWalk: false,
+ },
+ {
+ name: "RegularFileInSymlinkDirectory",
+ hasDirectoryTarget: true,
+ testWalk: true,
+ },
+ }
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ if tc.testWalk && !tc.hasDirectoryTarget {
+ t.Fatalf("Invalid test case: hasDirectoryTarget can't be false when testing symlink walk")
+ }
+
+ vfsObj, root, ctx, err := newVerityRoot(t, SHA256)
+ if err != nil {
+ t.Fatalf("newVerityRoot: %v", err)
+ }
+
+ var target string
+ if tc.hasDirectoryTarget {
+ target = "verity-test-dir"
+ if _, err := newDirFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newDirFD: %v", err)
+ }
+ } else {
+ target = "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ if tc.testWalk {
+ fileInTargetDirectory := target + "/" + "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, fileInTargetDirectory, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ symlink := "verity-test-symlink"
+ if err := dentryFromVD(t, root).symlinkLowerAt(ctx, vfsObj, target, symlink); err != nil {
+ t.Fatalf("SymlinkAt: %v", err)
+ }
+
+ fd, err := openVerityAt(ctx, vfsObj, root, symlink, linux.O_PATH|linux.O_NOFOLLOW, linux.ModeRegular)
+
+ if err != nil {
+ t.Fatalf("openVerityAt symlink: %v", err)
+ }
+
+ enableVerity(ctx, t, fd)
+
+ if _, err := vfsObj.ReadlinkAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(symlink),
+ }); err != nil {
+ t.Fatalf("ReadlinkAt: %v", err)
+ }
+
+ if tc.testWalk {
+ fileInSymlinkDirectory := symlink + "/verity-test-file"
+ // Ensure opening the verity enabled file in the symlink directory succeeds.
+ if _, err := openVerityAt(ctx, vfsObj, root, fileInSymlinkDirectory, linux.O_RDONLY, linux.ModeRegular); err != nil {
+ t.Errorf("open enabled file failed: %v", err)
+ }
+ }
+ })
+ }
+}
+
+// TestDeletedSymlinkFileReadFails ensures that reading value of a deleted verity enabled
+// symlink fails.
+func TestDeletedSymlinkFileReadFails(t *testing.T) {
+ testCases := []struct {
+ name string
+ // The original symlink is unlinked if deleteLink is true.
+ deleteLink bool
+ // The Merkle tree file is renamed if deleteMerkleFile is true.
+ deleteMerkleFile bool
+ // The symlink target is a directory.
+ hasDirectoryTarget bool
+ // The symlink target is a directory and contains a regular file which will be
+ // used to test walking a symlink.
+ testWalk bool
+ }{
+ {
+ name: "DeleteLinkRegularFile",
+ deleteLink: true,
+ deleteMerkleFile: false,
+ hasDirectoryTarget: false,
+ testWalk: false,
+ },
+ {
+ name: "DeleteMerkleRegFile",
+ deleteLink: false,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: false,
+ testWalk: false,
+ },
+ {
+ name: "DeleteLinkAndMerkleRegFile",
+ deleteLink: true,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: false,
+ testWalk: false,
+ },
+ {
+ name: "DeleteLinkDirectory",
+ deleteLink: true,
+ deleteMerkleFile: false,
+ hasDirectoryTarget: true,
+ testWalk: false,
+ },
+ {
+ name: "DeleteMerkleDirectory",
+ deleteLink: false,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: true,
+ testWalk: false,
+ },
+ {
+ name: "DeleteLinkAndMerkleDirectory",
+ deleteLink: true,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: true,
+ testWalk: false,
+ },
+ {
+ name: "DeleteLinkDirectoryWalk",
+ deleteLink: true,
+ deleteMerkleFile: false,
+ hasDirectoryTarget: true,
+ testWalk: true,
+ },
+ {
+ name: "DeleteMerkleDirectoryWalk",
+ deleteLink: false,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: true,
+ testWalk: true,
+ },
+ {
+ name: "DeleteLinkAndMerkleDirectoryWalk",
+ deleteLink: true,
+ deleteMerkleFile: true,
+ hasDirectoryTarget: true,
+ testWalk: true,
+ },
+ }
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ if tc.testWalk && !tc.hasDirectoryTarget {
+ t.Fatalf("Invalid test case: hasDirectoryTarget can't be false when testing symlink walk")
+ }
+
+ vfsObj, root, ctx, err := newVerityRoot(t, SHA256)
+ if err != nil {
+ t.Fatalf("newVerityRoot: %v", err)
+ }
+
+ var target string
+ if tc.hasDirectoryTarget {
+ target = "verity-test-dir"
+ if _, err := newDirFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newDirFD: %v", err)
+ }
+ } else {
+ target = "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ symlink := "verity-test-symlink"
+ if err := dentryFromVD(t, root).symlinkLowerAt(ctx, vfsObj, target, symlink); err != nil {
+ t.Fatalf("SymlinkAt: %v", err)
+ }
+
+ fd, err := openVerityAt(ctx, vfsObj, root, symlink, linux.O_PATH|linux.O_NOFOLLOW, linux.ModeRegular)
+
+ if err != nil {
+ t.Fatalf("openVerityAt symlink: %v", err)
+ }
+
+ if tc.testWalk {
+ fileInTargetDirectory := target + "/" + "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, fileInTargetDirectory, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ enableVerity(ctx, t, fd)
+
+ if tc.deleteLink {
+ if err := dentryFromVD(t, root).unlinkLowerAt(ctx, vfsObj, symlink); err != nil {
+ t.Fatalf("UnlinkAt: %v", err)
+ }
+ }
+ if tc.deleteMerkleFile {
+ if err := dentryFromVD(t, root).unlinkLowerMerkleAt(ctx, vfsObj, symlink); err != nil {
+ t.Fatalf("UnlinkAt: %v", err)
+ }
+ }
+ if _, err := vfsObj.ReadlinkAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(symlink),
+ }); err != syserror.EIO {
+ t.Fatalf("ReadlinkAt succeeded with modified symlink: %v", err)
+ }
+
+ if tc.testWalk {
+ fileInSymlinkDirectory := symlink + "/verity-test-file"
+ // Ensure opening the verity enabled file in the symlink directory fails.
+ if _, err := openVerityAt(ctx, vfsObj, root, fileInSymlinkDirectory, linux.O_RDONLY, linux.ModeRegular); err != syserror.EIO {
+ t.Errorf("Open succeeded with modified symlink: %v", err)
+ }
+ }
+ })
+ }
+}
+
+// TestModifiedSymlinkFileReadFails ensures that reading value of a modified verity enabled
+// symlink fails.
+func TestModifiedSymlinkFileReadFails(t *testing.T) {
+ testCases := []struct {
+ name string
+ // The symlink target is a directory.
+ hasDirectoryTarget bool
+ // The symlink target is a directory and contains a regular file which will be
+ // used to test walking a symlink.
+ testWalk bool
+ }{
+ {
+ name: "RegularFileTarget",
+ hasDirectoryTarget: false,
+ testWalk: false,
+ },
+ {
+ name: "DirectoryTarget",
+ hasDirectoryTarget: true,
+ testWalk: false,
+ },
+ {
+ name: "RegularFileInSymlinkDirectory",
+ hasDirectoryTarget: true,
+ testWalk: true,
+ },
+ }
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ if tc.testWalk && !tc.hasDirectoryTarget {
+ t.Fatalf("Invalid test case: hasDirectoryTarget can't be false when testing symlink walk")
+ }
+
+ vfsObj, root, ctx, err := newVerityRoot(t, SHA256)
+ if err != nil {
+ t.Fatalf("newVerityRoot: %v", err)
+ }
+
+ var target string
+ if tc.hasDirectoryTarget {
+ target = "verity-test-dir"
+ if _, err := newDirFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newDirFD: %v", err)
+ }
+ } else {
+ target = "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, target, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ // Create symlink which points to target file.
+ symlink := "verity-test-symlink"
+ if err := dentryFromVD(t, root).symlinkLowerAt(ctx, vfsObj, target, symlink); err != nil {
+ t.Fatalf("SymlinkAt: %v", err)
+ }
+
+ // Open symlink file to get the fd for ioctl in new step.
+ fd, err := openVerityAt(ctx, vfsObj, root, symlink, linux.O_PATH|linux.O_NOFOLLOW, linux.ModeRegular)
+ if err != nil {
+ t.Fatalf("OpenAt symlink: %v", err)
+ }
+
+ if tc.testWalk {
+ fileInTargetDirectory := target + "/" + "verity-test-file"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, fileInTargetDirectory, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ enableVerity(ctx, t, fd)
+
+ var newTarget string
+ if tc.hasDirectoryTarget {
+ newTarget = "verity-test-dir-new"
+ if _, err := newDirFD(ctx, t, vfsObj, root, newTarget, 0644); err != nil {
+ t.Fatalf("newDirFD: %v", err)
+ }
+ } else {
+ newTarget = "verity-test-file-new"
+ if _, _, err := newFileFD(ctx, t, vfsObj, root, newTarget, 0644); err != nil {
+ t.Fatalf("newFileFD: %v", err)
+ }
+ }
+
+ // Unlink symlink->target.
+ if err := dentryFromVD(t, root).unlinkLowerAt(ctx, vfsObj, symlink); err != nil {
+ t.Fatalf("UnlinkAt: %v", err)
+ }
+
+ // Link symlink->newTarget.
+ if err := dentryFromVD(t, root).symlinkLowerAt(ctx, vfsObj, newTarget, symlink); err != nil {
+ t.Fatalf("SymlinkAt: %v", err)
+ }
+
+ // Freshen lower dentry for symlink.
+ symlinkVD, err := vfsObj.GetDentryAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(symlink),
+ }, &vfs.GetDentryOptions{})
+ if err != nil {
+ t.Fatalf("Failed to get symlink dentry: %v", err)
+ }
+ symlinkDentry := dentryFromVD(t, symlinkVD)
+
+ symlinkLowerVD, err := dentryFromVD(t, root).getLowerAt(ctx, vfsObj, symlink)
+ if err != nil {
+ t.Fatalf("Failed to get symlink lower dentry: %v", err)
+ }
+ symlinkDentry.lowerVD = symlinkLowerVD
+
+ // Verify ReadlinkAt() fails.
+ if _, err := vfsObj.ReadlinkAt(ctx, auth.CredentialsFromContext(ctx), &vfs.PathOperation{
+ Root: root,
+ Start: root,
+ Path: fspath.Parse(symlink),
+ }); err != syserror.EIO {
+ t.Fatalf("ReadlinkAt succeeded with modified symlink: %v", err)
+ }
+
+ if tc.testWalk {
+ fileInSymlinkDirectory := symlink + "/verity-test-file"
+ // Ensure opening the verity enabled file in the symlink directory fails.
+ if _, err := openVerityAt(ctx, vfsObj, root, fileInSymlinkDirectory, linux.O_RDONLY, linux.ModeRegular); err != syserror.EIO {
+ t.Errorf("Open succeeded with modified symlink: %v", err)
+ }
+ }
+ })
+ }
+}
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 0aff2dd92..b0e13cdab 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -425,7 +425,9 @@ func (vfs *VirtualFilesystem) OpenAt(ctx context.Context, creds *auth.Credential
rp.mustBeDir = true
rp.mustBeDirOrig = true
}
- if opts.Flags&linux.O_PATH != 0 {
+ // Ignore O_PATH for verity, as verity performs extra operations on the fd for verification.
+ // The underlying filesystem that verity wraps opens the fd with O_PATH.
+ if opts.Flags&linux.O_PATH != 0 && rp.mount.fs.FilesystemType().Name() != "verity" {
vd, err := vfs.GetDentryAt(ctx, creds, pop, &GetDentryOptions{})
if err != nil {
return nil, err
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 00:37:22 +0000