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| author |   Matthew Garrett <mjg59@google.com> | 2018-05-15 10:38:26 -0700 |
|---|---|---|
| committer |   Mimi Zohar <zohar@linux.vnet.ibm.com> | 2018-05-18 15:34:45 -0400 |
| commit | fa516b66a1bfce1d72f1620c54bdfebc493000d1 (patch) | |
| tree | 26b2887ece19ada7ec0f756a9cc7720cee4d1291 /security/integrity/evm/Kconfig | |
| parent | EVM: turn evm_config_xattrnames into a list (diff) | |
| download | linux-dev-fa516b66a1bfce1d72f1620c54bdfebc493000d1.tar.xz linux-dev-fa516b66a1bfce1d72f1620c54bdfebc493000d1.zip | |
EVM: Allow runtime modification of the set of verified xattrs
Sites may wish to provide additional metadata alongside files in order
to make more fine-grained security decisions[1]. The security of this is
enhanced if this metadata is protected, something that EVM makes
possible. However, the kernel cannot know about the set of extended
attributes that local admins may wish to protect, and hardcoding this
policy in the kernel makes it difficult to change over time and less
convenient for distributions to enable.
This patch adds a new /sys/kernel/security/integrity/evm/evm_xattrs node,
which can be read to obtain the current set of EVM-protected extended
attributes or written to in order to add new entries. Extending this list
will not change the validity of any existing signatures provided that the
file in question does not have any of the additional extended attributes -
missing xattrs are skipped when calculating the EVM hash.
[1] For instance, a package manager could install information about the
package uploader in an additional extended attribute. Local LSM policy
could then be associated with that extended attribute in order to
restrict the privileges available to packages from less trusted
uploaders.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Diffstat (limited to 'security/integrity/evm/Kconfig')
| -rw-r--r-- | security/integrity/evm/Kconfig | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig index e825e0ae78e7..d593346d0bba 100644 --- a/security/integrity/evm/Kconfig +++ b/security/integrity/evm/Kconfig @@ -42,6 +42,17 @@ config EVM_EXTRA_SMACK_XATTRS additional info to the calculation, requires existing EVM labeled file systems to be relabeled. +config EVM_ADD_XATTRS + bool "Add additional EVM extended attributes at runtime" + depends on EVM + default n + help + Allow userland to provide additional xattrs for HMAC calculation. + + When this option is enabled, root can add additional xattrs to the + list used by EVM by writing them into + /sys/kernel/security/integrity/evm/evm_xattrs. + config EVM_LOAD_X509 bool "Load an X509 certificate onto the '.evm' trusted keyring" depends on EVM && INTEGRITY_TRUSTED_KEYRING |