bootloader: gracefully reboot after update completes #1148

liuming50 · 2019-03-21T10:18:43Z

This patch mainly aims to add a graceful reboot by executing
'/sbin/init 6' rather than calling reboot system call.

Signed-off-by: Ming Liu [email protected]

agners · 2019-03-21T13:15:29Z

The CI finding is probably relevant:

/aktualizr/src/libaktualizr/bootloader/bootloader.cc: In member function 'void Bootloader::reboot(bool)':
/aktualizr/src/libaktualizr/bootloader/bootloader.cc:184:13: error: ignoring return value of 'int system(const char*)', declared with attribute warn_unused_result [-Werror=unused-result]
       system("/sbin/init 6");
       ~~~~~~^~~~~~~~~~~~~~~~

Probably a good idea to check the return value and write a log message or similar in case something is wrong with the command...

liuming50 · 2019-03-21T13:18:42Z

Good suggestion, will send a V2 soon. //Ming Liu Stefan Agner <[email protected]> 於 2019年3月21日週四下午2:15寫道：

…

The CI finding is probably relevant: /aktualizr/src/libaktualizr/bootloader/bootloader.cc: In member function 'void Bootloader::reboot(bool)': /aktualizr/src/libaktualizr/bootloader/bootloader.cc:184:13: error: ignoring return value of 'int system(const char*)', declared with attribute warn_unused_result [-Werror=unused-result] system("/sbin/init 6"); ~~~~~~^~~~~~~~~~~~~~~~ Probably a good idea to check the return value and write a log message or similar in case something is wrong with the command... — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1148 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AHsYsvVcY1vQxNA9HzKVjb2Ur9xKuPcYks5vY4XxgaJpZM4cBGlg> .

agners · 2019-03-21T13:25:10Z

src/libaktualizr/bootloader/bootloader.cc

+    if ((stat ("/sbin/init", &st) >= 0) && (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))) {
+      if (system("/sbin/init 6") != 0) {
+        LOG_ERROR << "Failed to execute /sbin/init 6";
+      }


Tried to figure out whether there is a POSIX way to reboot a machine, but it seems reboot or similar is not part of the POSIX spec. This StackOverflow thread suggests the same: https://unix.stackexchange.com/questions/507259/is-there-a-posix-way-to-shutdown-a-unix-machine

Is there a reason you opted for /sbin/init 6? Runlevel seem to be a System V init system concept, and not really standardized either,... I feel that /sbin/reboot is probably better suited those days, as it clearly says what it's doing, and is supported by all init systems I know of (sysvinit, systemd, upstart)...

The reason for choosing '/sbin/init 6' instead of '/sbin/reboot' was that: I thought it's possible that '/sbin/reboot' does not exist on some sysvinit based systems, for instance, when busybox is being used, the option 'CONFIG_INIT' is optional, which means there could be no '/sbin/reboot' compiled.

And I verified the '/sbin/init 6' worked also for systemd. (But I did not verify it for upstart)

IMHO,
'reboot' should be part of Platform Abstraction Layer to enable platform specific implementations one of which can be specified/chosen during an image bitbaking and/or aktualizr building.
+
Default/Reference implementation targeting systemd-based system that would reboot by either calling system("systemctl reboot") or ::reboot() which effectively leads to the same effect (if you you look at the logs you can see that actually systemd takes control in case of ::reboot call and does exactly the same stuff as in case of calling systemctl reboot).

@mike-sul

Default/Reference implementation targeting systemd-based system that would reboot by either calling system("systemctl reboot") or ::reboot() which effectively leads to the same effect (if you you look at the logs you can see that actually systemd takes control in case of ::reboot call and does exactly the same stuff as in case of calling systemctl reboot).

Really? How? Isn't ::reboot calling the reboot syscall? man 2 reboot says that RB_AUTOBOOT is initiating a restart immediately, and data are lost unless synced before. How is systemd intercepting that syscall?

Yeah, your're right. I confused it with system("reboot") which leads to the same effect as system("systemctl reboot") since the 'reboot' file/cmd is a link to systemctl

root@qemux86-64:/sysroot/home/root# ls -l /usr/sbin/reboot lrwxrwxrwx 11 root root 18 Mar 21 15:11 /usr/sbin/reboot -> /usr/bin/systemctl

I apologize for making the incorrect statement.

liuming50 · 2019-03-21T14:12:25Z

@mike-sul, thanks for the explanation of how systemd handle reboot system call, did not know that before. But shall we also consider supporting sysvinit systems in which case "/sbin/init 6" or "/sbin/reboot" probably could be a more graceful way rather than "reboot" system call? //Ming Liu mike-sul <[email protected]> 於 2019年3月21日週四下午3:01寫道：

…

***@***.**** commented on this pull request. ------------------------------ In src/libaktualizr/bootloader/bootloader.cc <#1148 (comment)> : > if (setuid(0) != 0) { LOG_ERROR << "Failed to set/verify a root user so cannot reboot system programmatically"; + return; + } + + if ((stat ("/sbin/init", &st) >= 0) && (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))) { + if (system("/sbin/init 6") != 0) { + LOG_ERROR << "Failed to execute /sbin/init 6"; + } IMHO, 'reboot' should be part of Platform Abstraction Layer to enable platform specific implementations one of which can be specified/chosen during an image bitbaking and/or aktualizr building. + Default/Reference implementation targeting systemd-based system that would reboot by either calling system("systemctl reboot") or ::reboot() which effectively leads to the same effect (if you you look at the logs you can see that actually systemd takes control in case of ::reboot call and does exactly the same stuff as in case of calling systemctl reboot). — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1148 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AHsYstFTq6beKQCx-mqirN3Zv_PNuyasks5vY5C_gaJpZM4cBGlg> .

doanac · 2019-03-21T14:15:51Z

I think you should make the reboot command be a configuration option and the default value can be /sbin/reboot. Then all platforms will have a way to reboot. This might be nice for test automation also. ie - you could create a fake-reboot script to assert it gets called properly.

lbonn · 2019-03-22T09:22:55Z

@doanac I agree, it looks like it's the way to go at this point

liuming50 · 2019-03-22T10:55:58Z

@doanac will remake a V3 as you suggested.

pattivacek · 2019-04-23T15:07:47Z

@liuming50 Is this still something you are interested in? I think your plan sounded fine.

liuming50 · 2019-04-23T19:37:56Z

Hi, Patrick: Sorry for the delayed response, I was busy on some other tasks, yes, I would like to fix this, I actually have made a patch for that, just have not managed time to test/verify it, will do that in this week. the best, thank you Patrick Vacek <[email protected]> 於 2019年4月23日週二下午5:07寫道：

…

@liuming50 <https://github.com/liuming50> Is this still something you are interested in? I think your plan sounded fine. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1148 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB5RRMX6RUMUWHJ62INZZE3PR4Q4JANCNFSM4HAENFQA> .

pattivacek · 2019-04-24T07:17:49Z

Sorry for the delayed response, I was busy on some other tasks, yes, I would like to fix this, I actually have made a patch for that, just have not managed time to test/verify it, will do that in this week.

No problem, just wanted to check in. Thanks!

codecov-io · 2019-04-30T13:31:45Z

Codecov Report

Merging #1148 into master will increase coverage by 0.06%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #1148      +/-   ##
==========================================
+ Coverage   79.61%   79.68%   +0.06%     
==========================================
  Files         173      173              
  Lines       10315    10320       +5     
==========================================
+ Hits         8212     8223      +11     
+ Misses       2103     2097       -6

Impacted Files	Coverage Δ
src/libaktualizr/bootloader/bootloader.h	`100% <ø> (ø)`	⬆️
src/libaktualizr/bootloader/bootloader_config.h	`100% <ø> (ø)`	⬆️
src/libaktualizr/bootloader/bootloader_config.cc	`90% <100%> (+0.71%)`	⬆️
src/libaktualizr/bootloader/bootloader.cc	`49.23% <14.28%> (-0.77%)`	⬇️
src/libaktualizr-posix/ipuptanesecondary.cc	`82.66% <0%> (-4%)`	⬇️
src/aktualizr_primary/secondary.cc	`82.89% <0%> (-1.32%)`	⬇️
src/libaktualizr/storage/sqlstorage.cc	`76.02% <0%> (ø)`	⬆️
src/libaktualizr/storage/sql_utils.h	`85.91% <0%> (+1.4%)`	⬆️
src/libaktualizr/storage/sqlstorage_base.cc	`80.4% <0%> (+6.08%)`	⬆️
src/libaktualizr/storage/sqlstorage_base.h	`100% <0%> (+40%)`	⬆️

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liuming50 · 2019-04-30T13:33:52Z

As suggested by @doanac, I have made a V3 patch, please kindly help me review it.

Veified with the following setting in OE:

EXTRA_OECMAKE_append = " -DREBOOT_COMMAND='/sbin/reboot'"
EXTRA_OECMAKE_append = " -DREBOOT_COMMAND='/sbin/init 6'"
EXTRA_OECMAKE_append = " -DREBOOT_COMMAND='/path/to/non-exist'"

lbonn · 2019-05-02T12:08:34Z

Thanks, it looks like it would work!
However, having it fixed at compile-time seems a bit rigid: it's harder to test and configure.

An alternative would be to do it via regular configuration, for example reboot_command in bootloader's configuration. On oe side, it would need creating a small configuration fragment, but we already have some examples of that.

If you are still keen on doing the work, let us know if you have questions about that.

liuming50 · 2019-05-02T15:33:51Z

@lbonn Thanks for the review.

Yes, getting a preferred reboot command from configuration sounds like a better solution, will make a V4 if nobody has objection. @agners @doanac @patrickvacek please comment if you have some other suggestions, or I will work on the V4.

liuming50 · 2019-05-09T08:55:46Z

Please kindly help me review the V4 patch:

I have verified it with the following steps:

$ aktualizr --config /path/to/20-sota_autoprov.toml

Scenario 1: 20-sota_autoprov.toml

[bootloader]
reboot_command = "/sbin/reboot"

Scenario 2: 20-sota_autoprov.toml

[bootloader]
reboot_command = "/sbin/init 6"

Scenario 3: 20-sota_autoprov.toml

[bootloader]
reboot_command = "/path/to/non-exist"

lbonn · 2019-05-09T10:24:18Z

src/libaktualizr/bootloader/bootloader.h

@@ -29,6 +29,7 @@ class Bootloader {

  INvStorage& storage_;
  boost::filesystem::path reboot_sentinel_;
+  std::string reboot_command_;


It is only used in one place, so it probably doesn't need to be an attribute, simply a variable in the concerned method if needed.

lbonn · 2019-05-09T10:26:30Z

docs/configuration.adoc

@@ -163,4 +163,5 @@ Options for configuring boot-specific behavior
 | `rollback_mode`        | `"none"`                        | Controls rollback on supported platforms, see link:{aktualizr-github-url}/docs/rollback.adoc[]. Options: `"none"`, `"uboot_generic"`, `"uboot_masked"`
 | `reboot_sentinel_dir`  | `"/var/run/aktualizr-session"`  | Base directory for reboot detection sentinel. Must reside in a temporary file system.
 | `reboot_sentinel_name` | `"need_reboot"`                 | Name of the reboot detection sentinel.
+| `reboot_command`       | `"/sbin/reboot"`                | Command to reboot the system after update completes.


Great that you've updated the docs!
Would be extra helpful with a link to uptane.force_install_completion (reboot_command would only be used if it's on).

lbonn · 2019-05-09T10:36:47Z

src/libaktualizr/bootloader/bootloader.cc

+      return;
+    }
+
+    reboot_command_.copy(full_cmd, len);


Seems odd (and unsafe) to copy in a fixed buffer with the length of the original string as a parameter. Doing .copy(full_cmd, sizeof(full_cmd)-1) would be more logical.

However, even then, some points still bother me, as I think this part could be much simpler:

handling c strings when the c++ standard library should be sufficient

do we really need to parse the command and stat the file? Just system() and checking the return code + logging errors should be plenty

we'd probably want to run sync() in any case, even with a custom command

maybe not defaulting to ::reboot if the default command fails. It's really not the nominal case (probably misconfiguration) and rebooting anyway could make debugging more difficult

mike-sul · 2019-05-09T11:42:46Z

src/libaktualizr/bootloader/bootloader.cc

    } else {
+      LOG_WARNING << "The preferred reboot command: '" << reboot_command_ << "' does not exist or is not executable";
+      sync();
      ::reboot(RB_AUTOBOOT);


IMHO, system("reboot") (it will call 'systemd reboot' in our default case) would work in most of cases so I would use it as a default value in case if 'reboot_command' is not specified in the config. Not sure if it makes to fallback to it if the 'reboot_command' fails - agree with lbonn here.
Also, it looks a bit insecure/dangerous to allow an user to execute whatever command they specify in the config, it could be 'rm -rf /', 'cat /etc/passwd', etc :), perhaps the 'freedom' to choose the command can be narrowed downed to some pre-defined list.

aktualizr runs as root and should only read configurations writable by root + it does dangerous operations by nature. Using a hard-coded list sounds like a band-aid that can be bypassed.

A possible security check would be that the executable indeed belongs to root and is not writeable by group and others.

I don't think we should add another way for user to shoot themselves in a foot. How many ways to reboot a sytem do we really have to support? Also, those commands are very rarely change so we can simply use "reboot_command = systemv" and use /sbin/reboot explicitly in this case instead of default "systemctl reboot". If we really have to we can always expand this by adding "reboot_command = systemwhatever" which will map to another command to add support for some exotic system. Using arbitrary command is more flexible of course but I don't think it's worth it in this case.

In the end it doesn't make any difference, if we make room for a calling an arbitrary script with a fixed name, we can as well allow an arbitrary command. It doesn't add nor subtract any foot-gun.

My wish was primarily to allow this use case: https://github.com/toradex/meta-toradex-torizon/blob/a8b50aa8b9f7f14eb60ebc8fc68919ba87413804/recipes-sota/ostree/files/ostree-pending-reboot.path. Touching a file as a trigger to a systemd service seems really useful as it allows a variety of use cases which need close interaction with the init system.
See here for background: advancedtelematic/meta-updater#486.

In this case, the reboot command would just be touch /run/aktualizr-session/trigger_reboot

That make sense, nice. I wonder if we could always use reboot via this external path trigger.

mike-sul · 2019-07-30T08:58:50Z

@liuming50 Would you like to finalize this PR according to the latest comments ? As an option, I could take over this PR if you don't mind ?

liuming50 · 2019-07-30T09:15:39Z

Hi, I am glad if you could take over it, I’ve been quite busy recently and have not managed time to redo it. Thanks. //Ming Liu @liuming50 <https://github.com/liuming50> Would you like to finalize this

…

PR according to the latest comments ? As an option, I could take over this PR if you don't mind ? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1148?email_source=notifications&email_token=AB5RRMT5SA6MFI64Y6TC3TLQB77EZA5CNFSM4HAENFQKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD3DJNII#issuecomment-516331169>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB5RRMULLXU5IGCFS4ZEMHLQB77EZANCNFSM4HAENFQA> .

mike-sul · 2019-07-30T15:28:25Z

Hi, I am glad if you could take over it, I’ve been quite busy recently and have not managed time to redo it. Thanks. //Ming Liu @liuming50 https://github.com/liuming50 Would you like to finalize this
…
PR according to the latest comments ? As an option, I could take over this PR if you don't mind ? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1148?email_source=notifications&email_token=AB5RRMT5SA6MFI64Y6TC3TLQB77EZA5CNFSM4HAENFQKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD3DJNII#issuecomment-516331169>, or mute the thread https://github.com/notifications/unsubscribe-auth/AB5RRMULLXU5IGCFS4ZEMHLQB77EZANCNFSM4HAENFQA .

OK, so I am taking over it. Just rebase it with the current master and going to start from here.

This patch mainly aims to add a graceful way to reboot the system by executing a user preferred reboot command rather than calling reboot system call. The reboot command could be set in 'bootloader' section of a config file, it defaults to be '/sbin/reboot'. Signed-off-by: Ming Liu <[email protected]> Signed-off-by: Mykhaylo Sul <[email protected]>

mike-sul · 2019-07-31T10:33:10Z

@lbonn Please, review the updated version. Let's agree on the default reboot command, I see a few options here

/sbin/reboot, systemd reboot, system(reboot) - these three will have the same effect in our case
touch /run/aktualizr-session/trigger_reboot which will require adding corresponding functionality/recipe into meta-updater (I have no objection here and can do it)
don't have any default

lbonn · 2019-07-31T11:46:44Z

Great! Right now, the easiest would be to just use /sbin/reboot by default which is probably enough for our default integration layer in meta-updater.
At least now, integrators have a bit more control.

pattivacek · 2019-07-31T16:02:17Z

Replaced by #1274.

liuming50 mentioned this pull request Mar 21, 2019

OTA-2135: Aktualizr's config and recipe to auto reboot just after update advancedtelematic/meta-updater#486

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liuming50 force-pushed the bootloader-gracefully-reboot branch from 409cd87 to 4cc4bc7 Compare March 21, 2019 13:24

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liuming50 force-pushed the bootloader-gracefully-reboot branch from 4cc4bc7 to b101006 Compare April 30, 2019 13:31

liuming50 force-pushed the bootloader-gracefully-reboot branch from b101006 to c4a11c8 Compare May 9, 2019 08:47

liuming50 changed the title ~~bootloader: gracefully reboot using '/sbin/init 6'~~ bootloader: gracefully reboot after update completes May 9, 2019

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lbonn approved these changes Jul 31, 2019

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mike-sul mentioned this pull request Jul 31, 2019

Configurable reboot command #1274

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bootloader: gracefully reboot after update completes #1148

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