Commit faf99481 authored by Stefan Berger's avatar Stefan Berger Committed by Mimi Zohar
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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: default avatarMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Acked-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
parent f2b3fc42

security/integrity/evm/evm_crypto.c

+1 −1
Original line number Diff line number Diff line
@@ -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;