[PATCH 5.19 177/717] ima: fix blocking of security.ima xattrs of unsupported algorithms

Greg Kroah-Hartman
2022-10-22T07:46:31Z

From: Mimi Zohar <zohar@linux.ibm.com>

[ Upstream commit 5926586f291b53cb8a0c9631fc19489be1186e2d ]

Limit validating the hash algorithm to just security.ima xattr, not
the security.evm xattr or any of the protected EVM security xattrs,
nor posix acls.

Fixes: 50f742dd9147 ("IMA: block writes of the security.ima xattr with unsupported algorithms")
Reported-by: Christian Brauner <brauner@kernel.org>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/integrity/ima/ima_appraise.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index bde74fcecee3..3e0fbbd99534 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -750,22 +750,26 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
const struct evm_ima_xattr_data *xvalue = xattr_value;
int digsig = 0;
int result;
+ int err;

result = ima_protect_xattr(dentry, xattr_name, xattr_value,
xattr_value_len);
if (result == 1) {
if (!xattr_value_len || (xvalue->type >= IMA_XATTR_LAST))
return -EINVAL;
+
+ err = validate_hash_algo(dentry, xvalue, xattr_value_len);
+ if (err)
+ return err;
+
digsig = (xvalue->type == EVM_IMA_XATTR_DIGSIG);
} else if (!strcmp(xattr_name, XATTR_NAME_EVM) && xattr_value_len > 0) {
digsig = (xvalue->type == EVM_XATTR_PORTABLE_DIGSIG);
}
if (result == 1 || evm_revalidate_status(xattr_name)) {
- result = validate_hash_algo(dentry, xvalue, xattr_value_len);
- if (result)
- return result;
-
ima_reset_appraise_flags(d_backing_inode(dentry), digsig);
+ if (result == 1)
+ result = 0;
}
return result;
}
--
2.35.1