The security.evm HMAC and the original file signatures contain
filesystem specific data. As a result, the HMAC and signature
are not the same on the stacked and backing filesystems.
Don't copy up 'security.evm'.
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
include/linux/evm.h | 6 ++++++
security/integrity/evm/evm_main.c | 7 +++++++
security/security.c | 2 +-
3 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/include/linux/evm.h b/include/linux/evm.h
index 01fc495a83e2..36ec884320d9 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -31,6 +31,7 @@ extern void evm_inode_post_setxattr(struct dentry *dentry,
const char *xattr_name,
const void *xattr_value,
size_t xattr_value_len);
+extern int evm_inode_copy_up_xattr(const char *name);
extern int evm_inode_removexattr(struct mnt_idmap *idmap,
struct dentry *dentry, const char *xattr_name);
extern void evm_inode_post_removexattr(struct dentry *dentry,
@@ -117,6 +118,11 @@ static inline void evm_inode_post_setxattr(struct dentry *dentry,
return;
}
+static inline int evm_inode_copy_up_xattr(const char *name)
+{
+ return 0;
+}
+
static inline int evm_inode_removexattr(struct mnt_idmap *idmap,
struct dentry *dentry,
const char *xattr_name)
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 894570fe39bc..02adba635b02 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -863,6 +863,13 @@ void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
evm_update_evmxattr(dentry, NULL, NULL, 0);
}
+int evm_inode_copy_up_xattr(const char *name)
+{
+ if (strcmp(name, XATTR_NAME_EVM) == 0)
+ return 1; /* Discard */
+ return -EOPNOTSUPP;
+}
+
/*
* evm_inode_init_security - initializes security.evm HMAC value
*/
diff --git a/security/security.c b/security/security.c
index dcb3e7014f9b..f00ec4d988b8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2539,7 +2539,7 @@ int security_inode_copy_up_xattr(const char *name)
return rc;
}
- return LSM_RET_DEFAULT(inode_copy_up_xattr);
+ return evm_inode_copy_up_xattr(name);
}
EXPORT_SYMBOL(security_inode_copy_up_xattr);
--
2.39.3
