[RFC][PATCH 7/9] evm: make rootfs a special case

Mimi Zohar
2015-01-07T20:52:58Z

Both the EVM HMAC and signature xattr formats are file system
specific and can not be copied from one filesystem to another.

EVM differentiates files without any xattrs (INTEGRITY_UNKNOWN)
from those having protected xattrs (INTEGRITY_NOLABEL). This
patch treats the rootfs filesystem as a special case, returning
INTEGRITY_UNKNOWN.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
---
security/integrity/evm/evm_main.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index b392fe6..9c71af7 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -128,11 +128,16 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
if (rc <= 0) {
evm_status = INTEGRITY_FAIL;
if (rc == -ENODATA) {
+ struct super_block *sb = dentry->d_inode->i_sb;
+
rc = evm_find_protected_xattrs(dentry);
- if (rc > 0)
- evm_status = INTEGRITY_NOLABEL;
- else if (rc == 0)
+ if (rc == 0)
evm_status = INTEGRITY_NOXATTRS; /* new file */
+ else if (rc > 0 && sb->s_magic == TMPFS_MAGIC
+ && strcmp(sb->s_id, "rootfs") == 0)
+ evm_status = INTEGRITY_UNKNOWN;
+ else if (rc > 0)
+ evm_status = INTEGRITY_NOLABEL;
} else if (rc == -EOPNOTSUPP) {
evm_status = INTEGRITY_UNKNOWN;
}
--
1.8.1.4