Commit Graph

408 Commits

Author SHA1 Message Date
Chris Lamb
3d921155e0 gettime: Use secure_getenv over getenv. 2019-03-31 16:00:01 +01:00
Chris Lamb
fe34a2a0e4 Make the sp_lstchg shadow field reproducible (re. #71)
From <https://github.com/shadow-maint/shadow/pull/71>:

```
The third field in the /etc/shadow file (sp_lstchg) contains the date of
the last password change expressed as the number of days since Jan 1, 1970.
As this is a relative time, creating a user today will result in:

username:17238:0:99999:7:::
whilst creating the same user tomorrow will result in:

username:17239:0:99999:7:::
This has an impact for the Reproducible Builds[0] project where we aim to
be independent of as many elements the build environment as possible,
including the current date.

This patch changes the behaviour to use the SOURCE_DATE_EPOCH[1]
environment variable (instead of Jan 1, 1970) if valid.
```

This updated PR adds some missing calls to gettime (). This was originally
filed by Johannes Schauer in Debian as #917773 [2].

[0] https://reproducible-builds.org/
[1] https://reproducible-builds.org/specs/source-date-epoch/
[2] https://bugs.debian.org/917773
2019-03-31 16:00:01 +01:00
Giuseppe Scrivano
59c2dabb26 idmap: always seteuid to the owner of the namespace
simplify the condition for setting the euid of the process.  Now it is
always set when we are running as root, the issue was introduced with
the commit 52c081b02c

Changelog: 2018-11-24 - seh - enforce that euid only gets set to ruid if
   it currently == 0 (i.e. really was setuid-*root*).

Closes: https://github.com/genuinetools/img/issues/191

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2018-11-24 17:30:46 -06:00
Christian Brauner
52c081b02c
new{g,u}idmap: align setuid and fscaps behavior
Commit 1ecca8439d ("new[ug]idmap: not require CAP_SYS_ADMIN in the parent userNS")
does contain a wrong commit message, is lacking an explanation of the
issue, misses some simplifications and hardening features. This commit
tries to rectify this.

In (crazy) environment where all capabilities are dropped from the
capability bounding set apart from CAP_SET{G,U}ID setuid- and
fscaps-based new{g,u}idmap binaries behave differently when writing
complex mappings for an unprivileged user:

1. newuidmap is setuid

unshare -U sleep infinity &
newuidmap $? 0 100000 65536

First file_ns_capable(file, ns, CAP_SYS_ADMIN) is hit. This calls into
cap_capable() and hits the loop

for (;;) {
        /* Do we have the necessary capabilities? */
        if (ns == cred->user_ns)
                return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;

        /*
         * If we're already at a lower level than we're looking for,
         * we're done searching.
         */
        if (ns->level <= cred->user_ns->level)
                return -EPERM;

        /*
         * The owner of the user namespace in the parent of the
         * user namespace has all caps.
        */
        if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
                return 0;

        /*
         * If you have a capability in a parent user ns, then you have
         * it over all children user namespaces as well.
        */
        ns = ns->parent;
}

The first check fails and falls through to the end of the loop and
retrieves the parent user namespace and checks whether CAP_SYS_ADMIN is
available there which isn't.

2. newuidmap has CAP_SETUID as fscaps set

unshare -U sleep infinity &
newuidmap $? 0 100000 65536

The first file_ns_capable() check for CAP_SYS_ADMIN is passed since the
euid has not been changed:

if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
        return 0;

Now new_idmap_permitted() is hit which calls ns_capable(ns->parent,
CAP_SET{G,U}ID). This check passes since CAP_SET{G,U}ID is available in
the parent user namespace.
Now file_ns_capable(file, ns->parent, CAP_SETUID) is hit and the
cap_capable() loop (see above) is entered again. This passes

if (ns == cred->user_ns)
        return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;

since CAP_SET{G,U}ID is available in the parent user namespace. Now the
mapping can be written.

There is no need for this descrepancy between setuid and fscaps based
new{g,u}idmap binaries. The solution is to do a
seteuid() back to the unprivileged uid and PR_SET_KEEPCAPS to keep
CAP_SET{G,U}ID. The seteuid() will cause the
file_ns_capable(file, ns, CAP_SYS_ADMIN) check to pass and the
PR_SET_KEEPCAPS for CAP_SET{G,U}ID will cause the CAP_SET{G,U}ID to
pass.

Fixes: 1ecca8439d ("new[ug]idmap: not require CAP_SYS_ADMIN in the parent userNS")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2018-10-28 01:27:48 +02:00
Serge Hallyn
d5255da20b
Merge pull request #132 from giuseppe/no-cap-sys-admin
newuidmap/newgidmap: do not require CAP_SYS_ADMIN in the parent user namespace
2018-10-27 11:22:37 -05:00
Serge Hallyn
ff8b1ebafa
Merge pull request #118 from AdelieLinux/utmpx-only-support
[WIP] Support systems that only have utmpx
2018-10-23 22:35:19 -05:00
Giuseppe Scrivano
1ecca8439d
new[ug]idmap: not require CAP_SYS_ADMIN in the parent userNS
if the euid!=owner of the userns, the kernel returns EPERM when trying
to write the uidmap and there is no CAP_SYS_ADMIN in the parent
namespace.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
2018-10-22 16:57:50 +02:00
Tomas Mraz
fb97da1ce1 Fix some issues found in Coverity scan. 2018-10-10 12:22:04 +02:00
A. Wilcox
99dbd4b9ee
Support systems that only have utmpx
This allows shadow-utils to build on systems like Adélie, which have no
<utmp.h> header or `struct utmp`.  We use a <utmpx.h>-based daemon,
utmps[1], which uses `struct utmpx` only.

Tested both `login` and `logoutd` with utmps and both work correctly.

[1]: http://skarnet.org/software/utmps/
2018-06-24 00:13:12 -05:00
Jan Chren (rindeal)
2fd5815546 fix unguarded ENABLE_SUBIDS code 2018-06-18 15:51:27 +02:00
Serge Hallyn
48dcf7852e usermod: prevent a segv
in the case where prefix does not exist.

Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2018-05-08 21:37:55 -05:00
fariouche
73a876a056 Fix usermod crash
Return newly allocated pointers when the caller will free them.

Closes #110
2018-05-08 21:17:46 -05:00
fariouche
65b4f58703 add --prefix option: some fixes + fixed pwd.lock file location 2018-03-28 21:14:12 +02:00
fariouche
54551c7d6e Merge remote-tracking branch 'upstream/master' 2018-03-28 21:11:36 +02:00
fariouche
acaed3deab upstream merge 2018-01-23 23:10:19 +01:00
Josh Soref
dcf96e43fa spelling: mapping 2017-10-22 20:32:45 +00:00
Josh Soref
74fcf6f28d spelling: interactive 2017-10-22 20:24:32 +00:00
Josh Soref
e235f372ce spelling: gratuitously 2017-10-22 19:17:02 +00:00
Josh Soref
51f740e23e spelling: entered 2017-10-22 19:10:41 +00:00
Josh Soref
c751f4a6ec spelling: else 2017-10-22 19:08:39 +00:00
Josh Soref
66b1a59efe spelling: cumulative 2017-10-22 18:33:13 +00:00
Chris Lamb
cb610d54b4 Make the sp_lstchg shadow field reproducible.
The third field in the /etc/shadow file (sp_lstchg) contains the date of
the last password change expressed as the number of days since Jan 1, 1970.
As this is a relative time, creating a user today will result in:

   username:17238:0:99999:7:::

whilst creating the same user tomorrow will result in:

    username:17239:0:99999:7:::

This has an impact for the Reproducible Builds[0] project where we aim to
be independent of as many elements the build environment as possible,
including the current date.

This patch changes the behaviour to use the SOURCE_DATE_EPOCH[1]
environment variable (instead of Jan 1, 1970) if valid.

 [0] https://reproducible-builds.org/
 [1] https://reproducible-builds.org/specs/source-date-epoch/

Signed-off-by: Chris Lamb <lamby@debian.org>
2017-04-10 22:29:21 +01:00
Serge Hallyn
6eae751e70 user_busy: fix missing close of subuid file on error
Closes #69

Reported-by: plenkow
Signed-off-by: Serge Hallyn <serge@hallyn.com>
2017-03-23 17:07:46 -05:00
fariouche
b6b2c756c9 add --prefix option 2017-03-01 22:51:09 +01:00
Tomas Mraz
ee9e506af2 Make the group and user allocation more effective.
Previously, the allocation was optimized for an outdated
deployment style (that of /etc/group alongside nss_db). The issue
here is that this results in extremely poor performance when using
SSSD, Winbind or nss_ldap.

There were actually two serious bugs here that have been addressed:

1) Running getgrent() loops won't work in most SSSD or Winbind
environments, as full group enumeration is disabled by default.
This could easily result in auto-allocating a group that was
already in use. (This might result in a security issue as well, if
the shared GID is a privileged group).

2) For system groups, the loop was always iterating through the
complete SYS_GID_MIN->SYS_GID_MAX range. On SSSD and Winbind, this
means hundreds of round-trips to LDAP (unless the GIDs were
specifically configured to be ignored by the SSSD or winbindd).
To a user with a slow connection to their LDAP server, this would
appear as if groupadd -r was hung. (Though it would eventually
complete).

This patch changes the algorithm to be more favorable for LDAP
environments, at the expense of some performance when using nss_db.
Given that the DB is a local service, this should have a negligible
effect from a user's perspective.

With the new algorithm, we simply first iterate through all entries
in the local database with gr_next(), recording the IDs that are in
use. We then start from the highest presumed-available entry and
call getgrgid() to see if it is available. We continue this until
we come to the first unused GID. We then select that and return it.

If we make it through all the remaining IDs without finding a free
one, we start over from the beginning of the range and try to find
room in one of the gaps in the range.

The patch was originally written by Stephen Gallagher and applied
identically also to the user allocation by Tomáš Mráz.

Signed-off-by: Serge Hallyn <serge@hallyn.com>
2017-01-29 14:37:21 -06:00
Serge Hallyn
9e93c984f7 Merge pull request #17 from wking/includes-to-am-cppflags
*/Makefile.am: Replace INCLUDES with AM_CPPFLAGS
2016-12-07 00:01:54 -06:00
Serge Hallyn
ff2baed5db idmapping: add more checks for overflow
At this point they are redundant but should be safe.  Thanks to
Sebastian Krahmer for the first check.
2016-08-14 21:48:50 -05:00
Serge Hallyn
94da3dc5c8 also check upper for wrap 2016-08-14 21:48:45 -05:00
Serge Hallyn
7f5a14817d get_map_ranges: check for overflow
The kernel accepts u32 values, so make sure that userspace
is not passing large values.

Signed-off-by: Serge Hallyn <serge@hallyn.com>
2016-07-31 12:56:48 -05:00
W. Trevor King
c07397695a */Makefile.am: Replace INCLUDES with AM_CPPFLAGS
Catch up with Automake's [1], which was part of v1.6b, cut 2002-07-28
[2].  Avoids:

  $ autoreconf -v -f --install
  ...
  libmisc/Makefile.am:4: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
  ...
  src/Makefile.am:10: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
  ...

Consolidating with the earlier AM_CPPFLAGS avoids:

  $ autoreconf -v -f --install
  src/Makefile.am:72: warning: AM_CPPFLAGS multiply defined in condition TRUE ...
  src/Makefile.am:10: ... 'AM_CPPFLAGS' previously defined here
  autoreconf-2.69: Leaving directory `.'

[1]: http://git.savannah.gnu.org/cgit/automake.git/commit/?id=1415d22f6203206bc393fc4ea233123ba579222d
     Summary: automake.in (generate_makefile): Suggest using AM_CPPFLAGS instead of INCLUDES
     Date: 2002-07-09
[2]: http://git.savannah.gnu.org/cgit/automake.git/tag/?id=Release-1-6b
2016-04-29 17:30:18 -07:00
Stéphane Graber
65c2617140
Tweak uid/gid map default configuration
- Use an allocation of 65536 uids and gids to allow for POSIX-compliant
   user owned namespaces.
 - Don't allocate a uid/gid map to system users.
   Unfortunately checking for --system isn't quite enough as some
   distribution wrappers always call useradd without --system and take care
   of choosing a uid and gid themselves, so also check whether the
   requested uid/gid is in the user range.

This is taken from a patch I wrote for Ubuntu a couple years ago and
which somehow didn't make it upstream.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
2016-02-15 18:11:10 -05:00
Bastian Blank
d2fa8c5d4b Fix user busy errors at userdel
From: Bastian Blank <bastian.blank@credativ.de>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2015-11-17 10:53:55 -06:00
Serge Hallyn
533d2bab3d get_map_ranges: initialize argidx to 0 at top of loop
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2015-08-06 00:34:25 -05:00
Serge Hallyn
7edb32e75f Fix a resource leak in libmis/idmapping.c
Reported at https://alioth.debian.org/tracker/?func=detail&atid=411478&aid=315136&group_id=30580
by Alejandro Joya.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2015-08-06 00:10:13 -05:00
Eric W. Biederman
578947e661 newuidmap,newgidmap: Correct the range size sanity check in get_map_ranges
The number of ranges should be the ceiling of the number of arguments divided
by three.

Without this fix newuidmap and newgidmap always report and error and fail,
which is very much not what we want.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2013-09-10 17:51:40 -05:00
Nicolas François
2883ff6ad5 Include <stdio.h>
* libmisc/idmapping.c: Include <stdio.h> needed for fprintf() and
	stderr.
2013-08-16 01:13:20 +02:00
Nicolas François
7d5732cb49 Remove dead code.
* libmisc/find_new_sub_gids.c: Remove dead code.
	find_new_sub_gids() is always called with *range_count set to 0.
	It's more difficult to keep the subordinate GIDs and UIDs
	synchronized, than for the user's UID/GId because the count of
	subordinate IDs may differ.
	* libmisc/find_new_sub_uids.c: Likewise.
	* lib/subordinateio.h, lib/subordinateio.c: Remove APIs that are
	no more needed: is_sub_uid_range_free(), is_sub_gid_range_free(),
	is_range_free().
2013-08-15 17:30:19 +02:00
Nicolas François
e1a4b6e57b Document the semantic of ranges.
* libmisc/idmapping.h: Document what the upper and lower fields
	are in struct map_range.
	* man/newgidmap.1.xml: Document when the gid, gidlower and count
	argument are.
	* man/newuidmap.1.xml: Likewise for uid, uidlower and count.
2013-08-13 19:28:07 +02:00
Nicolas François
5884ba907c (shadow_random): Use long instead of size_t.
* libmisc/salt.c (shadow_random): Use long instead of size_t.
	Compatibility with size_t is easier to check since it's used for
	smaller numbers (salt size).
2013-08-13 19:16:24 +02:00
Nicolas François
bfbd83239e Fix handling of boundaries.
* lib/subordinateio.c: Fix handling of boundaries.
	* libmisc/find_new_sub_uids.c: Likewise.
	* libmisc/find_new_sub_gids.c: Likewise.
2013-08-13 00:11:24 +02:00
Nicolas François
d611d54ed4 Allow disabling of subordinate IDs.
* configure.in: Add configure options --enable-subordinate-ids /
	--disable-subordinate-ids. Enabled by default.
	* lib/prototypes.h: Include <config.h> before using its macros.
	* lib/commonio.h, lib/commonio.c: Define commonio_append only when
	ENABLE_SUBIDS is defined.
	* lib/prototypes.h, libmisc/find_new_sub_gids.c,
	libmisc/find_new_sub_uids.c: Likewise.
	* lib/subordinateio.h, lib/subordinateio.c: Likewise.
	* libmisc/user_busy.c: Only check if subordinate IDs are in use if
	ENABLE_SUBIDS is defined.
	* src/Makefile.am: Create newgidmap and newuidmap only if
	ENABLE_SUBIDS is defined.
	* src/newusers.c: Check for ENABLE_SUBIDS to enable support for
	subordinate IDs.
	* src/useradd.c: Likewise.
	* src/userdel.c: Likewise.
	* src/usermod.c: Likewise.
	* man/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
	man5/subgid.5, and man5/subuid.5 only if ENABLE_SUBIDS is defined.
	* man/fr/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
	man5/subgid.5, and man5/subuid.5 (not translated yet).
	* man/generate_mans.mak: Add xsltproc conditionals
	subids/no_subids.
	* man/login.defs.d/SUB_GID_COUNT.xml: Add dependency on subids
	condition.
	* man/login.defs.d/SUB_UID_COUNT.xml: Likewise.
	* man/usermod.8.xml: Document options for subordinate IDs and
	reference subgid(5) / subuid(5) depending on the subids condition.
2013-08-11 15:46:59 +02:00
Nicolas François
14ebc92d8c Remove unused variable.
* libmisc/salt.c: Remove unused variable.
2013-08-10 00:11:52 +02:00
Nicolas François
45986f8dc8 Fix for Alioth#314271 (musl libc)
* libmisc/utmp.c: Add include files needed for getaddrinfo().
	See Alioth#314271
2013-08-07 02:18:43 +02:00
Nicolas François
316bc6b3f4 Fix wording: secondary -> subordinate.
* libmisc/find_new_sub_gids.c: Fix wording: secondary ->
	subordinate.
	* libmisc/find_new_sub_uids.c: Likewise.
2013-08-07 01:01:33 +02:00
Nicolas François
ac53650da5 Remove duplicate check.
* libmisc/find_new_sub_gids.c: Remove duplicate check (duplicate
	at least in its intent).
2013-08-06 23:59:09 +02:00
Serge Hallyn
c0ce911b5e userns: add argument sanity checking
In find_new_sub_{u,g}ids, check for min, count and max values.

In idmapping.c:get_map_ranges(), make sure that the value passed
in for ranges did not overflow.  Couldn't happen with the current
code, but this is a sanity check for any future potential mis-uses.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2013-08-05 10:08:46 -05:00
Eric W. Biederman
673c2a6f9a newuidmap,newgidmap: New suid helpers for using subordinate uids and gids
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
2013-08-05 10:08:46 -05:00
Eric W. Biederman
89f7b0868c Add support for detecting busy subordinate user ids
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-08-05 10:08:45 -05:00
Eric W. Biederman
a8f26262cf Implement find_new_sub_uids find_new_sub_gids
Functions for finding new subordinate uid and gids ranges for use
with useradd.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-08-05 10:08:45 -05:00
Nicolas François
60fc4bbf57 Debian bug 677275 - random() max value
* libmisc/salt.c: random() max value is 2^31-1 (same as RAND_MAX
	on GNU). As it is not clear whether on some systems the max value
	can exceed this number and whether some systems have max values
	which would be lower, we take this into account when defining the
	salt size and number of rounds for SHA encrypted passwords. Higher
	values are favored.
2013-08-05 14:19:23 +02:00