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running_as_user: don't skip authentication when a chroot is set - #588
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running_as_user() let "sudo -u <self>" skip authentication unless an SELinux role/type, AppArmor profile or Solaris privilege set was in effect, but it did not consider the root directory. A -R directory (allowed by CHROOT=* or runchroot=*) or a runchroot set in Defaults was therefore applied without a password, even though chroot(2) is done as root before switching to the user. Treat a chroot like the other security context changes and require authentication.
millert
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Oct 29, 2026
millert
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The chroot code is slated to be removed in a future release (not 1.9.18) but while it is present it is good to have it work as well as possible.
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running_as_user()letscheck_user()skip authentication when the runas user is the invoking user, unless an SELinux role/type, AppArmor profile or Solaris privilege set is in effect. It does not look at the root directory, sosudo -u <self>with a-Rdirectory (allowed byCHROOT=*orrunchroot=*) or withrunchrootset in Defaults runs without a password, even though the front-end callschroot(2)as root before it switches to the user. The user ends up with a process rooted in a directory of their choosing, whichchroot(2)otherwise reserves for root, and any setuid program reachable there reads that tree's/etc/passwd,/etc/shadowand shared libraries. Withalice ALL=(ALL) CHROOT=* /usr/bin/jailtest "",sudo -n -u alice -R /home/alice/jail /usr/bin/jailtestran chrooted into the alice-owned directory with no password, while the same command with-u rootreported "a password is required";Defaults runchroot=/srv/jailbehaved the same way.Treat a chroot like the other security context changes: only take the shortcut when no
-Rdirectory was given andrunchrootis unset or*, the same testpolicy.cuses before it passeschroot=to the front-end. Running as yourself without a chroot still needs no password, and the chroot cases still work after authenticating. Checked end to end on Linux with sudo built and installed from main,make checkpasses there, and the macOS build with--enable-warnings --enable-werror --enable-sanitizeris clean. A per-ruleCHROOT=dirwith a non-root runas user currently fails earlier with "unable to set runas group vector" (nestedPERM_RUNAS), which is a separate issue.