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Allow replacing a read-only node with writable for same target 

PiperOrigin-RevId: 548942347
Change-Id: I4b22740ca27772831afcddb69d515c84aca04c51
pull/171/head
Wiktor Garbacz 2023-07-18 02:44:18 -07:00 committed by Copybara-Service
parent 4ba75ea0a2
commit 25f27ef935
3 changed files with 167 additions and 13 deletions
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68
sandboxed_api/sandbox2/mounts.cc
View File

@ -145,24 +145,54 @@ bool IsSameFile(const std::string& path1, const std::string& path2) {
return stat1.st_dev == stat2.st_dev && stat1.st_ino == stat2.st_ino;
}
bool IsEquivalentNode(const MountTree::Node& n1, const MountTree::Node& n2) {
bool IsWritable(const MountTree::Node& node) {
switch (node.node_case()) {
case MountTree::Node::kFileNode:
return node.file_node().writable();
case MountTree::Node::kDirNode:
return node.dir_node().writable();
case MountTree::Node::kRootNode:
return node.root_node().writable();
default:
return false;
}
}
bool HasSameTarget(const MountTree::Node& n1, const MountTree::Node& n2) {
// Return early when node types are different
if (n1.node_case() != n2.node_case()) {
return false;
}
// Compare proto fileds
switch (n1.node_case()) {
case MountTree::Node::kFileNode:
// Check whether files are the same (e.g. symlinks / hardlinks)
return IsSameFile(n1.file_node().outside(), n2.file_node().outside());
case MountTree::Node::kDirNode:
// Check whether dirs are the same (e.g. symlinks / hardlinks)
return IsSameFile(n1.dir_node().outside(), n2.dir_node().outside());
case MountTree::Node::kTmpfsNode:
return n1.tmpfs_node().tmpfs_options() == n2.tmpfs_node().tmpfs_options();
case MountTree::Node::kRootNode:
return true;
default:
return false;
}
}
bool IsEquivalentNode(const MountTree::Node& n1, const MountTree::Node& n2) {
if (!HasSameTarget(n1, n2)) {
return false;
}
// Compare proto fileds
switch (n1.node_case()) {
case MountTree::Node::kFileNode:
// Check whether files are the same (e.g. symlinks / hardlinks)
return n1.file_node().writable() == n2.file_node().writable() &&
IsSameFile(n1.file_node().outside(), n2.file_node().outside());
return n1.file_node().writable() == n2.file_node().writable();
case MountTree::Node::kDirNode:
// Check whether dirs are the same (e.g. symlinks / hardlinks)
return n1.dir_node().writable() == n2.dir_node().writable() &&
IsSameFile(n1.dir_node().outside(), n2.dir_node().outside());
return n1.dir_node().writable() == n2.dir_node().writable();
case MountTree::Node::kTmpfsNode:
return n1.tmpfs_node().tmpfs_options() == n2.tmpfs_node().tmpfs_options();
return true;
case MountTree::Node::kRootNode:
return n1.root_node().writable() == n2.root_node().writable();
default:
@ -275,6 +305,24 @@ absl::Status Mounts::Insert(absl::string_view path,
std::string(path).c_str());
return absl::OkStatus();
}
if (internal::HasSameTarget(curtree->node(), new_node)) {
if (!internal::IsWritable(curtree->node()) &&
internal::IsWritable(new_node)) {
SAPI_RAW_LOG(INFO,
"Chaning %s to writable, was insterted read-only before",
std::string(path).c_str());
*curtree->mutable_node() = new_node;
return absl::OkStatus();
}
if (internal::IsWritable(curtree->node()) &&
!internal::IsWritable(new_node)) {
SAPI_RAW_LOG(INFO,
"Inserting %s read-only is a nop, as it was insterted "
"writable before",
std::string(path).c_str());
return absl::OkStatus();
}
}
return absl::FailedPreconditionError(absl::StrCat(
"Inserting ", path, " twice with conflicting values ",
curtree->node().DebugString(), " vs. ", new_node.DebugString()));
@ -289,10 +337,6 @@ absl::Status Mounts::Insert(absl::string_view path,
return absl::OkStatus();
}
absl::Status Mounts::AddFile(absl::string_view path, bool is_ro) {
return AddFileAt(path, path, is_ro);
}
absl::Status Mounts::AddFileAt(absl::string_view outside,
absl::string_view inside, bool is_ro) {
MountTree::Node node;

10
sandboxed_api/sandbox2/mounts.h
View File

@ -29,6 +29,8 @@ namespace sandbox2 {
namespace internal {
bool IsSameFile(const std::string& path1, const std::string& path2);
bool IsWritable(const MountTree::Node& node);
bool HasSameTarget(const MountTree::Node& n1, const MountTree::Node& n2);
bool IsEquivalentNode(const MountTree::Node& n1, const MountTree::Node& n2);
} // namespace internal
@ -47,11 +49,17 @@ class Mounts {
Mounts& operator=(const Mounts&) = default;
Mounts& operator=(Mounts&&) = default;
absl::Status AddFile(absl::string_view path, bool is_ro = true);
absl::Status AddFile(absl::string_view path, bool is_ro = true) {
return AddFileAt(path, path, is_ro);
}
absl::Status AddFileAt(absl::string_view outside, absl::string_view inside,
bool is_ro = true);
absl::Status AddDirectory(absl::string_view path, bool is_ro = true) {
return AddDirectoryAt(path, path, is_ro);
}
absl::Status AddDirectoryAt(absl::string_view outside,
absl::string_view inside, bool is_ro = true);

102
sandboxed_api/sandbox2/mounts_test.cc
View File

@ -128,6 +128,18 @@ TEST(MountTreeTest, TestMultipleInsertionFileSymlink) {
EXPECT_THAT(mounts.AddFileAt(symlink_path, "/a"), IsOk());
}
TEST(MountTreeTest, TestMultipleInsertionUpgradeToWritable) {
Mounts mounts;
EXPECT_THAT(mounts.AddFile("/a"), IsOk());
EXPECT_THAT(mounts.AddFile("/a", /*is_ro=*/false), IsOk());
EXPECT_THAT(mounts.AddDirectory("/b"), IsOk());
EXPECT_THAT(mounts.AddDirectory("/b", /*is_ro=*/false), IsOk());
EXPECT_THAT(mounts.AddFile("/c", /*is_ro=*/false), IsOk());
EXPECT_THAT(mounts.AddFile("/c"), IsOk());
EXPECT_THAT(mounts.AddDirectory("/d", /*is_ro=*/false), IsOk());
EXPECT_THAT(mounts.AddDirectory("/d"), IsOk());
}
TEST(MountTreeTest, TestMultipleInsertionDirSymlink) {
Mounts mounts;
@ -265,6 +277,96 @@ TEST(MountTreeTest, TestList) {
// clang-format on
}
TEST(MountTreeTest, TestIsWritable) {
MountTree::Node nodes[7];
MountTree::FileNode* fn0 = nodes[0].mutable_file_node();
fn0->set_writable(false);
fn0->set_outside("foo");
MountTree::FileNode* fn1 = nodes[1].mutable_file_node();
fn1->set_writable(true);
fn1->set_outside("bar");
MountTree::DirNode* dn0 = nodes[2].mutable_dir_node();
dn0->set_writable(false);
dn0->set_outside("foo");
MountTree::DirNode* dn1 = nodes[3].mutable_dir_node();
dn1->set_writable(true);
dn1->set_outside("bar");
MountTree::RootNode* rn0 = nodes[4].mutable_root_node();
rn0->set_writable(false);
MountTree::RootNode* rn1 = nodes[5].mutable_root_node();
rn1->set_writable(true);
MountTree::TmpfsNode* tn0 = nodes[6].mutable_tmpfs_node();
tn0->set_tmpfs_options("option1");
EXPECT_FALSE(internal::IsWritable(nodes[0]));
EXPECT_TRUE(internal::IsWritable(nodes[1]));
EXPECT_FALSE(internal::IsWritable(nodes[2]));
EXPECT_TRUE(internal::IsWritable(nodes[3]));
EXPECT_FALSE(internal::IsWritable(nodes[4]));
EXPECT_TRUE(internal::IsWritable(nodes[5]));
EXPECT_FALSE(internal::IsWritable(nodes[6]));
}
TEST(MountTreeTest, TestHasSameTarget) {
MountTree::Node nodes[10];
MountTree::FileNode* fn0 = nodes[0].mutable_file_node();
fn0->set_writable(false);
fn0->set_outside("foo");
MountTree::FileNode* fn1 = nodes[1].mutable_file_node();
fn1->set_writable(true);
fn1->set_outside("foo");
MountTree::FileNode* fn2 = nodes[2].mutable_file_node();
fn2->set_writable(false);
fn2->set_outside("bar");
MountTree::DirNode* dn0 = nodes[3].mutable_dir_node();
dn0->set_writable(false);
dn0->set_outside("foo");
MountTree::DirNode* dn1 = nodes[4].mutable_dir_node();
dn1->set_writable(true);
dn1->set_outside("foo");
MountTree::DirNode* dn2 = nodes[5].mutable_dir_node();
dn2->set_writable(false);
dn2->set_outside("bar");
MountTree::TmpfsNode* tn0 = nodes[6].mutable_tmpfs_node();
tn0->set_tmpfs_options("option1");
MountTree::TmpfsNode* tn1 = nodes[7].mutable_tmpfs_node();
tn1->set_tmpfs_options("option2");
MountTree::RootNode* rn0 = nodes[8].mutable_root_node();
rn0->set_writable(false);
MountTree::RootNode* rn1 = nodes[9].mutable_root_node();
rn1->set_writable(true);
// Compare same file nodes
EXPECT_TRUE(internal::HasSameTarget(nodes[0], nodes[0]));
// Compare almost same file nodes (ro vs rw)
EXPECT_TRUE(internal::HasSameTarget(nodes[0], nodes[1]));
// Compare different file nodes
EXPECT_FALSE(internal::HasSameTarget(nodes[0], nodes[2]));
// Compare file node with dir node
EXPECT_FALSE(internal::HasSameTarget(nodes[0], nodes[3]));
// Compare same dir nodes
EXPECT_TRUE(internal::HasSameTarget(nodes[3], nodes[3]));
// Compare almost same dir nodes (ro vs rw)
EXPECT_TRUE(internal::HasSameTarget(nodes[3], nodes[4]));
// Compare different dir nodes
EXPECT_FALSE(internal::HasSameTarget(nodes[3], nodes[5]));
// Compare dir node with tmpfs node
EXPECT_FALSE(internal::HasSameTarget(nodes[3], nodes[6]));
// Compare same tmpfs nodes
EXPECT_TRUE(internal::HasSameTarget(nodes[6], nodes[6]));
// Compare different tmpfs nodes
EXPECT_FALSE(internal::HasSameTarget(nodes[6], nodes[7]));
// Compare dir node with root node
EXPECT_FALSE(internal::HasSameTarget(nodes[6], nodes[8]));
// Compare same root nodes
EXPECT_TRUE(internal::HasSameTarget(nodes[8], nodes[8]));
// Compare almost same root nodes (ro vs rw)
EXPECT_TRUE(internal::HasSameTarget(nodes[8], nodes[9]));
}
TEST(MountTreeTest, TestNodeEquivalence) {
MountTree::Node nodes[8];
MountTree::FileNode* fn0 = nodes[0].mutable_file_node();