cr_canseeothergids(): Use real instead of effective group membership
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Authored by olce on Jun 20 2023, 1:45 PM.

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Reviewers

mjg
kib
dchagin
mhorne
olce

Commits

rGf0951233c6d3: cr_canseeothergids(): Use real instead of effective group membership
rG26ff4836c888: cr_canseeothergids(): Use real instead of effective group membership
rGf482bc958437: cr_canseeothergids(): Use real instead of effective group membership
rG91658080f1a5: cr_canseeothergids(): Use real instead of effective group membership

Summary

Using the effective group and not the real one when testing membership has the
consequence that unprivileged processes cannot see setuid commands they launch
until these have relinquished their privileges. This is also in contradiction
with how the similar cr_canseeotheruids() works, i.e., by taking into account
real user IDs.

Fix this by substituting groupmember() with realgroupmember(). While here,
simplify the code.

PR: 272093

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Repository

rG FreeBSD src repository

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Build Status

Buildable 52177
Build 49068: arc lint + arc unit

Event Timeline

olce created this revision.Jun 20 2023, 1:45 PM

Herald added a subscriber: imp. · View Herald TranscriptJun 20 2023, 1:45 PM

olce requested review of this revision.Jun 20 2023, 1:45 PM

Harbormaster completed remote builds in B52177: Diff 123508.Jun 20 2023, 1:45 PM

olce added a parent revision: D40641: New realgroupmember().Jun 20 2023, 2:11 PM

olce added a child revision: D40643: realgroupmember(9): Link to groupmember(9), document the function.

olce added reviewers: mjg, kib, dchagin.Jun 20 2023, 9:03 PM

emaste added a subscriber: jamie.Jun 29 2023, 4:09 PM

emaste added a subscriber: emaste.

The change requires some elaboration in the description. The text from the PR would be fine.

sys/kern/kern_prot.c
1407	This is a style regression. Even though `see_other_gids` has an `int` type, it is a boolean variable and so we should check its truthiness directly.