[RFC PATCH v9 00/16] Integrity Policy Enforcement LSM (IPE)
by Fan Wu
Overview:
---------
IPE is a Linux Security Module which takes a complimentary approach to
access control. Whereas existing mandatory access control mechanisms
base their decisions on labels and paths, IPE instead determines
whether or not an operation should be allowed based on immutable
security properties of the system component the operation is being
performed on.
IPE itself does not mandate how the security property should be
evaluated, but relies on an extensible set of external property providers
to evaluate the component. IPE makes its decision based on reference
values for the selected properties, specified in the IPE policy.
The reference values represent the value that the policy writer and the
local system administrator (based on the policy signature) trust for the
system to accomplish the desired tasks.
One such provider is for example dm-verity, which is able to represent
the integrity property of a partition (its immutable state) with a digest.
IPE is compiled under CONFIG_SECURITY_IPE.
Use Cases
---------
IPE works best in fixed-function devices: Devices in which their purpose
is clearly defined and not supposed to be changed (e.g. network firewall
device in a data center, an IoT device, etcetera), where all software and
configuration is built and provisioned by the system owner.
IPE is a long-way off for use in general-purpose computing: the Linux
community as a whole tends to follow a decentralized trust model,
known as the web of trust, which IPE has no support for as of yet.
There are exceptions, such as the case where a Linux distribution
vendor trusts only their own keys, where IPE can successfully be used
to enforce the trust requirement.
Additionally, while most packages are signed today, the files inside
the packages (for instance, the executables), tend to be unsigned. This
makes it difficult to utilize IPE in systems where a package manager is
expected to be functional, without major changes to the package manager
and ecosystem behind it.
DIGLIM[1] is a system that when combined with IPE, could be used to
enable general purpose computing scenarios.
Policy:
-------
IPE policy is a plain-text policy composed of multiple statements
over several lines. There is one required line, at the top of the
policy, indicating the policy name, and the policy version, for
instance:
policy_name=Ex_Policy policy_version=0.0.0
The policy version indicates the current version of the policy. This is
used to prevent roll-back of policy to potentially insecure previous
versions of the policy.
The next portion of IPE policy, are rules. Rules are formed by key=value
pairs, known as properties. IPE rules require two keys: "action", which
determines what IPE does when it encounters a match against the policy
and "op", which determines when that rule should be evaluated.
Thus, a minimal rule is:
op=EXECUTE action=ALLOW
This example rule will allow any execution. A rule is required to have the
"op" property as the first token of a rule, and the "action" as the last
token of the rule.
Additional properties are used to restrict attributes about the files being
evaluated. These properties are intended to be deterministic attributes
that are resident in the kernel.
For example:
op=EXECUTE dmverity_signature=FALSE action=DENY
This rule with property dmverity_signature will deny any file not from
a signed dmverity volume to be executed.
All available properties for IPE described in the documentation patch of
this series.
Rules are evaluated top-to-bottom. As a result, any revocation rules,
or denies should be placed early in the file to ensure that these rules
are evaluated before a rule with "action=ALLOW" is hit.
Any unknown syntax in IPE policy will result in a fatal error to parse
the policy.
Additionally, a DEFAULT operation must be set for all understood
operations within IPE. For policies to remain completely forwards
compatible, it is recommended that users add a "DEFAULT action=ALLOW"
and override the defaults on a per-operation basis.
For more information about the policy syntax, see the kernel
documentation page.
Early Usermode Protection:
--------------------------
IPE can be provided with a policy at startup to load and enforce.
This is intended to be a minimal policy to get the system to a state
where userspace is setup and ready to receive commands, at which
point a policy can be deployed via securityfs. This "boot policy" can be
specified via the config, SECURITY_IPE_BOOT_POLICY, which accepts a path
to a plain-text version of the IPE policy to apply. This policy will be
compiled into the kernel. If not specified, IPE will be disabled until a
policy is deployed and activated through the method above.
Policy Examples:
----------------
Allow all:
policy_name=Allow_All policy_version=0.0.0
DEFAULT action=ALLOW
Allow only initial superblock:
policy_name=Allow_All_Initial_SB policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE boot_verified=TRUE action=ALLOW
Allow any signed dm-verity volume and the initial superblock:
policy_name=AllowSignedAndInitial policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE boot_verified=TRUE action=ALLOW
op=EXECUTE dmverity_signature=TRUE action=ALLOW
Prohibit execution from a specific dm-verity volume, while allowing
all signed volumes and the initial superblock:
policy_name=ProhibitSingleVolume policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE dmverity_roothash=sha256:401fcec5944823ae12f62726e8184407a5fa9599783f030dec146938 action=DENY
op=EXECUTE boot_verified=TRUE action=ALLOW
op=EXECUTE dmverity_signature=TRUE action=ALLOW
Allow only a specific dm-verity volume:
policy_name=AllowSpecific policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE dmverity_roothash=sha256:401fcec5944823ae12f62726e8184407a5fa9599783f030dec146938 action=ALLOW
Allow any signed fs-verity file
policy_name="AllowSignedFSVerity" policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE fsverity_signature=TRUE action=ALLOW
Deny a specific fs-verity file:
policy_name="ProhibitSpecificFSVF" policy_version=0.0.0
DEFAULT action=DENY
op=EXECUTE fsverity_digest=sha256:fd88f2b8824e197f850bf4c5109bea5cf0ee38104f710843bb72da796ba5af9e action=DENY
op=EXECUTE boot_verified=TRUE action=ALLOW
op=EXECUTE dmverity_signature=TRUE action=ALLOW
Deploying Policies:
-------------------
First sign a plain text policy, with a certificate that is present in
the SYSTEM_TRUSTED_KEYRING of your test machine. Through openssl, the
signing can be done via:
openssl smime -sign -in "$MY_POLICY" -signer "$MY_CERTIFICATE" \
-inkey "$MY_PRIVATE_KEY" -outform der -noattr -nodetach \
-out "$MY_POLICY.p7s"
Then, simply cat the file into the IPE's "new_policy" securityfs node:
cat "$MY_POLICY.p7s" > /sys/kernel/security/ipe/new_policy
The policy should now be present under the policies/ subdirectory, under
its "policy_name" attribute.
The policy is now present in the kernel and can be marked as active,
via the securityfs node:
echo 1 > "/sys/kernel/security/ipe/$MY_POLICY_NAME/active"
This will now mark the policy as active and the system will be enforcing
$MY_POLICY_NAME.
There is one requirement when marking a policy as active, the policy_version
attribute must either increase, or remain the same as the currently running
policy.
Policies can be updated via:
cat "$MY_UPDATED_POLICY.p7s" > \
"/sys/kernel/security/ipe/policies/$MY_POLICY_NAME/update"
Additionally, policies can be deleted via the "delete" securityfs
node. Simply write "1" to the corresponding node in the policy folder:
echo 1 > "/sys/kernel/security/ipe/policies/$MY_POLICY_NAME/delete"
There is only one requirement to delete policies, the policy being
deleted must not be the active policy.
NOTE: Any securityfs write to IPE's nodes will require CAP_MAC_ADMIN.
Integrations:
-------------
This patch series adds support for fsverity via digest and signature
(fsverity_signature and fsverity_digest), dm-verity by digest and
signature (dmverity_signature and dmverity_roothash), and trust for
the initramfs (boot_verified).
Please see the documentation patch for more information about the
integrations available.
Testing:
--------
KUnit Tests are available. Recommended kunitconfig:
CONFIG_KUNIT=y
CONFIG_SECURITY=y
CONFIG_SECURITYFS=y
CONFIG_PKCS7_MESSAGE_PARSER=y
CONFIG_SYSTEM_DATA_VERIFICATION=y
CONFIG_FS_VERITY=y
CONFIG_FS_VERITY_BUILTIN_SIGNATURES=y
CONFIG_BLOCK=y
CONFIG_MD=y
CONFIG_BLK_DEV_DM=y
CONFIG_DM_VERITY=y
CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG=y
CONFIG_NET=y
CONFIG_AUDIT=y
CONFIG_AUDITSYSCALL=y
CONFIG_SECURITY_IPE=y
CONFIG_IPE_PROP_DM_VERITY=y
CONFIG_IPE_PROP_FS_VERITY=y
CONFIG_SECURITY_IPE_KUNIT_TEST=y
Simply run:
make ARCH=um mrproper
./tools/testing/kunit/kunit.py run --kunitconfig <path/to/config>
And the tests will execute and report the result. For more indepth testing,
it will require you to create and mount a dm-verity volume or fs-verity
enabled file.
Documentation:
--------------
There is both documentation available on github at
https://microsoft.github.io/ipe, and Documentation in this patch series,
to be added in-tree.
Known Gaps:
-----------
IPE has two known gaps:
1. IPE cannot verify the integrity of anonymous executable memory, such as
the trampolines created by gcc closures and libffi (<3.4.2), or JIT'd code.
Unfortunately, as this is dynamically generated code, there is no way
for IPE to ensure the integrity of this code to form a trust basis. In all
cases, the return result for these operations will be whatever the admin
configures the DEFAULT action for "EXECUTE".
2. IPE cannot verify the integrity of interpreted languages' programs when
these scripts invoked via ``<interpreter> <file>``. This is because the
way interpreters execute these files, the scripts themselves are not
evaluated as executable code through one of IPE's hooks. Interpreters
can be enlightened to the usage of IPE by trying to mmap a file into
executable memory (+X), after opening the file and responding to the
error code appropriately. This also applies to included files, or high
value files, such as configuration files of critical system components.
Appendix:
---------
A. IPE Github Repository: https://github.com/microsoft/ipe
B. IPE Users' Guide: Documentation/admin-guide/LSM/ipe.rst
References:
-----------
1: https://lore.kernel.org/bpf/4d6932e96d774227b42721d9f645ba51@huawei.com/T/
FAQ:
----
Q: What is the difference between IMA and IPE?
A: See the documentation patch for more on this topic.
Previous Postings
-----------------
v1: https://lore.kernel.org/all/20200406181045.1024164-1-deven.desai@linux.mi...
v2: https://lore.kernel.org/all/20200406221439.1469862-1-deven.desai@linux.mi...
v3: https://lore.kernel.org/all/20200415162550.2324-1-deven.desai@linux.micro...
v4: https://lore.kernel.org/all/20200717230941.1190744-1-deven.desai@linux.mi...
v5: https://lore.kernel.org/all/20200728213614.586312-1-deven.desai@linux.mic...
v6: https://lore.kernel.org/all/20200730003113.2561644-1-deven.desai@linux.mi...
v7: https://lore.kernel.org/all/1634151995-16266-1-git-send-email-deven.desai...
v8: https://lore.kernel.org/all/1654714889-26728-1-git-send-email-deven.desai...
Changelog:
----------
v2:
Split the second patch of the previous series into two.
Minor corrections in the cover-letter and documentation
comments regarding CAP_MAC_ADMIN checks in IPE.
v3:
Address various comments by Jann Horn. Highlights:
Switch various audit allocators to GFP_KERNEL.
Utilize rcu_access_pointer() in various locations.
Strip out the caching system for properties
Strip comments from headers
Move functions around in patches
Remove kernel command line parameters
Reconcile the race condition on the delete node for policy by
expanding the policy critical section.
Address a few comments by Jonathan Corbet around the documentation
pages for IPE.
Fix an issue with the initialization of IPE policy with a "-0"
version, caused by not initializing the hlist entries before
freeing.
v4:
Address a concern around IPE's behavior with unknown syntax.
Specifically, make any unknown syntax a fatal error instead of a
warning, as suggested by Mickaël Salaün.
Introduce a new securityfs node, $securityfs/ipe/property_config,
which provides a listing of what properties are enabled by the
kernel and their versions. This allows usermode to predict what
policies should be allowed.
Strip some comments from c files that I missed.
Clarify some documentation comments around 'boot_verified'.
While this currently does not functionally change the property
itself, the distinction is important when IPE can enforce verified
reads. Additionally, 'KERNEL_READ' was omitted from the documentation.
This has been corrected.
Change SecurityFS and SHA1 to a reverse dependency.
Update the cover-letter with the updated behavior of unknown syntax.
Remove all sysctls, making an equivalent function in securityfs.
Rework the active/delete mechanism to be a node under the policy in
$securityfs/ipe/policies.
The kernel command line parameters ipe.enforce and ipe.success_audit
have returned as this functionality is no longer exposed through
sysfs.
v5:
Correct some grammatical errors reported by Randy Dunlap.
Fix some warnings reported by kernel test bot.
Change convention around security_bdev_setsecurity. -ENOSYS
is now expected if an LSM does not implement a particular @name,
as suggested by Casey Schaufler.
Minor string corrections related to the move from sysfs to securityfs
Correct a spelling of an #ifdef for the permissive argument.
Add the kernel parameters re-added to the documentation.
Fix a minor bug where the mode being audited on permissive switch
was the original mode, not the mode being swapped to.
Cleanup doc comments, fix some whitespace alignment issues.
v6:
Change if statement condition in security_bdev_setsecurity to be
more concise, as suggested by Casey Schaufler and Al Viro
Drop the 6th patch in the series, "dm-verity move signature check..."
due to numerous issues, and it ultimately providing no real value.
Fix the patch tree - the previous iteration appears to have been in a
torn state (patches 8+9 were merged). This has since been corrected.
v7:
* Reword cover letter to more accurate convey IPE's purpose
and latest updates.
* Refactor series to:
1. Support a context structure, enabling:
1. Easier Testing via KUNIT
2. A better architecture for future designs
2. Make parser code cleaner
* Move patch 01/12 to [14/16] of the series
* Split up patch 02/12 into four parts:
1. context creation [01/16]
2. audit [07/16]
3. evaluation loop [03/16]
4. access control hooks [05/16]
5. permissive mode [08/16]
* Split up patch 03/12 into two parts:
1. parser [02/16]
2. userspace interface [04/16]
* Reword and refactor patch 04/12 to [09/16]
* Squash patch 05/12, 07/12, 09/12 to [10/16]
* Squash patch 08/12, 10/12 to [11/16]
* Change audit records to MAC region (14XX) from Integrity region (18XX)
* Add FSVerity Support
* Interface changes:
1. "raw" was renamed to "pkcs7" and made read only
2. "raw"'s write functionality (update a policy) moved to "update"
3. introduced "version", "policy_name" nodes.
4. "content" renamed to "policy"
5. The boot policy can now be updated like any other policy.
* Add additional developer-level documentation
* Update admin-guide docs to reflect changes.
* Kunit tests
* Dropped CONFIG_SECURITY_IPE_PERMISSIVE_SWITCH - functionality can
easily come later with a small patch.
* Use partition0 for block_device for dm-verity patch
v8:
* Add changelog information to individual commits
* A large number of changes to the audit patch.
* split fs/ & security/ changes to two separate patches.
* split block/, security/ & drivers/md/ changes to separate patches.
* Add some historical context to what lead to the creation of IPE
in the documentation patch.
* Cover-letter changes suggested by Roberto Sassu.
v9:
* Rewrite IPE parser to use kernel match_table parser.
* Adapt existing IPE properties to the new parser.
* Remove ipe_context, quote policy syntax, kernel_read for simplicity.
* Add new function in the security file system to delete IPE policy.
* Make IPE audit builtin and change several audit formats.
* Make boot_verified property builtin
Deven Bowers (13):
security: add ipe lsm
ipe: add policy parser
ipe: add evaluation loop and introduce 'boot_verified' as a trust
provider
ipe: add userspace interface
ipe: add LSM hooks on execution and kernel read
uapi|audit|ipe: add ipe auditing support
ipe: add permissive toggle
block|security: add LSM blob to block_device
dm-verity: consume root hash digest and signature data via LSM hook
ipe: add support for dm-verity as a trust provider
scripts: add boot policy generation program
ipe: kunit test for parser
documentation: add ipe documentation
Fan Wu (3):
security: add new securityfs delete function
fsverity: consume builtin signature via LSM hook
ipe: enable support for fs-verity as a trust provider
Documentation/admin-guide/LSM/index.rst | 1 +
Documentation/admin-guide/LSM/ipe.rst | 729 ++++++++++++++++++
.../admin-guide/kernel-parameters.txt | 12 +
Documentation/security/index.rst | 1 +
Documentation/security/ipe.rst | 436 +++++++++++
MAINTAINERS | 8 +
block/bdev.c | 7 +
drivers/md/dm-verity-target.c | 25 +-
drivers/md/dm-verity-verify-sig.c | 16 +-
drivers/md/dm-verity-verify-sig.h | 10 +-
fs/verity/fsverity_private.h | 2 +-
fs/verity/open.c | 13 +-
fs/verity/signature.c | 1 +
include/linux/blk_types.h | 3 +
include/linux/dm-verity.h | 19 +
include/linux/fsverity.h | 2 +
include/linux/lsm_hook_defs.h | 5 +
include/linux/lsm_hooks.h | 12 +
include/linux/security.h | 23 +
include/uapi/linux/audit.h | 1 +
scripts/Makefile | 1 +
scripts/ipe/Makefile | 2 +
scripts/ipe/polgen/.gitignore | 1 +
scripts/ipe/polgen/Makefile | 6 +
scripts/ipe/polgen/polgen.c | 145 ++++
security/Kconfig | 11 +-
security/Makefile | 1 +
security/inode.c | 25 +
security/ipe/.gitignore | 1 +
security/ipe/Kconfig | 75 ++
security/ipe/Makefile | 32 +
security/ipe/audit.c | 279 +++++++
security/ipe/audit.h | 19 +
security/ipe/digest.c | 144 ++++
security/ipe/digest.h | 26 +
security/ipe/eval.c | 424 ++++++++++
security/ipe/eval.h | 60 ++
security/ipe/fs.c | 242 ++++++
security/ipe/fs.h | 17 +
security/ipe/hooks.c | 275 +++++++
security/ipe/hooks.h | 42 +
security/ipe/ipe.c | 97 +++
security/ipe/ipe.h | 22 +
security/ipe/policy.c | 259 +++++++
security/ipe/policy.h | 93 +++
security/ipe/policy_fs.c | 459 +++++++++++
security/ipe/policy_parser.c | 545 +++++++++++++
security/ipe/policy_parser.h | 11 +
security/ipe/policy_tests.c | 294 +++++++
security/security.c | 70 ++
50 files changed, 4988 insertions(+), 16 deletions(-)
create mode 100644 Documentation/admin-guide/LSM/ipe.rst
create mode 100644 Documentation/security/ipe.rst
create mode 100644 include/linux/dm-verity.h
create mode 100644 scripts/ipe/Makefile
create mode 100644 scripts/ipe/polgen/.gitignore
create mode 100644 scripts/ipe/polgen/Makefile
create mode 100644 scripts/ipe/polgen/polgen.c
create mode 100644 security/ipe/.gitignore
create mode 100644 security/ipe/Kconfig
create mode 100644 security/ipe/Makefile
create mode 100644 security/ipe/audit.c
create mode 100644 security/ipe/audit.h
create mode 100644 security/ipe/digest.c
create mode 100644 security/ipe/digest.h
create mode 100644 security/ipe/eval.c
create mode 100644 security/ipe/eval.h
create mode 100644 security/ipe/fs.c
create mode 100644 security/ipe/fs.h
create mode 100644 security/ipe/hooks.c
create mode 100644 security/ipe/hooks.h
create mode 100644 security/ipe/ipe.c
create mode 100644 security/ipe/ipe.h
create mode 100644 security/ipe/policy.c
create mode 100644 security/ipe/policy.h
create mode 100644 security/ipe/policy_fs.c
create mode 100644 security/ipe/policy_parser.c
create mode 100644 security/ipe/policy_parser.h
create mode 100644 security/ipe/policy_tests.c
--
2.39.0
1 year, 11 months
- 7
- 73
small patch for issue with rules that have been (incorrecly) copied from Windows
by Carlos De Avillez
Hello,
We have had at least a few instances where customers configured audit rules on Windows, and then incorrectly
moved the resulting '.rules' files to Linux.
These files still had the Windows line terminator (CRLF). 'augenrules' read them without issues and generated the
/etc/audit/audit.rules file.
But on loading the new audit.rules, 'auditctl -R' will receive a bad return code, and stop loading the rules. The
resulting error is a bit on the cryptic side, and our customers do not seem to catch it easily.
The proposed fix is simple, and resolves the issue when using 'augenrules'. Of course, if someone generates
/etc/audit/audit.rules directly, it could still fail, but I understand that we are moving to using 'augenrules' by
default.
Patch (against current head) is below.
Cheers,
..Carlos..
From 4ccae6353500d3870d4da8905ed01d18d36b066a Mon Sep 17 00:00:00 2001
From: C de-Avillez <cadeavil(a)microsoft.com>
Date: Fri, 10 Feb 2023 17:16:09 -0600
Subject: [PATCH] augenrules: make sure no lines in *.rules ends in CRLF,
otherwise 'auditctl -R' will then fail to fully load the rules.
---
init.d/augenrules | 1 +
1 file changed, 1 insertion(+)
diff --git a/init.d/augenrules b/init.d/augenrules
index edb2199..f74c6e2 100644
--- a/init.d/augenrules
+++ b/init.d/augenrules
@@ -84,6 +84,7 @@ BEGIN {
minus_b = "";
rest = 0;
} {
+ sub(/\r$/, "");
if (length($0) < 1) { next; }
if (match($0, "^\\s*#")) { next; }
if (match($0, "^\\s*-e")) { minus_e = $0; next; }
--
2.34.1
Carlos
de Avillez
Senior
Escalation Engineer
Microsoft Azure Technical Support
Customer Service and Support
Office: +1 (469) 7753777
cadeavil(a)microsoft.com
Working
hours: 10:00-19:00
US Central Time
Next days off during August 2020: 3, 10, 17, 24, 31
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working hours, please send email to azurebu(a)microsoft.com with
your case number, and availability.
We are always interested to hear your feedback. Please feel free
to reach my manager regarding the level of service you have received - spogge(a)microsoft.com
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Policy
1 year, 12 months
- 3
- 3
Help with setting up Auditd kernel repository
by Anurag Aggarwal
Hello All,
Will anyone help me with some documentation on how to build and test
auditd-kernel repository?
--
Anurag Aggarwal
2 years
- 2
- 3
run script after auditd rotates logs
by Christiansen, Edward - 0992 - MITLL
I would like to know if there is a way to tell auditd to run a script or
command after it rotates its logs. I can do this with logrotate, but would
much prefer something native to auditd. I spent some toime with Google and
found only logrotate solutions.
Thanks,
Ed Christiansen
Millstone Hill SysAdmin
2 years
- 3
- 3
audit userspace problems with io_uring async ops
by Paul Moore
Hi all,
We just recently started picking up audit-testsuite failures with the
latest upstream kernels and I tracked it down to a change in how the
IORING_OP_OPENAT operation is handled, and how Steve's audit userspace
displays async io_uring ops. It appears that when ausearch is used to
look for events it doesn't display async io_uring events (URINGOP
records/events without an associated SYSCALL record/event). Take the
following snippet from /var/log/audit/audit.log:
--- 287 ---
type=SYSCALL msg=audit(1677618568.199:287): arch=c000003e syscall=426
success=yes exit=1 a0=4 a1=1 a2=0 a3=0 items=1 ppid=1498 pid=1499
auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0
tty=pts1 ses=3 comm="iouring" exe="/.../iouring"
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
key="testsuite-1677618568-WJBbDxKg"ARCH=x86_64 SYSCALL=io_uring_enter ...
type=CWD msg=audit(1677618568.199:287):
cwd="/root/sources/audit-testsuite/tests/io_uring"
type=PATH msg=audit(1677618568.199:287): item=0
name="/tmp/iouring.4.txt" nametype=UNKNOWN ...
type=PROCTITLE msg=audit(1677618568.199:287):
proctitle=2E2F696F7572696E670074315F6368696C64
--- 288 ---
type=URINGOP msg=audit(1677618568.199:288): uring_op=18 success=yes exit=0
items=1 ppid=1498 pid=1499
uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
key="testsuite-1677618568-WJBbDxKg"URING_OP=openat ...
type=CWD msg=audit(1677618568.199:288):
cwd="/root/sources/audit-testsuite/tests/io_uring"
type=PATH msg=audit(1677618568.199:288): item=0 name="/tmp/iouring.4.txt"
inode=33 dev=00:22 mode=0100644 ouid=0 ogid=0 rdev=00:00
obj=unconfined_u:object_r:user_tmp_t:s0 nametype=NORMAL ...
--- 289 ---
type=SYSCALL msg=audit(1677618568.199:289): arch=c000003e syscall=426
success=yes exit=0 a0=4 a1=0 a2=1 a3=1 items=0 ppid=1498 pid=1499
auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0
tty=pts1 ses=3 comm="iouring" exe="/.../iouring"
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
key="testsuite-1677618568-WJBbDxKg"ARCH=x86_64 SYSCALL=io_uring_enter ...
type=PROCTITLE msg=audit(1677618568.199:289):
proctitle=2E2F696F7572696E670074315F6368696C64
... and the matching ausearch output:
% ausearch -i -k "testsuite-1677618568-WJBbDxKg"
----
type=PROCTITLE msg=audit(02/28/2023 16:09:28.199:287) :
proctitle=./iouring t1_child
type=PATH msg=audit(02/28/2023 16:09:28.199:287) : item=0
name=/tmp/iouring.4.txt nametype=UNKNOWN ...
type=CWD msg=audit(02/28/2023 16:09:28.199:287) :
cwd=/root/sources/audit-testsuite/tests/io_uring
type=SYSCALL msg=audit(02/28/2023 16:09:28.199:287) : arch=x86_64
syscall=io_uring_enter success=yes exit=1 a0=0x4 a1=0x1 a2=0x0 a3=0x0 items=1
ppid=1498 pid=1499 auid=root uid=root gid=root euid=root suid=root fsuid=root
egid=root sgid=root fsgid=root tty=pts1 ses=3 comm=iouring exe=/.../iouring
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
key=testsuite-1677618568-WJBbDxKg
----
type=PROCTITLE msg=audit(02/28/2023 16:09:28.199:289) :
proctitle=./iouring t1_child
type=SYSCALL msg=audit(02/28/2023 16:09:28.199:289) : arch=x86_64
syscall=io_uring_enter success=yes exit=0 a0=0x4 a1=0x0 a2=0x1 a3=0x1 items=0
ppid=1498 pid=1499 auid=root uid=root gid=root euid=root suid=root fsuid=root
egid=root sgid=root fsgid=root tty=pts1 ses=3 comm=iouring exe=/.../iouring
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
key=testsuite-1677618568-WJBbDxKg
----
... if you look closely you'll notice that the #289 event (the async
URINGOP) is missing from the ausearch output.
The good news is that this is easily reproducible on current upstream
kernels and Steve's v3.1 audit userspace release using the
audit-testsuite io_uring tests. This can also be seen in Rawhide with
current packages:
% uname -r
6.3.0-0.rc0.20230228gitae3419fb.9.1.secnext.fc39.x86_64
% rpm -q audit
audit-3.1-2.fc39.x86_64
% pwd
/root/sources/audit-testsuite/tests/io_uring
% git log --oneline | head -n 1
44c933e tests/filter_exclude: euid filtering now possible in exclude filter
Once ausearch is fixed we will also need to update the audit-testsuite
to add an explicit io_uring filter for the IORING_OP_OPENAT op. The
patch below is untested (blocked on ausearch), but I expect it to
resolve the issue in the test suite:
>>>
diff --git a/tests/io_uring/test b/tests/io_uring/test
index 9eb427a..df13af0 100755
--- a/tests/io_uring/test
+++ b/tests/io_uring/test
@@ -49,6 +49,7 @@ system("auditctl -D >& /dev/null");
# set our io_uring filters
system("auditctl -a exit,always -F arch=b$abi_bits -S io_uring_setup -k $key");
system("auditctl -a exit,always -F arch=b$abi_bits -S io_uring_enter -k $key");
+system("auditctl -a io_uring,always -S openat -k $key");
# run the "t1" test
system("$basedir/iouring t1");
>>>
For the kernel folks, the relevant commit is likely 0ffae640ad83
("io_uring: always go async for unsupported open flags"). I believe
what happened in the past is we caught the initial failing/-EAGAIN
io_uring op with the syscall record, e.g. #287 in the example above,
but now that IORING_OP_OPENAT goes straight to an async/io_wq op we
don't "see" it as ausearch isn't showing that (maybe needs to learn to
search URINGOP records too? dunno.). Arguably this was always a
problem with the test, we just got a bit lucky because io_uring would
attempt to do IORING_OP_OPENAT synchronously at first.
--
paul-moore.com
2 years
- 2
- 6
Clarification Around File System Auditing
by Amjad Gabbar
Hi Everyone,
I wanted some help in better understanding the workflow of file system
auditing(watch rules) vs Syscall Auditing(syscall rules). I know in general
file system auditing does not have the same performance impact as syscall
auditing, even though both make use of syscall exits for their evaluation.
>From the manpage - "Unlike most syscall auditing rules, watches do not
impact performance based on the number of rules sent to the kernel."
>From a previous thread, I found this excerpt regarding file watch rules vs
sycall rules -
"The reason it doesn't have performance impact like normal syscall rules is
because it gets moved to a list that is not evaluated every syscall. A
normal syscall rule will get evaluated for every syscall because it has to
see if the syscall number is of interest and then it checks the next rule."
Based on this I had a couple of questions:
For normal syscall rules, the evaluation happens as __audit_syscall_exit
<https://elixir.bootlin.com/linux/v6.1.10/C/ident/__audit_syscall_exit> calls
audit_filter_syscall
(https://elixir.bootlin.com/linux/v6.1.10/source/kernel/auditsc.c#L841)
Here, we check if the syscall is of interest or not in the audit_in_mask
<https://elixir.bootlin.com/linux/v6.1.10/C/ident/audit_in_mask> function.
Only if the syscall is of interest do we proceed with examining the task
and return on the first rule match.
1. What is the process or code path for watch rules? audit_filter_syscall
<https://elixir.bootlin.com/linux/v6.1.10/C/ident/audit_filter_syscall> is
called for watch rules as well. Then how is it that these are not called
for every syscall? Could you point me to the code where the evaluation
happens only once?
2. Also, do file watches only involve the open system call family (open,
openat etc). The man page implies the same, so just wanted to confirm.
I assume -w /etc -p wa is the same as -a always,exit -S open -S openat -F
dir=/etc?
Please correct any wrong assumption I may have as well.
Regards
2 years
- 3
- 6
Auditing nftables changes
by Bruce Elrick
Hello all,
I'm not sure if this list is appropriate for questions so please let
me know and otherwise ignore if this message is not appropriate.
I'm trying to help someone who is finally migrating from iptables to
nftables on the back-end and needs to therefore migrate their audit
capability.
Currently they have a single simple audit rule to detect when there is
a iptable change from any audit user apart from their service user
using a rule like the accepted answer given in this[0] StackExchange
question, although with added filters on the auid (I have to admit I
don't know the origin of auid=-1 events):
auditctl -a exit,always -F arch=b64 -F a2=64 -F auid!=-1 -F
auid!=${serviceuser_uid} -S setsockopt -k iptablesChange
They are migrating from Ubuntu bionic to jammy and still using the
iptables front-end but since the back-end changes from default
iptables to default nftables they need to change their audit rules
They did strace testing and noted the syscall changing from
setsockopt(4, SOL_IP, IPT_SO_SET_REPLACE,
"filter\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
80952) = 0
to
sendto(3, [{nlmsg_len=20,
nlmsg_type=NFNL_SUBSYS_NFTABLES<<8|NFT_MSG_GETGEN,
nlmsg_flags=NLM_F_REQUEST, nlmsg_seq=0, nlmsg_pid=0},
{nfgen_family=AF_UNSPEC, version=NFNETLINK_V0, res_id=htons(0)}], 20,
0, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 20
between the two versions.
In my own testing, I decided to approach from the audit tools
perspective so I created a broad rule to capture all system call
related to a test user:
auditctl -a always,exit -S all -F auid=1001 # 1001 is uid of testuser
Then I tried various operations using my testuser such as
iptables-restore of either a default-accept rule set with no rules or
with one or two simple drop rules. I also tested adding just a single
iptables rule. I then used ausearch to discover what the audit system
captured:
# ausearch -i -m NETFILTER_CFG
...
----
type=PROCTITLE msg=audit(03/07/2023 17:18:55.152:143044) :
proctitle=iptables-restore
type=SYSCALL msg=audit(03/07/2023 17:18:55.152:143044) :
arch=x86_64 syscall=sendmsg success=yes exit=764 a0=0x3
a1=0x7ffdb0e98db0 a2=0x0 a3=0x7ffdb0e98d9c items=0 ppid=5673 pid=5676
auid=testuser uid=root gid=root euid=root suid=root fsuid=root
egid=root sgid=root fsgid=root tty=pts2 ses=108 comm=iptables-restor
exe=/usr/sbin/xtables-nft-multi subj=unconfined key=(null)
type=NETFILTER_CFG msg=audit(03/07/2023 17:18:55.152:143044) :
table=filter:30 family=ipv4 entries=12 op=nft_unregister_table
pid=5676 subj=unconfined comm=iptables-restor
type=NETFILTER_CFG msg=audit(03/07/2023 17:18:55.152:143044) :
table=filter:30 family=ipv4 entries=7 op=nft_register_chain pid=5676
subj=unconfined comm=iptables-restor
----
type=PROCTITLE msg=audit(03/07/2023 17:23:04.390:144459) :
proctitle=sudo /usr/sbin/iptables -A OUTPUT -d 10.100.249.64 -j DROP
type=SOCKADDR msg=audit(03/07/2023 17:23:04.390:144459) : saddr={
saddr_fam=netlink nlnk-fam=16 nlnk-pid=0 }
type=SYSCALL msg=audit(03/07/2023 17:23:04.390:144459) :
arch=x86_64 syscall=sendmsg success=yes exit=304 a0=0x3
a1=0x7ffc80659110 a2=0x0 a3=0x7ffc806590fc items=0 ppid=5703 pid=5704
auid=testuser uid=root gid=root euid=root suid=root fsuid=root
egid=root sgid=root fsgid=root tty=pts2 ses=108 comm=iptables
exe=/usr/sbin/xtables-nft-multi subj=unconfined key=(null)
type=NETFILTER_CFG msg=audit(03/07/2023 17:23:04.390:144459) :
table=filter:31 family=ipv4 entries=1 op=nft_register_rule pid=5704
subj=unconfined comm=iptables
The event sequences seem to make sense with the sockaddr function
selecting the netlink family which agrees with the strace output.
With the change in the back-end to nftables, I can see in either case
that the setsockopt system call with a nice, crisp, single argument
(a2=64/IPT_SO_SET_REPLACE) option with either a sendto or sendmsg
system call but with a pointer to a message structure. I read that
audit rules cannot filter using data inside struct arguments.
My naive interpretation of this is that I'd need to have a rule that
captures all sendmsg syscalls with (auid!=-1 and
auid!=${serviceuser_uid} but I don't know enough about socket syscall
usage to know whether this is too much. I see that write(2) to a
socket is the same as send(2) without the flags so I might assume that
most socket syscalls that are sending data use write(2) and not
send/sendto/sendmsg(2) but I worry this would be too much audit data.
Anyone care to comment or point me in the correct direction?
Cheers...
Bruce
[0] https://unix.stackexchange.com/questions/206891/audit-on-changes-to-the-r...
--
Bruce Elrick, Ph.D.
Dedicated Support Engineer
Canonical
2 years
- 4
- 9
Key based rate limiter (audit_set_rate_limit)
by Anurag Aggarwal
Hello All,
The current rate limiter, audit_set_rate_limit limits all types of events.
In our case, we want to limit auditd events with a specific key, as they
are very noisy and consume very high CPU.
>From my understanding, this support is currently missing in AuditD.
Is my understanding correct?
--
Anurag Aggarwal
2 years, 1 month
- 4
- 14
How to define audit rule for one bit *not* set for a syscall argument?
by Richard Du
Hello all,
I'm trying to define an audit rule with auditctl for clone() syscall, and I
would expect that the a0 of clone() syscall (i.e. the clone_flags argument)
without the CLONE_THREAD flag bit being set.
int clone(int (*fn)(void *), void *stack, int flags, void *arg, ...
/* pid_t *parent_tid, void *tls, pid_t *child_tid */ );
>From man page of auditctl, -F option build a rule file: name, operation,
value.
-F [n=v | n!=v | n<v | n>v | n<=v | n>=v | n&v | n&=v]
I can understand that, the n&v (Audit_bitmask) means any bit of a bitmast
is set, and the n&=v (Audit_bittest) means all bits of a bitmask are set.
While my question is, how to build a rule which means "none of bit of a
bitmask is set", i.e. ( ! n&=v ). If the current audit comparator dosen't
support this, can we add the support in furture?
Thanks,
Richard
2 years, 1 month
- 2
- 2
[PATCH v38 00/39] LSM: Module stacking for AppArmor
by Casey Schaufler
This patchset provides the changes required for
the AppArmor security module to stack safely with any other.
There are additional changes required for SELinux and Smack
to coexist. These are primarily in the networking code and
will be addressed after these changes are upstream.
v38: Rebase to 6.0-rc7
- Discard the implementation of /proc/self/attr/context
- Discard the implementation of /proc/self/attr/display_lsm
- Implement a system call lsm_self_attr() which provides
a complete list of LSM process attributes.
- Implement a system call lsm_module_list() which provides
a list of the security modules active on the system.
- Implement a pair of prctl() options PR_LSM_ATTR_SET
and PR_LSM_ATTR_GET. These are used to control the LSM
that provides the values in /proc/.../attr entries.
- Make more of the infrastructure data changes early in the
patch set in support of the new system calls.
- Add a user interface header uapi/linux/lsm.h which contains
the format of data provided by lsm_self_attr() and the
integer LSM identifier values.
v37: Rebase to 5.19-rc3
- Audit changes should be complete, all comments have been
addressed.
- Address indexing an empty array for the case where no
built in security modules require data in struct lsmblob.
- Fix a few checkpatch complaints.
v36: Rebase to 5.19-rc1
- Yet another rework of the audit changes. Rearranging how the
timestamp is managed allows auxiliary records to be generated
correctly with a minimum of fuss.
- In the end no LSM interface scaffolding remains. Secids have
been replaced with lsmblob structures in all cases, including
IMA and NetLabel.
v35: Rebase to 5.18-rc2
- Address the case where CONFIG_SECURITY is enabled but
no security modules that use secid slots are included.
The resulting blob.secid[0] instances, although never
present in a call path, raised concerns.
- Address the case in interface_lsm where the BPF module
returns -EINVAL, resulting in a failed setting of the
value that would be otherwise allowed.
v34: Rebase to 5.18-rc1
- Incorporate feedback on the audit generation.
v33:
- Rework the supplimental audit record generation once more,
this time taking pseudo-code provided by Paul Moore as a
basis. The resulting code is considerably simpler and fits
better with the existing code flow.
v32: Rebase to 5.17-rc2
- Incorporate additional feedback from v30.
v31: Rebase to 5.16-rc4
- Incorporate feedback from Paul Moore on the audit
component changes.
v30: Rebase to 5.16-rc1
- Replace the integrity sub-system reuse of the audit
subsystem event matching functions with IMA specific
functions. This is done because audit needs to maintain
information about multiple security modules in audit
rules while IMA to restricts the information to a single
security module.
- The binder hooks have been changed and are no longer
called with sufficient information to identify the
interface_lsm. Pass that information in the binder
message, and use that in the compatibility decision.
- Refactor the audit changes.
v29: Rebase to 5.15-rc1
- Rework the supplimental audit record generation. Attach
a list of supplimental data to the audit_buffer and
generate the auxiliary records as needed on event end.
This should be usable for other auxiliary data, such as
container IDs. There is other ongoing audit work that
will require integration with this.
v28: Rebase to 5.14-rc2
- Provide IMA rules bounds checking (patch 04)
- Quote contexts in MAC_TASK_CONTEXTS and MAC_OBJ_CONTEXTS
audit records because of AppArmor's use of '=' in context
values. (patch 22,23)
v27: Fixes for landlock (patch 02)
- Rework the subject audit record generation. This version is
simpler and reflects feedback from Paul Moore. (patch 22)
v26: Rebase to 5.13-rc1
- Include the landlock security module.
- Accomodate change from security_task_getsecid() to
security_task_getsecid_obj() and security_task_getsecid_subj().
v25: Rebase to 5.12-rc2
Incorporate feedback from v24
- The IMA team suggested improvements to the integrity rule
processing.
v24: Rebase to 5.11-rc1
Incorporate feedback from v23
- Address the IMA team's concerns about "label collisions".
A label collision occurs when there is ambiguity about
which of multiple LSMs is being targeted in the definition
of an integrity check rule. A system with Smack and
AppArmor would be unable to distinguish which LSM is
important to an integrity rule referrencing the label
"unconfined" as that label is meaningful to both.
Provide a boot option to specify which LSM will be used in
IMA rules when multiple LSMs are present. (patch 04)
Pull LSM "slot" identification from later audit patches in
in support of this (patch 03).
- Pick up a few audit events that need to include supplimental
subject context records that had been missed in the
previous version.
v23: Rebase to 5.10-rc4
Incorporate feedback from v22
- Change /proc/*/attr/display to /proc/*/attr/interface_lsm to
make the purpose clearer. (patch 0012)
- Include ABI documentation. (patch 0012, 0022)
- Introduce LSM documentation updates with the patches where
the interfaces are added rather than at the end. (patch 0012, 0022)
Include more maintainers and mail lists in To: and Cc: directives.
v22: Rebase to 5.10-rc1
v21: Rebase to 5.9-rc4
Incorporate feedback from v20
- Further revert UDS SO_PEERSEC to use scaffolding around
the interfaces that use lsmblobs and store only a single
secid. The possibility of multiple security modules
requiring data here is still a future problem.
- Incorporate Richard Guy Briggs' non-syscall auxiliary
records patch (patch 0019-0021) in place of my "supplimental"
records implementation. [I'm not sure I've given proper
attestation. I will correct as appropriate]
v20: Rebase to 5.9-rc1
Change the BPF security module to use the lsmblob data. (patch 0002)
Repair length logic in subject label processing (patch 0015)
Handle -EINVAL from the empty BPF setprocattr hook (patch 0020)
Correct length processing in append_ctx() (patch 0022)
v19: Rebase to 5.8-rc6
Incorporate feedback from v18
- Revert UDS SO_PEERSEC implementation to use lsmblobs
directly, rather than allocating as needed. The correct
treatment of out-of-memory conditions in the later case
is difficult to define. (patch 0005)
- Use a size_t in append_ctx() (patch 0021)
- Fix a memory leak when creating compound contexts. (patch 0021)
Fix build error when CONFIG_SECURITY isn't set (patch 0013)
Fix build error when CONFIG_SECURITY isn't set (patch 0020)
Fix build error when CONFIG_SECURITY isn't set (patch 0021)
v18: Rebase to 5.8-rc3
Incorporate feedback from v17
- Null pointer checking in UDS (patch 0005)
Match changes in IMA code (patch 0012)
Fix the behavior of LSM context supplimental audit
records so that there's always exactly one when it's
appropriate for there to be one. This is a substantial
change that requires extention of the audit_context beyond
syscall events. (patch 0020)
v17: Rebase to 5.7-rc4
v16: Rebase to 5.6
Incorporate feedback from v15 - Thanks Stephen, Mimi and Paul
- Generally improve commit messages WRT scaffolding
- Comment ima_lsm_isset() (patch 0002)
- Some question may remain on IMA warning (patch 0002)
- Mark lsm_slot as __lsm_ro_after_init not __init_data (patch 0002)
- Change name of lsmblob variable in ima_match_rules() (patch 0003)
- Instead of putting a struct lsmblob into the unix_skb_parms
structure put a pointer to an allocated instance. There is
currently only space for 5 u32's in unix_skb_parms and it is
likely to get even tighter. Fortunately, the lifecycle
management of the allocated lsmblob is simple. (patch 0005)
- Dropped Acks due to the above change (patch 0005)
- Improved commentary on secmark labeling scaffolding. (patch 0006)
- Reduced secmark related labeling scaffolding. (patch 0006)
- Replace use of the zeroth entry of an lsmblob in scaffolding
with a function lsmblob_value() to hopefully make it less
obscure. (patch 0006)
- Convert security_secmark_relabel_packet to use lsmblob as
this reduces much of the most contentious scaffolding. (patch 0006)
- Dropped Acks due to the above change (patch 0006)
- Added BUILD_BUG_ON() for CIPSO tag 6. (patch 0018)
- Reworked audit subject information. Instead of adding fields in
the middle of existing records add a new record to the event. When
a separate record is required use subj="?". (patch 0020)
- Dropped Acks due to the above change (patch 0020)
- Reworked audit object information. Instead of adding fields in
the middle of existing records add a new record to the event. When
a separate record is required use obj="?". (patch 0021)
- Dropped Acks due to the above change (patch 0021)
- Enhanced documentation (patch 0022)
- Removed unnecessary error code check in security_getprocattr()
(patch 0021)
v15: Rebase to 5.6-rc1
- Revise IMA data use (patch 0002)
Incorporate feedback from v14
- Fix lockdown module registration naming (patch 0002)
- Revise how /proc/self/attr/context is gathered. (patch 0022)
- Revise access modes on /proc/self/attr/context. (patch 0022)
- Revise documentation on LSM external interfaces. (patch 0022)
v14: Rebase to 5.5-rc5
Incorporate feedback from v13
- Use an array of audit rules (patch 0002)
- Significant change, removed Acks (patch 0002)
- Remove unneeded include (patch 0013)
- Use context.len correctly (patch 0015)
- Reorder code to be more sensible (patch 0016)
- Drop SO_PEERCONTEXT as it's not needed yet (patch 0023)
v13: Rebase to 5.5-rc2
Incorporate feedback from v12
- Print lsmblob size with %z (Patch 0002)
- Convert lockdown LSM initialization. (Patch 0002)
- Restore error check in nft_secmark_compute_secid (Patch 0006)
- Correct blob scaffolding in ima_must_appraise() (Patch 0009)
- Make security_setprocattr() clearer (Patch 0013)
- Use lsm_task_display more widely (Patch 0013)
- Use passed size in lsmcontext_init() (Patch 0014)
- Don't add a smack_release_secctx() hook (Patch 0014)
- Don't print warning in security_release_secctx() (Patch 0014)
- Don't duplicate the label in nfs4_label_init_security() (Patch 0016)
- Remove reviewed-by as code has significant change (Patch 0016)
- Send the entire lsmblob for Tag 6 (Patch 0019)
- Fix description of socket_getpeersec_stream parameters (Patch 0023)
- Retain LSMBLOB_FIRST. What was I thinking? (Patch 0023)
- Add compound context to LSM documentation (Patch 0023)
v12: Rebase to 5.5-rc1
Fixed a couple of incorrect contractions in the text.
v11: Rebase to 5.4-rc6
Incorporate feedback from v10
- Disambiguate reading /proc/.../attr/display by restricting
all use of the interface to the current process.
- Fix a merge error in AppArmor's display attribute check
v10: Ask the security modules if the display can be changed.
v9: There is no version 9
v8: Incorporate feedback from v7
- Minor clean-up in display value management
- refactor "compound" context creation to use a common
append_ctx() function.
v7: Incorporate feedback from v6
- Make setting the display a privileged operation. The
availability of compound contexts reduces the need for
setting the display.
v6: Incorporate feedback from v5
- Add subj_<lsm>= and obj_<lsm>= fields to audit records
- Add /proc/.../attr/context to get the full context in
lsmname\0value\0... format as suggested by Simon McVittie
- Add SO_PEERCONTEXT for getsockopt() to get the full context
in the same format, also suggested by Simon McVittie.
- Add /sys/kernel/security/lsm_display_default to provide
the display default value.
v5: Incorporate feedback from v4
- Initialize the lsmcontext in security_secid_to_secctx()
- Clear the lsmcontext in all security_release_secctx() cases
- Don't use the "display" on strictly internal context
interfaces.
- The SELinux binder hooks check for cases where the context
"display" isn't compatible with SELinux.
v4: Incorporate feedback from v3
- Mark new lsm_<blob>_alloc functions static
- Replace the lsm and slot fields of the security_hook_list
with a pointer to a LSM allocated lsm_id structure. The
LSM identifies if it needs a slot explicitly. Use the
lsm_id rather than make security_add_hooks return the
slot value.
- Validate slot values used in security.c
- Reworked the "display" process attribute handling so that
it works right and doesn't use goofy list processing.
- fix display value check in dentry_init_security
- Replace audit_log of secids with '?' instead of deleting
the audit log
v3: Incorporate feedback from v2
- Make lsmblob parameter and variable names more
meaningful, changing "le" and "l" to "blob".
- Improve consistency of constant naming.
- Do more sanity checking during LSM initialization.
- Be a bit clearer about what is temporary scaffolding.
- Rather than clutter security_getpeersec_dgram with
otherwise unnecessary checks remove the apparmor
stub, which does nothing useful.
Patch 01 changes the LSM registration interface to pass a
structure lsm_id containing the name of the module instead of
just the LSM name itself.
Patch 02 introduces uapi/linux/lsm.h and numeric LSM identifiers.
The numeric ID is added to the lsm_id structure.
Patch 03 Adds the information about which process attributes are
supported by each LSM to the lsm_id structure.
Patch 04 introduces a table of LSM attribute data.
Patch 05 changes security_[gs]etprocattr() to use the LSM ID rather
than the LSM name.
Patch 06 implements the lsm_self_attr() system call.
Patch 07 separates the audit rule processing from the
integrity rule processing. They were never really the
same, but void pointers could hide that. The changes
following use the rule pointers differently in audit
and IMA, so keeping the code common is not a good idea.
Patch 08 moves management of the sock security blob
from the individual modules to the infrastructure.
Patches 09-10 introduce a structure "lsmblob" that will gradually
replace the "secid" as a shorthand for security module information.
At this point lsmblob contains an array of u32 secids, one "slot"
for each of the security modules compiled into the kernel that
used secids. A "slot" is allocated when a security module requests
one.
Patch 11 provides mechanism for the IMA subsystem to identify
explicitly which LSM is subject to IMA policy. This includes
a boot option for specifying the default and an additional option
in IMA rules "lsm=".
Patches 12-19 change LSM interfaces to use the lsmblob instead
of secids. It is important that the lsmblob be a fixed size entity
that does not have to be allocated. Several of the places
where it is used would have performance and/or locking
issues with dynamic allocation.
Patch 20 provides a mechanism for a process to identify which
security module's hooks should be used when displaying or
converting a security context string. A new prctl() options
PR_LSM_ATTR_[GS]ET get and set which security module to show.
Setting the value requires that all modules using the /proc
interfaces allow the transition. The interface LSM of other
processess can be neither read nor written.
Patch 21 Starts the process of changing how a security
context is represented. Since it is possible for a
security context to have been generated by more than one
security module it is now necessary to note which module
created a security context so that the correct "release"
hook can be called. There are several places where the
module that created a security context cannot be inferred.
This is achieved by introducing a "lsmcontext" structure
which contains the context string, its length and the
"slot" number of the security module that created it.
The security_release_secctx() interface is changed,
replacing the (string,len) pointer pair with a lsmcontext
pointer.
Patches 22-25 convert the security interfaces from
(string,len) pointer pairs to a lsmcontext pointer.
The slot number identifying the creating module is
added by the infrastructure. Where the security context
is stored for extended periods the data type is changed.
Patch 26 converts the Netlabel code to save lsmblob structures
instead of secids. This is not strictly necessary as there can
only be one security module that uses Netlabel at this point.
Using a lsmblob is much cleaner, as the interfaces that use the
data have all been converted.
Patch 27 adds checks to the binder hooks which verify
that both ends of a transaction use the same interface LSM.
Patch 28 adds a parameter to security_secid_to_secctx()
that indicates which of the security modules should be used
to provide the context.
Patches 29-33 update the audit system to better handle auxiliary
records. This requires rearranging the timestamp and serial number
handling. The skb pointer used to collect audit data is replaced
by a list of skb pointers.
Patch 34 adds a supplimental audit record for subject
LSM data when there are multiple security modules with such data.
The AUDIT_MAC_TASK_CONTEXTS record is used in conjuction with a
"subj=?" field to identify the subject data. The
AUDIT_MAC_TASK_CONTEXTS record identifies the security module
with the data: subj_selinux=xyz_t subj_apparmor=abc.
An example of the MAC_TASK_CONTEXTS (1420) record is:
type=UNKNOWN[1420]
msg=audit(1600880931.832:113)
subj_apparmor==unconfined
subj_smack=_
Patch 35 adds a supplimental audit record for object
LSM data when there are multiple security modules with such data.
The AUDIT_MAC_OBJ_CONTEXTS record is used in conjuction The
with a "obj=?" field to identify the object data.
The AUDIT_MAC_OBJ_CONTEXTS record identifies the security module
with the data: obj_selinux="xyz_t obj_apparmor="abc". While
AUDIT_MAC_TASK_CONTEXTS records will always contain an entry
for each possible security modules, AUDIT_MAC_OBJ_CONTEXTS
records will only contain entries for security modules for
which the object in question has data.
An example of the MAC_OBJ_CONTEXTS (1421) record is:
type=UNKNOWN[1421]
msg=audit(1601152467.009:1050):
obj_selinux=unconfined_u:object_r:user_home_t:s0
Patches 36-37 clean out scaffolding code.
With all interference on the AppArmor hooks removed,
Patch 38 removes the exclusive bit from AppArmor. An unnecessary
stub hook was also removed.
Patch 39 adds a system call lsm_module_list() that provides a set
of integer LSM ID values describing what is active on the system.
The Ubuntu project is using an earlier version of this patchset in
their distribution to enable stacking for containers.
Performance measurements to date have the change within the "noise".
The sockperf and dbench results are on the order of 0.2% to 0.8%
difference, with better performance being as common as worse. The
benchmarks were run with AppArmor and Smack on Ubuntu.
https://github.com/cschaufler/lsm-stacking.git#stack-6.0-rc7-38
Casey Schaufler (39):
LSM: Identify modules by more than name
LSM: Add an LSM identifier for external use
LSM: Identify the process attributes for each module
LSM: Maintain a table of LSM attribute data
proc: Use lsmids instead of lsm names for attrs
LSM: lsm_self_attr syscall for LSM self attributes
integrity: disassociate ima_filter_rule from security_audit_rule
LSM: Infrastructure management of the sock security
LSM: Add the lsmblob data structure.
LSM: provide lsm name and id slot mappings
IMA: avoid label collisions with stacked LSMs
LSM: Use lsmblob in security_audit_rule_match
LSM: Use lsmblob in security_kernel_act_as
LSM: Use lsmblob in security_secctx_to_secid
LSM: Use lsmblob in security_secid_to_secctx
LSM: Use lsmblob in security_ipc_getsecid
LSM: Use lsmblob in security_current_getsecid
LSM: Use lsmblob in security_inode_getsecid
LSM: Use lsmblob in security_cred_getsecid
LSM: Specify which LSM to display
LSM: Ensure the correct LSM context releaser
LSM: Use lsmcontext in security_secid_to_secctx
LSM: Use lsmcontext in security_inode_getsecctx
Use lsmcontext in security_dentry_init_security
LSM: security_secid_to_secctx in netlink netfilter
NET: Store LSM netlabel data in a lsmblob
binder: Pass LSM identifier for confirmation
LSM: security_secid_to_secctx module selection
Audit: Keep multiple LSM data in audit_names
Audit: Create audit_stamp structure
LSM: Add a function to report multiple LSMs
Audit: Allow multiple records in an audit_buffer
Audit: Add record for multiple task security contexts
audit: multiple subject lsm values for netlabel
Audit: Add record for multiple object contexts
netlabel: Use a struct lsmblob in audit data
LSM: Removed scaffolding function lsmcontext_init
AppArmor: Remove the exclusive flag
LSM: Create lsm_module_list system call
Documentation/ABI/testing/ima_policy | 8 +-
arch/x86/entry/syscalls/syscall_64.tbl | 2 +
drivers/android/binder.c | 47 ++-
drivers/android/binder_internal.h | 1 +
fs/ceph/super.h | 3 +-
fs/ceph/xattr.c | 15 +-
fs/fuse/dir.c | 35 +-
fs/nfs/dir.c | 2 +-
fs/nfs/inode.c | 17 +-
fs/nfs/internal.h | 8 +-
fs/nfs/nfs4proc.c | 14 +-
fs/nfs/nfs4xdr.c | 22 +-
fs/nfsd/nfs4xdr.c | 20 +-
fs/proc/base.c | 29 +-
fs/proc/internal.h | 2 +-
include/linux/audit.h | 21 +-
include/linux/cred.h | 3 +-
include/linux/lsm_hooks.h | 15 +-
include/linux/nfs4.h | 8 +-
include/linux/nfs_fs.h | 2 +-
include/linux/security.h | 292 +++++++++++--
include/linux/syscalls.h | 2 +
include/net/netlabel.h | 10 +-
include/net/scm.h | 15 +-
include/uapi/asm-generic/unistd.h | 8 +-
include/uapi/linux/audit.h | 2 +
include/uapi/linux/lsm.h | 67 +++
include/uapi/linux/prctl.h | 4 +
kernel/audit.c | 261 +++++++++---
kernel/audit.h | 18 +-
kernel/auditfilter.c | 29 +-
kernel/auditsc.c | 160 +++----
kernel/cred.c | 12 +-
kernel/sys_ni.c | 4 +
net/ipv4/cipso_ipv4.c | 26 +-
net/ipv4/ip_sockglue.c | 12 +-
net/netfilter/nf_conntrack_netlink.c | 24 +-
net/netfilter/nf_conntrack_standalone.c | 11 +-
net/netfilter/nfnetlink_queue.c | 38 +-
net/netfilter/nft_meta.c | 10 +-
net/netfilter/xt_SECMARK.c | 7 +-
net/netlabel/netlabel_kapi.c | 6 +-
net/netlabel/netlabel_unlabeled.c | 98 +++--
net/netlabel/netlabel_unlabeled.h | 2 +-
net/netlabel/netlabel_user.c | 10 +-
net/netlabel/netlabel_user.h | 2 +-
security/Makefile | 1 +
security/apparmor/include/apparmor.h | 3 +-
security/apparmor/include/net.h | 6 +-
security/apparmor/lsm.c | 110 ++---
security/apparmor/net.c | 2 +-
security/bpf/hooks.c | 14 +-
security/commoncap.c | 9 +-
security/integrity/ima/ima.h | 32 +-
security/integrity/ima/ima_api.c | 6 +-
security/integrity/ima/ima_appraise.c | 11 +-
security/integrity/ima/ima_main.c | 62 +--
security/integrity/ima/ima_policy.c | 92 +++-
security/landlock/cred.c | 2 +-
security/landlock/fs.c | 2 +-
security/landlock/ptrace.c | 2 +-
security/landlock/setup.c | 7 +
security/landlock/setup.h | 1 +
security/loadpin/loadpin.c | 10 +-
security/lockdown/lockdown.c | 9 +-
security/lsm_syscalls.c | 206 +++++++++
security/safesetid/lsm.c | 10 +-
security/security.c | 539 +++++++++++++++++++++---
security/selinux/hooks.c | 115 +++--
security/selinux/include/classmap.h | 3 +-
security/selinux/include/objsec.h | 5 +
security/selinux/include/security.h | 1 +
security/selinux/netlabel.c | 25 +-
security/selinux/ss/services.c | 4 +-
security/smack/smack.h | 6 +
security/smack/smack_access.c | 2 +-
security/smack/smack_lsm.c | 85 ++--
security/smack/smack_netfilter.c | 4 +-
security/smack/smackfs.c | 12 +-
security/tomoyo/tomoyo.c | 10 +-
security/yama/yama_lsm.c | 9 +-
81 files changed, 2063 insertions(+), 758 deletions(-)
create mode 100644 include/uapi/linux/lsm.h
create mode 100644 security/lsm_syscalls.c
--
2.37.3
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