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gvisor/test/syscalls/linux/proc_net_unix.cc

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// Copyright 2019 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "gtest/gtest.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_format.h"
#include "absl/strings/str_join.h"
#include "absl/strings/str_split.h"
#include "test/syscalls/linux/unix_domain_socket_test_util.h"
#include "test/util/file_descriptor.h"
#include "test/util/fs_util.h"
#include "test/util/test_util.h"
namespace gvisor {
namespace testing {
namespace {
using absl::StrCat;
using absl::StreamFormat;
using absl::StrFormat;
constexpr char kProcNetUnixHeader[] =
"Num RefCount Protocol Flags Type St Inode Path";
// Possible values of the "st" field in a /proc/net/unix entry. Source: Linux
// kernel, include/uapi/linux/net.h.
enum {
SS_FREE = 0, // Not allocated
SS_UNCONNECTED, // Unconnected to any socket
SS_CONNECTING, // In process of connecting
SS_CONNECTED, // Connected to socket
SS_DISCONNECTING // In process of disconnecting
};
// UnixEntry represents a single entry from /proc/net/unix.
struct UnixEntry {
uintptr_t addr;
uint64_t refs;
uint64_t protocol;
uint64_t flags;
uint64_t type;
uint64_t state;
uint64_t inode;
std::string path;
};
// Abstract socket paths can have either trailing null bytes or '@'s as padding
// at the end, depending on the linux version. This function strips any such
// padding.
void StripAbstractPathPadding(std::string* s) {
const char pad_char = s->back();
if (pad_char != '\0' && pad_char != '@') {
return;
}
const auto last_pos = s->find_last_not_of(pad_char);
if (last_pos != std::string::npos) {
s->resize(last_pos + 1);
}
}
// Precondition: addr must be a unix socket address (i.e. sockaddr_un) and
// addr->sun_path must be null-terminated. This is always the case if addr comes
// from Linux:
//
// Per man unix(7):
//
// "When the address of a pathname socket is returned (by [getsockname(2)]), its
// length is
//
// offsetof(struct sockaddr_un, sun_path) + strlen(sun_path) + 1
//
// and sun_path contains the null-terminated pathname."
std::string ExtractPath(const struct sockaddr* addr) {
const char* path =
reinterpret_cast<const struct sockaddr_un*>(addr)->sun_path;
// Note: sockaddr_un.sun_path is an embedded character array of length
// UNIX_PATH_MAX, so we can always safely dereference the first 2 bytes below.
//
// We also rely on the path being null-terminated.
if (path[0] == 0) {
std::string abstract_path = StrCat("@", &path[1]);
StripAbstractPathPadding(&abstract_path);
return abstract_path;
}
return std::string(path);
}
// Returns a parsed representation of /proc/net/unix entries.
PosixErrorOr<std::vector<UnixEntry>> ProcNetUnixEntries() {
std::string content;
RETURN_IF_ERRNO(GetContents("/proc/net/unix", &content));
bool skipped_header = false;
std::vector<UnixEntry> entries;
std::vector<std::string> lines = absl::StrSplit(content, '\n');
std::cerr << "<contents of /proc/net/unix>" << std::endl;
for (std::string line : lines) {
// Emit the proc entry to the test output to provide context for the test
// results.
std::cerr << line << std::endl;
if (!skipped_header) {
EXPECT_EQ(line, kProcNetUnixHeader);
skipped_header = true;
continue;
}
if (line.empty()) {
continue;
}
// Parse a single entry from /proc/net/unix.
//
// Sample file:
//
// clang-format off
//
// Num RefCount Protocol Flags Type St Inode Path"
// ffffa130e7041c00: 00000002 00000000 00010000 0001 01 1299413685 /tmp/control_server/13293772586877554487
// ffffa14f547dc400: 00000002 00000000 00010000 0001 01 3793 @remote_coredump
//
// clang-format on
//
// Note that from the second entry, the inode number can be padded using
// spaces, so we need to handle it separately during parsing. See
// net/unix/af_unix.c:unix_seq_show() for how these entries are produced. In
// particular, only the inode field is padded with spaces.
UnixEntry entry;
// Process the first 6 fields, up to but not including "Inode".
std::vector<std::string> fields =
absl::StrSplit(line, absl::MaxSplits(' ', 6));
if (fields.size() < 7) {
return PosixError(EINVAL, StrFormat("Invalid entry: '%s'\n", line));
}
// AtoiBase can't handle the ':' in the "Num" field, so strip it out.
std::vector<std::string> addr = absl::StrSplit(fields[0], ':');
ASSIGN_OR_RETURN_ERRNO(entry.addr, AtoiBase(addr[0], 16));
ASSIGN_OR_RETURN_ERRNO(entry.refs, AtoiBase(fields[1], 16));
ASSIGN_OR_RETURN_ERRNO(entry.protocol, AtoiBase(fields[2], 16));
ASSIGN_OR_RETURN_ERRNO(entry.flags, AtoiBase(fields[3], 16));
ASSIGN_OR_RETURN_ERRNO(entry.type, AtoiBase(fields[4], 16));
ASSIGN_OR_RETURN_ERRNO(entry.state, AtoiBase(fields[5], 16));
absl::string_view rest = absl::StripAsciiWhitespace(fields[6]);
fields = absl::StrSplit(rest, absl::MaxSplits(' ', 1));
if (fields.empty()) {
return PosixError(
EINVAL, StrFormat("Invalid entry, missing 'Inode': '%s'\n", line));
}
ASSIGN_OR_RETURN_ERRNO(entry.inode, AtoiBase(fields[0], 10));
entry.path = "";
if (fields.size() > 1) {
entry.path = fields[1];
StripAbstractPathPadding(&entry.path);
}
entries.push_back(entry);
}
std::cerr << "<end of /proc/net/unix>" << std::endl;
return entries;
}
// Finds the first entry in 'entries' for which 'predicate' returns true.
// Returns true on match, and sets 'match' to point to the matching entry.
bool FindBy(std::vector<UnixEntry> entries, UnixEntry* match,
std::function<bool(const UnixEntry&)> predicate) {
for (int i = 0; i < entries.size(); ++i) {
if (predicate(entries[i])) {
*match = entries[i];
return true;
}
}
return false;
}
bool FindByPath(std::vector<UnixEntry> entries, UnixEntry* match,
const std::string& path) {
return FindBy(entries, match,
[path](const UnixEntry& e) { return e.path == path; });
}
TEST(ProcNetUnix, Exists) {
const std::string content =
ASSERT_NO_ERRNO_AND_VALUE(GetContents("/proc/net/unix"));
const std::string header_line = StrCat(kProcNetUnixHeader, "\n");
if (IsRunningOnGvisor()) {
// Should be just the header since we don't have any unix domain sockets
// yet.
EXPECT_EQ(content, header_line);
} else {
// However, on a general linux machine, we could have abitrary sockets on
// the system, so just check the header.
EXPECT_THAT(content, ::testing::StartsWith(header_line));
}
}
TEST(ProcNetUnix, FilesystemBindAcceptConnect) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
FilesystemBoundUnixDomainSocketPair(SOCK_STREAM).Create());
std::string path1 = ExtractPath(sockets->first_addr());
std::string path2 = ExtractPath(sockets->second_addr());
std::cerr << StreamFormat("Server socket address (path1): %s\n", path1);
std::cerr << StreamFormat("Client socket address (path2): %s\n", path2);
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
if (IsRunningOnGvisor()) {
EXPECT_EQ(entries.size(), 2);
}
// The server-side socket's path is listed in the socket entry...
UnixEntry s1;
EXPECT_TRUE(FindByPath(entries, &s1, path1));
// ... but the client-side socket's path is not.
UnixEntry s2;
EXPECT_FALSE(FindByPath(entries, &s2, path2));
}
TEST(ProcNetUnix, AbstractBindAcceptConnect) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractBoundUnixDomainSocketPair(SOCK_STREAM).Create());
std::string path1 = ExtractPath(sockets->first_addr());
std::string path2 = ExtractPath(sockets->second_addr());
std::cerr << StreamFormat("Server socket address (path1): '%s'\n", path1);
std::cerr << StreamFormat("Client socket address (path2): '%s'\n", path2);
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
if (IsRunningOnGvisor()) {
EXPECT_EQ(entries.size(), 2);
}
// The server-side socket's path is listed in the socket entry...
UnixEntry s1;
EXPECT_TRUE(FindByPath(entries, &s1, path1));
// ... but the client-side socket's path is not.
UnixEntry s2;
EXPECT_FALSE(FindByPath(entries, &s2, path2));
}
TEST(ProcNetUnix, SocketPair) {
// Under gvisor, ensure a socketpair() syscall creates exactly 2 new
// entries. We have no way to verify this under Linux, as we have no control
// over socket creation on a general Linux machine.
SKIP_IF(!IsRunningOnGvisor());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
ASSERT_EQ(entries.size(), 0);
auto sockets =
ASSERT_NO_ERRNO_AND_VALUE(UnixDomainSocketPair(SOCK_STREAM).Create());
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
EXPECT_EQ(entries.size(), 2);
}
TEST(ProcNetUnix, StreamSocketStateUnconnectedOnBind) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractUnboundUnixDomainSocketPair(SOCK_STREAM).Create());
ASSERT_THAT(bind(sockets->first_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
const std::string address = ExtractPath(sockets->first_addr());
UnixEntry bind_entry;
ASSERT_TRUE(FindByPath(entries, &bind_entry, address));
EXPECT_EQ(bind_entry.state, SS_UNCONNECTED);
}
TEST(ProcNetUnix, StreamSocketStateStateUnconnectedOnListen) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractUnboundUnixDomainSocketPair(SOCK_STREAM).Create());
ASSERT_THAT(bind(sockets->first_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
const std::string address = ExtractPath(sockets->first_addr());
UnixEntry bind_entry;
ASSERT_TRUE(FindByPath(entries, &bind_entry, address));
EXPECT_EQ(bind_entry.state, SS_UNCONNECTED);
ASSERT_THAT(listen(sockets->first_fd(), 5), SyscallSucceeds());
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
UnixEntry listen_entry;
ASSERT_TRUE(
FindByPath(entries, &listen_entry, ExtractPath(sockets->first_addr())));
EXPECT_EQ(listen_entry.state, SS_UNCONNECTED);
// The bind and listen entries should refer to the same socket.
EXPECT_EQ(listen_entry.inode, bind_entry.inode);
}
TEST(ProcNetUnix, StreamSocketStateStateConnectedOnAccept) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractUnboundUnixDomainSocketPair(SOCK_STREAM).Create());
const std::string address = ExtractPath(sockets->first_addr());
ASSERT_THAT(bind(sockets->first_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
ASSERT_THAT(listen(sockets->first_fd(), 5), SyscallSucceeds());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
UnixEntry listen_entry;
ASSERT_TRUE(
FindByPath(entries, &listen_entry, ExtractPath(sockets->first_addr())));
ASSERT_THAT(connect(sockets->second_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
int clientfd;
ASSERT_THAT(clientfd = accept(sockets->first_fd(), nullptr, nullptr),
SyscallSucceeds());
// Find the entry for the accepted socket. UDS proc entries don't have a
// remote address, so we distinguish the accepted socket from the listen
// socket by checking for a different inode.
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
UnixEntry accept_entry;
ASSERT_TRUE(FindBy(
entries, &accept_entry, [address, listen_entry](const UnixEntry& e) {
return e.path == address && e.inode != listen_entry.inode;
}));
EXPECT_EQ(accept_entry.state, SS_CONNECTED);
// Listen entry should still be in SS_UNCONNECTED state.
ASSERT_TRUE(FindBy(entries, &listen_entry,
[&sockets, listen_entry](const UnixEntry& e) {
return e.path == ExtractPath(sockets->first_addr()) &&
e.inode == listen_entry.inode;
}));
EXPECT_EQ(listen_entry.state, SS_UNCONNECTED);
}
TEST(ProcNetUnix, DgramSocketStateDisconnectingOnBind) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractUnboundUnixDomainSocketPair(SOCK_DGRAM).Create());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
// On gVisor, the only two UDS on the system are the ones we just created and
// we rely on this to locate the test socket entries in the remainder of the
// test. On a generic Linux system, we have no easy way to locate the
// corresponding entries, as they don't have an address yet.
if (IsRunningOnGvisor()) {
ASSERT_EQ(entries.size(), 2);
for (auto e : entries) {
ASSERT_EQ(e.state, SS_DISCONNECTING);
}
}
ASSERT_THAT(bind(sockets->first_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
const std::string address = ExtractPath(sockets->first_addr());
UnixEntry bind_entry;
ASSERT_TRUE(FindByPath(entries, &bind_entry, address));
EXPECT_EQ(bind_entry.state, SS_UNCONNECTED);
}
TEST(ProcNetUnix, DgramSocketStateConnectingOnConnect) {
auto sockets = ASSERT_NO_ERRNO_AND_VALUE(
AbstractUnboundUnixDomainSocketPair(SOCK_DGRAM).Create());
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
// On gVisor, the only two UDS on the system are the ones we just created and
// we rely on this to locate the test socket entries in the remainder of the
// test. On a generic Linux system, we have no easy way to locate the
// corresponding entries, as they don't have an address yet.
if (IsRunningOnGvisor()) {
ASSERT_EQ(entries.size(), 2);
for (auto e : entries) {
ASSERT_EQ(e.state, SS_DISCONNECTING);
}
}
ASSERT_THAT(bind(sockets->first_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
const std::string address = ExtractPath(sockets->first_addr());
UnixEntry bind_entry;
ASSERT_TRUE(FindByPath(entries, &bind_entry, address));
ASSERT_THAT(connect(sockets->second_fd(), sockets->first_addr(),
sockets->first_addr_size()),
SyscallSucceeds());
entries = ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
// Once again, we have no easy way to identify the connecting socket as it has
// no listed address. We can only identify the entry as the "non-bind socket
// entry" on gVisor, where we're guaranteed to have only the two entries we
// create during this test.
if (IsRunningOnGvisor()) {
ASSERT_EQ(entries.size(), 2);
UnixEntry connect_entry;
ASSERT_TRUE(
FindBy(entries, &connect_entry, [bind_entry](const UnixEntry& e) {
return e.inode != bind_entry.inode;
}));
EXPECT_EQ(connect_entry.state, SS_CONNECTING);
}
}
} // namespace
} // namespace testing
} // namespace gvisor
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