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| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Pierre Warnier
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b516b87be8 |
docs: the upstream suite is not GNU, and is mostly BSD-licensed (#322)
* docs: the upstream suite is not GNU, and is mostly BSD-licensed The README called the original shadow-utils a GNU project and GPL-2.0+, and CONTRIBUTING grounded the clean-room policy on that. Neither holds, as #320 points out: shadow-maint/shadow is not a GNU project, and its tree is mostly BSD-3-Clause with GPL-2.0-or-later files among it -- su.c, vipw.c, contributed scripts, some translated manuals. Checked against Debian's copyright file for the package and Fedora's licence tag, BSD-3-Clause AND GPL-2.0-or-later, not against the source. The policy stands, on the accurate ground: this is an independent MIT implementation that copies from neither part. Copying from the BSD part would carry attribution terms this project does not take on; from the GPL part, a derivative work; sorting files by licence would mean reading them. So the rule is unchanged: do not read that tree. Every "GNU" that meant upstream is now "upstream" or "the distribution's package": README, CONTRIBUTING, Makefile, the man pages' section heading, the e2e image and suite, test comments. make test-gnu-compat is make test-upstream-compat and its script is renamed with it. The 2026-05-04 audit record gets an erratum at the top and is otherwise left as it was run. * docs: the last upstream-as-GNU mentions in the compat suite and the tool table * tests: say upstream, not GNU, in the test comments and skip messages too * tests: one more * docs: keep the README's clean-room line as it was, reworded around it |
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Pierre Warnier
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ab6b3df367 |
chage: let a user read their own aging line (#310)
`chage -l` is the one mode a user may run, on their own account, and it did not work for them: `make install` put chage at 0755, which cannot read /etc/shadow, and the multicall binary dropped its privilege before running it. The Makefile's own comment placed chage in bin "for chage -l, the one mode a user may run on their own account". The packaged binaries settle the contract: Debian ships chage 2755 root:shadow, the same as expiry; Fedora and Arch have no shadow group and ship it 4755 root. chage now follows expiry -- setgid shadow, or setuid root where the group is absent, and an applet that keeps euid 0 in the multicall binary. chage decides what the caller may do from the real uid, and --root is refused before the chroot on the same basis, so the privilege buys a user their own line and nothing else. Verified with the per-tool binaries installed in the debian image under both layouts; as an unprivileged user under each, chage -l on the own account answers, chage -l root, chage -M 5 and chage --root are refused, and the shadow field is unchanged afterwards. The deployment suite gains those four assertions for the multicall layout. |
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Pierre Warnier
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91c9fc12a5 |
install: cope with a system that has no shadow group (#309)
`make install` put expiry setgid `shadow`, which is how Debian and Ubuntu ship it, and failed outright wherever that group does not exist: Fedora and Arch have none -- /etc/shadow there is readable by root alone -- and a packager's chroot may lack it whatever the target. The Arch packager had to sed the Makefile (#306), and the result, setgid to a group with no rights on the file, left expiry unable to read it for anyone but root. On those systems the GNU tool that reads /etc/shadow on a user's behalf, chage, is setuid root; that is the convention expiry now follows where the group is absent. It buys a user nothing more: expiry checks the real uid and reads that one line. SHADOW_GROUP names a group that goes by another name. The choice is made once, at make time, from getent, and the install summary says which layout was used. Verified in the debian image with the group (2755 root:shadow) and with SHADOW_GROUP pointing at a group that does not exist (4755 root), and in the fedora image, where `make install` now completes; under each layout `expiry -c` answers an unprivileged user. |
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Pierre Warnier
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f2fca43a66 |
tests: run a release's archives before trusting them (#304)
`make verify-release TAG=0.5.0` downloads the three published archives, checks their digests, and runs each in a container of the kind it is meant for: Debian 12 for the glibc archive, Alpine for the static one, qemu in the debian image for arm64, where tests/arm64-smoke.sh runs as well. Every archive is installed setuid root and reached through a symlink, the way `make install-multicall` deploys it, and called by an unprivileged user; a spoofed argv[0] must still be refused. That last part is the one thing no suite did. They all run as root, where the argv[0] check is skipped, and the deployment image is glibc, so every static archive from 0.2.2 to 0.4.0 shipped aborting every setuid call and nobody ran one that way. Against 0.4.0 this reports it (and the arm64 and applet checks, which follow the checked-out tree, as an older tag is expected to). Against 0.5.0: 21 checks, none failed. It runs on the host rather than in a container because it drives docker and gh; the Makefile comment and CONTRIBUTING say so. The README's archive section said two archives where there are three, five NSS-dependent tools where there are eleven, and four setuid applets where there are eight; corrected while the section was open. |
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Pierre Warnier
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7e28940874 |
expiry, and usermod's subordinate-id options (#299)
* usermod: add and remove subordinate id ranges GNU usermod has -v/--add-subuids, -V/--del-subuids, -w/--add-subgids and -W/--del-subgids; ours had none of them, which came to light while writing the tests for newuidmap. The range helpers live in shadow_core::subid so whatever next touches /etc/subuid reads the same file the same way. The behaviour was established by running the GNU tool: a range the user already holds is not added twice; a removal trims an entry it overlaps, splits one it cuts through the middle of, deletes one it covers, and ignores a range never held; nothing checks other users' entries, since an administrator may share a range on purpose; and an invalid range -- reversed, not two numbers, above the 32-bit ids the kernel maps -- is exit 3 with the GNU wording, before any file is written. Entries are keyed by the login name given on the command line and are not renamed by -l, as GNU's are not: a range is a grant to a name. -V is GNU's letter for the deletion, so clap's own -V for --version had to go; --version stays. * expiry: check and enforce password expiration expiry is the twenty-eighth tool and the last the Scope table lists as in scope. It judges the caller's own /etc/shadow line as login would: silent when all is well, a warning inside warn_days, a forced change through PAM when the password has expired, a refusal when the account has. Shell profiles run it so a session that did not come through login -- a display manager, an ssh key -- still meets the aging policy. The rules are in shadow_core::shadow::Aging, one function over the aging fields with checked arithmetic, since every input is read from a file anyone who can write /etc/shadow chooses. Its order is login's: account expiry first, then a last change of 0 or an aged-out password, then the warning window, with a maximum age of 10000 or more meaning never as chage -l prints it. A locked password is a policy of its own and is not reported. The GNU tool is setgid shadow -- enough to read the file, no more -- and the change goes through PAM as the caller. The per-tool install ships it the same way, a new install class. The single setuid binary keeps euid 0 for it, having nothing narrower to offer. Under --prefix it reports and never changes anything, since a PAM change would act on this system's account of the same name; that is also what lets the required-change path be asserted in the integration tests without a prompt, while the e2e suite drives the prompt itself on a real user under a pty and checks the hash changed. groupmems is not coming. Debian 13 and Fedora do not ship it, and on Ubuntu 24.04 every action fails against PAM's default for want of a /etc/pam.d/groupmems: a tool one distribution ships and none can use. The Scope table says so. Verified: make check clean with the unprivileged run; 935 tests on alpine and 950 on fedora with PAM; 410 e2e assertions against a real install; 59 GNU comparisons; 35 arm64 assertions under emulation. * shadow-core: stop asking nscd to invalidate a shadow cache it never had Every passwd, chage and chpasswd ended with `nscd -i shadow`, and on a host running nscd that printed "nscd: 'shadow' is not a known database" on the user's terminal each time. nscd caches passwd, group, hosts, services and netgroup; the passwd entries it holds carry the `x` placeholder, so a password change leaves nothing of nscd's stale. Only the databases nscd knows are passed to it now. sss_cache still gets -U for a shadow change, which is right: sssd does cache what a password change affects. |
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Pierre Warnier
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aa987bb390 |
newuidmap, newgidmap: set the id maps of a user namespace (#298)
The setuid helpers that write /proc/<pid>/uid_map and gid_map: what Podman and rootless Docker call for every container they start. The kernel lets an unprivileged process map exactly one id into a namespace it created, its own; everything a container needs beyond that takes the privilege these carry, and they hand it out only within the ranges /etc/subuid and /etc/subgid grant the caller. Fedora ships them in shadow-utils; with these two, every tool the two reference distributions ship from the suite exists here. What is checked before anything is written was established by running the GNU helpers against a real user namespace, never by reading them: the operands must be a target and plain-decimal triples, a zero count is the overflow message; every outside range must sit inside one granted range -- an entry by login name or by numeric uid -- or be the caller's own id mapped once; root is exempt from neither, as newuidmap(1) says; and the target process must belong to the caller by real uid, account uid and the owner of /proc/<pid>, with all three named when they disagree. Overlapping ranges are refused by name; the kernel would refuse them with a bare EINVAL, so the message costs nothing and changes no accepted outcome. The map file is opened through a descriptor held on /proc/<pid>, so a pid recycled between the check and the write cannot redirect it, and the `fd:N` form takes such a descriptor from a caller that did its own checks. It is re-opened through /proc/self/fd rather than adopted, which keeps the tool free of unsafe. The tests do the real thing. A test user creates a namespace with unshare and the helper runs as that user, unprivileged, against it: the own-id mapping lands and the kernel's uid_map reads it back, the second write is refused by the kernel and reported, the fd form works, and every refusal is checked against the same live target. That runs on glibc and musl alike. The Debian image gains the uidmap package so tests/gnu-compat.sh can hold the helpers against GNU's. They take no --help -- any bad command line is the usage text and exit 1 -- so the comparison is on the refusals the two share rather than on help. Verified: make check clean with the unprivileged run; 912 tests on alpine and 934 on fedora with PAM; 393 e2e assertions against a real install, the kernel-visible writes included; 57 GNU comparisons; 34 arm64 assertions under emulation. |
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Pierre Warnier
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4ac1bdfe32 |
login: begin a session on the system (#297)
* shadow-core: take /etc/.pwd.lock before the per-file lock FileLock took the per-file `.lock` first and `/etc/.pwd.lock` second. Two tools working on different files at once could then meet in the classic shape: one holding passwd.lock and waiting for .pwd.lock, the other holding shadow.lock and waiting for passwd.lock's holder to let go of .pwd.lock. Neither can move; both sit out the fifteen-second timeout; both fail -- on a system that was merely busy. Sampling the lock files every 250 ms while the whole suite ran showed it plainly: a chpasswd held shadow.lock for 28 s and a useradd held passwd, group and gshadow for 14 s, each waiting on the other, and seven tests failed with "timed out" on one lock or the other. Three runs after the change: no failures, and the suite back from 35-50 s to 17 s. .pwd.lock now comes first, the order lckpwdf(3) and the GNU tools use and the only one that cannot deadlock: whoever holds it is the only process asking for per-file locks, so it never waits for anyone who is waiting for it. If the per-file lock then cannot be taken, the .pwd.lock reference is given back, so nothing is held on failure. * useradd: lock the shadow file with the others, and write it first useradd wrote /etc/passwd and the group files in one transaction, then opened /etc/shadow on its own afterwards -- under a comment claiming the first locks were still held, which they were not: commit_all releases them. A shadow lock that timed out at that point left the account half made: a passwd line with no shadow line, which a second useradd then reported as already existing. That is exactly what turned up when the login tests put the suite under load. The shadow file is now locked with passwd, group and gshadow before anything is written, and written first, for the reason pwconv writes shadow first: a failure between the writes must never leave a passwd line whose hash is nowhere. The old write_shadow_entry helper stays for its unit test only. A regression test puts a directory where the shadow file should be and checks that useradd fails with /etc/passwd untouched. Before this change the passwd line was written and the failure came after. * login: begin a session on the system login is the twenty-fifth tool and the one uutils/login was archived towards. It is what getty runs on a terminal: it prompts for a name and, through the `login` PAM service, a password; refuses after LOGIN_RETRIES failures or LOGIN_TIMEOUT seconds; opens the PAM session and takes its environment; records the login in utmp and wtmp; hands the terminal to the user; runs the login shell as the user; and when the shell exits, closes the session and records the logout. Which login to match was a question. Debian 13 and Ubuntu 25.10 take login from util-linux, but every release in service -- Ubuntu 20.04, 22.04 and 24.04, Debian 12 -- ships shadow's; the two were run side by side on real pseudo-terminals and agree on everything that matters. This implements the option set they share (-p, -f, -h, name) plus util-linux's -H and --help, which conflict with nothing. There is no -h for help: -h has been the remote host since telnetd. -r, the rlogin protocol, is refused. util-linux's vhangup is not reproduced; shadow's login, which the installed base runs, does not do it either. A wrong password and an unknown name get the same words, after the same delay. -f skips authentication and with it the auth stack, pam_nologin included, as both tools do. A missing home falls back to / with a notice when DEFAULT_HOME allows. The shell runs as a child so the session can be closed afterwards; it gets a clean signal mask, login keeps its own, and groups, gid and uid are dropped in that order in one pre_exec. shadow-core grew what login needed and nothing had: pam setcred, open_session, close_session, user and environment; utmp/wtmp recording; getpwnam through NSS; a getty-style spawn_with_controlling_tty; spawn_as_user; and a watchdog. Without the pam feature the applet says PAM is not compiled in and exits: a login that cannot authenticate is not a login, and the static musl archive is documented accordingly. The tests drive the real binary on a pseudo-terminal the way getty would, answering each prompt once it appears: autologin, the environment with and without -p, a wrong then a right password, an unknown user, the retry limit, the missing home, and the terminal handover. Writing them under the full parallel suite is what exposed the two fixes committed before this one. Verified: make check clean with the unprivileged run; 892 tests on alpine and 882 on fedora; 368 e2e assertions against a real install, including the password path on a pty; 52 GNU comparisons; 32 arm64 assertions under emulation. * docker: give the Fedora image the login PAM service Fedora ships /etc/pam.d/login in util-linux, which the test image did not install. With no service file PAM falls back to `other`, which on Fedora denies everything: `login -f` failed its account check and the password path was refused before any prompt, so every login test failed there and only there. util-linux is now installed, which is what any real Fedora has. The login tests then run through Fedora's own stack -- pam_selinux, pam_loginuid, pam_namespace -- and pass, which makes it the second PAM configuration the session code is exercised against rather than a gap. |
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Pierre Warnier
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ea2c85cf6c |
pwconv, pwunconv, grpconv, grpunconv: convert to and from shadow files (#295)
* pwconv, pwunconv, grpconv, grpunconv: convert to and from shadow files
These four complete the set both Debian and Fedora ship: every tool the two
distributions agree on now exists here. pwconv moves password hashes out of
the world-readable /etc/passwd into /etc/shadow, creating it if need be, and
reconciles the two; pwunconv merges them back and removes /etc/shadow;
grpconv and grpunconv do the same for the group files. They are one engine
with a selector, and the other three crates are the selector.
The order of writes is the substance of the change. pwconv writes shadow
before passwd: the hashes are copied into the shadow file and only then
replaced by `x`, so a failure between the two writes leaves them where they
were rather than nowhere. pwunconv writes passwd before it removes shadow:
for a moment the hashes exist twice, which is recoverable, where the other
order would have a moment with none. The removal happens while the lock on
the shadow file is still held, so no other tool can slip in between the last
read of the file and its disappearance.
What pwconv does was established by running the GNU tool:
- A hash found in passwd beside an existing shadow line is the newer of the
two -- it got there through a tool or an edit that did not know about
shadow -- so it replaces the shadow hash and the change is dated; the
aging is kept.
- A passwd line with no shadow line gets one, dated today, with the aging
from PASS_MIN_DAYS, PASS_MAX_DAYS and PASS_WARN_AGE. The hash field is
copied as it stands, an `x` included: an `x` in the hash field matches no
password, which is the honest state of an account whose hash was lost.
- A shadow line for an account no longer in passwd is dropped.
- A consistent system is left byte for byte alone.
A shadow file this run creates is made 0640 root:shadow, the layout the
distributions ship, with the `shadow` group looked up in the tree being
converted rather than through the name service: under --prefix or --root the
host's shadow group says nothing about the target's. Where the tree has no
such group the file stays 0600 root, the atomic writer's default.
The e2e suite uses the other tools as witnesses rather than only reading
files back: after pwunconv and pwconv the hash is byte for byte what it was,
passwd -S still reports the account as having a password, and after
grpunconv and grpconv sg still admits a non-member with the group password
and still refuses a wrong one.
Verified: 878 tests on debian, alpine and fedora; make check clean including
the unprivileged run; 356 e2e assertions against a real install; 51 GNU
comparisons; 31 arm64 assertions under emulation, the round trip included.
* tests: hand children their stdin as a file, not a pipe
The integration binary died on two CI runners with SIGPIPE: "write on a
pipe with no one to read". Not a failing test -- the test runner itself was
killed, part way through, and every test after it never ran.
Two things combine. The batch tools exit as soon as an input line is bad,
so a child fed "staff\n" has closed its stdin within a millisecond of
starting. And the `uumain` that `#[uucore::main]` generates resets SIGPIPE
to its default disposition every time it runs, in-process, for GNU pipeline
compatibility; several tests call `uumain` in-process -- deliberately, where
the tool would exec -- so once any of them has run, the whole test binary
has SIGPIPE at default. From then on a stdin write that lands after the
child has gone is not an EPIPE the helper could handle but a signal that
ends the process. The window is a few microseconds wide, which is why it
showed up on loaded CI runners and never locally.
The helpers now write the input to a file in the prefix tree and hand the
child that file as its stdin. A file has no reader to lose, so the class is
gone regardless of what the signal disposition is at the time. Applied to
chpasswd's helper too, which had the same shape and the same latent hazard.
Fifteen runs of the integration binary at sixteen threads after the change:
no failures. The race could not be reproduced on demand before it, so that
number is not a before-and-after; the diagnosis rests on uucore's source and
on the two CI logs.
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Pierre Warnier
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8575f629a8 |
vipw, vigr: edit the account files under the suite's lock (#294)
vipw and vigr are the nineteenth and twentieth tools, and the fourth and
fifth of the nine that both Debian and Fedora ship and we did not. They
hand /etc/passwd, /etc/shadow, /etc/group or /etc/gshadow to the
administrator's editor under the same lock every other tool takes, and
install the result atomically. vigr is vipw with the group file as its
default -- the GNU suite ships it as a symlink -- so it is a crate that calls
uu_vipw::run with a different default and nothing else.
The reason the tool exists is the lock, so that is what the e2e suite proves:
with the editor open on /etc/passwd, a concurrent useradd waits rather than
failing or racing, and both changes land.
Two deliberate departures from GNU, both established by running its binary:
- The edited file is parsed before it is installed. GNU installs whatever
the editor saved: a line with no colons went in, and so did
`evil::0:0:::/bin/sh`, a UID 0 account with an empty password field.
Here a file the rest of the suite could not read back is refused. The
check is structural -- pwck and grpck still judge the contents -- and
when it refuses, the edit is kept beside the file rather than discarded.
An administrator whose ten minutes of work vanished would use a raw
editor next time, which is the outcome this tool exists to prevent.
- Changes are detected by content, not by timestamp. GNU compares
modification times in whole seconds, so an edit saved within the same
second as the copy was made is silently thrown away. The first probe of
the GNU tool hit exactly that: every scripted edit came back
"unchanged" until the script was slowed down.
The working copy sits beside the target as passwd.edit, created under a
zeroed umask with the original's mode and ownership, so a copy of
/etc/shadow is never more readable than /etc/shadow. A stale copy from a
crashed run is replaced, and the editor is handed the live contents.
vipw blocks SIGINT and friends for the whole edit so a Ctrl-C aimed at the
editor cannot kill it holding the lock. That mask would be inherited by the
editor, which then could not be interrupted at all, so
shadow_core::process::spawn_with_signals_unblocked starts the child with a
clean mask -- one pre_exec in the module where unsafe is allowed.
Verified: 852 tests on debian, alpine and fedora; make check clean including
the unprivileged run; 319 e2e assertions against a real install; 47 GNU
comparisons; 24 arm64 assertions under emulation.
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Pierre Warnier
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5db310fc88 |
newusers: create or update accounts in batch (#293)
newusers is the eighteenth tool and the third of the nine that both Debian
and Fedora ship and we did not. One input line of seven fields produces a
whole account: the passwd record, the hashed shadow record, a group, and the
home directory with the skeleton copied in.
Every line is parsed, every name validated, every group resolved and every
password hashed before anything is written. A batch with one bad line leaves
the system exactly as it was, including for the good lines above it -- the
failure mode is "nothing happened", not "the first two hundred accounts
exist and the rest do not". That is the whole reason to reach for this tool
over a shell loop around useradd.
Home directory creation moved to shadow_core::home rather than being copied.
useradd's version forces the umask so the requested mode is exact, and hands
over ownership through a descriptor opened O_NOFOLLOW so nobody who can write
the parent can swap in a symlink between the mkdir and the chown. A second
copy of that is a second chance to get it wrong, and the mistake would be
silent. useradd now calls the shared one and its own tests still pass.
Three deliberate divergences, all established by running the GNU tool:
- An empty password field is refused before anything is written. Hashing
"" gives a valid hash that a bare Enter matches. GNU passes the empty
field to PAM, which refuses it *after* creating the account, leaving a
half-made account behind -- verified.
- A pw_gid naming a group that does not exist is refused. GNU falls back to
the user's own ID and creates no group, so the account is left pointing
at a GID that is not there, which grpck then reports.
- A missing parent directory is created, as useradd -b does. GNU's newusers
fails there, which makes it disagree with GNU's own useradd on the same
path.
--badname is implemented rather than stubbed: it drops the portability rules
on the login name while keeping the checks that stop a name from corrupting
the file or being read as an option, which is what makes the flag safe to
offer at all. It is what lets a domain-qualified name from a directory join
through.
The e2e suite re-hashes the stored field with its own salt and compares, so a
tool that wrote a well-formed hash of the wrong string would fail; the
negative control, the same check against a different password, is asserted to
fail. An earlier version of that assertion ended in `|| true` and was
therefore always green -- worth saying, because it is the failure mode these
checks exist to catch.
Verified: 828 tests on debian, alpine and fedora; make check clean, including
the unprivileged run; 297 e2e assertions against a real install; 45 GNU
comparisons; 22 arm64 assertions under emulation.
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Pierre Warnier
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f37939d9fc |
chgpasswd: set group passwords in batch (#292)
* chgpasswd: set group passwords in batch
chgpasswd is chpasswd's counterpart for groups: it reads group:password
lines from stdin and applies them. It is the seventeenth tool and the second
of the nine that both Debian and Fedora ship and we did not.
It follows chpasswd's rule, which is what makes a batch tool safe to run
unattended: every line is parsed, every group resolved and every password
hashed before any file is written, so a batch naming one group that does not
exist changes nothing rather than applying the lines above it and stopping.
The two account files are then written in one transaction.
Where the hash goes was established by running the GNU tool, not by reading
it. With /etc/gshadow present the hash belongs there and /etc/group keeps the
`x` placeholder -- /etc/group is world-readable. Without it the hash goes
into /etc/group, and no gshadow file is created: conjuring one up would
change how every other tool on the host reads group passwords.
Three deliberate divergences, all refusals:
- `-c NONE`, which GNU honours by storing the password as clear text in
/etc/gshadow. A readable group password is worth no more than none at
all, and `-e` already writes a field verbatim when that is what is
wanted. The message says so, or an operator would just try `-c MD5`.
- `-m` and `-c MD5`/`-c DES`, as chpasswd already refuses them.
- An empty password in plaintext mode: hashing "" yields a valid hash that
a bare Enter matches, which is a group anyone can enter rather than a
group with no password. `-e ''` remains the way to clear the field.
A field containing a colon is refused, since it would split the gshadow line
and corrupt the file. The GNU tool refuses it too and likewise leaves the
file untouched, so this is agreement, not divergence.
The e2e suite checks the tools against each other rather than only against
the files: the password chgpasswd sets is the one sg then accepts from a
non-member, and a wrong one is refused. A hash written in a format nothing
can verify would pass a file-shape assertion and fail this one.
Verified: 798 tests on debian, alpine and fedora; make check clean; 273 e2e
assertions against a real install; 44 GNU comparisons.
* tests: run the suite as an unprivileged user too
Sixteen of the chgpasswd tests assumed root. They passed locally because
every container in docker-compose.yml runs as root, and failed in the one CI
job that does not.
Worse than the two that failed outright were the ones that passed for the
wrong reason: a test asserting exit 1 got exit 1 from "permission denied"
rather than from the condition it meant to check, so it was green while
testing nothing. Only the two expecting exit 0 gave the game away.
The guard itself is what chpasswd already does -- skip_unless_root() on every
test that writes an account file. The two that only exercise argument parsing
keep running everywhere, since clap answers before the root check.
The gap that let this through was local, so the fix is too: `make
test-unprivileged` re-runs the already-built test binaries as an ordinary
user, and `make check` now does it after the root run. Removing one guard
again makes it fail with "Permission denied", which is how it was verified.
SHADOW_TEST_REQUIRE_ROOT is cleared for that run on purpose: it exists to
turn a skip into a failure when the suite *is* root, which is the opposite
case.
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Pierre Warnier
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651ed5c62b |
sg: run a command with a different primary group (#291)
sg is the sixteenth tool, and the first of the nine that both Debian and
Fedora ship and we did not. It runs a single command with a different
primary group: newgrp for one command instead of for a whole shell.
sg and newgrp are not merely similar. They decide who may enter a group by
the same rules and enter it the same way, and the distributions ship sg as a
symlink to the setuid newgrp binary -- one implementation, dispatched on
argv[0]. So the shared half moves into shadow_core::group_switch and both
tools call it, which is what keeps them from drifting apart. The multicall
binary already dispatches on argv[0], so it needs only the new applet.
sg execs the command rather than forking and waiting for it. The shell then
is the process, so the command's exit status reaches the caller unaltered:
`sg staff -c 'exit 7'` exits 7 and a command that cannot be run exits 127,
without sg reconstructing a wait status. This matches what the GNU tool does
and costs a process.
Writing the shared module turned up two things wrong in newgrp:
- It refused a group with no password without prompting, and prompted when
the group had one. Whether a prompt appeared therefore told any caller
which groups have passwords set, which is a list of the ones worth
attacking. Both tools now prompt either way and refuse afterwards.
- It rebuilt the supplementary group list with initgroups() alone, which
builds it from the member lists in /etc/group -- where a primary group
never appears. `newgrp staff` therefore dropped the group the caller
started in, costing them access to their own files until they left the
shell. The original group is added back, which needs setgroups(2) and so
has to happen before the setuid privilege is given up.
Both were established by running the GNU tools, not by reading them.
sg is setuid for the reason newgrp is: a caller who is not a member has to
be checked against the group password in /etc/gshadow, which is root-only.
Removing sg from the setuid list fails six assertions in the e2e suite --
including for a plain member, since initgroups() itself needs the privilege
-- and nothing else in the suite covers it.
Verified: 763 tests on debian, alpine and fedora; 255 e2e assertions against
a real setuid install, covering a member, a non-member with the group
password, a wrong password, a passwordless group and exit-status
propagation; 43 GNU comparisons; 19 arm64 assertions under emulation.
|
||
|
Pierre Warnier
|
604b96aa6b |
tests: cross-build for arm64 and actually run it (#290)
The release has published an arm64 archive since 0.3.0 and nothing had ever executed one. CI builds it on a native arm64 runner and ships it, so a binary that was broken on that architecture would reach a user before anyone ran it; the checks so far went as far as the ELF header and the linked libraries. make test-arm64 cross-compiles the multicall binary and runs it under qemu user-mode emulation against a prefixed tree: useradd with a home and a supplementary group, chpasswd producing a SHA-512 hash, chage computing its dates, gpasswd adding a member, usermod renaming across files, userdel -r, and pwck reading back what the others wrote. Eighteen assertions, all passing on the current tree. Emulation is enough for what actually differs across architectures -- integer widths, struct layouts, and the crypt and PAM FFI boundaries -- and it needs no arm64 machine and no binfmt handler on the host, which rootless Docker cannot register anyway. The cross toolchain is installed by the target rather than baked into the image: it is 32 packages, and every other job would carry them for a check that runs occasionally. Also confirmed the published 0.4.0 arm64 archive runs, by the same route. |
||
 Jocelyn Le SageandPierre Warnier
|
8361bf512b |
gpasswd: added implementation of gpasswd (#282)
* gpasswd: added implementation of gpasswd
* gpasswd: rebase onto main and port to the current APIs
Rebases jlesage's implementation onto a main that moved a long way under
it, and carries it onto the interfaces that landed since the branch was
cut. The tool's behaviour is unchanged and still matches GNU on every
path probed.
What the rebase had to resolve:
- shadow-rs.spec and debian/ were revived by the merge; both were
deleted because neither could build.
- The standalone dispatch() and hand-written --list predate the single
applets() table, which now drives both. gpasswd joins the table.
- The five shadow-core parser features it asked for no longer exist.
- The fourteen [[test]] targets are one; test_gpasswd joins it.
- README, Makefile and PLATFORM-SUPPORT described the pre-#239
privilege model, in which every applet ran with euid 0.
What changed beyond the rebase:
- gpasswd keeps its privilege in the multicall build. It is setuid in
GNU and the branch marks it setuid for the per-tool install, but
SETUID_APPLETS still listed four names, so the multicall build would
have dropped privilege and no group administrator could have used it
-- silently.
- Comments in /etc/group survive. It read entries only and wrote them
back, which erases every comment, blank line and NIS compatibility
line in the file. The locked-file transaction keeps them, and commits
group and gshadow together so a bad value cannot leave the pair
disagreeing.
- The duplicated EchoGuard and password reader are gone, replaced by
shadow_core::tty, which blocks interrupts for the read so Ctrl-C at
the prompt cannot leave the terminal with echo off.
- The print macros are replaced. They panic when the stream is closed,
which a setuid-root tool must not do part way through a change.
These were the only five in the repository and no lint caught them,
so clippy::print_stdout and print_stderr are now denied
workspace-wide, with the test crate exempt.
The GNU comparison suite gains gpasswd: the unknown-group, unknown-user
and non-member exit codes, all three of which match.
CONTRIBUTING's licence list also said ISC, BSD-2-Clause, CC0-1.0, Zlib
and MPL-2.0 were acceptable, which stopped being true when deny.toml was
narrowed to the graph. It now says what deny.toml enforces.
---------
Co-authored-by: Pierre Warnier <pierre@warnier.net>
|
||
|
Pierre Warnier
|
acc1771bc2 |
tests: exercise the PAM stack against known permit and deny services (#281)
The only PAM coverage was the deployment image authenticating a real account. That cannot exercise a *refusal* without relying on a wrong password being wrong, and it cannot tell a refusal apart from a conversation that never reached the stack -- which is exactly the failure that broke password changes earlier this week and took three rounds to find. The glibc images now define two throwaway services, one backed by pam_permit and one by pam_deny, and shadow-core tests the wrapper against both: the permit stack authenticates and passes account management, the deny stack refuses with the stack's own answer rather than a conversation error, and a service with no configuration at all does not authenticate. The tests skip where the services are absent, which is any machine but the containers. CI also gains an all-features clippy pass. The completions feature and the shadow-core feature gates were compiled by no job, so a lint or a compile error in them could reach main unnoticed. make check runs it too. |
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|
Pierre Warnier
|
02fefda42c |
ci: compare against GNU for real, pin the actions by digest, one make check (#275)
* ci: pin the actions by digest A tag is a moving pointer. Whoever controls the action's repository can repoint v7 at any commit, and every workflow in the project runs it on the next push with write access to the checkout. A digest cannot be repointed. The tag stays in a trailing comment so the version is still readable, and Renovate's pinGitHubActionDigests preset is enabled so the digests are kept current the same way every other dependency is -- as a pull request that CI has run, rather than silently. * tests: make the GNU comparison real, and run it in CI The suite compared full output for exactly two commands and, for the other twelve, only that both tools exit 0 on --help. It ran nowhere. It now compares what is actually a contract. 'passwd -S' and 'chage -l' are parsed by monitoring and provisioning scripts, so their output is compared byte for byte across eleven aging configurations -- including the cases this project got wrong until recently: a last change of 0, the threshold above which a maximum age reads never, and cleared fields. Exit codes are compared on ten error paths. --help output is deliberately not compared: ours comes from clap and is meant to differ. One difference is deliberate and now asserted as such, so it cannot be mistaken for a regression the day it changes by accident. GNU parses dates leniently and rolls them over -- 'chage -d 2025-02-29' stores 1 March and '-d 2025-13-01' stores 1 January 2026. An administrator who typed one of those made a mistake, and silently storing a different date than the one they wrote is a poor answer for a field that decides when an account stops working. We refuse it; chage(1) says so. 38 comparisons, all as expected, and a CI job runs them. 'make check' is now the single definition of what CI gates on -- fmt, clippy with and without pam, and the tests in both configurations. The pre-push hook and CONTRIBUTING refer to it instead of each carrying their own copy of the command list, and the two hook systems are documented as the non-overlapping things they are. |
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|
Pierre Warnier
|
9cd5eef4ac |
Install layout, aarch64 archives, pinned images, and a pre-push hook worth keeping (#272)
* hooks: stop reproducing CI in pre-push The hook ran fmt, clippy and the test suite on Debian, Alpine and Fedora in series, on every push. That is several minutes for a push that may carry nothing: pushing the 0.2.2 tag moved one object and still blocked for over two minutes. The predictable result was that every push in the last batch of work used --no-verify, and a hook that is always skipped protects nothing while still costing time whenever someone forgets to skip it. It now runs the workspace tests once, on Debian, and returns immediately for a push that carries no new commits -- a tag, a branch deletion, or a branch the remote already has. git hands the hook one line per ref on stdin; the ranges it names are asked for a single commit, and if there are none there is nothing to test. Everything the hook dropped is already a required check on the pull request, running in parallel with retries: fmt, clippy and the tests with and without pam, MSRV, cargo-deny, the static musl archive, the three-distro matrix as root, and the end-to-end deployment image. Closes #231. * install: put the user-facing tools in bin, not sbin All fourteen binaries went to $(PREFIX)/sbin, which is not on a normal user's PATH: passwd was 'command not found' for exactly the people it is setuid for. GNU shadow splits them, verified against the Debian package -- passwd, chage, chfn, chsh and newgrp in /usr/bin, the other nine in /usr/sbin. Both install targets do the same now, and the multicall symlinks in bin point at the absolute path of the binary in sbin. chage is in bin for 'chage -l', the one mode a user may run on their own account. The deployment suite follows each tool to the directory it belongs in, and asserts that all five are reachable by name for an unprivileged user, which is the property the split exists for. make test also runs the suite with pam now. install ships binaries built with it, so a run without it covered a build nobody ships. * docker: pin the base images, drop the unused nextest download rust:latest, rust:alpine and fedora:latest meant a new toolchain or distro release landed on main with no pull request and no signal, and clippy gains lints between Rust releases. They are pinned to what the images resolve to today -- rust 1.98 on Trixie and Alpine 3.23, Fedora 44 -- and Renovate's Dockerfile manager proposes the bumps, so a toolchain change arrives as a reviewable PR that CI has run. Each image also downloaded cargo-nextest from get.nexte.st/latest on every build: unpinned, unverified, and never invoked -- nothing in the repository runs 'cargo nextest'. cargo-deny, which is used, keeps its pinned version and checksum. * deny: allow exactly the licences the graph uses The allow list carried ISC, BSD-2-Clause, CC0-1.0 and Zlib, none of which appears anywhere in the dependency graph. A list wider than the graph means a crate arriving under a new licence passes silently; the point of the check is that such an arrival is a decision someone records. It is now MIT, Apache-2.0, BSD-3-Clause (subtle, for the constant-time comparison in shadow-core::crypt) and Unicode-3.0 (tinystr and unicode-ident, via uucore's fluent stack), taken from 'cargo deny --all-features list'. Two crates carry a copyleft option in a dual licence and are accepted under the other half; that is now written down rather than left for the next reader to work out. All four checks pass with the narrower list. * ci: run the advisory workflow on a schedule only It also ran on every push touching a manifest or the lockfile, where the Cargo Deny job in ci.yml had already checked the same advisory database alongside licences and bans. Two tools reporting the same finding on the same commit is noise. What the pull request job cannot do is notice an advisory published against code nobody has touched, which is the reason to keep a scheduled run. That is now all this workflow does, plus manual dispatch. * packaging: remove the RPM spec and debian directory Neither can build. debian/ has no changelog at all, so dpkg-buildpackage stops before it starts: dpkg-buildpackage: error: cannot open file debian/changelog and shadow-rs.spec pins version 0.2.0 against a 0.2.2 workspace, points at the pre-transfer repository URL, and lists a %files layout that 'make install' does not produce -- it names the multicall binary, which only install-multicall builds, and puts every tool in sbin, which is no longer where half of them go. Shipping packaging that claims to work and does not is worse than shipping none, and this would have produced a package declaring 'Provides: passwd, login' on a system whose real passwd it replaced. Releases are the archives dist publishes; a distribution packager writes these against their own policy anyway. * release: publish an aarch64 archive The pipeline shipped x86_64 only. arm64 servers and Apple-silicon containers are common enough that a missing archive is a real gap. It builds on a native arm64 runner rather than cross-compiling, which is what makes it straightforward: shadow-core::crypt links crypt(3) and the pam feature links libpam, so a cross build would need an arm64 sysroot carrying both, while a native runner installs them from apt like any other build. dist has picked a native runner for aarch64 since 0.30. Both runners are pinned to 24.04. dist's defaults are ubuntu-22.04 and ubuntu-22.04-arm, and 22.04 enters deprecation on 2026-09-17 with the image unsupported from 2027-04-17; the pin keeps the two archives on the same generation and off an image that is about to start failing. The higher runner raises the glibc floor for the dynamically linked archives, which is what the static musl archive is there for. release.yml is regenerated by 'dist generate'; 'dist plan' now lists three archives and resolves ubuntu-24.04-arm for the arm64 job. Closes #222. |
||
|
Pierre Warnier
|
881aad13c7 |
shadow-rs: drop the setuid privilege for applets that are not meant to have it (#239)
* shadow-rs: drop the setuid privilege for applets that are not meant to have it The per-tool install marks only passwd, chfn, chsh and newgrp setuid; a multicall install has to make the one binary setuid, which gave every applet euid 0. Any local user could run 'shadow-rs pwck -s' or 'grpck -s' and have /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow rewritten as root. Before an applet outside that set runs, the binary now calls setuid(getuid()), so the real, effective and saved uid are all the caller's and the two layouts share one privilege model. It fails closed if the kernel does not take the privilege away. Dispatch and --list are driven by one table instead of two hand-kept lists, and an exit code outside 0..=255 no longer clamps to success. The deployment test checks that testrunner's pwck -s and grpck -s leave the files' inode and ownership untouched. * docs: the multicall binary keeps euid 0 for the four self-service tools only |
||
|
Pierre Warnier
|
52c2debe8b |
release: publish a labelled static musl archive (#224) (#237)
* shadow-core: link libcrypt only where it exists; refuse pam on static musl musl implements crypt(3) inside libc and ships no libcrypt. Asking for -lcrypt there made a cross-build for x86_64-unknown-linux-musl fall through to the host's glibc-built libxcrypt and fail on glibc-only symbols; Alpine only worked because musl-dev ships an empty libcrypt.a. Linux-PAM loads its modules with dlopen, which static musl does not have, and no distribution ships libpam.a. Building the pam feature into a crt-static musl binary is therefore a configuration error; reject it at compile time instead of producing a binary whose authentication path can never work. The crypt tests stated the musl behaviour wrongly (musl does honour rounds=; it lacks yescrypt). They now assert the real behaviour per target instead of skipping. * release: publish a static musl archive next to the glibc one dist cannot vary cargo features per target and pam must be off for musl, so the musl archive is built by 'make dist-musl' and attached by dist as an extra artifact of the same release. The target enforces the lockfile, checks the binary has no DT_NEEDED entry and packs it with the licence, changelog, README and PLATFORM-SUPPORT.md so the trade-off travels with the binary. The archive name carries a -static suffix so it is never mistaken for the glibc build. CI runs the same make target on every pull request, smoke-tests the archive, runs shadow-core's unit tests against static musl and checks that the pam feature is rejected there, so a tag is never the first time the archive is built. * docs: describe both release archives and what the static musl one gives up The README now lists the two archives side by side with the one question a reader has to answer (is PAM, NSS or yescrypt needed on this host?), and PLATFORM-SUPPORT.md is rewritten around the archive that now exists: how it is built, which CI job guards it, and the exact effect of each gap. CONTRIBUTING listed two unsafe-permitted modules; there are three. * chore: use the canonical uutils/shadow repository URL The repository is uutils/shadow; the old shadow-rs name is a redirect. The README badges already used the new name while package metadata, the --help footer and SECURITY.md still pointed at the old one. |
||
|
Pierre Warnier
|
9f197e0e50 |
chfn, chsh: authenticate the caller before applying a change (#235)
* shadow-core: move PrivDrop out of passwd The RAII guard that drops the effective UID for the PAM conversation lived inside uu_passwd, but it is process-level privilege handling that any setuid tool needs. Move it next to the seteuid wrapper it calls. Two changes while moving it: the error type becomes io::Result rather than PasswdError so other tools can use it, and the failure-to-restore message goes through uucore::show_error! instead of a hardcoded "passwd:" prefix, so it names whichever tool is running. * chfn, chsh: authenticate the caller before applying a change Both tools are installed setuid-root. They correctly restrict a non-root caller to their own account, checked against the real UID — but they never verify who is asking. Anyone with access to an unlocked session could change that user's login shell or GECOS field, and changing a login shell is a foothold. GNU prompts for the password here, and distributions already ship the service definitions we were ignoring: /etc/pam.d/chfn and /etc/pam.d/chsh both let root through with pam_rootok and fall back to common-auth for everyone else. CONTRIBUTING treats a difference from GNU as a bug, so this is one. Authenticate through PAM for non-root callers, reusing the pattern passwd already uses: drop to the real UID for the conversation so modules see the actual caller, then authenticate and check account validity. Without the pam feature there is no way to verify anyone, so the tools refuse rather than apply an unauthenticated change. That is a behaviour change for that build only, and the safe direction for a setuid binary. It also means every install path must enable the feature — 'make build' only enabled it for passwd, which would have shipped two setuid tools that reject all non-root use. Fixed, and the end-to-end assertion now covers all three tools instead of passwd alone. CI gained 'cargo test --features pam': the feature changes behaviour rather than only adding code, so both configurations need testing. |
||
|
Pierre Warnier
|
3de8b506ac |
build: ship binaries with PAM so passwd can change passwords (#220) (#225)
`pam` is not a default cargo feature, so every build path except the e2e
image compiled the interactive change path out of `passwd`. The tool
could report and lock accounts but not change a password:
$ passwd alice
shadow-rs: PAM support is not compiled in — cannot change password
interactively
That covered the release archive, `make install` (the default install of
14 standalone binaries) and `make install-multicall`. Only the e2e image
passed --features pam, and its assertions stop at `passwd -S`, which
works without PAM — hence nobody noticed.
Enable the feature in the release build and in both Makefile targets, and
install libpam0g-dev on the release runner. The PAM headers are already a
documented build requirement.
Add an e2e assertion that the installed passwd is linked against libpam,
so this cannot regress silently again.
Closes #220.
|
||
 Sylvestre Ledru
|
cb8ce5ebd2 |
cargo: rename package to uu_shadow. shadow-rs is already used
https://crates.io/crates/uu_grep is a precedent |
||
|
Pierre Warnier
|
d89b4aaa64 |
Makefile: drop PROFILE var, fix stale comments
Address Copilot review round 2: - Remove PROFILE variable and hardcode --release / target/release/. Cargo maps "dev" profile to target/debug/ (not target/dev/), so PROFILE=dev would silently break install. Nobody installs debug builds of setuid-root tools. - Fix stale comments in Makefile and README that referenced the old "chmod on symlink follows through" approach. The current code uses install -Dm4755 directly. |
||
|
Pierre Warnier
|
de1e96c605 |
Makefile: single cargo build + atomic install -Dm mode
Address review comments on #139: - build: replace 14-call loop with a single `cargo build --workspace --bins --exclude shadow-rs` invocation, eliminating per-tool Cargo startup/metadata overhead. Matches the uutils/coreutils GNUmakefile pattern. - install: use `install -Dm4755` / `install -Dm0755` to set mode atomically during install instead of post-install chmod. Errors no longer swallowed: if install can't set the setuid bit, `make install` now fails loudly. - install-multicall: same — `install -Dm4755` sets the shadow-rs binary setuid in one step. |
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|
Pierre Warnier
|
698eaf7cf3 |
make install: default to standalone per-tool binaries (#138)
Switch the default install to build and install 14 standalone per-tool binaries with a least-privilege setuid layout matching GNU shadow-utils. Only passwd/chfn/chsh/newgrp are setuid-root; the other 10 tools are 0755. The previous multicall install is preserved as `make install-multicall` for container/embedded use cases where the ~14x disk savings matter and the enlarged setuid attack surface is acceptable. The old layout chmod'd symlinks pointing to the multicall binary, which (because chmod follows symlinks) marked the underlying ELF setuid-root. That meant all 14 tools ran with euid=0 when invoked via symlink. Each tool's internal getuid() check was defense-in-depth, not OS-level least privilege. The standalone layout gives the latter. Raised by @oech3 in uutils/coreutils#11828. |