From: Zhan Xusheng Date: Sat, 25 Jul 2026 08:00:04 +0000 (+0800) Subject: fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf6c993c0feca7984797e634deba3c80342e199a;p=thirdparty%2Fkernel%2Flinux.git fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy() fscrypt_ioctl_set_policy() calls inode_owner_or_capable() with &nop_mnt_idmap before allowing an encryption policy to be set, instead of the idmap of the mount the ioctl was issued on. fscrypt is used by filesystems that support idmapped mounts (e.g. ext4, f2fs), so on such a mount this compares the caller's fsuid against the unmapped on-disk owner rather than the mapped owner: the actual owner can be wrongly denied with -EACCES and an unrelated caller wrongly allowed. Use file_mnt_idmap(filp) instead. Fixes: 14f3db5542e6 ("ext4: support idmapped mounts") Cc: stable@vger.kernel.org Signed-off-by: Zhan Xusheng Link: https://patch.msgid.link/20260725080004.929328-1-zhanxusheng1024@gmail.com Signed-off-by: Eric Biggers --- diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 9915e39362db..c80b24a941ad 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -534,7 +534,7 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg) return -EFAULT; policy.version = version; - if (!inode_owner_or_capable(&nop_mnt_idmap, inode)) + if (!inode_owner_or_capable(file_mnt_idmap(filp), inode)) return -EACCES; ret = mnt_want_write_file(filp);