diff options
| author | Stefan Berger <stefanb@linux.ibm.com> | 2024-02-23 12:25:11 -0500 |
|---|---|---|
| committer | Mimi Zohar <zohar@linux.ibm.com> | 2024-04-09 17:14:57 -0400 |
| commit | 47add87ad181473e5ef2438918669540ba5016a6 (patch) | |
| tree | c684b07c6bea4a972cf5f6609d210859c16e9d23 | |
| parent | cd9b909a117210bfd77a89bb06a3154c1fc51b51 (diff) | |
evm: Enforce signatures on unsupported filesystem for EVM_INIT_X509
Unsupported filesystems currently do not enforce any signatures. Add
support for signature enforcement of the "original" and "portable &
immutable" signatures when EVM_INIT_X509 is enabled.
The "original" signature type contains filesystem specific metadata.
Thus it cannot be copied up and verified. However with EVM_INIT_X509
and EVM_ALLOW_METADATA_WRITES enabled, the "original" file signature
may be written.
When EVM_ALLOW_METADATA_WRITES is not set or once it is removed from
/sys/kernel/security/evm by setting EVM_INIT_HMAC for example, it is not
possible to write or remove xattrs on the overlay filesystem.
This change still prevents EVM from writing HMAC signatures on
unsupported filesystem when EVM_INIT_HMAC is enabled.
Co-developed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
| -rw-r--r-- | security/integrity/evm/evm_main.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index c1ca0894cd8a..cfb4f9809369 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -192,7 +192,11 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, iint->evm_status == INTEGRITY_PASS_IMMUTABLE)) return iint->evm_status; - if (is_unsupported_fs(dentry)) + /* + * On unsupported filesystems without EVM_INIT_X509 enabled, skip + * signature verification. + */ + if (!(evm_initialized & EVM_INIT_X509) && is_unsupported_fs(dentry)) return INTEGRITY_UNKNOWN; /* if status is not PASS, try to check again - against -ENOMEM */ @@ -261,7 +265,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, evm_status = INTEGRITY_PASS_IMMUTABLE; } else if (!IS_RDONLY(inode) && !(inode->i_sb->s_readonly_remount) && - !IS_IMMUTABLE(inode)) { + !IS_IMMUTABLE(inode) && + !is_unsupported_fs(dentry)) { evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len); @@ -419,9 +424,6 @@ enum integrity_status evm_verifyxattr(struct dentry *dentry, if (!evm_key_loaded() || !evm_protected_xattr(xattr_name)) return INTEGRITY_UNKNOWN; - if (is_unsupported_fs(dentry)) - return INTEGRITY_UNKNOWN; - return evm_verify_hmac(dentry, xattr_name, xattr_value, xattr_value_len); } |