Handbook Talk:AMD64/Installation/Stage

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A comment [[User:Larry|Larry]] 13:52, 13 May 2024 (UTC)
: A reply [[User:Sally|Sally]] 11:29, 14 May 2024 (UTC)
:: Another reply [[User:Larry|Larry]] 03:51, 23 May 2024 (UTC)
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Portage and stage3 security recommendations

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This discussion needs help as of 2016-10-30.
Tip: To get this fixed sooner, use {{Proposal}}.

As outlined at bugs #597804 and #597800 portage does not operate securely by default. Changes that seem to be pending include:

  • stage3 images will include cryptographic keys for the automated establishment of trust
  • stage3 images will include a gentoo key management utility

While these are promising improvements, they have been pending for 4 years already and may not be completed soon, and are not enough to fully secure portage's operation, which currently requires manual processes.

Therefore, currently it would seem useful to add a pointer right here in the installation instructions to the secure portage configuration information already documented at Working with Gentoo / Portage Features / Fetching Files / Validated Portage tree snapshots. It might be better to move it here, rather than keep it there, since it's now critical.

Note that the secure sync only works for emerge-webrsync and no security is possible with traditional rsync. Walter (talk) 23:02, 29 October 2016 (UTC)

Note that securing portage is pointless if the stage3 image downloaded has been compromised. Therefore I would suggest as a related change taking the current text regarding validation of stage3 and promoting it to its own subheading: Validating the stage tarball. In addition, the current text does not explain the problems with man in the middle attacks (in recent years well documented as utilized by state actors) that cannot be resolved with the current recommended process (ie. download stage3 and digests at same time over same network link from an official gentoo mirror - none of which are encrypted under any protocol = both digest and stage3 are compromised at the same time, therefore cannot be trusted). The current text is misleading. Suggested order of content:
  • Big fat warning box saying that while the step is optional, if you skip this step there is absolutely no guarantee that you will ever have a secure system and it is highly recommended to bother.
Rationale: Importance currently understated. New users perhaps unfamiliar with significance.
  • Method of obtaining the Gentoo keys on a non-Gentoo host system being used as an install platform should be described. This uses HTTPS to obtain the key IDs, followed by the HKP GPG keyserver protocol (an unencrypted protocol based upon HTTP) to obtain the keys. Probably the keys themselves should be provided via HTTPS.
Note: The URL for the keys is apparently the Wiki page over here.
Rationale: Required for subsequent steps.
  • Info box on additional high-assurance step of double-validating — re-fetching the same keys from another device/network connection or proxy server, preferably from a different mirror, eg. via smartphone with mobile data, Tor, a secure proxy, or an ssh tunnel (bold underlined super-obvious highlight that critically this must be run from outside the chroot - otherwise you are running potentially compromised code and giving it your remote server credentials!) to a network-geographically disparate server.
Rationale: This protects against failures in SSL (eg. state-level attackers able to forge certificates to enable SSL MITM), locally compromised SSL certificate chains, MITM attacks on the current HKP (= HTTP = unencrypted) based GPG key acquisition process, and compromised mirrors.
  • GPG validation of the stage3.
Note: Text currently present.
Rationale: Requirement for subsequent steps.
  • Digest validation.
Note: Currently before the above, and pointless from a security standpoint without first doing the above.
Rationale: Validates downloaded binary.
  • Immediate transition to a new top-level heading (between Installing a stage tarball and Configuring compile option) called Securing portage, with existing content from over here, and a big fat warning box that it is required to maintain system integrity (as per original point).
-- Walter (talk) 23:18, 29 October 2016 (UTC)
I saw your comment on bug #597800 pointing here. And I think you should also add your points as a new first chapter in the Security_Handbook even before the Pre installation concerns section.

--Charles17 (talk) 09:56, 28 December 2016 (UTC)

Your suggestions and concerns did not go unnoticed. I did see them but have no gotten around to them at the moment. As for the present, it would probably be a good idea to capture the practical steps to integrate these changes in wiki markup in the Security Handbook as Charles17 suggested. I will review them and make determinations on each of them over the course of the next few days. Kind regards, --Maffblaster (talk) 21:53, 29 December 2016 (UTC)

Updates accordingly the signature verification process

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In section Verifying and validating, the provided instructions don’t work for the verification of the DIGEST file and its (supposedly) detached signature.

user $ gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz{.DIGESTS.asc,}
gpg: not a detached signature
zsh: exit 2     gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz{.DIGESTS.asc,}

Same with the DIGEST file:

user $ gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS{.asc,}
gpg: not a detached signature
zsh: exit 2     gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS{.asc,}

However, it looks like this is a signature itself is valid, and holds the content of the DIGEST file, but doesn’t allow to verify the DIGEST file itself:

user $ gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS.asc
../..
gpg: Good signature from "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" [unknown]
../..
gpg: WARNING: not a detached signature; file 'stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS' was NOT verified!
user $ gpg --decrypt stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS.asc
# SHA512 HASH
cc4207cf06ccc0aac16664e878815f35d12fb0bb3ecb9351db0b0b144b02a969be81a6d205fef68d7f39df0d31e9499c63464d2656a6faf16e64dd8fa6aa5478  stage3-amd64-hardened-20210113T214504Z.tar.xz
# WHIRLPOOL HASH
aa25fcae36ca8497270f4a99a255dd8b6afaccb103a8d9ce7e08f646231c8475b90e7b906e2e83185414f40eb34aabd6369f2c07ee1d499410c4932252f7e144  stage3-amd64-hardened-20210113T214504Z.tar.xz
# SHA512 HASH
805fadf0205411719d992b3145ca1b45385c6fae6042c0e5f343854cc341784c5ede451cc5a220084a125bdfae5454151b4535dab0392f15cf75dd33393f679b  stage3-amd64-hardened-20210113T214504Z.tar.xz.CONTENTS.gz
# WHIRLPOOL HASH
b3d475fb211344e7c5de080b1170dbb1365bd5f9ef506fe6592eef3bd3d933ddcf2011e507331f6ca7753150f9e8f1288d1e3e10d705ed6d3682666441eb2c96  stage3-amd64-hardened-20210113T214504Z.tar.xz.CONTENTS.gz
gpg: Signature made jeu. 14 janv. 2021 05:41:04 CET
gpg:                using RSA key 534E4209AB49EEE1C19D96162C44695DB9F6043D
gpg: Good signature from "Gentoo Linux Release Engineering (Automated Weekly Release Key) <releng@gentoo.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 13EB BDBE DE7A 1277 5DFD  B1BA BB57 2E0E 2D18 2910
     Subkey fingerprint: 534E 4209 AB49 EEE1 C19D  9616 2C44 695D B9F6 043D

Two possible outcomes:

  1. Create a real detachable signature (to Infrastructure team, I guess):

When using gpg(1), the correction option to create a detachable signature is "--detach-sign", as follow (with --armor, for only ASCII content):

user $ gpg --detach-sign --armor stage3-[…].DIGESTS

On its own, GnuPG will create an "asc" suffixed file (with --armor, it’s ".sig").

  1. Update the instructions as follow:

Currently, with this issue, we can’t check the content of the DIGEST file itself, using the "--verify" option.

user $ gpg --verify stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS.asc
../..
gpg: WARNING: not a detached signature; file 'stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS' was NOT verified!

We can fix the instruction and provide a way to see the signed content thanks to "--decrypt" option; however, "decrypt" is not an obvious way to verify a signature, but it allows to check its content when disregarding stderr (same as above):

user $ gpg --decrypt stage3-amd64-hardened-20210113T214504Z.tar.xz.DIGESTS.asc 2> /dev/null
# SHA512 HASH
cc4207cf06ccc0aac16664e878815f35d12fb0bb3ecb9351db0b0b144b02a969be81a6d205fef68d7f39df0d31e9499c63464d2656a6faf16e64dd8fa6aa5478  stage3-amd64-hardened-20210113T214504Z.tar.xz
# WHIRLPOOL HASH
aa25fcae36ca8497270f4a99a255dd8b6afaccb103a8d9ce7e08f646231c8475b90e7b906e2e83185414f40eb34aabd6369f2c07ee1d499410c4932252f7e144  stage3-amd64-hardened-20210113T214504Z.tar.xz
# SHA512 HASH
805fadf0205411719d992b3145ca1b45385c6fae6042c0e5f343854cc341784c5ede451cc5a220084a125bdfae5454151b4535dab0392f15cf75dd33393f679b  stage3-amd64-hardened-20210113T214504Z.tar.xz.CONTENTS.gz
# WHIRLPOOL HASH
b3d475fb211344e7c5de080b1170dbb1365bd5f9ef506fe6592eef3bd3d933ddcf2011e507331f6ca7753150f9e8f1288d1e3e10d705ed6d3682666441eb2c96  stage3-amd64-hardened-20210113T214504Z.tar.xz.CONTENTS.gz

For me, the fix is the solution 1; it’s not a wiki issue, it looks like a signed process fault, and I guess this discussion is not at the right place.

But I might be wrong ;-)

By the way, I might have found a link to this issue: bug #587486

Thican (talk) 00:42, 17 January 2021 (UTC)

Minor typo

Talk status
This discussion is done as of 2023-09-03.

At the very bottom of the page, there is a space missing in "Then continue withInstalling the Gentoo base system." --Dhirsbrunner (talk) 02:16, 16 June 2023 (UTC)

Looks like this was fixed at some point, but I'm not sure when! Thanks! --Maffblaster (talk) 08:14, 3 September 2023 (UTC)

Minor typo in the verification command

Talk status
This discussion is done as of 2024-05-11.

This line:

root #gpg --verify stage3-amd64-<release>-<init>.tar.xz.DIGEST

should be replaced with this one (DIGEST -> DIGESTS):

root #gpg --verify stage3-amd64-<release>-<init>.tar.xz.DIGESTS

-- Lars Hint (talk) 15:08, 29 January 2024 (UTC)

Fixed in Special:Diff/1298131/1298154, thanks!
--csfore (talk) 18:40, 11 May 2024 (UTC)

Minor clarification of pwd

Talk status
This discussion is done.

Total nit--I suggest moving the "the current directory should be set to the location of the mount used for the install" comment to somewhere more appropriate. I didn't need to set up my clock manually, so I missed this comment. Maybe putting it right under the "Downloading the stage file" heading, before "Setting the date and time" would be better.

--Emptonaut (talk) 23:27, 19 February 2024 (UTC)

Change position of cd /mnt/gentoo

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The section: "Before downloading the stage file, the current directory should be set to the location of the mount used for the install, (most likely /mnt/gentoo): cd /mnt/gentoo" should be moved from Setting the date and time/Manual TO BE the first step in "Downloading the stage file" (before Setting the date and time) because it is misleading in its current place. See also forums post: https://forums.gentoo.org/viewtopic-t-1167640-highlight-.html

--Pietinger 15:56, 02 March 2024 (UTC)

As discussed in #gentoo-wiki, this is an oversight and should be resolved. I think this fix should become part of Handbook:Parts/Installation/Disks
The fix should become:
Proposed changes - Please make edits here until a final revision is agreed upon.

Continue mounting additional (custom) partitions as necessary using the mount command.
Note
If /tmp/ needs to reside on a separate partition, be sure to change its permissions after mounting:
root #chmod 1777 /tmp
This also holds for /var/tmp.

Finally, change the current working directory to /mnt/gentoo to make the rest of the installation easier.

root #cd /mnt/gentoo
— The preceding unsigned comment was added by Immolo (talkcontribs) 2024-03-04T23:40:11
I think even better is: Make "Setting the date and time" as a main chapter: 2. Setting the date and time -> 2.1 Automatic + 2.2 Manual and then 3 Downloading the stage file -> 3.1 Changing to /mnt/gento + 3.2 Graphical browsers + 3.3 Command-line browsers ... and so on ... --Pietinger 16:25, 04 April 2024 (UTC)