From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> Date: Fri, 22 Dec 2017 15:32:35 +0100 The kernel should not calculate new hmacs for mounts done by non-root users. Update evm_calc_hmac_or_hash() to refuse to calculate new hmacs for mounts for non-init user namespaces. Cc: linux-integrity@xxxxxxxxxxxxxxx Cc: linux-security-module@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: James Morris <james.l.morris@xxxxxxxxxx> Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx> Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> Signed-off-by: Dongsu Park <dongsu@xxxxxxxxxx> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> --- Mimi this patch has been floating around for a while and it appears to be the only piece missing from the vfs to make unprivileged mounts safe (at least semantically). Do you want to merge this through your integrity tree or should merge this through my userns tree? security/integrity/evm/evm_crypto.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index a46fba322340..facf9cdd577d 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -200,7 +200,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, int size; bool ima_present = false; - if (!(inode->i_opflags & IOP_XATTR)) + if (!(inode->i_opflags & IOP_XATTR) || + inode->i_sb->s_user_ns != &init_user_ns) return -EOPNOTSUPP; desc = init_desc(type); -- 2.14.1
