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Nobody else's mac.conf(5) has any entries for jails, so they get a
trivial ENOENT and we fail before we can fetch any jail parameters.
Most notably, this breaks `jls -s` / `jls -n` if you do not have any
loaded policy that applies jail labels.
Add an entry that works for everyone, and hardcode that as an ENOENT
fallback in libjail to provide a smoother transition. This is probably
not harmful to leave in long-term, since mac.conf(5) will override it.
This unearthed one additional issue, in that mac_get_prison() in the
MAC framework handled the no-label-policies bit wrong. We don't want
to break jail utilities enumerating jail parameters automatically, so
we must ingest the label in all cases -- we can still use it as a small
optimization to avoid trying to copy out any label. We will break
things if a non-optional element is specified in the copied in label,
but that's expected.
The APIs dedicated to jaildescs remain unphased, since they won't be
used in the same way.
Fixes: db3b39f063d9f05 ("libjail: extend struct handlers [...]")
Fixes: bd55cbb50c58876 ("kern: add a mac.label jail parameter")
Reported by: jlduran (on behalf of Jenkins)
Reviewed by: jlduran
Differential Revision: https://reviews.freebsd.org/D54786
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Have it take a `struct mac` and we'll paper over the difference for
jail(8)/jls(8) in libjail(3). The mac_syscalls.h model is taken from
mac_set_proc_*() that were previously done.
Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D53958
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A future commit to the area will further our jail integration and add
a use for this: the struct mac itself was already copied in as part of
vfs_buildopts(), so we only need to copyin the strings.
We add an explicit flag argument because the jail operation will need to
do it while holding the prison lock.
Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D53957
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We'll still add an old-fashioned jail param to configure jail MAC
labels, but for testing it's really easy to grab a jaildesc and use
that.
Reviewed by: jamie, olce
Differential Revision: https://reviews.freebsd.org/D53956
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This adds the following hooks:
- mpo_prison_check_attach: check for subject capability to attach to
a given jail
- mpo_prison_check_create: check for subject capability to create a
jail with the given option set
- mpo_prison_check_get: check for subject capability to fetch the
given parameters for a jail
- mpo_prison_check_set: check for subject capability to set the
given parameters for a jail
- mpo_prison_check_remove: check for subject capability to remove the
jail
check_get wouldn't typically be a privileged operation, but is included
to give MAC policies a wider range of capabilities at a relatively low
cost. We also add two more for the purpose of label propagation:
- mpo_prison_created: surface the creation of a jail so that one can
do propagation to, e.g., the root vnode or any mounts
- mpo_prison_attached: attach an existing process to the jail so that
one can propagate the jail label to the process, as appropriate.
It is unclear if this is preferred vs. having separate associate entry
points for each type of object we might associate. That would split
these up like so:
- prison_created -> prison_associate_vnode
- prison_attached -> prison_associate_proc
Some sample policy ideas that should be feasible to implement with this
set of hooks, in case it's inspiring:
- mac_bomb: policy that allows a poudriere user to construct jails
without root privilege, given a restricted set of jail parameters.
Slap a warning label on it.
- mac_capsule: policy that realizes the capsule idea that I pitched[0]
on -jail@ to create jails that are effectively immutable once
sealed, using these hooks and a label.
Perhaps a silly idea, but a downstream could consider a scenario where
it can implement special jail enumeration using a MAC policy and a
cooperating application that specifies non-parameter options to filter
the results.
[0] https://lists.freebsd.org/archives/freebsd-jail/2025-September/000550.html
Reviewed by: olce (slightly earlier version)
Differential Revision: https://reviews.freebsd.org/D53954
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A last-minute change to the jail MAC entry points in D53954 is going to
pass the jail_[gs]et(2) flags to mac_prison_check_[gs]et() so that a
policy can, e.g., reject or allow a change if the intent is to
immediately attach, or disallow some fetching of dying jails.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D54658
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Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D53953
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Reported by: markj
Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D54052
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This removes mac_label_copyin32() as mac_label_copyin() can now handle
both native and 32-bit struct mac objects.
Reviewed by: olce, brooks
Obtained from: CheriBSD
Sponsored by: AFRL, DARPA
Differential Revision: https://reviews.freebsd.org/D53755
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- s/Authenticateion/Authentication/
MFC after: 5 days
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When system call auditing is enabled, every audited call
does a lookup in the evclass hash table. This table
appears to be insert only (eg, nothing can be removed)
and protecting it with an rwlock is overkill. Using
an rwlock causes just the atomic operations to maintain
uncontended rwlock state to be responsible for measurable
overhead on high core count servers making lots of system calls.
Given that the evclass hash table can never have items removed,
only added, using a mutex to serialize additions and converting
to ck_list allows sufficient protection for lockless lookups.
In a contrived example of 64 cores, all reading 1 byte from their
own file, this change increases performance from 5M reads/sec
to 70M reads/sec on an AMD 7502P.
Reviewed by: markj, mjg, glebius (privately)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D53176
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Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D52045
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MFC after: 1 week
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MFC after: 1 week
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Contrary to my initial belief, vn_fullpath() does return a vnode's path
from the current chroot, and not from the global root (which would have
been a bug also, but without security consequences). This enables
a "confused deputy"-like scenario where a chroot(2) can change which
executable can be authorized by MAC/do, which is even more problematic
for unprivileged chroot(2).
This was found by re-examining the code following two close events:
1. Shawn Webb sent a mail to freebsd-hackers@ on 08/05 saying that in
HardenedBSD they had added a check on P2_NO_NEW_PRIVS (in
mac_do_priv_grant()), which I responded to on 08/20 saying that
P2_NO_NEW_PRIVS was not necessary for mac_do(4), with a correct
reasoning but based on the wrong above-mentioned assumption about
vn_fullpath().
2. I reviewed some code by Kushagra Srivastava (GSoC 2025 student
working on mac_do(4)/mdo(1)) adding the ability to specify which
executables can spawn processes that mac_do(4) may decide to
authorize (others are simply ignored), which currently is hardcoded
to '/usr/bin/mdo'.
MFC after: 3 days
Event: EuroBSDCon 2025
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52758
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As 'cr_gid' was in fact stored in cr_groups[0],
rule_grant_supplementary_groups() would loop only on further elements of
cr_groups[]. Now that cr_groups[0] is not 'cr_gid' anymore, but some
supplementary group, take it into account.
Fixes: be1f7435ef218b1d ("kern: start tracking cr_gid outside of cr_groups[]")
MFC after: 5 days
MFC to: stable/15
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52271
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Fixes: be1f7435ef218b1d ("kern: start tracking cr_gid outside of cr_groups[]")
MFC after: 5 days
MFC to: stable/15
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D52270
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Currently it is impossible for a privileged, jailed process to set audit
session state. This can result in suprising audit event misattribution.
For example, suppose a user ssh'es into a jail and restarts a service;
normally, sshd sets audit state such that events generated by the SSH
session are attributed to the newly authenticated user, but in a jail,
the corresponding setaudit(2) call fails, so events are attributed to
the user who had started sshd in the jail (typically the user who had
started the jail itself by some means).
While this behaviour is reasonable, administrators might want to trust
the jailed sshd to reset audit state, such that the authenticated user
appears in audit logs. Add a jail knob to enable this. Add a simple
regression test.
This is a reapplication of commit 246d7e9fc23928 following a revert.
The audit system calls must preserve the old behaviour of returning
ENOSYS if the system call is disallowed within a jail, as some
applications depend on that behaviour.
Reviewed by: kevans, jamie (previous version)
MFC after: 1 week
Sponsored by: Modirum MDPay
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D51719
Differential Revision: https://reviews.freebsd.org/D52572
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Changing audit system calls to return EPERM instead of ENOSYS when
invoked from a jail breaks some userspace applications. Revert for now
until a more complete change is reviewed.
This reverts commit 246d7e9fc23928be22db38220f5439f5cdee5264.
PR: 289645
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Currently it is impossible for a privileged, jailed process to set audit
session state. This can result in suprising audit event misattribution.
For example, suppose a user ssh'es into a jail and restarts a service;
normally, sshd sets audit state such that events generated by the SSH
session are attributed to the newly authenticated user, but in a jail,
the corresponding setaudit(2) call fails, so events are attributed to
the user who had started sshd in the jail (typically the user who had
started the jail itself by some means).
While this behaviour is reasonable, administrators might want to trust
the jailed sshd to reset audit state, such that the authenticated user
appears in audit logs. Add a jail knob to enable this. Add a simple
regression test.
Reviewed by: kevans, jamie
MFC after: 1 week
Sponsored by: Modirum MDPay
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D51719
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From M_DO to M_MAC_DO. While here, make the descriptions more accurate.
(Commit message by olce@.)
Reviewed by: olce
MFC after: 3 days
Sponsored by: Google LLC (GSoC 2025)
Sponsored by: The FreeBSD Foundation
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We can assert that a vnode lock is held whenever INVARIANTS is
configured.
Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D51698
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A future change may split cr_gid out of cr_groups[0] so that there's a
cleaner separation between the supplemental groups and the effective
group. Do the mechanical conversion where we can, and drop some
comments where we need further work because some assumptions about
cr_gid == cr_groups[0] have been made.
This should not be a functional change, but downstreams and other
out-of-tree code are advised to investigate their usage of cr_groups
sooner rather than later, as a future change will render assumptions
about these two being equivalent harmful.
Reviewed by: asomers, kib, olce
Differential Revision: https://reviews.freebsd.org/D51153
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AUDIT_SYSCALL_EXIT() and indirectly audit_commit() is intended to be
called from arbitrary top-level context. This means that any sleepable
locks can be owned by the caller, and which makes the sleeping in
audit_commit() forbidden.
Since we need to sleep for the record in audit_alloc() anyway, move the
sleep for the queue limit there. At worst, if the audit is suspended is
disabled when we actually reach the commit location, this means that we
lost time uselessly.
PR: 287566
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D50879
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Switch to using sys/stdarg.h for va_list type and va_* builtins.
Make an attempt to insert the include in a sensible place. Where
style(9) was followed this is easy, where it was ignored, aim for the
first block of sys/*.h headers and don't get too fussy or try to fix
other style bugs.
Reviewed by: imp
Exp-run by: antoine (PR 286274)
Pull Request: https://github.com/freebsd/freebsd-src/pull/1595
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MDF_HAS_PRIMARY_CLAUSE only concerns groups, not users, and is thus not
set in the latter case.
This change only has an effect on INVARIANTS builds.
PR: 287057
MFC after: 10 minutes
Sponsored by: The FreeBSD Foundation
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kernel process will not have valid p_textvp
Reviewed by: stevek
Differential Revision: https://reviews.freebsd.org/D50368
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Previously, we would accept only ':' as the separator, which makes
parsing of the rule specification harder for humans, especially those
people that are used to UNIX systems where ':' is used as the separator
in PATH. With ':', the <from> and <to> parts can look like two
different elements that are unrelated, especially to these eyes.
Change parse_single_rule() so that '>' is also accepted as a separator
between <from> and <to>, and promote it as the one to use. During
a transition period, we will still allow the use of ':' for backwards
compatibility.
The manual page update comes from separate revision D49628. ':' has
been completely removed from it on purpose.
Reviewed by: bapt, manpages (ziaee)
MFC after: 5 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D49627
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No functional change.
MFC after: 5 days
Sponsored by: The FreeBSD Foundation
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A string loader tunable requires setting the len parameter to a nonzero
value, typically the size of the string, to have the flag CTLFLAG_TUN
work correctly [1] [2].
Without this fix security.mac.{biba,lomac}.trusted_interfaces would
have no effect at all.
[1] 3da1cf1e88f8 Extend the meaning of the CTLFLAG_TUN flag to automatically ...
[2] 6a3287f889b0 Fix regression issue after r267961. Handle special string case ...
Reviewed by: olce, kib
Fixes: af3b2549c4ba Pull in r267961 and r267973 again ...
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D48898
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Noted by: cy
Fixes: 53ece2bea9ffa654aaa50e (audit(9): do not touch VFS if panicing)
MFC after: 3 days
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Reported by: bz
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syscallenter() has a slow path to handle syscall auditing and dtrace
syscall tracing. It uses AUDIT_SYSCALL_ENTER() to check whether to take
the slow path, but this macro also has side effects: it writes the audit
log entry. When systrace (dtrace syscall tracing) is enabled, this
would get short-circuited, and we end up not writing audit log entries.
Introduce a pure macro to check whether auditing is enabled, use it in
syscallenter() instead of AUDIT_SYSCALL_ENTER().
Reviewed by: kib
Reported by: Joe Duin <jd@firexfly.com>
Fixes: 2f7292437d0c ("Merge audit and systrace checks")
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D48448
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grant_supplementary_group_from_flags() had been used in previous
versions of the recent changes, but recently has not been needed
anymore. It has been kept around just in case deliberately, by analogy
with grant_primary_group_from_flags() (this one still being used).
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Approved by: emaste (mentor)
Sponsored by: The FreeBSD Foundation
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We intend MAC/do to authorize transitions based on the "real" identity
information of the calling process, rather than transiently-acquired
effective IDs.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47845
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We only browse these forward and never need to remove arbitrary elements
from them.
No functional change (intended).
Reviewed by: bapt, emaste
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47624
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To this end, we introduce the strsep_noblanks() function, designed to be
a drop-in replacement for strstep(), and use it in place of the latter.
We had taken care of calling strsep() even when the remaining sub-string
was not delimited (i.e., with empty string as its second argument), so
this commit only has mechanical replacements of existing calls.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47623
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Use the most common pattern to browse and delete elements of a list, as it reads quicker.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47622
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TL;DR:
Now monitor setcred() calls, and reject or grant them according to the
new rules specification.
Drop monitoring setuid() and setgroups(). As previously explained in
the commit introducing the setcred() system call, MAC/do must know the
entire new credentials while the old ones are still available to be able
to approve or reject the requested changes. To this end, the chosen
approach was to introduce a new system call, setcred(), instead of
modifying existing ones to be able to participate in a "prepare than
commit"-like protocol.
******
The MAC framework typically calls several hooks of its registered
policies as part of the privilege checking/granting process. Each
system call calls some dedicated hook early, to which it usually passes
the same arguments it received, whose goal is to forcibly deny access to
the functionality when needed (i.e., a single deny by any policy
globally denies the access). Then, the system call usually calls
priv_check() or priv_check_cred() an unspecified number of times, each
of which may trigger calls to two generic MAC hooks. The first such
call is to mac_priv_check(), and always happens. Its role is to deny
access early and forcibly, as can be done also in system calls'
dedicated early hooks (with different reach, however). The second,
mac_priv_grant(), is called only if the priv_check*() and
prison_priv_check() generic code doesn't handle the request by itself,
i.e., doesn't explicitly grant access (to the super user, or to all
users for a few specific privileges). It allows any single policy to
grant the requested access (regardless of whether the other policies do
so or not).
MAC/do currently only has an effect on processes spawned from the
'/usr/bin/mdo' executable. It implements all setcred() hooks, called
via mac_cred_setcred_enter(), mac_cred_check_setcred() and
mac_cred_setcred_exit(). In the first one, implemented in
mac_do_setcred_enter(), it checks if MAC/do has to apply to the current
process, allocates (or re-uses) per-thread data to be later used by the
other hooks (those of setcred() and the mac_priv_grant() one, called by
priv_check*()) and fills them with the current context (the rules to
apply). This is both because memory allocations cannot be performed
while holding the process lock and to ensure that all hooks called by
a single setcred() see the same rules to apply (not doing this would be
a security hazard as rules are concurrently changed by the
administrator, as explained in more details below). In the second one
(implemented by mac_do_check_setcred()), it stores in MAC/do's
per-thread data the new credentials. Indeed, the next MAC/do's hook
implementation to be called, mac_do_priv_grant() (implementing the
mac_priv_grant() hook) must have knowledge of the new credentials that
setcred() wants to install in order to validate them (or not), which the
MAC framework can't provide as the priv_check*() API only passes the
current credentials and a specific privilege number to the
mac_priv_check() and mac_priv_grant() hooks. By contrast, the very
point of MAC/do is to grant the privilege of changing credentials not
only based on the current ones but also on the seeked-for ones.
The MAC framework's constraints that mac_priv_grant() hooks are called
without context and that MAC modules must compose (each module may
implement any of the available hooks, and in particular those of
setcred()) impose some aspects of MAC/do's design. Because MAC/do's
rules are tied to jails, accessing the current rules requires holding
the corresponding jail's lock. As other policies might try to grab the
same jail's lock in the same hooks, it is not possible to keep the
rules' jail's lock between mac_do_setcred_enter() and
mac_do_priv_grant() to ensure that the rules are still alive. We have
thus augmented 'struct rules' with a reference count, and its lifecyle
is now decoupled from being referenced or not by a jail. As a thread
enters mac_cred_setcred_enter(), it grabs a hold on the current rules
and keeps a pointer to them in the per-thread data. In its
mac_do_setcred_exit(), MAC/do just "frees" the per-thread data, in
particular by dropping the referenced rules (we wrote "frees" within
guillemets, as in fact the per-thread structure is reused, and only
freed when a thread exits or the module is unloaded).
Additionally, ensuring that all hooks have a consistent view of the
rules to apply might become crucial if we augment MAC/do with forceful
access denial policies in the future (i.e., policies that forcibly
disable access regardless of other MAC policies wanting to grant that
access). Indeed, without the above-mentioned design, if newly installed
rules start to forcibly deny some specific transitions, and some thread
is past the mac_cred_check_setcred() hook but before the
mac_priv_grant() one, the latter may grant some privileges that should
have been rejected first by the former (depending on the content of
user-supplied rules).
A previous version of this change used to implement access denial
mandated by the '!' and '-' GID flags in mac_do_check_setcred() with the
goal to have this rejection prevail over potential other MAC modules
authorizing the transition. However, this approach had two drawbacks.
First, it was incompatible both conceptually and in the current
implementation with multiple rules being treated as an inclusive
disjunction, where any single rule granting access is enough for MAC/do
to grant access. Explicit denial requested by one matching rule could
prevent another rule from granting access. The implementation could
have been fixed, but the conflation of rules being considered as
disjoint for explicit granting but conjunct for forced denial would have
remained. Second, MAC/do applies only to processes spawned from
a particular executable, and imposing system-wide restrictions on only
these processes is conceptually strange and probably not very useful.
In the end, we moved the implementation of explicit access denial into
mac_do_priv_grant(), along with the interpretation of other target
clauses.
The separate definition of 'struct mac_do_data_header' may seem odd, as
it is only used in 'struct mac_do_setcred_data'. It is a remnant of an
earlier version that was not using setcred(), but rather implemented
hooks for setuid() and setgroups(). We however kept it, as it clearly
separates the machinery to pass data from dedicated system call hooks to
priv_grant() from the actual data that MAC/do needs to monitor a call to
setcred() specifically. It may be useful in the future if we evolve
MAC/do to also grant privileges through other system calls (each seen as
a complete credentials transition on its own).
The target supplementary groups are checked with merge-like algorithms
leveraging the fact that all supplementary groups in credentials
('struct ucred') and in each rule ('struct rule') are sorted, avoiding
to start a binary search for each considered GID which is asymptotically
more costly. All access granting/denial is thus at most linear and in
at most the sum of the number of requested groups, currently held ones
and those contained in the rule, per applicable rule. This should be
enough in all practical cases. There is however still room for more
optimizations, without or with changes in rules' data structures, if the
need ever arises.
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47620
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This is going to be used in subsequent commits to keep rules alive even
if disconnected from their jail in the meantime. We'll indeed have to
release the prison lock between two uses (outright rejection, final
granting) where the rules must absolutely stay the same for security reasons.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47619
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This new system call allows to set all necessary credentials of
a process in one go: Effective, real and saved UIDs, effective, real and
saved GIDs, supplementary groups and the MAC label. Its advantage over
standard credential-setting system calls (such as setuid(), seteuid(),
etc.) is that it enables MAC modules, such as MAC/do, to restrict the
set of credentials some process may gain in a fine-grained manner.
Traditionally, credential changes rely on setuid binaries that call
multiple credential system calls and in a specific order (setuid() must
be last, so as to remain root for all other credential-setting calls,
which would otherwise fail with insufficient privileges). This
piecewise approach causes the process to transiently hold credentials
that are neither the original nor the final ones. For the kernel to
enforce that only certain transitions of credentials are allowed, either
these possibly non-compliant transient states have to disappear (by
setting all relevant attributes in one go), or the kernel must delay
setting or checking the new credentials. Delaying setting credentials
could be done, e.g., by having some mode where the standard system calls
contribute to building new credentials but without committing them. It
could be started and ended by a special system call. Delaying checking
could mean that, e.g., the kernel only verifies the credentials
transition at the next non-credential-setting system call (we just
mention this possibility for completeness, but are certainly not
endorsing it).
We chose the simpler approach of a new system call, as we don't expect
the set of credentials one can set to change often. It has the
advantages that the traditional system calls' code doesn't have to be
changed and that we can establish a special MAC protocol for it, by
having some cleanup function called just before returning (this is
a requirement for MAC/do), without disturbing the existing ones.
The mac_cred_check_setcred() hook is passed the flags received by
setcred() (including the version) and both the old and new kernel's
'struct ucred' instead of 'struct setcred' as this should simplify
evolving existing hooks as the 'struct setcred' structure evolves. The
mac_cred_setcred_enter() and mac_cred_setcred_exit() hooks are always
called by pairs around potential calls to mac_cred_check_setcred().
They allow MAC modules to allocate/free data they may need in their
mac_cred_check_setcred() hook, as the latter is called under the current
process' lock, rendering sleepable allocations impossible. MAC/do is
going to leverage these in a subsequent commit. A scheme where
mac_cred_check_setcred() could return ERESTART was considered but is
incompatible with proper composition of MAC modules.
While here, add missing includes and declarations for standalone
inclusion of <sys/ucred.h> both from kernel and userspace (for the
latter, it has been working thanks to <bsm/audit.h> already including
<sys/types.h>).
Reviewed by: brooks
Approved by: markj (mentor)
Relnotes: yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47618
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So that administrators can more easily know what the problem is with the
rules they are trying to set.
The new sysctl 'security.mac.do.print_parse_error' controls whether
trying to set sysctl 'security.mac.do.rules' with invalid rules triggers
printing of the error on the system console.
Setting jail parameters directlty reports an error to the calling
process thanks to the VFS options mechanism used by the jail machinery,
so is not controlled by the new sysctl setting.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47617
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Supporting group targets is a requirement for MAC/do to be able to
enforce a limited set of valid new groups passed to setgroups().
Additionally, it must be possible for this set of groups to also depend
on the target UID, since users and groups are quite tied in UNIX (users
are automatically placed in only the groups specified through
'/etc/passwd' (primary group) and '/etc/group' (supplementary ones)).
These requirements call for a re-design of the specification of the
rules specification string and of 'struct rule'.
A rules specification string is now a list of rules separated by ';'
(instead of ','). One rule is still composed of a "from" part and
a "to" (or "target") part, both being separated by ':' (as before).
The first part, "from", is matched against the credentials of the
process calling setuid()/setgroups(). Its specification remains
unchanged: It is a '<type>=<id>' clause, where <type> is either "uid" or
"gid" and <id> an UID or GID.
The second part, "to", is now a comma-separated (',') list of
'<flags><type>=<id>' clauses similar to that of the "from" part, with
the extensions that <id> may also be "*" or "any" or ".", and that
<flags> may contain at most one of the '+', '-' and '!' characters when
<type> is GID. "*" and "any" both designate any ID for the <type>, and
are aliases to each other. In front of them, only the "+" flag is
allowed (in addition to the previous rules). "." designates the
process' current IDs for the <type>, as explained below.
For GIDs, an absence of flag indicates that the specified GID is allowed
as the real, effective and/or saved GIDs (the "primary" groups).
Conversely, the presence of any allowed flag indicates that the
specification concerns supplementary groups. The '+' flag in front of
"gid" indicates that the ID is allowed as a supplementary group. The
'!' flag indicates that the ID is mandatory, i.e., must be listed in the
supplementary groups. The '-' flag indicates that the GID must not be
listed in the supplementary groups. A specification with '-' is only
useful in conjunction with a '+'-tagged specification where only one of
them has <id> ".", or if other MAC policies are loaded that would give
access to other, unwanted groups.
"." indicates some ID that the calling process already has on privilege
check. For type "uid", it designates any of the real, effective or
saved UIDs. For type "gid", its effect depends on the presence of one
of the '+', '-' or '!' flags. If no flag is present, it designates any
of the real, effective or saved GIDs. If one is present, it designates
any of the supplementary groups.
If the "to" part doesn't specify any explicit UID, any of the UIDs of
the calling process is implied (it is as if "uid=." had been specified).
Similarly, if it doesn't specify any explicit GID, "gid=.,!gid=." is
assumed, meaning that all the groups of the calling process are implied
and must be present. More precisely, each of the desired real,
effective and saved GIDs must be one of the current real, effective or
saved GID, whereas all others (the supplementary ones) must be the same
as those that are current.
No two clauses in a single "to" list may display the same <id>, except
for GIDs but only if, each time the same <id> appears, it does so with
a different flag (no flag counting as a separate flag) and all the
specified flags are not contradictory (e.g., it is possible to have the
same GID appear with no flag and the "+" flag, but the same GID with
both "+" and "-" will be rejected).
'struct rule' now holds arrays of UIDs (field 'uids') and GIDs (field
'gids') that are admissible as targets, with accompanying flags (such as
MDF_SUPP_MUST, representing the '!' flag). Some flags are also held by
ID type, including flags associated to individual IDs, as MDF_CURRENT in
these flags stands for the process being privilege-checked's current
IDs, to which ID flags apply. As a departure from this scheme, "*" or
"any" as <id> for GIDs is either represented by MDF_ANY or MDF_ANY_SUPP.
This is to make it coexist with a "."/MDF_CURRENT specification for the
other category of groups (among primary and supplementary groups), which
needs to be qualified by the usual GID flags.
This commit contains only the changes to parse the new rules and to
build their representation. The privilege granting part is not fixed
here, beyond what making compilation work requires (and, in preparation
for some subsequent commit, minimal adaptations to the matching logic in
check_setuid()).
Approved by: markj (mentor)
Relnotes: yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47616
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This variable is static and holds the OSD slot number for jails that
MAC/do uses to store rules.
In the same vein as previous renames, simplify it by removing the
redundant prefix, as this name cannot appear in code outside of
'mac_do.c', nor in stack traces on panic.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47772
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Have a static constant array mapping numerical ID types to their
canonical representations ('id_type_to_str').
New parse_id_type() that parses a type thanks to 'id_type_to_str' and
with a special case to accept also 'any'.
Have parse_rule_element() use parse_id_type(). A later commit will add
a second call to the latter for the destination ID.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47615
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Introduce strtoui_strict(), which signals an error on overflow contrary
to the in-kernel strto*() family of functions which have no 'errno' to
set and thus do not allow callers to distinguish a genuine maximum value
on input and overflow.
It is built on top of strtoq() and the 'quad_t' type in order to achieve
this distinction and also to still support negative inputs with the
usual meaning for these functions. See the introduced comments for more
details.
Use strtoui_strict() to read IDs instead of strtol().
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47614
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This is in preparation for introducing a common conversion function for
IDs and to simplify code a bit by removing the from-IDs union and not
having to introduce a new one for to-IDs in a later commit.
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47613
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The ID field was allowed to be empty, which would be then parsed as 0 by
strtol(). There remains bugs in this function, where parsing for from-
or to- IDs accepts spaces and produces 0, but this will conveniently be
fixed in a later commit introducing strtoui_strict().
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47612
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Add newlines to separate logical blocks. Remove braces around 'if's
non-compound substatements.
No functional change (intended).
Reviewed by: bapt
Approved by: markj (mentor)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47611
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