Modify the Chrome Linux zygote to support a ZygoteForkHelper for flexible
fork implementations.
BUG=nativeclient:480
TEST=existing zygote tests
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=92787
Review URL: http://codereview.chromium.org/7397003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@92858 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/browser/zygote_main_linux.cc b/content/browser/zygote_main_linux.cc
index 99a7735..95b3975b 100644
--- a/content/browser/zygote_main_linux.cc
+++ b/content/browser/zygote_main_linux.cc
@@ -37,9 +37,11 @@
#include "content/common/sandbox_methods_linux.h"
#include "content/common/set_process_title.h"
#include "content/common/unix_domain_socket_posix.h"
+#include "content/common/zygote_fork_delegate_linux.h"
#include "seccompsandbox/sandbox.h"
#include "skia/ext/SkFontHost_fontconfig_control.h"
#include "unicode/timezone.h"
+#include "ipc/ipc_switches.h"
#if defined(OS_LINUX)
#include <sys/epoll.h>
@@ -97,8 +99,9 @@
// runs it.
class Zygote {
public:
- explicit Zygote(int sandbox_flags)
- : sandbox_flags_(sandbox_flags) {
+ explicit Zygote(int sandbox_flags, ZygoteForkDelegate* helper)
+ : sandbox_flags_(sandbox_flags),
+ helper_(helper) {
}
bool ProcessRequests() {
@@ -165,6 +168,7 @@
case ZygoteHost::kCmdFork:
// This function call can return multiple times, once per fork().
return HandleForkRequest(fd, pickle, iter, fds);
+
case ZygoteHost::kCmdReap:
if (!fds.empty())
break;
@@ -247,9 +251,12 @@
// sandbox, it returns the real PID of the child process as it
// appears outside the sandbox, rather than returning the PID inside
// the sandbox.
- int ForkWithRealPid() {
- if (!g_suid_sandbox_active)
+ int ForkWithRealPid(const std::string& process_type, std::vector<int>& fds,
+ const std::string& channel_switch) {
+ const bool use_helper = (helper_ && helper_->CanHelp(process_type));
+ if (!(use_helper || g_suid_sandbox_active)) {
return fork();
+ }
int dummy_fd;
ino_t dummy_inode;
@@ -270,7 +277,13 @@
goto error;
}
- pid = fork();
+ if (use_helper) {
+ fds.push_back(dummy_fd);
+ fds.push_back(pipe_fds[0]);
+ pid = helper_->Fork(fds);
+ } else {
+ pid = fork();
+ }
if (pid < 0) {
goto error;
} else if (pid == 0) {
@@ -294,33 +307,43 @@
dummy_fd = -1;
close(pipe_fds[0]);
pipe_fds[0] = -1;
- uint8_t reply_buf[512];
- Pickle request;
- request.WriteInt(LinuxSandbox::METHOD_GET_CHILD_WITH_INODE);
- request.WriteUInt64(dummy_inode);
-
- const ssize_t r = UnixDomainSocket::SendRecvMsg(
- kMagicSandboxIPCDescriptor, reply_buf, sizeof(reply_buf), NULL,
- request);
- if (r == -1) {
- LOG(ERROR) << "Failed to get child process's real PID";
- goto error;
- }
-
base::ProcessId real_pid;
- Pickle reply(reinterpret_cast<char*>(reply_buf), r);
- void* iter2 = NULL;
- if (!reply.ReadInt(&iter2, &real_pid))
- goto error;
- if (real_pid <= 0) {
- // METHOD_GET_CHILD_WITH_INODE failed. Did the child die already?
- LOG(ERROR) << "METHOD_GET_CHILD_WITH_INODE failed";
- goto error;
+ if (g_suid_sandbox_active) {
+ uint8_t reply_buf[512];
+ Pickle request;
+ request.WriteInt(LinuxSandbox::METHOD_GET_CHILD_WITH_INODE);
+ request.WriteUInt64(dummy_inode);
+
+ const ssize_t r = UnixDomainSocket::SendRecvMsg(
+ kMagicSandboxIPCDescriptor, reply_buf, sizeof(reply_buf), NULL,
+ request);
+ if (r == -1) {
+ LOG(ERROR) << "Failed to get child process's real PID";
+ goto error;
+ }
+
+ Pickle reply(reinterpret_cast<char*>(reply_buf), r);
+ void* iter = NULL;
+ if (!reply.ReadInt(&iter, &real_pid))
+ goto error;
+ if (real_pid <= 0) {
+ // METHOD_GET_CHILD_WITH_INODE failed. Did the child die already?
+ LOG(ERROR) << "METHOD_GET_CHILD_WITH_INODE failed";
+ goto error;
+ }
+ real_pids_to_sandbox_pids[real_pid] = pid;
}
- real_pids_to_sandbox_pids[real_pid] = pid;
- if (HANDLE_EINTR(write(pipe_fds[1], "x", 1)) != 1) {
- LOG(ERROR) << "Failed to synchronise with child process";
- goto error;
+ if (use_helper) {
+ real_pid = pid;
+ if (!helper_->AckChild(pipe_fds[1], channel_switch)) {
+ LOG(ERROR) << "Failed to synchronise with zygote fork helper";
+ goto error;
+ }
+ } else {
+ if (HANDLE_EINTR(write(pipe_fds[1], "x", 1)) != 1) {
+ LOG(ERROR) << "Failed to synchronise with child process";
+ goto error;
+ }
}
close(pipe_fds[1]);
return real_pid;
@@ -342,12 +365,19 @@
// Handle a 'fork' request from the browser: this means that the browser
// wishes to start a new renderer.
- bool HandleForkRequest(int fd, const Pickle& pickle, void* iter,
- std::vector<int>& fds) {
+ bool HandleForkRequest(int fd, const Pickle& pickle,
+ void* iter, std::vector<int>& fds) {
std::vector<std::string> args;
int argc, numfds;
base::GlobalDescriptors::Mapping mapping;
base::ProcessId child;
+ std::string process_type;
+ std::string channel_id;
+ const std::string channel_id_prefix = std::string("--")
+ + switches::kProcessChannelID + std::string("=");
+
+ if (!pickle.ReadString(&iter, &process_type))
+ goto error;
if (!pickle.ReadInt(&iter, &argc))
goto error;
@@ -357,6 +387,8 @@
if (!pickle.ReadString(&iter, &arg))
goto error;
args.push_back(arg);
+ if (arg.compare(0, channel_id_prefix.length(), channel_id_prefix) == 0)
+ channel_id = arg;
}
if (!pickle.ReadInt(&iter, &numfds))
@@ -374,7 +406,7 @@
mapping.push_back(std::make_pair(
static_cast<uint32_t>(kSandboxIPCChannel), kMagicSandboxIPCDescriptor));
- child = ForkWithRealPid();
+ child = ForkWithRealPid(process_type, fds, channel_id);
if (!child) {
#if defined(SECCOMP_SANDBOX)
@@ -447,6 +479,7 @@
ProcessMap real_pids_to_sandbox_pids;
const int sandbox_flags_;
+ ZygoteForkDelegate* helper_;
};
// With SELinux we can carve out a precise sandbox, so we don't have to play
@@ -705,7 +738,8 @@
#endif // CHROMIUM_SELINUX
-bool ZygoteMain(const MainFunctionParams& params) {
+bool ZygoteMain(const MainFunctionParams& params,
+ ZygoteForkDelegate* forkdelegate) {
#if !defined(CHROMIUM_SELINUX)
g_am_zygote_or_renderer = true;
#endif
@@ -724,6 +758,15 @@
}
#endif // SECCOMP_SANDBOX
+ if (forkdelegate != NULL) {
+ VLOG(1) << "ZygoteMain: initializing fork delegate";
+ forkdelegate->Init(getenv("SBX_D") != NULL, // g_suid_sandbox_active,
+ kBrowserDescriptor,
+ kMagicSandboxIPCDescriptor);
+ } else {
+ VLOG(1) << "ZygoteMain: fork delegate is NULL";
+ }
+
// Turn on the SELinux or SUID sandbox
if (!EnterSandbox()) {
LOG(FATAL) << "Failed to enter sandbox. Fail safe abort. (errno: "
@@ -760,7 +803,7 @@
}
#endif // SECCOMP_SANDBOX
- Zygote zygote(sandbox_flags);
+ Zygote zygote(sandbox_flags, forkdelegate);
// This function call can return multiple times, once per fork().
return zygote.ProcessRequests();
}
