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init: cleanup is_first_stage conditionals 

A recent change to the is_first_stage conditionals created a unneeded
else { } block as both the code in the else { } block and any code
that runs after it are both in the second stage of init.  A first step
to clean this up is to remove this else block.

Secondly, given the above confusion, it makes sense to simplify the two
if (is_first_stage) conditions into one, which only now requires
duplicating one line to initialize logging and the actual "init
first/second stage started!" logs.

Lastly, there are a few commands ran at the beginning of both init
stages that do not need to be,

* boot_clock::time_point start_time = boot_clock::now();
This is only used in the first stage so keep it there

* umask(0);
umasks are preserved across execve() so it only needs to be set in the
first stage

* chmod("/proc/cmdline", 0440);
This needs to be moved until after /proc is mounted in the first
stage, but otherwise only needs to be done once

Test: Boot bullhead, check umask, check cmdline permissions, check
boot time property

Change-Id: Idb7df1d4330960ce282d9609f5c62281ee2638b9
This commit is contained in:
Tom Cherry 2017-03-16 18:08:56 -07:00
parent e323976e74
commit 34e70410ee
1 changed files with 51 additions and 48 deletions
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99
init/init.cpp
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@ -1108,27 +1108,26 @@ int main(int argc, char** argv) {
return watchdogd_main(argc, argv);
}
boot_clock::time_point start_time = boot_clock::now();
// Clear the umask.
umask(0);
add_environment("PATH", _PATH_DEFPATH);
bool is_first_stage = (getenv("INIT_SECOND_STAGE") == nullptr);
// Don't expose the raw commandline to unprivileged processes.
chmod("/proc/cmdline", 0440);
// Get the basic filesystem setup we need put together in the initramdisk
// on / and then we'll let the rc file figure out the rest.
if (is_first_stage) {
boot_clock::time_point start_time = boot_clock::now();
// Clear the umask.
umask(0);
// Get the basic filesystem setup we need put together in the initramdisk
// on / and then we'll let the rc file figure out the rest.
mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755");
mkdir("/dev/pts", 0755);
mkdir("/dev/socket", 0755);
mount("devpts", "/dev/pts", "devpts", 0, NULL);
#define MAKE_STR(x) __STRING(x)
mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC));
// Don't expose the raw commandline to unprivileged processes.
chmod("/proc/cmdline", 0440);
gid_t groups[] = { AID_READPROC };
setgroups(arraysize(groups), groups);
mount("sysfs", "/sys", "sysfs", 0, NULL);
@ -1136,15 +1135,13 @@ int main(int argc, char** argv) {
mknod("/dev/kmsg", S_IFCHR | 0600, makedev(1, 11));
mknod("/dev/random", S_IFCHR | 0666, makedev(1, 8));
mknod("/dev/urandom", S_IFCHR | 0666, makedev(1, 9));
}
// Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
// talk to the outside world...
InitKernelLogging(argv);
// Now that tmpfs is mounted on /dev and we have /dev/kmsg, we can actually
// talk to the outside world...
InitKernelLogging(argv);
LOG(INFO) << "init " << (is_first_stage ? "first" : "second") << " stage started!";
LOG(INFO) << "init first stage started!";
if (is_first_stage) {
if (!early_mount()) {
LOG(ERROR) << "Failed to mount required partitions early ...";
panic();
@ -1168,41 +1165,47 @@ int main(int argc, char** argv) {
char* path = argv[0];
char* args[] = { path, nullptr };
if (execv(path, args) == -1) {
PLOG(ERROR) << "execv(\"" << path << "\") failed";
security_failure();
}
} else {
// Indicate that booting is in progress to background fw loaders, etc.
close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));
execv(path, args);
property_init();
// If arguments are passed both on the command line and in DT,
// properties set in DT always have priority over the command-line ones.
process_kernel_dt();
process_kernel_cmdline();
// Propagate the kernel variables to internal variables
// used by init as well as the current required properties.
export_kernel_boot_props();
// Make the time that init started available for bootstat to log.
property_set("ro.boottime.init", getenv("INIT_STARTED_AT"));
property_set("ro.boottime.init.selinux", getenv("INIT_SELINUX_TOOK"));
// Set libavb version for Framework-only OTA match in Treble build.
property_set("ro.boot.init.avb_version", std::to_string(AVB_MAJOR_VERSION).c_str());
// Clean up our environment.
unsetenv("INIT_SECOND_STAGE");
unsetenv("INIT_STARTED_AT");
unsetenv("INIT_SELINUX_TOOK");
// Now set up SELinux for second stage.
selinux_initialize(false);
// execv() only returns if an error happened, in which case we
// panic and never fall through this conditional.
PLOG(ERROR) << "execv(\"" << path << "\") failed";
security_failure();
}
// At this point we're in the second stage of init.
InitKernelLogging(argv);
LOG(INFO) << "init second stage started!";
// Indicate that booting is in progress to background fw loaders, etc.
close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));
property_init();
// If arguments are passed both on the command line and in DT,
// properties set in DT always have priority over the command-line ones.
process_kernel_dt();
process_kernel_cmdline();
// Propagate the kernel variables to internal variables
// used by init as well as the current required properties.
export_kernel_boot_props();
// Make the time that init started available for bootstat to log.
property_set("ro.boottime.init", getenv("INIT_STARTED_AT"));
property_set("ro.boottime.init.selinux", getenv("INIT_SELINUX_TOOK"));
// Set libavb version for Framework-only OTA match in Treble build.
property_set("ro.boot.init.avb_version", std::to_string(AVB_MAJOR_VERSION).c_str());
// Clean up our environment.
unsetenv("INIT_SECOND_STAGE");
unsetenv("INIT_STARTED_AT");
unsetenv("INIT_SELINUX_TOOK");
// Now set up SELinux for second stage.
selinux_initialize(false);
// These directories were necessarily created before initial policy load
// and therefore need their security context restored to the proper value.
// This must happen before /dev is populated by ueventd.