Chester reports that it is necessary to introduce a new way to pass
the EFI secure boot status between the EFI stub and the core kernel
on ARM systems. The usual way of obtaining this information is by
checking the SecureBoot and SetupMode EFI variables, but this can
only be done after the EFI variable workqueue is created, which
occurs in a subsys_initcall(), whereas arch_ima_get_secureboot()
is called much earlier by the IMA framework.
However, the IMA framework itself is started as a late_initcall,
and the only reason the call to arch_ima_get_secureboot() occurs
so early is because it happens in the context of a __setup()
callback that parses the ima_appraise= command line parameter.
So let's refactor this code a little bit, by using a core_param()
callback to capture the command line argument, and deferring any
reasoning based on its contents to the IMA init routine.
Cc: Chester Lin <clin@suse.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Link: https://lore.kernel.org/linux-arm-kernel/20200904072905.25332-2-clin@suse.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reported-by: kernel test robot <lkp@intel.com> [missing core_param()]
[zohar@linux.ibm.com: included linux/module.h]
Tested-by: Chester Lin <clin@suse.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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Merge tag 'integrity-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
Pull integrity updates from Mimi Zohar:
"Continuing IMA policy rule cleanup and validation in particular for
measuring keys, adding/removing/updating informational and error
messages (e.g. "ima_appraise" boot command line option), and other bug
fixes (e.g. minimal data size validation before use, return code and
NULL pointer checking)"
* tag 'integrity-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
ima: Fix NULL pointer dereference in ima_file_hash
evm: Check size of security.evm before using it
ima: Remove semicolon at the end of ima_get_binary_runtime_size()
ima: Don't ignore errors from crypto_shash_update()
ima: Use kmemdup rather than kmalloc+memcpy
integrity: include keyring name for unknown key request
ima: limit secure boot feedback scope for appraise
integrity: invalid kernel parameters feedback
ima: add check for enforced appraise option
integrity: Use current_uid() in integrity_audit_message()
ima: Fail rule parsing when asymmetric key measurement isn't supportable
ima: Pre-parse the list of keyrings in a KEY_CHECK rule
Only emit an unknown/invalid message when setting the IMA appraise mode
to anything other than "enforce", when secureboot is enabled.
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
[zohar@linux.ibm.com: updated commit message]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
The "enforce" string is allowed as an option for ima_appraise= kernel
paramenter per kernel-paramenters.txt and should be considered on the
parameter setup checking as a matter of completeness. Also it allows futher
checking on the options being passed by the user.
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
The IMA_APPRAISE_BOOTPARAM config allows enabling different "ima_appraise="
modes - log, fix, enforce - at run time, but not when IMA architecture
specific policies are enabled. This prevents properly labeling the
filesystem on systems where secure boot is supported, but not enabled on the
platform. Only when secure boot is actually enabled should these IMA
appraise modes be disabled.
This patch removes the compile time dependency and makes it a runtime
decision, based on the secure boot state of that platform.
Test results as follows:
-> x86-64 with secure boot enabled
[ 0.015637] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix
[ 0.015668] ima: Secure boot enabled: ignoring ima_appraise=fix boot parameter option
-> powerpc with secure boot disabled
[ 0.000000] Kernel command line: <...> ima_policy=appraise_tcb ima_appraise=fix
[ 0.000000] Secure boot mode disabled
-> Running the system without secure boot and with both options set:
CONFIG_IMA_APPRAISE_BOOTPARAM=y
CONFIG_IMA_ARCH_POLICY=y
Audit prompts "missing-hash" but still allow execution and, consequently,
filesystem labeling:
type=INTEGRITY_DATA msg=audit(07/09/2020 12:30:27.778:1691) : pid=4976
uid=root auid=root ses=2
subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 op=appraise_data
cause=missing-hash comm=bash name=/usr/bin/evmctl dev="dm-0" ino=493150
res=no
Cc: stable@vger.kernel.org
Fixes: d958083a8f ("x86/ima: define arch_get_ima_policy() for x86")
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Cc: stable@vger.kernel.org # 5.0
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Take the properties of the kexec kernel's inode and the current task
ownership into consideration when matching a KEXEC_CMDLINE operation to
the rules in the IMA policy. This allows for some uniformity when
writing IMA policy rules for KEXEC_KERNEL_CHECK, KEXEC_INITRAMFS_CHECK,
and KEXEC_CMDLINE operations.
Prior to this patch, it was not possible to write a set of rules like
this:
dont_measure func=KEXEC_KERNEL_CHECK obj_type=foo_t
dont_measure func=KEXEC_INITRAMFS_CHECK obj_type=foo_t
dont_measure func=KEXEC_CMDLINE obj_type=foo_t
measure func=KEXEC_KERNEL_CHECK
measure func=KEXEC_INITRAMFS_CHECK
measure func=KEXEC_CMDLINE
The inode information associated with the kernel being loaded by a
kexec_kernel_load(2) syscall can now be included in the decision to
measure or not
Additonally, the uid, euid, and subj_* conditionals can also now be
used in KEXEC_CMDLINE rules. There was no technical reason as to why
those conditionals weren't being considered previously other than
ima_match_rules() didn't have a valid inode to use so it immediately
bailed out for KEXEC_CMDLINE operations rather than going through the
full list of conditional comparisons.
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Limit measuring keys to those keys being loaded onto a given set of
keyrings only and when the user id (uid) matches if uid is specified
in the policy.
This patch defines a new IMA policy option namely "keyrings=" that
can be used to specify a set of keyrings. If this option is specified
in the policy for "measure func=KEY_CHECK" then only the keys
loaded onto a keyring given in the "keyrings=" option are measured.
If uid is specified in the policy then the key is measured only if
the current user id matches the one specified in the policy.
Added a new parameter namely "keyring" (name of the keyring) to
process_buffer_measurement(). The keyring name is passed to
ima_get_action() to determine the required action.
ima_match_rules() is updated to check keyring in the policy, if
specified, for KEY_CHECK function.
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Asymmetric private keys are used to sign multiple files. The kernel
currently supports checking against blacklisted keys. However, if the
public key is blacklisted, any file signed by the blacklisted key will
automatically fail signature verification. Blacklisting the public key
is not fine enough granularity, as we might want to only blacklist a
particular file.
This patch adds support for checking against the blacklisted hash of
the file, without the appended signature, based on the IMA policy. It
defines a new policy option "appraise_flag=check_blacklist".
In addition to the blacklisted binary hashes stored in the firmware
"dbx" variable, the Linux kernel may be configured to load blacklisted
binary hashes onto the .blacklist keyring as well. The following
example shows how to blacklist a specific kernel module hash.
$ sha256sum kernel/kheaders.ko
77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
kernel/kheaders.ko
$ grep BLACKLIST .config
CONFIG_SYSTEM_BLACKLIST_KEYRING=y
CONFIG_SYSTEM_BLACKLIST_HASH_LIST="blacklist-hash-list"
$ cat certs/blacklist-hash-list
"bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3"
Update the IMA custom measurement and appraisal policy
rules (/etc/ima-policy):
measure func=MODULE_CHECK template=ima-modsig
appraise func=MODULE_CHECK appraise_flag=check_blacklist
appraise_type=imasig|modsig
After building, installing, and rebooting the kernel:
545660333 ---lswrv 0 0 \_ blacklist:
bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
measure func=MODULE_CHECK template=ima-modsig
appraise func=MODULE_CHECK appraise_flag=check_blacklist
appraise_type=imasig|modsig
modprobe: ERROR: could not insert 'kheaders': Permission denied
10 0c9834db5a0182c1fb0cdc5d3adcf11a11fd83dd ima-sig
sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40
2 /usr/lib/modules/5.4.0-rc3+/kernel/kernel/kheaders.ko
10 82aad2bcc3fa8ed94762356b5c14838f3bcfa6a0 ima-modsig
sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40
2 /usr/lib/modules/5.4.0rc3+/kernel/kernel/kheaders.ko sha256:77fa889b3
5a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
3082029a06092a864886f70d010702a082028b30820287020101310d300b0609608648
016503040201300b06092a864886f70d01070131820264....
10 25b72217cc1152b44b134ce2cd68f12dfb71acb3 ima-buf
sha256:8b58427fedcf8f4b20bc8dc007f2e232bf7285d7b93a66476321f9c2a3aa132
b blacklisted-hash
77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
[zohar@linux.ibm.com: updated patch description]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1572492694-6520-8-git-send-email-zohar@linux.ibm.com
Obtain the modsig and calculate its corresponding hash in
ima_collect_measurement().
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Implement the appraise_type=imasig|modsig option, allowing IMA to read and
verify modsig signatures.
In case a file has both an xattr signature and an appended modsig, IMA will
only use the appended signature if the key used by the xattr signature
isn't present in the IMA or platform keyring.
Because modsig verification needs to convert from an integrity keyring id
to the keyring itself, add an integrity_keyring_from_id() function in
digsig.c so that integrity_modsig_verify() can use it.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Verify xattr signature in a separate function so that the logic in
ima_appraise_measurement() remains clear when it gains the ability to also
verify an appended module signature.
The code in the switch statement is unchanged except for having to
dereference the status and cause variables (since they're now pointers),
and fixing the style of a block comment to appease checkpatch.
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Pull integrity updates from Mimi Zohar:
"Bug fixes, code clean up, and new features:
- IMA policy rules can be defined in terms of LSM labels, making the
IMA policy dependent on LSM policy label changes, in particular LSM
label deletions. The new environment, in which IMA-appraisal is
being used, frequently updates the LSM policy and permits LSM label
deletions.
- Prevent an mmap'ed shared file opened for write from also being
mmap'ed execute. In the long term, making this and other similar
changes at the VFS layer would be preferable.
- The IMA per policy rule template format support is needed for a
couple of new/proposed features (eg. kexec boot command line
measurement, appended signatures, and VFS provided file hashes).
- Other than the "boot-aggregate" record in the IMA measuremeent
list, all other measurements are of file data. Measuring and
storing the kexec boot command line in the IMA measurement list is
the first buffer based measurement included in the measurement
list"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
integrity: Introduce struct evm_xattr
ima: Update MAX_TEMPLATE_NAME_LEN to fit largest reasonable definition
KEXEC: Call ima_kexec_cmdline to measure the boot command line args
IMA: Define a new template field buf
IMA: Define a new hook to measure the kexec boot command line arguments
IMA: support for per policy rule template formats
integrity: Fix __integrity_init_keyring() section mismatch
ima: Use designated initializers for struct ima_event_data
ima: use the lsm policy update notifier
LSM: switch to blocking policy update notifiers
x86/ima: fix the Kconfig dependency for IMA_ARCH_POLICY
ima: Make arch_policy_entry static
ima: prevent a file already mmap'ed write to be mmap'ed execute
x86/ima: check EFI SetupMode too
Even though struct evm_ima_xattr_data includes a fixed-size array to hold a
SHA1 digest, most of the code ignores the array and uses the struct to mean
"type indicator followed by data of unspecified size" and tracks the real
size of what the struct represents in a separate length variable.
The only exception to that is the EVM code, which correctly uses the
definition of struct evm_ima_xattr_data.
So make this explicit in the code by removing the length specification from
the array in struct evm_ima_xattr_data. Also, change the name of the
element from digest to data since in most places the array doesn't hold a
digest.
A separate struct evm_xattr is introduced, with the original definition of
evm_ima_xattr_data to be used in the places that actually expect that
definition, specifically the EVM HMAC code.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Admins may wish to log different measurements using different IMA
templates. Add support for overriding the default template on a per-rule
basis.
Inspired-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 315 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.
This patch fixes the following warnings:
security/integrity/ima/ima_template_lib.c:85:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/integrity/ima/ima_policy.c:940:18: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/integrity/ima/ima_policy.c:943:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/integrity/ima/ima_policy.c:972:21: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/integrity/ima/ima_policy.c:974:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/smack/smack_lsm.c:3391:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
security/apparmor/domain.c:569:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
Warning level 3 was used: -Wimplicit-fallthrough=3
Also, add a missing break statement to fix the following warning:
security/integrity/ima/ima_appraise.c:116:26: warning: this statement may fall through [-Wimplicit-fallthrough=]
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
From Mimi:
In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load
syscall. Different signature verification methods exist for verifying
the kexec'ed kernel image. This pull request adds additional support
in IMA to prevent loading unsigned kernel images via the kexec_load
syscall, independently of the IMA policy rules, based on the runtime
"secure boot" flag. An initial IMA kselftest is included.
In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.
(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here.)
On secure boot enabled systems, the bootloader verifies the kernel
image and possibly the initramfs signatures based on a set of keys. A
soft reboot(kexec) of the system, with the same kernel image and
initramfs, requires access to the original keys to verify the
signatures.
This patch allows IMA-appraisal access to those original keys, now
loaded on the platform keyring, needed for verifying the kernel image
and initramfs signatures.
[zohar@linux.ibm.com: only use platform keyring if it's enabled (Thiago)]
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.
This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.
The advantage in removing such instances is that module.h itself
sources about 15 other headers; adding significantly to what we feed
cpp, and it can obscure what headers we are effectively using.
Since module.h might have been the implicit source for init.h
(for __init) and for export.h (for EXPORT_SYMBOL) we consider each
instance for the presence of either and replace as needed.
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: linux-security-module@vger.kernel.org
Cc: linux-integrity@vger.kernel.org
Cc: keyrings@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
just check ->f_mode in ima_appraise_measurement()
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replace nested ifs in the EVM xattr verification logic with a switch
statement, making the code easier to understand.
Also, add comments to the if statements in the out section and constify the
cause variable.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
This patch addresses the fuse privileged mounted filesystems in
environments which are unwilling to accept the risk of trusting the
signature verification and want to always fail safe, but are for example
using a pre-built kernel.
This patch defines a new builtin policy named "fail_securely", which can
be specified on the boot command line as an argument to "ima_policy=".
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Dongsu Park <dongsu@kinvolk.io>
Cc: Alban Crequy <alban@kinvolk.io>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
FUSE can be mounted by unprivileged users either today with fusermount
installed with setuid, or soon with the upcoming patches to allow FUSE
mounts in a non-init user namespace.
This patch addresses the new unprivileged non-init mounted filesystems,
which are untrusted, by failing the signature verification.
This patch defines two new flags SB_I_IMA_UNVERIFIABLE_SIGNATURE and
SB_I_UNTRUSTED_MOUNTER.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Dongsu Park <dongsu@kinvolk.io>
Cc: Alban Crequy <alban@kinvolk.io>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
The existing BPRM_CHECK functionality in IMA validates against the
credentials of the existing process, not any new credentials that the
child process may transition to. Add an additional CREDS_CHECK target
and refactor IMA to pass the appropriate creds structure. In
ima_bprm_check(), check with both the existing process credentials and
the credentials that will be committed when the new process is started.
This will not change behaviour unless the system policy is extended to
include CREDS_CHECK targets - BPRM_CHECK will continue to check the same
credentials that it did previously.
After this patch, an IMA policy rule along the lines of:
measure func=CREDS_CHECK subj_type=unconfined_t
will trigger if a process is executed and runs as unconfined_t, ignoring
the context of the parent process. This is in contrast to:
measure func=BPRM_CHECK subj_type=unconfined_t
which will trigger if the process that calls exec() is already executing
in unconfined_t, ignoring the context that the child process executes
into.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Changelog:
- initialize ima_creds_status
The builtin ima_appraise_tcb policy, which is specified on the boot
command line, can be replaced with a custom policy, normally early in
the boot process. Custom policies can be more restrictive in some ways,
like requiring file signatures, but can be less restrictive in other
ways, like not appraising mutable files. With a less restrictive policy
in place, files in the builtin policy might not be hashed and labeled
with a security.ima hash. On reboot, files which should be labeled in
the ima_appraise_tcb are not labeled, possibly preventing the system
from booting properly.
To resolve this problem, this patch extends the existing IMA policy
actions "measure", "dont_measure", "appraise", "dont_appraise", and
"audit" with "hash" and "dont_hash". The new "hash" action will write
the file hash as security.ima, but without requiring the file to be
appraised as well.
For example, the builtin ima_appraise_tcb policy includes the rule,
"appraise fowner=0". Adding the "hash fowner=0" rule to a custom
policy, will cause the needed file hashes to be calculated and written
as security.ima xattrs.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Before IMA appraisal was introduced, IMA was using own integrity cache
lock along with i_mutex. process_measurement and ima_file_free took
the iint->mutex first and then the i_mutex, while setxattr, chmod and
chown took the locks in reverse order. To resolve the potential deadlock,
i_mutex was moved to protect entire IMA functionality and the redundant
iint->mutex was eliminated.
Solution was based on the assumption that filesystem code does not take
i_mutex further. But when file is opened with O_DIRECT flag, direct-io
implementation takes i_mutex and produces deadlock. Furthermore, certain
other filesystem operations, such as llseek, also take i_mutex.
More recently some filesystems have replaced their filesystem specific
lock with the global i_rwsem to read a file. As a result, when IMA
attempts to calculate the file hash, reading the file attempts to take
the i_rwsem again.
To resolve O_DIRECT related deadlock problem, this patch re-introduces
iint->mutex. But to eliminate the original chmod() related deadlock
problem, this patch eliminates the requirement for chmod hooks to take
the iint->mutex by introducing additional atomic iint->attr_flags to
indicate calling of the hooks. The allowed locking order is to take
the iint->mutex first and then the i_rwsem.
Original flags were cleared in chmod(), setxattr() or removwxattr()
hooks and tested when file was closed or opened again. New atomic flags
are set or cleared in those hooks and tested to clear iint->flags on
close or on open.
Atomic flags are following:
* IMA_CHANGE_ATTR - indicates that chATTR() was called (chmod, chown,
chgrp) and file attributes have changed. On file open, it causes IMA
to clear iint->flags to re-evaluate policy and perform IMA functions
again.
* IMA_CHANGE_XATTR - indicates that setxattr or removexattr was called
and extended attributes have changed. On file open, it causes IMA to
clear iint->flags IMA_DONE_MASK to re-appraise.
* IMA_UPDATE_XATTR - indicates that security.ima needs to be updated.
It is cleared if file policy changes and no update is needed.
* IMA_DIGSIG - indicates that file security.ima has signature and file
security.ima must not update to file has on file close.
* IMA_MUST_MEASURE - indicates the file is in the measurement policy.
Fixes: Commit 6552321831 ("xfs: remove i_iolock and use i_rwsem in
the VFS inode instead")
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
The EVM signature includes the inode number and (optionally) the
filesystem UUID, making it impractical to ship EVM signatures in
packages. This patch adds a new portable format intended to allow
distributions to include EVM signatures. It is identical to the existing
format but hardcodes the inode and generation numbers to 0 and does not
include the filesystem UUID even if the kernel is configured to do so.
Removing the inode means that the metadata and signature from one file
could be copied to another file without invalidating it. This is avoided
by ensuring that an IMA xattr is present during EVM validation.
Portable signatures are intended to be immutable - ie, they will never
be transformed into HMACs.
Based on earlier work by Dmitry Kasatkin and Mikhail Kurinnoi.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc: Mikhail Kurinnoi <viewizard@viewizard.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Custom policies can require file signatures based on LSM labels. These
files are normally created and only afterwards labeled, requiring them
to be signed.
Instead of requiring file signatures based on LSM labels, entire
filesystems could require file signatures. In this case, we need the
ability of writing new files without requiring file signatures.
The definition of a "new" file was originally defined as any file with
a length of zero. Subsequent patches redefined a "new" file to be based
on the FILE_CREATE open flag. By combining the open flag with a file
size of zero, this patch relaxes the file signature requirement.
Fixes: 1ac202e978 ima: accept previously set IMA_NEW_FILE
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Commit b65a9cfc2c ("Untangling ima mess, part 2: deal with counters")
moved the call of ima_file_check() from may_open() to do_filp_open() at a
point where the file descriptor is already opened.
This breaks the assumption made by IMA that file descriptors being closed
belong to files whose access was granted by ima_file_check(). The
consequence is that security.ima and security.evm are updated with good
values, regardless of the current appraisal status.
For example, if a file does not have security.ima, IMA will create it after
opening the file for writing, even if access is denied. Access to the file
will be allowed afterwards.
Avoid this issue by checking the appraisal status before updating
security.ima.
Cc: stable@vger.kernel.org
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
A non-zero value is converted to 1 when assigned to a bool variable, so the
conditional operator in is_ima_appraise_enabled is redundant.
The value of a comparison operator is either 1 or 0 so the conditional
operator in ima_inode_setxattr is redundant as well.
Confirmed that the patch is correct by comparing the object file from
before and after the patch. They are identical.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
If the file doesn't have an xattr, ima_appraise_measurement sets cause to
"missing-hash" while if there's an xattr but it's a digest instead of a
signature it sets cause to "IMA-signature-required".
Fix it by setting cause to "IMA-signature-required" in both cases.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
These changes are too small to warrant their own patches:
The keyid and sig_size members of struct signature_v2_hdr are in BE format,
so use a type that makes this assumption explicit. Also, use beXX_to_cpu
instead of __beXX_to_cpu to read them.
Change integrity_kernel_read to take a void * buffer instead of char *
buffer, so that callers don't have to use a cast if they provide a buffer
that isn't a char *.
Add missing #endif comment in ima.h pointing out which macro it refers to.
Add missing fall through comment in ima_appraise.c.
Constify mask_tokens and func_tokens arrays.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Only return enabled if in enforcing mode, not fix or log modes.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Changes:
- Define is_ima_appraise_enabled() as a bool (Thiago Bauermann)
Modifying the attributes of a file makes ima_inode_post_setattr reset
the IMA cache flags. So if the file, which has just been created,
is opened a second time before the first file descriptor is closed,
verification fails since the security.ima xattr has not been written
yet. We therefore have to look at the IMA_NEW_FILE even if the file
already existed.
With this patch there should no longer be an error when cat tries to
open testfile:
$ rm -f testfile
$ ( echo test >&3 ; touch testfile ; cat testfile ) 3>testfile
A file being new is no reason to accept that it is missing a digital
signature demanded by the policy.
Signed-off-by: Daniel Glöckner <dg@emlix.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
In general the handling of IMA/EVM xattrs is good, but I found
a few locations where either the xattr size or the value of the
type field in the xattr are not checked. Add a few simple checks
to these locations to prevent malformed or malicious xattrs from
causing problems.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Userspace applications have been modified to write security xattrs,
but they are not context aware. In the case of security.ima, the
security xattr can be either a file hash or a file signature.
Permitting writing one, but not the other requires the application to
be context aware.
In addition, userspace applications might write files to a staging
area, which might not be in policy, and then change some file metadata
(eg. owner) making it in policy. As a result, these files are not
labeled properly.
This reverts commit c68ed80c97, which
prevents writing file hashes as security.ima xattrs.
Requested-by: Patrick Ohly <patrick.ohly@intel.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Pull vfs xattr updates from Al Viro:
"xattr stuff from Andreas
This completes the switch to xattr_handler ->get()/->set() from
->getxattr/->setxattr/->removexattr"
* 'work.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: Remove {get,set,remove}xattr inode operations
xattr: Stop calling {get,set,remove}xattr inode operations
vfs: Check for the IOP_XATTR flag in listxattr
xattr: Add __vfs_{get,set,remove}xattr helpers
libfs: Use IOP_XATTR flag for empty directory handling
vfs: Use IOP_XATTR flag for bad-inode handling
vfs: Add IOP_XATTR inode operations flag
vfs: Move xattr_resolve_name to the front of fs/xattr.c
ecryptfs: Switch to generic xattr handlers
sockfs: Get rid of getxattr iop
sockfs: getxattr: Fail with -EOPNOTSUPP for invalid attribute names
kernfs: Switch to generic xattr handlers
hfs: Switch to generic xattr handlers
jffs2: Remove jffs2_{get,set,remove}xattr macros
xattr: Remove unnecessary NULL attribute name check
Right now, various places in the kernel check for the existence of
getxattr, setxattr, and removexattr inode operations and directly call
those operations. Switch to helper functions and test for the IOP_XATTR
flag instead.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Ima tries to call ->setxattr() on overlayfs dentry after having locked
underlying inode, which results in a deadlock.
Reported-by: Krisztian Litkey <kli@iki.fi>
Fixes: 4bacc9c923 ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
IMA avoids re-measuring files by storing the current state as a flag in
the integrity cache. It will then skip adding a new measurement log entry
if the cache reports the file as already measured.
If a policy measures an already measured file to a new PCR, the measurement
will not be added to the list. This patch implements a new bitfield for
specifying which PCR the file was measured into, rather than if it was
measured.
Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Different policy rules may extend different PCRs. This patch retrieves
the specific PCR for the matched rule. Subsequent patches will include
the rule specific PCR in the measurement list and extend the appropriate
PCR.
Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Commit 3034a14 "ima: pass 'opened' flag to identify newly created files"
stopped identifying empty files as new files. However new empty files
can be created using the mknodat syscall. On systems with IMA-appraisal
enabled, these empty files are not labeled with security.ima extended
attributes properly, preventing them from subsequently being opened in
order to write the file data contents. This patch defines a new hook
named ima_post_path_mknod() to mark these empty files, created using
mknodat, as new in order to allow the file data contents to be written.
In addition, files with security.ima xattrs containing a file signature
are considered "immutable" and can not be modified. The file contents
need to be written, before signing the file. This patch relaxes this
requirement for new files, allowing the file signature to be written
before the file contents.
Changelog:
- defer identifying files with signatures stored as security.ima
(based on Dmitry Rozhkov's comments)
- removing tests (eg. dentry, dentry->d_inode, inode->i_size == 0)
(based on Al's review)
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Al Viro <<viro@zeniv.linux.org.uk>
Tested-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
Changing file metadata (eg. uid, guid) could result in having to
re-appraise a file's integrity, but does not change the "new file"
status nor the security.ima xattr. The IMA_PERMIT_DIRECTIO and
IMA_DIGSIG_REQUIRED flags are policy rule specific. This patch
only resets these flags, not the IMA_NEW_FILE or IMA_DIGSIG flags.
With this patch, changing the file timestamp will not remove the
file signature on new files.
Reported-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Tested-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
Each time a file is read by the kernel, the file should be re-measured and
the file signature re-appraised, based on policy. As there is no need to
preserve the status information, this patch replaces the firmware and
module specific cache status with a generic one named read_file.
This change simplifies adding support for other files read by the kernel.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Petko Manolov <petkan@mip-labs.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
This patch defines a new IMA hook ima_post_read_file() for measuring
and appraising files read by the kernel. The caller loads the file into
memory before calling this function, which calculates the hash followed by
the normal IMA policy based processing.
Changelog v5:
- fail ima_post_read_file() if either file or buf is NULL
v3:
- rename ima_hash_and_process_file() to ima_post_read_file()
v1:
- split patch
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cleanup the function arguments by using "ima_hooks" enumerator as needed.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Petko Manolov <petkan@mip-labs.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Instead of passing pointers to pointers to ima_collect_measurent() to
read and return the 'security.ima' xattr value, this patch moves the
functionality to the calling process_measurement() to directly read
the xattr and pass only the hash algo to the ima_collect_measurement().
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
