Commit Graph

431 Commits

Author SHA1 Message Date
Serge Hallyn
2b22a6909d libsubid: don't print error messages on stderr by default
Closes #325

Add a new subid_init() function which can be used to specify the
stream on which error messages should be printed.  (If you want to
get fancy you can redirect that to memory :)  If subid_init() is
not called, use stderr.  If NULL is passed, then /dev/null will
be used.

This patch also fixes up the 'Prog', which previously had to be
defined by any program linking against libsubid.  Now, by default
in libsubid it will show (subid).  Once subid_init() is called,
it will use the first variable passed to subid_init().

Signed-off-by: Serge Hallyn <serge@hallyn.com>
2021-05-15 12:38:55 -05:00
Serge Hallyn
3ac8d97825
Merge pull request #323 from cgzones/selinux
SELinux modernizations
2021-05-07 08:32:01 -05:00
Christian Brauner
91d4ab622b
libmisc: retain setfcap when mapping uid 0
When uid 0 maps host uid 0 into the child userns newer kernels require
CAP_SETFCAP be retained as this allows the caller to create fscaps that
are valid in the ancestor userns. This was a security issue (in very
rare circumstances). So whenever host uid 0 is mapped, retain
CAP_SETFCAP if the caller had it.
Userspace won't need to set CAP_SETFCAP on newuidmap as this is really
only a scenario that real root should be doing which always has
CAP_SETFCAP. And if they don't then they are in a locked-down userns.
(LXC sometimes maps host uid 0 during chown operations in a helper
 userns but will not rely on newuidmap for that. But we don't want to
 risk regressing callers that want to rely on this behavior.)

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-05-06 19:04:42 +02:00
Christian Göttsche
eb1d2de0e9 set_selinux_file_context(): prepare context for actual file type
Search the SELinux selabel database for the file type to be created.
Not specifying the file mode can cause an incorrect file context to be
returned.

Also prepare contexts in commonio_close() for the generic database
filename, not with the backup suffix appended, to ensure the desired
file context after the final rename.

Closes: #322

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>
2021-05-06 16:58:10 +02:00
Serge Hallyn
8492dee663 subids: support nsswitch
Closes #154

When starting any operation to do with subuid delegation, check
nsswitch for a module to use.  If none is specified, then use
the traditional /etc/subuid and /etc/subgid files.

Currently only one module is supported, and there is no fallback
to the files on errors.  Several possibilities could be considered:

1. in case of connection error, fall back to files
2. in case of unknown user, also fall back to files

etc...

When non-files nss module is used, functions to edit the range
are not supported.  It may make sense to support it, but it also
may make sense to require another tool to be used.

libsubordinateio also uses the nss_ helpers.  This is how for instance
lxc could easily be converted to supporting nsswitch.

Add a set of test cases, including a dummy libsubid_zzz module.  This
hardcodes values such that:

'ubuntu' gets 200000 - 300000
'user1' gets 100000 - 165536
'error' emulates an nss module error
'unknown' emulates a user unknown to the nss module
'conn' emulates a connection error ot the nss module

Changes to libsubid:

Change the list_owner_ranges api: return a count instead of making the array
null terminated.

This is a breaking change, so bump the libsubid abi major number.

Rename free_subuid_range and free_subgid_range to ungrant_subuid_range,
because otherwise it's confusing with free_subid_ranges which frees
    memory.

Run libsubid tests in jenkins

Switch argument order in find_subid_owners

Move the db locking into subordinateio.c

Signed-off-by: Serge Hallyn <serge@hallyn.com>
2021-04-16 21:02:37 -05:00
Serge Hallyn
514c1328b6 try again to fix libmisc sharing problem
Issue #297 reported seeing

*** Warning: Linking the shared library libsubid.la against the
*** static library ../libmisc/libmisc.a is not portable!

which commit b5fb1b38ee was supposed
to fix.  But a few commits later it's back.  So try to fix it
in the way the bug reporter suggested.  This broke builds some
other ways, namely a few missing library specifications, so add
those.

Signed-off-by: Serge Hallyn <serge@hallyn.com>
2021-04-11 17:42:04 -05:00
Rodolphe Bréard
5cd04d03f9 Add yescrypt support 2021-02-01 22:11:10 +01:00
w00475903
e24700fd5d xfree: move xfree() function to xmalloc.c
Signed-off-by: whzhe <wanghongzhe@huawei.com>
2020-10-15 21:52:06 -04:00
Serge Hallyn
77be9c35c7
Merge pull request #244 from sthibaul/master
Fix hurd build
2020-04-23 10:56:48 -05:00
Serge Hallyn
25b1a8d591 remove unused and misleading 'owner' argument from find_new_sub*
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2020-04-17 16:32:44 -05:00
Samuel Thibault
5de28353d4 Fix hurd build
Do not include <sys/prctl.h> we don't have <sys/capability.h>, we don't
need prctl in that case anyway.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
2020-04-17 21:50:48 +02:00
Colin Hogben
12ce42be44 libmisc: Accept --root=path and --prefix=path option syntax
Recognise --root=path in addition to --root path (and similarly for
--prefix) to match the syntax accepted by getopt_long.

Fixes #218
2020-02-07 21:57:12 +00:00
Tomas Mraz
fd4405b763 Do not mistake a regular user process for a namespaced one
In case there is a regular user with a process running on a system
with uid falling into a namespaced uid range of another user.
The user with the colliding namespaced uid range will not be
allowed to be deleted without forcing the action with -f.

The user_busy() is adjusted to check whether the suspected process
is really a namespaced process in a different namespace.
2020-01-21 09:16:10 +01:00
Serge Hallyn
9f7f3b013e silence compiler warnings
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2020-01-12 07:31:26 -06:00
prez
2958bd050b Initial bcrypt support 2019-12-01 11:00:57 -06:00
Serge Hallyn
b03df41906 remove unused variables
parent, user_id, and group_id are unused.

Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2019-10-12 20:03:32 -05:00
Serge Hallyn
991fee82df
Merge pull request #180 from thkukuk/libeconf
Add support for a vendor directory and libeconf
2019-10-05 22:34:29 -05:00
Thorsten Kukuk
b52ce71c27 Add support for a vendor directory and libeconf
With this, it is possible for Linux distributors to store their
supplied default configuration files somewhere below /usr, while
/etc only contains the changes made by the user. The new option
--enable-vendordir defines where the shadow suite should additional
look for login.defs if this file is not in /etc.
libeconf is a key/value configuration file reading library, which
handles the split of configuration files in different locations
and merges them transparently for the application.
2019-10-05 22:17:49 -05:00
ed
a2cd3e9ef0 chkname.c, pwck.c, useradd.c, usermod.c, newusers.c: Allow names that do not conform to standards
Closes #121.

Changelog: squashed commits fixing tab style
Changelog: update 'return true' to match file's style (no parens).
2019-10-04 18:40:41 -05:00
Serge Hallyn
aff40d8515 libmisc/btrfs: no sense trying to calculate 'btrfs' string
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2019-05-03 22:40:14 -07:00
Serge Hallyn
51cfc1f89a libmisc/btrfs: find btrfs command
Ubuntu for instance keeps it in /bin, not /sbin.  So look
for it in our usual places.

Signed-off-by: Serge Hallyn <shallyn@cisco.com>
2019-05-03 22:39:53 -07:00
Adam Majer
50b23584d7 Add autotools support for BtrFS option
Feature is enabled by default, if headers are available. It can be
turned off explictly.
2019-05-03 22:38:23 -07:00
Adam Majer
c1d36a8acb Add support for btrfs subvolumes for user homes
new switch added to useradd command, --btrfs-subvolume-home. When
specified *and* the filesystem is detected as btrfs, it will create a
subvolume for user's home instead of a plain directory. This is done via
`btrfs subvolume` command.  Specifying the new switch while trying to
create home on non-btrfs will result in an error.

userdel -r will handle and remove this subvolume transparently via
`btrfs subvolume` command. Previosuly this failed as you can't rmdir a
subvolume.

usermod, when moving user's home across devices, will detect if the home
is a subvolume and issue an error messages instead of copying it. Moving
user's home (as subvolume) on same btrfs works transparently.
2019-05-03 22:38:23 -07:00
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