We want to add additional evm control nodes, and it'd be preferable not
to clutter up the securityfs root directory any further. Create a new
integrity directory, move the ima directory into it, create an evm
directory for the evm attribute and add compatibility symlinks.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.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>
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>
The CONFIG_IMA_LOAD_X509 and CONFIG_EVM_LOAD_X509 options permit
loading x509 signed certificates onto the trusted keyrings without
verifying the x509 certificate file's signature.
This patch replaces the call to the integrity_read_file() specific
function with the common kernel_read_file_from_path() function.
To avoid verifying the file signature, this patch defines
READING_X509_CERTFICATE.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
To keep track of which measurements have been extended to which PCRs, this
patch defines a new integrity_iint_cache field named measured_pcrs. This
field is a bitmask of the PCRs measured. Each bit corresponds to a PCR
index. For example, bit 10 corresponds to PCR 10.
Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.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>
This patch defines a configuration option and the evm_load_x509() hook
to load an X509 certificate onto the EVM trusted kernel keyring.
Changes in v4:
* Patch description updated
Changes in v3:
* Removed EVM_X509_PATH definition. CONFIG_EVM_X509_PATH is used
directly.
Changes in v2:
* default key patch changed to /etc/keys
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Require all keys added to the EVM keyring be signed by an
existing trusted key on the system trusted keyring.
This patch also switches IMA to use integrity_init_keyring().
Changes in v3:
* Added 'init_keyring' config based variable to skip initializing
keyring instead of using __integrity_init_keyring() wrapper.
* Added dependency back to CONFIG_IMA_TRUSTED_KEYRING
Changes in v2:
* Replace CONFIG_EVM_TRUSTED_KEYRING with IMA and EVM common
CONFIG_INTEGRITY_TRUSTED_KEYRING configuration option
* Deprecate CONFIG_IMA_TRUSTED_KEYRING but keep it for config
file compatibility. (Mimi Zohar)
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Pull security layer updates from James Morris:
"In terms of changes, there's general maintenance to the Smack,
SELinux, and integrity code.
The IMA code adds a new kconfig option, IMA_APPRAISE_SIGNED_INIT,
which allows IMA appraisal to require signatures. Support for reading
keys from rootfs before init is call is also added"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (23 commits)
selinux: Remove security_ops extern
security: smack: fix out-of-bounds access in smk_parse_smack()
VFS: refactor vfs_read()
ima: require signature based appraisal
integrity: provide a hook to load keys when rootfs is ready
ima: load x509 certificate from the kernel
integrity: provide a function to load x509 certificate from the kernel
integrity: define a new function integrity_read_file()
Security: smack: replace kzalloc with kmem_cache for inode_smack
Smack: Lock mode for the floor and hat labels
ima: added support for new kernel cmdline parameter ima_template_fmt
ima: allocate field pointers array on demand in template_desc_init_fields()
ima: don't allocate a copy of template_fmt in template_desc_init_fields()
ima: display template format in meas. list if template name length is zero
ima: added error messages to template-related functions
ima: use atomic bit operations to protect policy update interface
ima: ignore empty and with whitespaces policy lines
ima: no need to allocate entry for comment
ima: report policy load status
ima: use path names cache
...
Define configuration option to load X509 certificate into the
IMA trusted kernel keyring. It implements ima_load_x509() hook
to load X509 certificate into the .ima trusted kernel keyring
from the root filesystem.
Changes in v3:
* use ima_policy_flag in ima_get_action()
ima_load_x509 temporarily clears ima_policy_flag to disable
appraisal to load key. Use it to skip appraisal rules.
* Key directory path changed to /etc/keys (Mimi)
* Expand IMA_LOAD_X509 Kconfig help
Changes in v2:
* added '__init'
* use ima_policy_flag to disable appraisal to load keys
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Provide the function to load x509 certificates from the kernel into the
integrity kernel keyring.
Changes in v2:
* configuration option removed
* function declared as '__init'
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This patch defines a new function called integrity_read_file()
to read file from the kernel into a buffer. Subsequent patches
will read a file containing the public keys and load them onto
the IMA keyring.
This patch moves and renames ima_kernel_read(), the non-security
checking version of kernel_read(), to integrity_kernel_read().
Changes in v3:
* Patch descriptions improved (Mimi)
* Add missing cast (kbuild test robot)
Changes in v2:
* configuration option removed
* function declared as '__init'
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
integrity_init_keyring() is used only from kernel '__init'
functions. Add it there as well.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Stefan Berger
Matthew Garrett
Thiago Jung Bauermann
Mimi Zohar
Dmitry Kasatkin
Christoph Hellwig
Eric Richter
James Morris
David Howells
Dmitry Kasatkin
Dmitry Kasatkin
Linus Torvalds