From 63ffb573df66aea034d07fd00483d0a3cd4fed66 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 22 Nov 2022 03:04:00 +0100 Subject: efi: vars: prohibit reading random seed variables In anticipation of putting random seeds in EFI variables, it's important that the random GUID namespace of variables remains hidden from userspace. We accomplish this by not populating efivarfs with entries from that GUID, as well as denying the creation of new ones in that GUID. Signed-off-by: Jason A. Donenfeld Signed-off-by: Ard Biesheuvel --- fs/efivarfs/inode.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs/efivarfs/inode.c') diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c index 939e5e242b98..617f3ad2485e 100644 --- a/fs/efivarfs/inode.c +++ b/fs/efivarfs/inode.c @@ -91,6 +91,10 @@ static int efivarfs_create(struct user_namespace *mnt_userns, struct inode *dir, err = guid_parse(dentry->d_name.name + namelen + 1, &var->var.VendorGuid); if (err) goto out; + if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) { + err = -EPERM; + goto out; + } if (efivar_variable_is_removable(var->var.VendorGuid, dentry->d_name.name, namelen)) -- cgit v1.2.3