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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"While we have a small number of SELinux patches for v5.11, there are a
few changes worth highlighting:
- Change the LSM network hooks to pass flowi_common structs instead
of the parent flowi struct as the LSMs do not currently need the
full flowi struct and they do not have enough information to use it
safely (missing information on the address family).
This patch was discussed both with Herbert Xu (representing team
netdev) and James Morris (representing team
LSMs-other-than-SELinux).
- Fix how we handle errors in inode_doinit_with_dentry() so that we
attempt to properly label the inode on following lookups instead of
continuing to treat it as unlabeled.
- Tweak the kernel logic around allowx, auditallowx, and dontauditx
SELinux policy statements such that the auditx/dontauditx are
effective even without the allowx statement.
Everything passes our test suite"
* tag 'selinux-pr-20201214' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
lsm,selinux: pass flowi_common instead of flowi to the LSM hooks
selinux: Fix fall-through warnings for Clang
selinux: drop super_block backpointer from superblock_security_struct
selinux: fix inode_doinit_with_dentry() LABEL_INVALID error handling
selinux: allow dontauditx and auditallowx rules to take effect without allowx
selinux: fix error initialization in inode_doinit_with_dentry()
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A followup change to tcp_request_sock_op would have to drop the 'const'
qualifier from the 'route_req' function as the
'security_inet_conn_request' call is moved there - and that function
expects a 'struct sock *'.
However, it turns out its also possible to add a const qualifier to
security_inet_conn_request instead.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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As pointed out by Herbert in a recent related patch, the LSM hooks do
not have the necessary address family information to use the flowi
struct safely. As none of the LSMs currently use any of the protocol
specific flowi information, replace the flowi pointers with pointers
to the address family independent flowi_common struct.
Reported-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.
Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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 fix from Paul Moore:
"One small SELinux patch to make sure we return an error code when an
allocation fails. It passes all of our tests, but given the nature of
the patch that isn't surprising"
* tag 'selinux-pr-20201113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: Fix error return code in sel_ib_pkey_sid_slow()
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Fix to return a negative error code from the error handling case
instead of 0 in function sel_ib_pkey_sid_slow(), as done elsewhere
in this function.
Cc: stable@vger.kernel.org
Fixes: 409dcf31538a ("selinux: Add a cache for quicker retreival of PKey SIDs")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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It appears to have been needed for selinux_complete_init() in the past,
but today it's useless.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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A previous fix, commit 83370b31a915 ("selinux: fix error initialization
in inode_doinit_with_dentry()"), changed how failures were handled
before a SELinux policy was loaded. Unfortunately that patch was
potentially problematic for two reasons: it set the isec->initialized
state without holding a lock, and it didn't set the inode's SELinux
label to the "default" for the particular filesystem. The later can
be a problem if/when a later attempt to revalidate the inode fails
and SELinux reverts to the existing inode label.
This patch should restore the default inode labeling that existed
before the original fix, without affecting the LABEL_INVALID marking
such that revalidation will still be attempted in the future.
Fixes: 83370b31a915 ("selinux: fix error initialization in inode_doinit_with_dentry()")
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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This allows for dontauditing very specific ioctls e.g. TCGETS without
dontauditing every ioctl or granting additional permissions.
Now either an allowx, dontauditx or auditallowx rules enables checking
for extended permissions.
Signed-off-by: Jonathan Hettwer <j2468h@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Mark the inode security label as invalid if we cannot find
a dentry so that we will retry later rather than marking it
initialized with the unlabeled SID.
Fixes: 9287aed2ad1f ("selinux: Convert isec->lock into a spinlock")
Signed-off-by: Tianyue Ren <rentianyue@kylinos.cn>
[PM: minor comment tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here is the big set of char, misc, and other assorted driver subsystem
patches for 5.10-rc1.
There's a lot of different things in here, all over the drivers/
directory. Some summaries:
- soundwire driver updates
- habanalabs driver updates
- extcon driver updates
- nitro_enclaves new driver
- fsl-mc driver and core updates
- mhi core and bus updates
- nvmem driver updates
- eeprom driver updates
- binder driver updates and fixes
- vbox minor bugfixes
- fsi driver updates
- w1 driver updates
- coresight driver updates
- interconnect driver updates
- misc driver updates
- other minor driver updates
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (396 commits)
binder: fix UAF when releasing todo list
docs: w1: w1_therm: Fix broken xref, mistakes, clarify text
misc: Kconfig: fix a HISI_HIKEY_USB dependency
LSM: Fix type of id parameter in kernel_post_load_data prototype
misc: Kconfig: add a new dependency for HISI_HIKEY_USB
firmware_loader: fix a kernel-doc markup
w1: w1_therm: make w1_poll_completion static
binder: simplify the return expression of binder_mmap
test_firmware: Test partial read support
firmware: Add request_partial_firmware_into_buf()
firmware: Store opt_flags in fw_priv
fs/kernel_file_read: Add "offset" arg for partial reads
IMA: Add support for file reads without contents
LSM: Add "contents" flag to kernel_read_file hook
module: Call security_kernel_post_load_data()
firmware_loader: Use security_post_load_data()
LSM: Introduce kernel_post_load_data() hook
fs/kernel_read_file: Add file_size output argument
fs/kernel_read_file: Switch buffer size arg to size_t
fs/kernel_read_file: Remove redundant size argument
...
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"A decent number of SELinux patches for v5.10, twenty two in total. The
highlights are listed below, but all of the patches pass our test
suite and merge cleanly.
- A number of changes to how the SELinux policy is loaded and managed
inside the kernel with the goal of improving the atomicity of a
SELinux policy load operation.
These changes account for the bulk of the diffstat as well as the
patch count. A special thanks to everyone who contributed patches
and fixes for this work.
- Convert the SELinux policy read-write lock to RCU.
- A tracepoint was added for audited SELinux access control events;
this should help provide a more unified backtrace across kernel and
userspace.
- Allow the removal of security.selinux xattrs when a SELinux policy
is not loaded.
- Enable policy capabilities in SELinux policies created with the
scripts/selinux/mdp tool.
- Provide some "no sooner than" dates for the SELinux checkreqprot
sysfs deprecation"
* tag 'selinux-pr-20201012' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (22 commits)
selinux: provide a "no sooner than" date for the checkreqprot removal
selinux: Add helper functions to get and set checkreqprot
selinux: access policycaps with READ_ONCE/WRITE_ONCE
selinux: simplify away security_policydb_len()
selinux: move policy mutex to selinux_state, use in lockdep checks
selinux: fix error handling bugs in security_load_policy()
selinux: convert policy read-write lock to RCU
selinux: delete repeated words in comments
selinux: add basic filtering for audit trace events
selinux: add tracepoint on audited events
selinux: Create new booleans and class dirs out of tree
selinux: Standardize string literal usage for selinuxfs directory names
selinux: Refactor selinuxfs directory populating functions
selinux: Create function for selinuxfs directory cleanup
selinux: permit removing security.selinux xattr before policy load
selinux: fix memdup.cocci warnings
selinux: avoid dereferencing the policy prior to initialization
selinux: fix allocation failure check on newpolicy->sidtab
selinux: refactor changing booleans
selinux: move policy commit after updating selinuxfs
...
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As with the kernel_load_data LSM hook, add a "contents" flag to the
kernel_read_file LSM hook that indicates whether the LSM can expect
a matching call to the kernel_post_read_file LSM hook with the full
contents of the file. With the coming addition of partial file read
support for kernel_read_file*() API, the LSM will no longer be able
to always see the entire contents of a file during the read calls.
For cases where the LSM must read examine the complete file contents,
it will need to do so on its own every time the kernel_read_file
hook is called with contents=false (or reject such cases). Adjust all
existing LSMs to retain existing behavior.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There are a few places in the kernel where LSMs would like to have
visibility into the contents of a kernel buffer that has been loaded or
read. While security_kernel_post_read_file() (which includes the
buffer) exists as a pairing for security_kernel_read_file(), no such
hook exists to pair with security_kernel_load_data().
Earlier proposals for just using security_kernel_post_read_file() with a
NULL file argument were rejected (i.e. "file" should always be valid for
the security_..._file hooks, but it appears at least one case was
left in the kernel during earlier refactoring. (This will be fixed in
a subsequent patch.)
Since not all cases of security_kernel_load_data() can have a single
contiguous buffer made available to the LSM hook (e.g. kexec image
segments are separately loaded), there needs to be a way for the LSM to
reason about its expectations of the hook coverage. In order to handle
this, add a "contents" argument to the "kernel_load_data" hook that
indicates if the newly added "kernel_post_load_data" hook will be called
with the full contents once loaded. That way, LSMs requiring full contents
can choose to unilaterally reject "kernel_load_data" with contents=false
(which is effectively the existing hook coverage), but when contents=true
they can allow it and later evaluate the "kernel_post_load_data" hook
once the buffer is loaded.
With this change, LSMs can gain coverage over non-file-backed data loads
(e.g. init_module(2) and firmware userspace helper), which will happen
in subsequent patches.
Additionally prepare IMA to start processing these cases.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h
include file. That header gets pulled in just about everywhere
and doesn't really need functions not related to the general fs interface.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com
Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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checkreqprot data member in selinux_state struct is accessed directly by
SELinux functions to get and set. This could cause unexpected read or
write access to this data member due to compiler optimizations and/or
compiler's reordering of access to this field.
Add helper functions to get and set checkreqprot data member in
selinux_state struct. These helper functions use READ_ONCE and
WRITE_ONCE macros to ensure atomic read or write of memory for
this data member.
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Suggested-by: Paul Moore <paul@paul-moore.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Use READ_ONCE/WRITE_ONCE for all accesses to the
selinux_state.policycaps booleans to prevent compiler
mischief.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Remove the security_policydb_len() calls from sel_open_policy() and
instead update the inode size from the size returned from
security_read_policy().
Since after this change security_policydb_len() is only called from
security_load_policy(), remove it entirely and just open-code it there.
Also, since security_load_policy() is always called with policy_mutex
held, make it dereference the policy pointer directly and drop the
unnecessary RCU locking.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Move the mutex used to synchronize policy changes (reloads and setting
of booleans) from selinux_fs_info to selinux_state and use it in
lockdep checks for rcu_dereference_protected() calls in the security
server functions. This makes the dependency on the mutex explicit
in the code rather than relying on comments.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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There are a few bugs in the error handling for security_load_policy().
1) If the newpolicy->sidtab allocation fails then it leads to a NULL
dereference. Also the error code was not set to -ENOMEM on that
path.
2) If policydb_read() failed then we call policydb_destroy() twice
which meands we call kvfree(p->sym_val_to_name[i]) twice.
3) If policydb_load_isids() failed then we call sidtab_destroy() twice
and that results in a double free in the sidtab_destroy_tree()
function because entry.ptr_inner and entry.ptr_leaf are not set to
NULL.
One thing that makes this code nice to deal with is that none of the
functions return partially allocated data. In other words, the
policydb_read() either allocates everything successfully or it frees
all the data it allocates. It never returns a mix of allocated and
not allocated data.
I re-wrote this to only free the successfully allocated data which
avoids the double frees. I also re-ordered selinux_policy_free() so
it's in the reverse order of the allocation function.
Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[PM: partially merged by hand due to merge fuzz]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Convert the policy read-write lock to RCU. This is significantly
simplified by the earlier work to encapsulate the policy data
structures and refactor the policy load and boolean setting logic.
Move the latest_granting sequence number into the selinux_policy
structure so that it can be updated atomically with the policy.
Since removing the policy rwlock and moving latest_granting reduces
the selinux_ss structure to nothing more than a wrapper around the
selinux_policy pointer, get rid of the extra layer of indirection.
At present this change merely passes a hardcoded 1 to
rcu_dereference_check() in the cases where we know we do not need to
take rcu_read_lock(), with the preceding comment explaining why.
Alternatively we could pass fsi->mutex down from selinuxfs and
apply a lockdep check on it instead.
Based in part on earlier attempts to convert the policy rwlock
to RCU by Kaigai Kohei [1] and by Peter Enderborg [2].
[1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/
[2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Drop a repeated word in comments.
{open, is, then}
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: selinux@vger.kernel.org
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
[PM: fix subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.
[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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This patch adds further attributes to the event. These attributes are
helpful to understand the context of the message and can be used
to filter the events.
There are three common items. Source context, target context and tclass.
There are also items from the outcome of operation performed.
An event is similar to:
<...>-1309 [002] .... 6346.691689: selinux_audited:
requested=0x4000000 denied=0x4000000 audited=0x4000000
result=-13
scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023
tcontext=system_u:object_r:bin_t:s0 tclass=file
With systems where many denials are occurring, it is useful to apply a
filter. The filtering is a set of logic that is inserted with
the filter file. Example:
echo "tclass==\"file\" " > events/avc/selinux_audited/filter
This adds that we only get tclass=file.
The trace can also have extra properties. Adding the user stack
can be done with
echo 1 > options/userstacktrace
Now the output will be
runcon-1365 [003] .... 6960.955530: selinux_audited:
requested=0x4000000 denied=0x4000000 audited=0x4000000
result=-13
scontext=system_u:system_r:cupsd_t:s0-s0:c0.c1023
tcontext=system_u:object_r:bin_t:s0 tclass=file
runcon-1365 [003] .... 6960.955560: <user stack trace>
=> <00007f325b4ce45b>
=> <00005607093efa57>
Signed-off-by: Peter Enderborg <peter.enderborg@sony.com>
Reviewed-by: Thiébaud Weksteen <tweek@google.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The audit data currently captures which process and which target
is responsible for a denial. There is no data on where exactly in the
process that call occurred. Debugging can be made easier by being able to
reconstruct the unified kernel and userland stack traces [1]. Add a
tracepoint on the SELinux denials which can then be used by userland
(i.e. perf).
Although this patch could manually be added by each OS developer to
trouble shoot a denial, adding it to the kernel streamlines the
developers workflow.
It is possible to use perf for monitoring the event:
# perf record -e avc:selinux_audited -g -a
^C
# perf report -g
[...]
6.40% 6.40% audited=800000 tclass=4
|
__libc_start_main
|
|--4.60%--__GI___ioctl
| entry_SYSCALL_64
| do_syscall_64
| __x64_sys_ioctl
| ksys_ioctl
| binder_ioctl
| binder_set_nice
| can_nice
| capable
| security_capable
| cred_has_capability.isra.0
| slow_avc_audit
| common_lsm_audit
| avc_audit_post_callback
| avc_audit_post_callback
|
It is also possible to use the ftrace interface:
# echo 1 > /sys/kernel/debug/tracing/events/avc/selinux_audited/enable
# cat /sys/kernel/debug/tracing/trace
tracer: nop
entries-in-buffer/entries-written: 1/1 #P:8
[...]
dmesg-3624 [001] 13072.325358: selinux_denied: audited=800000 tclass=4
The tclass value can be mapped to a class by searching
security/selinux/flask.h. The audited value is a bit field of the
permissions described in security/selinux/av_permissions.h for the
corresponding class.
[1] https://source.android.com/devices/tech/debug/native_stack_dump
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Suggested-by: Joel Fernandes <joelaf@google.com>
Reviewed-by: Peter Enderborg <peter.enderborg@sony.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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In order to avoid concurrency issues around selinuxfs resource availability
during policy load, we first create new directories out of tree for
reloaded resources, then swap them in, and finally delete the old versions.
This fix focuses on concurrency in each of the two subtrees swapped, and
not concurrency between the trees. This means that it is still possible
that subsequent reads to eg the booleans directory and the class directory
during a policy load could see the old state for one and the new for the other.
The problem of ensuring that policy loads are fully atomic from the perspective
of userspace is larger than what is dealt with here. This commit focuses on
ensuring that the directories contents always match either the new or the old
policy state from the perspective of userspace.
In the previous implementation, on policy load /sys/fs/selinux is updated
by deleting the previous contents of
/sys/fs/selinux/{class,booleans} and then recreating them. This means
that there is a period of time when the contents of these directories do not
exist which can cause race conditions as userspace relies on them for
information about the policy. In addition, it means that error recovery in
the event of failure is challenging.
In order to demonstrate the race condition that this series fixes, you
can use the following commands:
while true; do cat /sys/fs/selinux/class/service/perms/status
>/dev/null; done &
while true; do load_policy; done;
In the existing code, this will display errors fairly often as the class
lookup fails. (In normal operation from systemd, this would result in a
permission check which would be allowed or denied based on policy settings
around unknown object classes.) After applying this patch series you
should expect to no longer see such error messages.
Signed-off-by: Daniel Burgener <dburgener@linux.microsoft.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Switch class and policy_capabilities directory names to be referred to with
global constants, consistent with booleans directory name. This will allow
for easy consistency of naming in future development.
Signed-off-by: Daniel Burgener <dburgener@linux.microsoft.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Make sel_make_bools and sel_make_classes take the specific elements of
selinux_fs_info that they need rather than the entire struct.
This will allow a future patch to pass temporary elements that are not in
the selinux_fs_info struct to these functions so that the original elements
can be preserved until we are ready to perform the switch over.
Signed-off-by: Daniel Burgener <dburgener@linux.microsoft.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Separating the cleanup from the creation will simplify two things in
future patches in this series. First, the creation can be made generic,
to create directories not tied to the selinux_fs_info structure. Second,
we will ultimately want to reorder creation and deletion so that the
deletions aren't performed until the new directory structures have already
been moved into place.
Signed-off-by: Daniel Burgener <dburgener@linux.microsoft.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Currently SELinux denies attempts to remove the security.selinux xattr
always, even when permissive or no policy is loaded. This was originally
motivated by the view that all files should be labeled, even if that label
is unlabeled_t, and we shouldn't permit files that were once labeled to
have their labels removed entirely. This however prevents removing
SELinux xattrs in the case where one "disables" SELinux by not loading
a policy (e.g. a system where runtime disable is removed and selinux=0
was not specified). Allow removing the xattr before SELinux is
initialized. We could conceivably permit it even after initialization
if permissive, or introduce a separate permission check here.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Use kmemdup rather than duplicating its implementation
Generated by: scripts/coccinelle/api/memdup.cocci
Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
CC: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Certain SELinux security server functions (e.g. security_port_sid,
called during bind) were not explicitly testing to see if SELinux
has been initialized (i.e. initial policy loaded) and handling
the no-policy-loaded case. In the past this happened to work
because the policydb was statically allocated and could always
be accessed, but with the recent encapsulation of policy state
and conversion to dynamic allocation, we can no longer access
the policy state prior to initialization. Add a test of
!selinux_initialized(state) to all of the exported functions that
were missing them and handle appropriately.
Fixes: 461698026ffa ("selinux: encapsulate policy state, refactor policy load")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The allocation check of newpolicy->sidtab is null checking if
newpolicy is null and not newpolicy->sidtab. Fix this.
Addresses-Coverity: ("Logically dead code")
Fixes: c7c556f1e81b ("selinux: refactor changing booleans")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Refactor the logic for changing SELinux policy booleans in a similar
manner to the refactoring of policy load, thereby reducing the
size of the critical section when the policy write-lock is held
and making it easier to convert the policy rwlock to RCU in the
future. Instead of directly modifying the policydb in place, modify
a copy and then swap it into place through a single pointer update.
Only fully copy the portions of the policydb that are affected by
boolean changes to avoid the full cost of a deep policydb copy.
Introduce another level of indirection for the sidtab since changing
booleans does not require updating the sidtab, unlike policy load.
While we are here, create a common helper for notifying
other kernel components and userspace of a policy change and call it
from both security_set_bools() and selinux_policy_commit().
Based on an old (2004) patch by Kaigai Kohei [1] to convert the policy
rwlock to RCU that was deferred at the time since it did not
significantly improve performance and introduced complexity. Peter
Enderborg later submitted a patch series to convert to RCU [2] that
would have made changing booleans a much more expensive operation
by requiring a full policydb_write();policydb_read(); sequence to
deep copy the entire policydb and also had concerns regarding
atomic allocations.
This change is now simplified by the earlier work to encapsulate
policy state in the selinux_policy struct and to refactor
policy load. After this change, the last major obstacle to
converting the policy rwlock to RCU is likely the sidtab live
convert support.
[1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/
[2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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With the refactoring of the policy load logic in the security
server from the previous change, it is now possible to split out
the committing of the new policy from security_load_policy() and
perform it only after successful updating of selinuxfs. Change
security_load_policy() to return the newly populated policy
data structures to the caller, export selinux_policy_commit()
for external callers, and introduce selinux_policy_cancel() to
provide a way to cancel the policy load in the event of an error
during updating of the selinuxfs directory tree. Further, rework
the interfaces used by selinuxfs to get information from the policy
when creating the new directory tree to take and act upon the
new policy data structure rather than the current/active policy.
Update selinuxfs to use these updated and new interfaces. While
we are here, stop re-creating the policy_capabilities directory
on each policy load since it does not depend on the policy, and
stop trying to create the booleans and classes directories during
the initial creation of selinuxfs since no information is available
until first policy load.
After this change, a failure while updating the booleans and class
directories will cause the entire policy load to be canceled, leaving
the original policy intact, and policy load notifications to userspace
will only happen after a successful completion of updating those
directories. This does not (yet) provide full atomicity with respect
to the updating of the directory trees themselves.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Encapsulate the policy state in its own structure (struct
selinux_policy) that is separately allocated but referenced from the
selinux_ss structure. The policy state includes the SID table
(particularly the context structures), the policy database, and the
mapping between the kernel classes/permissions and the policy values.
Refactor the security server portion of the policy load logic to
cleanly separate loading of the new structures from committing the new
policy. Unify the initial policy load and reload code paths as much
as possible, avoiding duplicated code. Make sure we are taking the
policy read-lock prior to any dereferencing of the policy. Move the
copying of the policy capability booleans into the state structure
outside of the policy write-lock because they are separate from the
policy and are read outside of any policy lock; possibly they should
be using at least READ_ONCE/WRITE_ONCE or smp_load_acquire/store_release.
These changes simplify the policy loading logic, reduce the size of
the critical section while holding the policy write-lock, and should
facilitate future changes to e.g. refactor the entire policy reload
logic including the selinuxfs code to make the updating of the policy
and the selinuxfs directory tree atomic and/or to convert the policy
read-write lock to RCU.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Presently mdp does not enable any SELinux policy capabilities
in the dummy policy it generates. Thus, policies derived from
it will by default lack various features commonly used in modern
policies such as open permission, extended socket classes, network
peer controls, etc. Split the policy capability definitions out into
their own headers so that we can include them into mdp without pulling in
other kernel headers and extend mdp generate policycap statements for the
policy capabilities known to the kernel. Policy authors may wish to
selectively remove some of these from the generated policy.
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull checkpoint-restore updates from Christian Brauner:
"This enables unprivileged checkpoint/restore of processes.
Given that this work has been going on for quite some time the first
sentence in this summary is hopefully more exciting than the actual
final code changes required. Unprivileged checkpoint/restore has seen
a frequent increase in interest over the last two years and has thus
been one of the main topics for the combined containers &
checkpoint/restore microconference since at least 2018 (cf. [1]).
Here are just the three most frequent use-cases that were brought forward:
- The JVM developers are integrating checkpoint/restore into a Java
VM to significantly decrease the startup time.
- In high-performance computing environment a resource manager will
typically be distributing jobs where users are always running as
non-root. Long-running and "large" processes with significant
startup times are supposed to be checkpointed and restored with
CRIU.
- Container migration as a non-root user.
In all of these scenarios it is either desirable or required to run
without CAP_SYS_ADMIN. The userspace implementation of
checkpoint/restore CRIU already has the pull request for supporting
unprivileged checkpoint/restore up (cf. [2]).
To enable unprivileged checkpoint/restore a new dedicated capability
CAP_CHECKPOINT_RESTORE is introduced. This solution has last been
discussed in 2019 in a talk by Google at Linux Plumbers (cf. [1]
"Update on Task Migration at Google Using CRIU") with Adrian and
Nicolas providing the implementation now over the last months. In
essence, this allows the CRIU binary to be installed with the
CAP_CHECKPOINT_RESTORE vfs capability set thereby enabling
unprivileged users to restore processes.
To make this possible the following permissions are altered:
- Selecting a specific PID via clone3() set_tid relaxed from userns
CAP_SYS_ADMIN to CAP_CHECKPOINT_RESTORE.
- Selecting a specific PID via /proc/sys/kernel/ns_last_pid relaxed
from userns CAP_SYS_ADMIN to CAP_CHECKPOINT_RESTORE.
- Accessing /proc/pid/map_files relaxed from init userns
CAP_SYS_ADMIN to init userns CAP_CHECKPOINT_RESTORE.
- Changing /proc/self/exe from userns CAP_SYS_ADMIN to userns
CAP_CHECKPOINT_RESTORE.
Of these four changes the /proc/self/exe change deserves a few words
because the reasoning behind even restricting /proc/self/exe changes
in the first place is just full of historical quirks and tracking this
down was a questionable version of fun that I'd like to spare others.
In short, it is trivial to change /proc/self/exe as an unprivileged
user, i.e. without userns CAP_SYS_ADMIN right now. Either via ptrace()
or by simply intercepting the elf loader in userspace during exec.
Nicolas was nice enough to even provide a POC for the latter (cf. [3])
to illustrate this fact.
The original patchset which introduced PR_SET_MM_MAP had no
permissions around changing the exe link. They too argued that it is
trivial to spoof the exe link already which is true. The argument
brought up against this was that the Tomoyo LSM uses the exe link in
tomoyo_manager() to detect whether the calling process is a policy
manager. This caused changing the exe links to be guarded by userns
CAP_SYS_ADMIN.
All in all this rather seems like a "better guard it with something
rather than nothing" argument which imho doesn't qualify as a great
security policy. Again, because spoofing the exe link is possible for
the calling process so even if this were security relevant it was
broken back then and would be broken today. So technically, dropping
all permissions around changing the exe link would probably be
possible and would send a clearer message to any userspace that relies
on /proc/self/exe for security reasons that they should stop doing
this but for now we're only relaxing the exe link permissions from
userns CAP_SYS_ADMIN to userns CAP_CHECKPOINT_RESTORE.
There's a final uapi change in here. Changing the exe link used to
accidently return EINVAL when the caller lacked the necessary
permissions instead of the more correct EPERM. This pr contains a
commit fixing this. I assume that userspace won't notice or care and
if they do I will revert this commit. But since we are changing the
permissions anyway it seems like a good opportunity to try this fix.
With these changes merged unprivileged checkpoint/restore will be
possible and has already been tested by various users"
[1] LPC 2018
1. "Task Migration at Google Using CRIU"
https://www.youtube.com/watch?v=yI_1cuhoDgA&t=12095
2. "Securely Migrating Untrusted Workloads with CRIU"
https://www.youtube.com/watch?v=yI_1cuhoDgA&t=14400
LPC 2019
1. "CRIU and the PID dance"
https://www.youtube.com/watch?v=LN2CUgp8deo&list=PLVsQ_xZBEyN30ZA3Pc9MZMFzdjwyz26dO&index=9&t=2m48s
2. "Update on Task Migration at Google Using CRIU"
https://www.youtube.com/watch?v=LN2CUgp8deo&list=PLVsQ_xZBEyN30ZA3Pc9MZMFzdjwyz26dO&index=9&t=1h2m8s
[2] https://github.com/checkpoint-restore/criu/pull/1155
[3] https://github.com/nviennot/run_as_exe
* tag 'cap-checkpoint-restore-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
selftests: add clone3() CAP_CHECKPOINT_RESTORE test
prctl: exe link permission error changed from -EINVAL to -EPERM
prctl: Allow local CAP_CHECKPOINT_RESTORE to change /proc/self/exe
proc: allow access in init userns for map_files with CAP_CHECKPOINT_RESTORE
pid_namespace: use checkpoint_restore_ns_capable() for ns_last_pid
pid: use checkpoint_restore_ns_capable() for set_tid
capabilities: Introduce CAP_CHECKPOINT_RESTORE
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"Beyond the usual smattering of bug fixes, we've got three small
improvements worth highlighting:
- improved SELinux policy symbol table performance due to a reworking
of the insert and search functions
- allow reading of SELinux labels before the policy is loaded,
allowing for some more "exotic" initramfs approaches
- improved checking an error reporting about process
class/permissions during SELinux policy load"
* tag 'selinux-pr-20200803' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: complete the inlining of hashtab functions
selinux: prepare for inlining of hashtab functions
selinux: specialize symtab insert and search functions
selinux: Fix spelling mistakes in the comments
selinux: fixed a checkpatch warning with the sizeof macro
selinux: log error messages on required process class / permissions
scripts/selinux/mdp: fix initial SID handling
selinux: allow reading labels before policy is loaded
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This patch introduces CAP_CHECKPOINT_RESTORE, a new capability facilitating
checkpoint/restore for non-root users.
Over the last years, The CRIU (Checkpoint/Restore In Userspace) team has
been asked numerous times if it is possible to checkpoint/restore a
process as non-root. The answer usually was: 'almost'.
The main blocker to restore a process as non-root was to control the PID
of the restored process. This feature available via the clone3 system
call, or via /proc/sys/kernel/ns_last_pid is unfortunately guarded by
CAP_SYS_ADMIN.
In the past two years, requests for non-root checkpoint/restore have
increased due to the following use cases:
* Checkpoint/Restore in an HPC environment in combination with a
resource manager distributing jobs where users are always running as
non-root. There is a desire to provide a way to checkpoint and
restore long running jobs.
* Container migration as non-root
* We have been in contact with JVM developers who are integrating
CRIU into a Java VM to decrease the startup time. These
checkpoint/restore applications are not meant to be running with
CAP_SYS_ADMIN.
We have seen the following workarounds:
* Use a setuid wrapper around CRIU:
See https://github.com/FredHutch/slurm-examples/blob/master/checkpointer/lib/checkpointer/checkpointer-suid.c
* Use a setuid helper that writes to ns_last_pid.
Unfortunately, this helper delegation technique is impossible to use
with clone3, and is thus prone to races.
See https://github.com/twosigma/set_ns_last_pid
* Cycle through PIDs with fork() until the desired PID is reached:
This has been demonstrated to work with cycling rates of 100,000 PIDs/s
See https://github.com/twosigma/set_ns_last_pid
* Patch out the CAP_SYS_ADMIN check from the kernel
* Run the desired application in a new user and PID namespace to provide
a local CAP_SYS_ADMIN for controlling PIDs. This technique has limited
use in typical container environments (e.g., Kubernetes) as /proc is
typically protected with read-only layers (e.g., /proc/sys) for
hardening purposes. Read-only layers prevent additional /proc mounts
(due to proc's SB_I_USERNS_VISIBLE property), making the use of new
PID namespaces limited as certain applications need access to /proc
matching their PID namespace.
The introduced capability allows to:
* Control PIDs when the current user is CAP_CHECKPOINT_RESTORE capable
for the corresponding PID namespace via ns_last_pid/clone3.
* Open files in /proc/pid/map_files when the current user is
CAP_CHECKPOINT_RESTORE capable in the root namespace, useful for
recovering files that are unreachable via the file system such as
deleted files, or memfd files.
See corresponding selftest for an example with clone3().
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20200719100418.2112740-2-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Move (most of) the definitions of hashtab_search() and hashtab_insert()
to the header file. In combination with the previous patch, this avoids
calling the callbacks indirectly by function pointers and allows for
better optimization, leading to a drastic performance improvement of
these operations.
With this patch, I measured a speed up in the following areas (measured
on x86_64 F32 VM with 4 CPUs):
1. Policy load (`load_policy`) - takes ~150 ms instead of ~230 ms.
2. `chcon -R unconfined_u:object_r:user_tmp_t:s0:c381,c519 /tmp/linux-src`
where /tmp/linux-src is an extracted linux-5.7 source tarball -
takes ~522 ms instead of ~576 ms. This is because of many
symtab_search() calls in string_to_context_struct() when there are
many categories specified in the context.
3. `stress-ng --msg 1 --msg-ops 10000000` - takes 12.41 s instead of
13.95 s (consumes 18.6 s of kernel CPU time instead of 21.6 s).
This is thanks to security_transition_sid() being ~43% faster after
this patch.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Refactor searching and inserting into hashtabs to pave the way for
converting hashtab_search() and hashtab_insert() to inline functions in
the next patch. This will avoid indirect calls and allow the compiler to
better optimize individual callers, leading to a significant performance
improvement.
In order to avoid the indirect calls, the key hashing and comparison
callbacks need to be extracted from the hashtab struct and passed
directly to hashtab_search()/_insert() by the callers so that the
callback address is always known at compile time. The kernel's
rhashtable library (<linux/rhashtable*.h>) does the same thing.
This of course makes the hashtab functions slightly easier to misuse by
passing a wrong callback set, but unfortunately there is no better way
to implement a hash table that is both generic and efficien |
