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chroot: fix gid being set by uid with --userspec #10307 #10465

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chroot: fix gid being set by uid with --userspec #10307 #10465

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1b4df95
chroot: fix gid being set by uid with --userspec
cerdelen Jan 24, 2026
5e7eccd
chroot: check using sync user that has uid != gid
cerdelen Jan 26, 2026
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14 changes: 12 additions & 2 deletions src/uu/chroot/src/chroot.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ use std::os::unix::prelude::OsStrExt;
use std::os::unix::process::CommandExt;
use std::path::{Path, PathBuf};
use std::process;
use uucore::entries::{Locate, Passwd, grp2gid, usr2uid};
use uucore::entries::{Locate, Passwd, grp2gid, usr2gid, usr2uid};
use uucore::error::{UResult, UUsageError};
use uucore::fs::{MissingHandling, ResolveMode, canonicalize};
use uucore::libc::{self, chroot, setgid, setgroups, setuid};
Expand Down Expand Up @@ -279,6 +279,16 @@ fn name_to_uid(name: &str) -> Result<libc::uid_t, ChrootError> {
}
}

/// Get the GID for the given username, falling back to numeric parsing.
fn usr_name_to_gid(name: &str) -> Result<libc::gid_t, ChrootError> {
match usr2gid(name) {
Ok(gid) => Ok(gid),
Err(_) => name
.parse::<libc::gid_t>()
.map_err(|_| ChrootError::NoSuchGroup),
}
}

/// Get the GID for the given group name, falling back to numeric parsing.
///
/// According to the documentation of GNU `chroot`, "POSIX requires that
Expand Down Expand Up @@ -401,7 +411,7 @@ fn set_context(options: &Options) -> UResult<()> {
}
Some(UserSpec::UserOnly(user)) => {
let uid = name_to_uid(user)?;
let gid = uid as libc::gid_t;
let gid = usr_name_to_gid(user)?;
let strategy = Strategy::FromUID(uid, false);
set_supplemental_gids_with_strategy(strategy, options.groups.as_ref())?;
set_gid(gid).map_err(|e| ChrootError::SetGidFailed(user.to_owned(), e))?;
Expand Down
5 changes: 5 additions & 0 deletions src/uucore/src/lib/features/entries.rs
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Expand Up @@ -356,6 +356,11 @@ pub fn usr2uid(name: &str) -> IOResult<uid_t> {
Passwd::locate(name).map(|p| p.uid)
}

#[inline]
pub fn usr2gid(name: &str) -> IOResult<uid_t> {
Passwd::locate(name).map(|p| p.gid)
}

#[inline]
pub fn grp2gid(name: &str) -> IOResult<gid_t> {
Group::locate(name).map(|p| p.gid)
Expand Down
25 changes: 25 additions & 0 deletions tests/by-util/test_chroot.rs
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Expand Up @@ -327,3 +327,28 @@ fn test_chroot_extra_arg() {
print!("Test skipped; requires root user");
}
}

#[test]
fn test_chroot_userspec_does_not_set_gid_with_uid() {
use uucore::entries::{usr2gid, usr2uid};

let ts = TestScenario::new(util_name!());
if let Ok(uid) = usr2uid("sync") {
if let Ok(gid) = usr2gid("sync") {
if gid == uid {
println!("Test skipped; requires sync user to have uid != gid");
return;
}
// Ubuntu has a sync user whose gid is 65534 per default
if let Ok(result) = run_ucmd_as_root(&ts, &["--userspec=sync", "/", "id", "-g"]) {
result.success().no_stderr().stdout_is("{gid}");
} else {
println!("Test skipped; requires root user");
}
} else {
println!("Test skipped; requires 'sync' user");
}
} else {
println!("Test skipped; requires 'sync' user");
}
}
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