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This commit reverts 5b0eea835d4e ("selinux: introduce an initial SID
for early boot processes") as it was found to cause problems on
distros with old SELinux userspace tools/libraries, specifically
Ubuntu 16.04.
Hopefully we will be able to re-add this functionality at a later
date, but let's revert this for now to help ensure a stable and
backwards compatible SELinux tree.
Link: https://lore.kernel.org/selinux/87edkseqf8.fsf@mail.lhotse
Acked-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Three LSMs register the implementations for the "capget" hook: AppArmor,
SELinux, and the normal capability code. Looking at the function
implementations we may observe that the first parameter "target" is not
changing.
Mark the first argument "target" of LSM hook security_capget() as
"const" since it will not be changing in the LSM hook.
cap_capget() LSM hook declaration exceeds the 80 characters per line
limit. Split the function declaration to multiple lines to decrease the
line length.
Signed-off-by: Khadija Kamran <kamrankhadijadj@gmail.com>
Acked-by: John Johansen <john.johansen@canonical.com>
[PM: align the cap_capget() declaration, spelling fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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After commit f22f9aaf6c3d ("selinux: remove the runtime disable
functionality"), the comment on selinux_hooks[] is out-of-date,
remove the last paragraph about runtime disable functionality.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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In case virtual memory is being marked as executable by default, SELinux
checks regarding explicit potential dangerous use are disabled.
Inform the user about it.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Use a NULL instead of a zero to resolve a int/pointer mismatch.
Cc: Paolo Abeni <pabeni@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307210332.4AqFZfzI-lkp@intel.com/
Fixes: dd51fcd42fd6 ("selinux: introduce and use lsm_ad_net_init*() helpers")
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Perf traces of network-related workload shows a measurable overhead
inside the network-related selinux hooks while zeroing the
lsm_network_audit struct.
In most cases we can delay the initialization of such structure to the
usage point, avoiding such overhead in a few cases.
Additionally, the audit code accesses the IP address information only
for AF_INET* families, and selinux_parse_skb() will fill-out the
relevant fields in such cases. When the family field is zeroed or the
initialization is followed by the mentioned parsing, the zeroing can be
limited to the sk, family and netif fields.
By factoring out the audit-data initialization to new helpers, this
patch removes some duplicate code and gives small but measurable
performance gain under UDP flood.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Update my email address; MAINTAINERS was updated some time ago.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The kernel print statements do not append an implicit newline to format
strings.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Change "NSA SELinux" to just "SELinux" in Kconfig help text and
comments. While NSA was the original primary developer and continues to
help maintain SELinux, SELinux has long since transitioned to a wide
community of developers and maintainers. SELinux has been part of the
mainline Linux kernel for nearly 20 years now [1] and has received
contributions from many individuals and organizations.
[1] https://lore.kernel.org/lkml/Pine.LNX.4.44.0308082228470.1852-100000@home.osdl.org/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Use the identical types in assignments of local variables for the
destination.
Merge tail calls into return statements.
Avoid using leading underscores for function local variable.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The sk_getsecid hook shouldn't need to modify its socket argument.
Make it const so that callers of security_sk_classify_flow() can use a
const struct sock *.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Currently, SELinux doesn't allow distinguishing between kernel threads
and userspace processes that are started before the policy is first
loaded - both get the label corresponding to the kernel SID. The only
way a process that persists from early boot can get a meaningful label
is by doing a voluntary dyntransition or re-executing itself.
Reusing the kernel label for userspace processes is problematic for
several reasons:
1. The kernel is considered to be a privileged domain and generally
needs to have a wide range of permissions allowed to work correctly,
which prevents the policy writer from effectively hardening against
early boot processes that might remain running unintentionally after
the policy is loaded (they represent a potential extra attack surface
that should be mitigated).
2. Despite the kernel being treated as a privileged domain, the policy
writer may want to impose certain special limitations on kernel
threads that may conflict with the requirements of intentional early
boot processes. For example, it is a good hardening practice to limit
what executables the kernel can execute as usermode helpers and to
confine the resulting usermode helper processes. However, a
(legitimate) process surviving from early boot may need to execute a
different set of executables.
3. As currently implemented, overlayfs remembers the security context of
the process that created an overlayfs mount and uses it to bound
subsequent operations on files using this context. If an overlayfs
mount is created before the SELinux policy is loaded, these "mounter"
checks are made against the kernel context, which may clash with
restrictions on the kernel domain (see 2.).
To resolve this, introduce a new initial SID (reusing the slot of the
former "init" initial SID) that will be assigned to any userspace
process started before the policy is first loaded. This is easy to do,
as we can simply label any process that goes through the
bprm_creds_for_exec LSM hook with the new init-SID instead of
propagating the kernel SID from the parent.
To provide backwards compatibility for existing policies that are
unaware of this new semantic of the "init" initial SID, introduce a new
policy capability "userspace_initial_context" and set the "init" SID to
the same context as the "kernel" SID unless this capability is set by
the policy.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Currently, the LSM infrastructure supports only one LSM providing an xattr
and EVM calculating the HMAC on that xattr, plus other inode metadata.
Allow all LSMs to provide one or multiple xattrs, by extending the security
blob reservation mechanism. Introduce the new lbs_xattr_count field of the
lsm_blob_sizes structure, so that each LSM can specify how many xattrs it
needs, and the LSM infrastructure knows how many xattr slots it should
allocate.
Modify the inode_init_security hook definition, by passing the full
xattr array allocated in security_inode_init_security(), and the current
number of xattr slots in that array filled by LSMs. The first parameter
would allow EVM to access and calculate the HMAC on xattrs supplied by
other LSMs, the second to not leave gaps in the xattr array, when an LSM
requested but did not provide xattrs (e.g. if it is not initialized).
Introduce lsm_get_xattr_slot(), which LSMs can call as many times as the
number specified in the lbs_xattr_count field of the lsm_blob_sizes
structure. During each call, lsm_get_xattr_slot() increments the number of
filled xattrs, so that at the next invocation it returns the next xattr
slot to fill.
Cleanup security_inode_init_security(). Unify the !initxattrs and
initxattrs case by simply not allocating the new_xattrs array in the
former. Update the documentation to reflect the changes, and fix the
description of the xattr name, as it is not allocated anymore.
Adapt both SELinux and Smack to use the new definition of the
inode_init_security hook, and to call lsm_get_xattr_slot() to obtain and
fill the reserved slots in the xattr array.
Move the xattr->name assignment after the xattr->value one, so that it is
done only in case of successful memory allocation.
Finally, change the default return value of the inode_init_security hook
from zero to -EOPNOTSUPP, so that BPF LSM correctly follows the hook
conventions.
Reported-by: Nicolas Bouchinet <nicolas.bouchinet@clip-os.org>
Link: https://lore.kernel.org/linux-integrity/Y1FTSIo+1x+4X0LS@archlinux/
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: minor comment and variable tweaks, approved by RS]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Currently, when an NFS filesystem that supports passing LSM/SELinux
labels is mounted during early boot (before the SELinux policy is
loaded), it ends up mounted without the labeling support (i.e. with
Fedora policy all files get the generic NFS label
system_u:object_r:nfs_t:s0).
This is because the information that the NFS mount supports passing
labels (communicated to the LSM layer via the kern_flags argument of
security_set_mnt_opts()) gets lost and when the policy is loaded the
mount is initialized as if the passing is not supported.
Fix this by noting the "native labeling" in newsbsec->flags (using a new
SE_SBNATIVE flag) on the pre-policy-loaded call of
selinux_set_mnt_opts() and then making sure it is respected on the
second call from delayed_superblock_init().
Additionally, make inode_doinit_with_dentry() initialize the inode's
label from its extended attributes whenever it doesn't find it already
intitialized by the filesystem. This is needed to properly initialize
pre-existing inodes when delayed_superblock_init() is called. It should
not trigger in any other cases (and if it does, it's still better to
initialize the correct label instead of leaving the inode unlabeled).
Fixes: eb9ae686507b ("SELinux: Add new labeling type native labels")
Tested-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: fixed 'Fixes' tag format]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Newly added subflows should inherit the LSM label from the associated
MPTCP socket regardless of the current context.
This patch implements the above copying sid and class from the MPTCP
socket context, deleting the existing subflow label, if any, and then
re-creating the correct one.
The new helper reuses the selinux_netlbl_sk_security_free() function,
and the latter can end-up being called multiple times with the same
argument; we additionally need to make it idempotent.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The array of mount tokens in only used in match_opt_prefix() and never
modified.
The array of symtab names is never modified and only used in the
DEBUG_HASHES configuration as output.
The array of files for the SElinux filesystem sub-directory `ss` is
similar to the other `struct tree_descr` usages only read from to
construct the containing entries.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Found by codespell(1)
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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After working with the larger SELinux-based distros for several
years, we're finally at a place where we can disable the SELinux
runtime disable functionality. The existing kernel deprecation
notice explains the functionality and why we want to remove it:
The selinuxfs "disable" node allows SELinux to be disabled at
runtime prior to a policy being loaded into the kernel. If
disabled via this mechanism, SELinux will remain disabled until
the system is rebooted.
The preferred method of disabling SELinux is via the "selinux=0"
boot parameter, but the selinuxfs "disable" node was created to
make it easier for systems with primitive bootloaders that did not
allow for easy modification of the kernel command line.
Unfortunately, allowing for SELinux to be disabled at runtime makes
it difficult to secure the kernel's LSM hooks using the
"__ro_after_init" feature.
It is that last sentence, mentioning the '__ro_after_init' hardening,
which is the real motivation for this change, and if you look at the
diffstat you'll see that the impact of this patch reaches across all
the different LSMs, helping prevent tampering at the LSM hook level.
From a SELinux perspective, it is important to note that if you
continue to disable SELinux via "/etc/selinux/config" it may appear
that SELinux is disabled, but it is simply in an uninitialized state.
If you load a policy with `load_policy -i`, you will see SELinux
come alive just as if you had loaded the policy during early-boot.
It is also worth noting that the "/sys/fs/selinux/disable" file is
always writable now, regardless of the Kconfig settings, but writing
to the file has no effect on the system, other than to display an
error on the console if a non-zero/true value is written.
Finally, in the several years where we have been working on
deprecating this functionality, there has only been one instance of
someone mentioning any user visible breakage. In this particular
case it was an individual's kernel test system, and the workaround
documented in the deprecation notice ("selinux=0" on the kernel
command line) resolved the issue without problem.
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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We originally promised that the SELinux 'checkreqprot' functionality
would be removed no sooner than June 2021, and now that it is March
2023 it seems like it is a good time to do the final removal. The
deprecation notice in the kernel provides plenty of detail on why
'checkreqprot' is not desirable, with the key point repeated below:
This was a compatibility mechanism for legacy userspace and
for the READ_IMPLIES_EXEC personality flag. However, if set to
1, it weakens security by allowing mappings to be made executable
without authorization by policy. The default value of checkreqprot
at boot was changed starting in Linux v4.4 to 0 (i.e. check the
actual protection), and Android and Linux distributions have been
explicitly writing a "0" to /sys/fs/selinux/checkreqprot during
initialization for some time.
Along with the official deprecation notice, we have been discussing
this on-list and directly with several of the larger SELinux-based
distros and everyone is happy to see this feature finally removed.
In an attempt to catch all of the smaller, and DIY, Linux systems
we have been writing a deprecation notice URL into the kernel log,
along with a growing ssleep() penalty, when admins enabled
checkreqprot at runtime or via the kernel command line. We have
yet to have anyone come to us and raise an objection to the
deprecation or planned removal.
It is worth noting that while this patch removes the checkreqprot
functionality, it leaves the user visible interfaces (kernel command
line and selinuxfs file) intact, just inert. This should help
prevent breakages with existing userspace tools that correctly, but
unnecessarily, disable checkreqprot at boot or runtime. Admins
that attempt to enable checkreqprot will be met with a removal
message in the kernel log.
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Linus observed that the pervasive passing of selinux_state pointers
introduced by me in commit aa8e712cee93 ("selinux: wrap global selinux
state") adds overhead and complexity without providing any
benefit. The original idea was to pave the way for SELinux namespaces
but those have not yet been implemented and there isn't currently
a concrete plan to do so. Remove the passing of the selinux_state
pointers, reverting to direct use of the single global selinux_state,
and likewise remove passing of child pointers like the selinux_avc.
The selinux_policy pointer remains as it is needed for atomic switching
of policies.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303101057.mZ3Gv5fK-lkp@intel.com/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm
Pull lsm updates from Paul Moore:
- Improve the error handling in the device cgroup such that memory
allocation failures when updating the access policy do not
potentially alter the policy.
- Some minor fixes to reiserfs to ensure that it properly releases
LSM-related xattr values.
- Update the security_socket_getpeersec_stream() LSM hook to take
sockptr_t values.
Previously the net/BPF folks updated the getsockopt code in the
network stack to leverage the sockptr_t type to make it easier to
pass both kernel and __user pointers, but unfortunately when they did
so they didn't convert the LSM hook.
While there was/is no immediate risk by not converting the LSM hook,
it seems like this is a mistake waiting to happen so this patch
proactively does the LSM hook conversion.
- Convert vfs_getxattr_alloc() to return an int instead of a ssize_t
and cleanup the callers. Internally the function was never going to
return anything larger than an int and the callers were doing some
very odd things casting the return value; this patch fixes all that
and helps bring a bit of sanity to vfs_getxattr_alloc() and its
callers.
- More verbose, and helpful, LSM debug output when the system is booted
with "lsm.debug" on the command line. There are examples in the
commit description, but the quick summary is that this patch provides
better information about which LSMs are enabled and the ordering in
which they are processed.
- General comment and kernel-doc fixes and cleanups.
* tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
lsm: Fix description of fs_context_parse_param
lsm: Add/fix return values in lsm_hooks.h and fix formatting
lsm: Clarify documentation of vm_enough_memory hook
reiserfs: Add missing calls to reiserfs_security_free()
lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
device_cgroup: Roll back to original exceptions after copy failure
LSM: Better reporting of actual LSMs at boot
lsm: make security_socket_getpeersec_stream() sockptr_t safe
audit: Fix some kernel-doc warnings
lsm: remove obsoleted comments for security hooks
fs: edit a comment made in bad taste
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Commit 4ff09db1b79b ("bpf: net: Change sk_getsockopt() to take the
sockptr_t argument") made it possible to call sk_getsockopt()
with both user and kernel address space buffers through the use of
the sockptr_t type. Unfortunately at the time of conversion the
security_socket_getpeersec_stream() LSM hook was written to only
accept userspace buffers, and in a desire to avoid having to change
the LSM hook the commit author simply passed the sockptr_t's
userspace buffer pointer. Since the only sk_getsockopt() callers
at the time of conversion which used kernel sockptr_t buffers did
not allow SO_PEERSEC, and hence the
security_socket_getpeersec_stream() hook, this was acceptable but
also very fragile as future changes presented the possibility of
silently passing kernel space pointers to the LSM hook.
There are several ways to protect against this, including careful
code review of future commits, but since relying on code review to
catch bugs is a recipe for disaster and the upstream eBPF maintainer
is "strongly against defensive programming", this patch updates the
LSM hook, and all of the implementations to support sockptr_t and
safely handle both user and kernel space buffers.
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].
So far posix acls were passed as a void blob to the security and
integrity modules. Some of them like evm then proceed to interpret the
void pointer and convert it into the kernel internal struct posix acl
representation to perform their integrity checking magic. This is
obviously pretty problematic as that requires knowledge that only the
vfs is guaranteed to have and has lead to various bugs. Add a proper
security hook for setting posix acls and pass down the posix acls in
their appropriate vfs format instead of hacking it through a void
pointer stored in the uapi format.
I spent considerate time in the security module infrastructure and
audited all codepaths. SELinux has no restrictions based on the posix
acl values passed through it. The capability hook doesn't need to be
called either because it only has restrictions on security.* xattrs. So
these are all fairly simply hooks for SELinux.
Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Pull vfs constification updates from Al Viro:
"whack-a-mole: constifying struct path *"
* tag 'pull-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ecryptfs: constify path
spufs: constify path
nd_jump_link(): constify path
audit_init_parent(): constify path
__io_setxattr(): constify path
do_proc_readlink(): constify path
overlayfs: constify path
fs/notify: constify path
may_linkat(): constify path
do_sys_name_to_handle(): constify path
->getprocattr(): attribute name is const char *, TYVM...
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm
Pull LSM updates from Paul Moore:
"Seven patches for the LSM layer and we've got a mix of trivial and
significant patches. Highlights below, starting with the smaller bits
first so they don't get lost in the discussion of the larger items:
- Remove some redundant NULL pointer checks in the common LSM audit
code.
- Ratelimit the lockdown LSM's access denial messages.
With this change there is a chance that the last visible lockdown
message on the console is outdated/old, but it does help preserve
the initial series of lockdown denials that started the denial
message flood and my gut feeling is that these might be the more
valuable messages.
- Open userfaultfds as readonly instead of read/write.
While this code obviously lives outside the LSM, it does have a
noticeable impact on the LSMs with Ondrej explaining the situation
in the commit description. It is worth noting that this patch
languished on the VFS list for over a year without any comments
(objections or otherwise) so I took the liberty of pulling it into
the LSM tree after giving fair notice. It has been in linux-next
since the end of August without any noticeable problems.
- Add a LSM hook for user namespace creation, with implementations
for both the BPF LSM and SELinux.
Even though the changes are fairly small, this is the bulk of the
diffstat as we are also including BPF LSM selftests for the new
hook.
It's also the most contentious of the changes in this pull request
with Eric Biederman NACK'ing the LSM hook multiple times during its
development and discussion upstream. While I've never taken NACK's
lightly, I'm sending these patches to you because it is my belief
that they are of good quality, satisfy a long-standing need of
users and distros, and are in keeping with the existing nature of
the LSM layer and the Linux Kernel as a whole.
The patches in implement a LSM hook for user namespace creation
that allows for a granular approach, configurable at runtime, which
enables both monitoring and control of user namespaces. The general
consensus has been that this is far preferable to the other
solutions that have been adopted downstream including outright
removal from the kernel, disabling via system wide sysctls, or
various other out-of-tree mechanisms that users have been forced to
adopt since we haven't been able to provide them an upstream
solution for their requests. Eric has been steadfast in his
objections to this LSM hook, explaining that any restrictions on
the user namespace could have significant impact on userspace.
While there is the possibility of impacting userspace, it is
important to note that this solution only impacts userspace when it
is requested based on the runtime configuration supplied by the
distro/admin/user. Frederick (the pathset author), the LSM/security
community, and myself have tried to work with Eric during
development of this patchset to find a mutually acceptable
solution, but Eric's approach and unwillingness to engage in a
meaningful way have made this impossible. I have CC'd Eric directly
on this pull request so he has a chance to provide his side of the
story; there have been no objections outside of Eric's"
* tag 'lsm-pr-20221003' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
lockdown: ratelimit denial messages
userfaultfd: open userfaultfds with O_RDONLY
selinux: Implement userns_create hook
selftests/bpf: Add tests verifying bpf lsm userns_create hook
bpf-lsm: Make bpf_lsm_userns_create() sleepable
security, lsm: Introduce security_create_user_ns()
lsm: clean up redundant NULL pointer check
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull SELinux updates from Paul Moore:
"Six SELinux patches, all are simple and easily understood, but a list
of the highlights is below:
- Use 'grep -E' instead of 'egrep' in the SELinux policy install
script.
Fun fact, this seems to be GregKH's *second* dedicated SELinux
patch since we transitioned to git (ignoring merges, the SPDX
stuff, and a trivial fs reference removal when lustre was yanked);
the first was back in 2011 when selinuxfs was placed in
/sys/fs/selinux. Oh, the memories ...
- Convert the SELinux policy boolean values to use signed integer
types throughout the SELinux kernel code.
Prior to this we were using a mix of signed and unsigned integers
which was probably okay in this particular case, but it is
definitely not a good idea in general.
- Remove a reference to the SELinux runtime disable functionality in
/etc/selinux/config as we are in the process of deprecating that.
See [1] for more background on this if you missed the previous
notes on the deprecation.
- Minor cleanups: remove unneeded variables and function parameter
constification"
Link: https://github.com/SELinuxProject/selinux-kernel/wiki/DEPRECATE-runtime-disable [1]
* tag 'selinux-pr-20221003' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: remove runtime disable message in the install_policy.sh script
selinux: use "grep -E" instead of "egrep"
selinux: remove the unneeded result variable
selinux: declare read-only parameters const
selinux: use int arrays for boolean values
selinux: remove an unneeded variable in sel_make_class_dir_entries()
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Return the value avc_has_perm() directly instead of storing it in
another redundant variable.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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cast of ->d_name.name to char * is completely wrong - nothing is
allowed to modify its contents.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Add a SELinux access control for the iouring IORING_OP_URING_CMD
command. This includes the addition of a new permission in the
existing "io_uring" object class: "cmd". The subject of the new
permission check is the domain of the process requesting access, the
object is the open file which points to the device/file that is the
target of the IORING_OP_URING_CMD operation. A sample policy rule
is shown below:
allow <domain> <file>:io_uring { cmd };
Cc: stable@vger.kernel.org
Fixes: ee692a21e9bf ("fs,io_uring: add infrastructure for uring-cmd")
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Unprivileged user namespace creation is an intended feature to enable
sandboxing, however this feature is often used to as an initial step to
perform a privilege escalation attack.
This patch implements a new user_namespace { create } access control
permission to restrict which domains allow or deny user namespace
creation. This is necessary for system administrators to quickly protect
their systems while waiting for vulnerability patches to be applied.
This permission can be used in the following way:
allow domA_t domA_t : user_namespace { create };
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"A relatively small set of patches for SELinux this time, eight patches
in total with really only one significant change.
The highlights are:
- Add support for proper labeling of memfd_secret anonymous inodes.
This will allow LSMs that implement the anonymous inode hooks to
apply security policy to memfd_secret() fds.
- Various small improvements to memory management: fixed leaks, freed
memory when needed, boundary checks.
- Hardened the selinux_audit_data struct with __randomize_layout.
- A minor documentation tweak to fix a formatting/style issue"
* tag 'selinux-pr-20220801' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: selinux_add_opt() callers free memory
selinux: Add boundary check in put_entry()
selinux: fix memleak in security_read_state_kernel()
docs: selinux: add '=' signs to kernel boot options
mm: create security context for memfd_secret inodes
selinux: fix typos in comments
selinux: drop unnecessary NULL check
selinux: add __randomize_layout to selinux_audit_data
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The selinux_add_opt() function may need to allocate memory for the
mount options if none has already been allocated, but there is no
need to free that memory on error as the callers handle that. Drop
the existing kfree() on error to help increase consistency in the
selinux_add_opt() error handling.
This patch also changes selinux_add_opt() to return -EINVAL when
the mount option value, @s, is NULL. It currently return -ENOMEM.
Link: https://lore.kernel.org/lkml/20220611090550.135674-1-xiujianfeng@huawei.com/T/
Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: fix subject, rework commit description language]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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`selinux_add_opt()` stopped taking ownership of the passed context since
commit 70f4169ab421 ("selinux: parse contexts for mount options early").
unreferenced object 0xffff888114dfd140 (size 64):
comm "mount", pid 15182, jiffies 4295687028 (age 796.340s)
hex dump (first 32 bytes):
73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f system_u:object_
72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65 r:test_filesyste
backtrace:
[<ffffffffa07dbef4>] kmemdup_nul+0x24/0x80
[<ffffffffa0d34253>] selinux_sb_eat_lsm_opts+0x293/0x560
[<ffffffffa0d13f08>] security_sb_eat_lsm_opts+0x58/0x80
[<ffffffffa0af1eb2>] generic_parse_monolithic+0x82/0x180
[<ffffffffa0a9c1a5>] do_new_mount+0x1f5/0x550
[<ffffffffa0a9eccb>] path_mount+0x2ab/0x1570
[<ffffffffa0aa019e>] __x64_sys_mount+0x20e/0x280
[<ffffffffa1f47124>] do_syscall_64+0x34/0x80
[<ffffffffa200007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
unreferenced object 0xffff888108e71640 (size 64):
comm "fsmount", pid 7607, jiffies 4295044974 (age 1601.016s)
hex dump (first 32 bytes):
73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f system_u:object_
72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65 r:test_filesyste
backtrace:
[<ffffffff861dc2b1>] memdup_user+0x21/0x90
[<ffffffff861dc367>] strndup_user+0x47/0xa0
[<ffffffff864f6965>] __do_sys_fsconfig+0x485/0x9f0
[<ffffffff87940124>] do_syscall_64+0x34/0x80
[<ffffffff87a0007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
Cc: stable@vger.kernel.org
Fixes: 70f4169ab421 ("selinux: parse contexts for mount options early")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Signed-off-by: Jonas Lindner <jolindner@gmx.de>
[PM: fixed duplicated subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Commit e3489f8974e1 ("selinux: kill selinux_sb_get_mnt_opts()")
introduced a NULL check on the context after a successful call to
security_sid_to_context(). This is on the one hand redundant after
checking for success and on the other hand insufficient on an actual
NULL pointer, since the context is passed to seq_escape() leading to a
call of strlen() on it.
Reported by Clang analyzer:
In file included from security/selinux/hooks.c:28:
In file included from ./include/linux/tracehook.h:50:
In file included from ./include/linux/memcontrol.h:13:
In file included from ./include/linux/cgroup.h:18:
./include/linux/seq_file.h:136:25: warning: Null pointer passed as 1st argument to string length function [unix.cstring.NullArg]
seq_escape_mem(m, src, strlen(src), flags, esc);
^~~~~~~~~~~
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Log the anonymous inode class name in the security hook
inode_init_security_anon. This name is the key for name based type
transitions on the anon_inode security class on creation. Example:
type=AVC msg=audit(02/16/22 22:02:50.585:216) : avc: granted \
{ create } for pid=2136 comm=mariadbd anonclass=[io_uring] \
scontext=system_u:system_r:mysqld_t:s0 \
tcontext=system_u:system_r:mysqld_iouring_t:s0 tclass=anon_inode
Add a new LSM audit data type holding the inode and the class name.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: adjusted 'anonclass' to be a trusted string, cgzones approved]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The checkreqprot functionality was disabled by default back in
Linux v4.4 (2015) with commit 2a35d196c160e3 ("selinux: change
CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE default") and it was
officially marked as deprecated in Linux v5.7. It was always a
bit of a hack to workaround very old userspace and to the best of
our knowledge, the checkreqprot functionality has been disabled by
Linux distributions for quite some time.
This patch moves the deprecation messages from KERN_WARNING to
KERN_ERR and adds a five second sleep to anyone using it to help
draw their attention to the deprecation and provide a URL which
helps explain things in more detail.
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Get rid of redundant assignments which end up in values not being
read either because they are overwritten or the function ends.
Reported by clang-tidy [deadcode.DeadStores]
Signed-off-by: Michal Orzel <michalorzel.eng@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull ptrace cleanups from Eric Biederman:
"This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was around
task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where anything left in tracehook.h was
some weird strange thing that was difficult to understand"
* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Remove duplicated include in ptrace.c
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
ptrace: Return the signal to continue with from ptrace_stop
ptrace: Move setting/clearing ptrace_message into ptrace_stop
tracehook: Remove tracehook.h
resume_user_mode: Move to resume_user_mode.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Introduce task_work_pending
task_work: Remove unnecessary include from posix_timers.h
ptrace: Remove tracehook_signal_handler
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Move ptrace_report_syscall into ptrace.h
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Now that all of the definitions have moved out of tracehook.h into
ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in
tracehook.h so remove it.
Update the few files that were depending upon tracehook.h to bring in
definitions to use the headers they need directly.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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These ioctls are equivalent to fcntl(fd, F_SETFD, flags), which SELinux
always allows too. Furthermore, a failed FIOCLEX could result in a file
descriptor being leaked to a process that should not have access to it.
As this patch removes access controls, a policy capability needs to be
enabled in policy to always allow these ioctls.
Based-on-patch-by: Demi Marie Obenour <demiobenour@gmail.com>
Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Those return statements at the end of a void function are redundant.
Reported by clang-tidy [readability-redundant-control-flow]
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Do this by extracting the peer labeling per-association logic from
selinux_sctp_assoc_request() into a new helper
selinux_sctp_process_new_assoc() and use this helper in both
selinux_sctp_assoc_request() and selinux_sctp_assoc_established(). This
ensures that the peer labeling behavior as documented in
Documentation/security/SCTP.rst is applied both on the client and server
side:
"""
An SCTP socket will only have one peer label assigned to it. This will be
assigned during the establishment of the first association. Any further
associations on this socket will have their packet peer label compared to
the sockets peer label, and only if they are different will the
``association`` permission be validated. This is validated by checking the
socket peer sid against the received packets peer sid to determine whether
the association should be allowed or denied.
"""
At the same time, it also ensures that the peer label of the association
is set to the correct value, such that if it is peeled off into a new
socket, the socket's peer label will then be set to the association's
peer label, same as it already works on the server side.
While selinux_inet_conn_established() (which we are replacing by
selinux_sctp_assoc_established() for SCTP) only deals with assigning a
peer label to the connection (socket), in case of SCTP we need to also
copy the (local) socket label to the association, so that
selinux_sctp_sk_clone() can then pick it up for the new socket in case
of SCTP peeloff.
Careful readers will notice that the selinux_sctp_process_new_assoc()
helper also includes the "IPv4 packet received over an IPv6 socket"
check, even though it hadn't been in selinux_sctp_assoc_request()
before. While such check is not necessary in
selinux_inet_conn_request() (because struct request_sock's family field
is already set according to the skb's family), here it is needed, as we
don't have request_sock and we take the initial family from the socket.
In selinux_sctp_assoc_established() it is similarly needed as well (and
also selinux_inet_conn_established() already has it).
Fixes: 72e89f50084c ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Based-on-patch-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Commit b8b87fd954b4 ("selinux: Fix selinux_sb_mnt_opts_compat()")
started to parse mount options into SIDs in selinux_add_opt() if policy
has already been loaded. Since it's extremely unlikely that anyone would
depend on the ability to set SELinux contexts on fs_context before
loading the policy and then mounting that context after simplify the
logic by always parsing the options early.
Note that the multi-step mounting is only possible with the new
fscontext mount API and wasn't possible before its introduction.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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When running the SELinux code through sparse, there are a handful of
warnings. This patch resolves some of these warnings caused by
"__rcu" mismatches.
% make W=1 C=1 security/selinux/
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Avoid unnecessary parsing of sids that have already been parsed via
selinux_sb_eat_lsm_opts().
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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