nixpkgs/pkgs/applications/networking/browsers/chromium/sandbox_userns_31.patch
aszlig 3af40ade24
chromium: Add missing patch for version 31.
I accidentally forgot to add the new patch for version 31, sorry for the
noise and evaluation error caused by this:

http://hydra.nixos.org/jobset/nixos/trunk-combined#tabs-errors

And thanks to @iElectric for noticing.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
2013-09-17 13:05:20 +02:00

298 lines
11 KiB
Diff

commit ff4e8b4af04c58fc4c58ee7ed108aefcdc26a960
Author: aszlig <aszlig@redmoonstudios.org>
Date: Thu May 16 14:17:56 2013 +0200
zygote: Add support for user namespaces on Linux.
The implementation is done by patching the Zygote host to execute the sandbox
binary with CLONE_NEWUSER and setting the uid and gid mapping so that the child
process is using uid 0 and gid 0 which map to the current user of the parent.
Afterwards, the sandbox will continue as if it was called as a setuid binary.
In addition, this adds new_user_namespace as an option in process_util in order
to set the UID and GID mapping correctly. The reason for this is that just
passing CLONE_NEWUSER to clone_flags doesn't help in LaunchProcess(), because
without setting the mappings exec*() will clear the process's capability sets.
If the kernel doesn't support unprivileged user namespaces and the sandbox
binary doesn't have the setuid flag, the Zygote main process will run without a
sandbox. This is to mimic the behaviour if no SUID sandbox binary path is set.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
diff --git a/base/process/launch.cc b/base/process/launch.cc
index 1329a5a..ec28fdf 100644
--- a/base/process/launch.cc
+++ b/base/process/launch.cc
@@ -24,6 +24,7 @@ LaunchOptions::LaunchOptions()
new_process_group(false)
#if defined(OS_LINUX)
, clone_flags(0)
+ , new_user_namespace(false)
#endif // OS_LINUX
#if defined(OS_CHROMEOS)
, ctrl_terminal_fd(-1)
diff --git a/base/process/launch.h b/base/process/launch.h
index ac2df5e..34a3851 100644
--- a/base/process/launch.h
+++ b/base/process/launch.h
@@ -100,6 +100,9 @@ struct BASE_EXPORT LaunchOptions {
#if defined(OS_LINUX)
// If non-zero, start the process using clone(), using flags as provided.
int clone_flags;
+
+ // If true, start the process in a new user namespace.
+ bool new_user_namespace;
#endif // defined(OS_LINUX)
#if defined(OS_CHROMEOS)
diff --git a/base/process/launch_posix.cc b/base/process/launch_posix.cc
index de6286d..9333494 100644
--- a/base/process/launch_posix.cc
+++ b/base/process/launch_posix.cc
@@ -37,6 +37,13 @@
#include "base/threading/platform_thread.h"
#include "base/threading/thread_restrictions.h"
+#if defined(OS_LINUX)
+#include <sched.h>
+#if !defined(CLONE_NEWUSER)
+#define CLONE_NEWUSER 0x10000000
+#endif
+#endif
+
#if defined(OS_CHROMEOS)
#include <sys/ioctl.h>
#endif
@@ -294,13 +301,23 @@ bool LaunchProcess(const std::vector<std::string>& argv,
pid_t pid;
#if defined(OS_LINUX)
- if (options.clone_flags) {
+ int map_pipe_fd[2];
+ int flags = options.clone_flags;
+
+ if (options.new_user_namespace) {
+ flags |= CLONE_NEWUSER;
+ if (pipe(map_pipe_fd) < 0) {
+ DPLOG(ERROR) << "user namespace pipe";
+ return false;
+ }
+ }
+
+ if (options.clone_flags || options.new_user_namespace) {
// Signal handling in this function assumes the creation of a new
// process, so we check that a thread is not being created by mistake
// and that signal handling follows the process-creation rules.
- RAW_CHECK(
- !(options.clone_flags & (CLONE_SIGHAND | CLONE_THREAD | CLONE_VM)));
- pid = syscall(__NR_clone, options.clone_flags, 0, 0, 0);
+ RAW_CHECK(!(flags & (CLONE_SIGHAND | CLONE_THREAD | CLONE_VM)));
+ pid = syscall(__NR_clone, flags, 0, 0, 0);
} else
#endif
{
@@ -318,6 +335,21 @@ bool LaunchProcess(const std::vector<std::string>& argv,
} else if (pid == 0) {
// Child process
+#if defined(OS_LINUX)
+ if (options.new_user_namespace) {
+ // Close the write end of the pipe so we get an EOF when the parent closes
+ // the FD. This is to avoid race conditions when the UID/GID mappings are
+ // written _after_ execvp().
+ close(map_pipe_fd[1]);
+
+ char dummy;
+ if (HANDLE_EINTR(read(map_pipe_fd[0], &dummy, 1)) != 0) {
+ RAW_LOG(ERROR, "Unexpected input in uid/gid mapping pipe.");
+ _exit(127);
+ }
+ }
+#endif
+
// DANGER: fork() rule: in the child, if you don't end up doing exec*(),
// you call _exit() instead of exit(). This is because _exit() does not
// call any previously-registered (in the parent) exit handlers, which
@@ -433,6 +465,40 @@ bool LaunchProcess(const std::vector<std::string>& argv,
_exit(127);
} else {
// Parent process
+#if defined(OS_LINUX)
+ if (options.new_user_namespace) {
+ // We need to write UID/GID mapping here to map the current user outside
+ // the namespace to the root user inside the namespace in order to
+ // correctly "fool" the child process.
+ char buf[256];
+ int map_fd, map_len;
+
+ snprintf(buf, sizeof(buf), "/proc/%d/uid_map", pid);
+ map_fd = open(buf, O_RDWR);
+ DPCHECK(map_fd >= 0);
+ snprintf(buf, sizeof(buf), "0 %d 1", geteuid());
+ map_len = strlen(buf);
+ if (write(map_fd, buf, map_len) != map_len) {
+ RAW_LOG(WARNING, "Can't write to uid_map.");
+ }
+ close(map_fd);
+
+ snprintf(buf, sizeof(buf), "/proc/%d/gid_map", pid);
+ map_fd = open(buf, O_RDWR);
+ DPCHECK(map_fd >= 0);
+ snprintf(buf, sizeof(buf), "0 %d 1", getegid());
+ map_len = strlen(buf);
+ if (write(map_fd, buf, map_len) != map_len) {
+ RAW_LOG(WARNING, "Can't write to gid_map.");
+ }
+ close(map_fd);
+
+ // Close the pipe on the parent, so the child can continue doing the
+ // execvp() call.
+ close(map_pipe_fd[1]);
+ }
+#endif
+
if (options.wait) {
// While this isn't strictly disk IO, waiting for another process to
// finish is the sort of thing ThreadRestrictions is trying to prevent.
diff --git a/content/browser/zygote_host/zygote_host_impl_linux.cc b/content/browser/zygote_host/zygote_host_impl_linux.cc
index fea43b5..95cbe07 100644
--- a/content/browser/zygote_host/zygote_host_impl_linux.cc
+++ b/content/browser/zygote_host/zygote_host_impl_linux.cc
@@ -121,25 +121,31 @@ void ZygoteHostImpl::Init(const std::string& sandbox_cmd) {
sandbox_binary_ = sandbox_cmd.c_str();
- // A non empty sandbox_cmd means we want a SUID sandbox.
- using_suid_sandbox_ = !sandbox_cmd.empty();
+ bool userns_sandbox = false;
+ const std::vector<std::string> cmd_line_unwrapped(cmd_line.argv());
- if (using_suid_sandbox_) {
+ if (!sandbox_cmd.empty()) {
struct stat st;
if (stat(sandbox_binary_.c_str(), &st) != 0) {
LOG(FATAL) << "The SUID sandbox helper binary is missing: "
<< sandbox_binary_ << " Aborting now.";
}
- if (access(sandbox_binary_.c_str(), X_OK) == 0 &&
- (st.st_uid == 0) &&
- (st.st_mode & S_ISUID) &&
- (st.st_mode & S_IXOTH)) {
+ if (access(sandbox_binary_.c_str(), X_OK) == 0) {
+ using_suid_sandbox_ = true;
+
cmd_line.PrependWrapper(sandbox_binary_);
scoped_ptr<sandbox::SetuidSandboxClient>
sandbox_client(sandbox::SetuidSandboxClient::Create());
sandbox_client->SetupLaunchEnvironment();
+
+ if (!((st.st_uid == 0) &&
+ (st.st_mode & S_ISUID) &&
+ (st.st_mode & S_IXOTH))) {
+ userns_sandbox = true;
+ sandbox_client->SetNoSuid();
+ }
} else {
LOG(FATAL) << "The SUID sandbox helper binary was found, but is not "
"configured correctly. Rather than run without sandboxing "
@@ -163,7 +169,19 @@ void ZygoteHostImpl::Init(const std::string& sandbox_cmd) {
base::ProcessHandle process = -1;
base::LaunchOptions options;
options.fds_to_remap = &fds_to_map;
+ if (userns_sandbox)
+ options.new_user_namespace = true;
base::LaunchProcess(cmd_line.argv(), options, &process);
+
+ if (process == -1 && userns_sandbox) {
+ LOG(ERROR) << "User namespace sandbox failed to start, running without "
+ << "sandbox! You need at least kernel 3.8.0 with CONFIG_USER_NS "
+ << "enabled in order to use the sandbox without setuid bit.";
+ using_suid_sandbox_ = false;
+ options.new_user_namespace = false;
+ base::LaunchProcess(cmd_line_unwrapped, options, &process);
+ }
+
CHECK(process != -1) << "Failed to launch zygote process";
if (using_suid_sandbox_) {
diff --git a/content/zygote/zygote_main_linux.cc b/content/zygote/zygote_main_linux.cc
index 567b305..1089233 100644
--- a/content/zygote/zygote_main_linux.cc
+++ b/content/zygote/zygote_main_linux.cc
@@ -426,6 +426,13 @@ static bool EnterSuidSandbox(LinuxSandbox* linux_sandbox,
*has_started_new_init = true;
}
+ // Don't set non-dumpable, as it causes trouble when the host tries to find
+ // the zygote process (XXX: Not quite sure why this happens with user
+ // namespaces). Fortunately, we also have the seccomp filter sandbox which
+ // should disallow the use of ptrace.
+ if (setuid_sandbox->IsNoSuid())
+ return true;
+
#if !defined(OS_OPENBSD)
// Previously, we required that the binary be non-readable. This causes the
// kernel to mark the process as non-dumpable at startup. The thinking was
diff --git a/sandbox/linux/suid/client/setuid_sandbox_client.cc b/sandbox/linux/suid/client/setuid_sandbox_client.cc
index 34231d4..36e3201 100644
--- a/sandbox/linux/suid/client/setuid_sandbox_client.cc
+++ b/sandbox/linux/suid/client/setuid_sandbox_client.cc
@@ -166,6 +166,10 @@ bool SetuidSandboxClient::IsInNewNETNamespace() const {
return env_->HasVar(kSandboxNETNSEnvironmentVarName);
}
+bool SetuidSandboxClient::IsNoSuid() const {
+ return env_->HasVar(kSandboxNoSuidVarName);
+}
+
bool SetuidSandboxClient::IsSandboxed() const {
return sandboxed_;
}
@@ -175,5 +179,9 @@ void SetuidSandboxClient::SetupLaunchEnvironment() {
SetSandboxAPIEnvironmentVariable(env_);
}
+void SetuidSandboxClient::SetNoSuid() {
+ env_->SetVar(kSandboxNoSuidVarName, "1");
+}
+
} // namespace sandbox
diff --git a/sandbox/linux/suid/client/setuid_sandbox_client.h b/sandbox/linux/suid/client/setuid_sandbox_client.h
index a9f6536..2e8113a 100644
--- a/sandbox/linux/suid/client/setuid_sandbox_client.h
+++ b/sandbox/linux/suid/client/setuid_sandbox_client.h
@@ -39,6 +39,8 @@ class SetuidSandboxClient {
bool IsInNewPIDNamespace() const;
// Did the setuid helper create a new network namespace ?
bool IsInNewNETNamespace() const;
+ // Is sandboxed without SUID binary ?
+ bool IsNoSuid() const;
// Are we done and fully sandboxed ?
bool IsSandboxed() const;
@@ -46,6 +48,8 @@ class SetuidSandboxClient {
// helper.
void SetupLaunchEnvironment();
+ void SetNoSuid();
+
private:
// Holds the environment. Will never be NULL.
base::Environment* env_;
diff --git a/sandbox/linux/suid/common/sandbox.h b/sandbox/linux/suid/common/sandbox.h
index aad4ff8..bd710d5 100644
--- a/sandbox/linux/suid/common/sandbox.h
+++ b/sandbox/linux/suid/common/sandbox.h
@@ -18,6 +18,7 @@ static const char kAdjustLowMemMarginSwitch[] = "--adjust-low-mem";
static const char kSandboxDescriptorEnvironmentVarName[] = "SBX_D";
static const char kSandboxHelperPidEnvironmentVarName[] = "SBX_HELPER_PID";
+static const char kSandboxNoSuidVarName[] = "SBX_NO_SUID";
static const long kSUIDSandboxApiNumber = 1;
static const char kSandboxEnvironmentApiRequest[] = "SBX_CHROME_API_RQ";