Re: [PATCH bpf-next 1/6] bpf: introduce BPF_PROG_TYPE_FILE_FILTER
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: 2018-10-05 05:13:31
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On Wed, Oct 03, 2018 at 07:57:45PM -0700, Alexei Starovoitov wrote:
quoted hunk ↗ jump to hunk
@@ -15,6 +15,7 @@ #include <linux/bpf.h> #include <linux/bpf-cgroup.h> #include <net/sock.h> +#include <../fs/mount.h>
No.
+ struct file *file = NULL; + struct inode *inode; + struct super_block *sb; + struct mount *mnt;
Fuck, no.
+ case offsetof(struct bpf_file_info, mnt_id): + /* dst = real_mount(file->f_path.mnt)->mnt_id */ + mnt = real_mount(LD_1(file->f_path.mnt)); + LD_n(mnt->mnt_id);
NAK. Anything in struct mount is private to just a couple of files in fs/*.c. Don't do that. And keep in mind that internal details can and will be changed at zero notice, so be careful with adding such stuff. Another problem is your direct poking in ->i_ino. It's not something directly exposed to userland at the moment and it should not become such. Filesystem has every right to have ->getattr() set ->ino (== ->st_ino value) in whichever way it likes; the same goes for ->dev.