From faf994811e0548df854e5fd946f3094725fcd9b5 Mon Sep 17 00:00:00 2001 From: Stefan Berger Date: Fri, 23 Feb 2024 12:25:07 -0500 Subject: [PATCH] evm: Use the metadata inode to calculate metadata hash Changes to file attributes (mode bits, uid, gid) on the lower layer are not taken into account when d_backing_inode() is used when a file is accessed on the overlay layer and this file has not yet been copied up. This is because d_backing_inode() does not return the real inode of the lower layer but instead returns the backing inode which in this case holds wrong file attributes. Further, when CONFIG_OVERLAY_FS_METACOPY is enabled and a copy-up is triggered due to file metadata changes, then the metadata are held by the backing inode while the data are still held by the real inode. Therefore, use d_inode(d_real(dentry, D_REAL_METADATA)) to get to the file's metadata inode and use it to calculate the metadata hash with. Co-developed-by: Mimi Zohar Signed-off-by: Stefan Berger Acked-by: Amir Goldstein Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_crypto.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 7552d49d0725..35416f55391c 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -223,7 +223,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, size_t req_xattr_value_len, uint8_t type, struct evm_digest *data) { - struct inode *inode = d_backing_inode(dentry); + struct inode *inode = d_inode(d_real(dentry, D_REAL_METADATA)); struct xattr_list *xattr; struct shash_desc *desc; size_t xattr_size = 0;