geli attach multiple providers (no kernel changes)

[woodsb02]

Summary

Note: This diff is implementation option 2 of 2

Unlike D9396, this implementation does not modify the kernel. This is achieved by creating a new child geom request for each provider being attached, and passing each request to the kernel one by one.

Allow attaching of multiple geli providers at once if they use same
passphrase and keyfiles.

This is helpful when the providers being attached are not used for boot,
and therefore the existing code to first try the cached password when
tasting the providers during boot does not apply.

Multiple providers with the same passphrase and keyfiles can be attached
at the same time during system start-up by adding the following to
rc.conf:

geli_groups="storage backup"
geli_storage_flags="-k /etc/geli/storage.keys"
geli_storage_devices="ada0 ada1"
geli_backup_flags="-j /etc/geli/backup.passfile -k /etc/geli/backup.keys"
geli_backup_devices="ada2 ada3"

Test Plan

Tested using md(4) memory disks to confirm multiple providers can be attached if they use the same passphrase and keyfiles, but each provider fails to attach if the passphrase / keyfile combination fails to decrypt its master key.

mdconfig -s 1m -u 0
mdconfig -s 1m -u 1
mdconfig -s 1m -u 2
mdconfig -s 1m -u 3
geli init md0   # set password to "test"
geli init md1   # set password to "test"
geli init md2   # set password to "test123"
geli init md3   # set password to "test"
geli attach -v md0 md1  # enter password "test"
geli status
geli detach md0 md1

geli attach -v md0 md1 md2 md3  # enter password "test"
geli status
geli detach md0 md1 md3

mdconfig -s 1m -u 4
mdconfig -s 1m -u 5
mdconfig -s 1m -u 6
dd if=/dev/random of=/tmp/test.key bs=64 count=1
echo te > /tmp/pass1.txt
echo st > /tmp/pass2.txt
geli init -s 4096 -K /tmp/test.key -J /tmp/pass1.txt -J /tmp/pass2.txt md4
geli init -s 4096 -K /tmp/test.key md5  # set password "test123"
geli init -s 4096 -K /tmp/test.key -J /tmp/pass1.txt -J /tmp/pass2.txt md6
geli attach -k /tmp/test.key -j /tmp/pass1.txt -j /tmp/pass2.txt -v md4 md5 md6
geli status
geli detach md4 md6

mdconfig -d -u 0
mdconfig -d -u 1
mdconfig -d -u 2
mdconfig -d -u 3
mdconfig -d -u 4
mdconfig -d -u 5
mdconfig -d -u 6
rm /tmp/test.key /tmp/pass1.txt /tmp/pass2.txt

Expected output:

Attached to md0.
Attached to md1.
Done.
      Name  Status  Components
   md0.eli  ACTIVE  md0
   md1.eli  ACTIVE  md1

Attached to md0.
Attached to md1.
geli: Wrong key for md2.
Attached to md3.
geli: At least one provider failed to attach.
      Name  Status  Components
   md0.eli  ACTIVE  md0
   md1.eli  ACTIVE  md1
   md3.eli  ACTIVE  md3

Attached to md4.
geli: Wrong key for md5.
Attached to md6.
geli: At least one provider failed to attach.
      Name  Status  Components
   md4.eli  ACTIVE  md4
   md6.eli  ACTIVE  md6

[woodsb02]

Fix geli attach using keyfile(s) or passfile(s).
This code is now fully functional.

[oshogbo]

A little out of topic:
@woodsb02 you mentioned that geli detach behaves different - it's accepting multiple devices.
What do you think about making them behave the same - and re implemented geli detach for multiple providers in the userland?
This will make happy both sides - those who want to have kernel as simple you can and those that want to have consistent API.

I will came back here for code review but just had such idea, for now.

[woodsb02]

Implement comment from delphij:

• If device group in rc script is empty, use continue instead of break to carry on with the next device group instead of skipping all devices groups.

Implement comments from sobomax:

• Use strlen instead of strcmp to check for empty cached_passphrase
• Use strlcpy instead of memcpy for strings
• Consistently use curly braces to surround variable names in rc script

[woodsb02]

Implement comment from jilles:

• Revert previous change from $(geli_make_list) and ${geli_make_list}

[woodsb02]

Update diff to implement comments from wblock, delphij, sobomax in D9396

Also rebase diff on r334554.

[woodsb02]

Rebase on r335667

[sobomax]

Looks fine to me. Just two small code nits.

lib/geom/eli/geom_eli.c

522 ↗

(On Diff #44467)

Add {} around the "true" block to avoid ambiguity.

if (nfiles == -1) {

524 ↗

(On Diff #44467)

} else if (nfiles == 0) {

[bcr]

OK from manpages. Don't forget to bump the .Dd at the beginning of the man page with the date of the commit.
Thanks!