On Tue, Oct 10, 2023 at 12:09 AM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote:
>
>
>
> On 9/28/2023 6:57 AM, Andrii Nakryiko wrote:
> > Add few new mount options to BPF FS that allow to specify that a given
> > BPF FS instance allows creation of BPF token (added in the next patch),
> > and what sort of operations are allowed under BPF token. As such, we get
> > 4 new mount options, each is a bit mask
> > - `delegate_cmds` allow to specify which bpf() syscall commands are
> > allowed with BPF token derived from this BPF FS instance;
> > - if BPF_MAP_CREATE command is allowed, `delegate_maps` specifies
> > a set of allowable BPF map types that could be created with BPF token;
> > - if BPF_PROG_LOAD command is allowed, `delegate_progs` specifies
> > a set of allowable BPF program types that could be loaded with BPF token;
> > - if BPF_PROG_LOAD command is allowed, `delegate_attachs` specifies
> > a set of allowable BPF program attach types that could be loaded with
> > BPF token; delegate_progs and delegate_attachs are meant to be used
> > together, as full BPF program type is, in general, determined
> > through both program type and program attach type.
> >
> > Currently, these mount options accept the following forms of values:
> > - a special value "any", that enables all possible values of a given
> > bit set;
> > - numeric value (decimal or hexadecimal, determined by kernel
> > automatically) that specifies a bit mask value directly;
> > - all the values for a given mount option are combined, if specified
> > multiple times. E.g., `mount -t bpf nodev /path/to/mount -o
> > delegate_maps=0x1 -o delegate_maps=0x2` will result in a combined 0x3
> > mask.
> >
> SNIP
> > return 0;
> > @@ -740,10 +786,14 @@ static int populate_bpffs(struct dentry *parent)
> > static int bpf_fill_super(struct super_block *sb, struct fs_context *fc)
> > {
> > static const struct tree_descr bpf_rfiles[] = { { "" } };
> > - struct bpf_mount_opts *opts = fc->fs_private;
> > + struct bpf_mount_opts *opts = sb->s_fs_info;
> > struct inode *inode;
> > int ret;
> >
> > + /* Mounting an instance of BPF FS requires privileges */
> > + if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN))
> > + return -EPERM;
> > +
> > ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
> > if (ret)
> > return ret;
> > @@ -765,7 +815,10 @@ static int bpf_get_tree(struct fs_context *fc)
> >
> > static void bpf_free_fc(struct fs_context *fc)
> > {
> > - kfree(fc->fs_private);
> > + struct bpf_mount_opts *opts = fc->s_fs_info;
> > +
> > + if (opts)
> > + kfree(opts);
> > }
> >
>
> The NULL check is not needed here, use kfree(fc->s_fs_info) will be enough.
yep, dropped the check
> > static const struct fs_context_operations bpf_context_ops = {
> > @@ -787,17 +840,32 @@ static int bpf_init_fs_context(struct fs_context *fc)
> >
> > opts->mode = S_IRWXUGO;
> >
> > - fc->fs_private = opts;
> > + /* start out with no BPF token delegation enabled */
> > + opts->delegate_cmds = 0;
> > + opts->delegate_maps = 0;
> > + opts->delegate_progs = 0;
> > + opts->delegate_attachs = 0;
> > +
> > + fc->s_fs_info = opts;
> > fc->ops = &bpf_context_ops;
> > return 0;
> > }
> >
> > +static void bpf_kill_super(struct super_block *sb)
> > +{
> > + struct bpf_mount_opts *opts = sb->s_fs_info;
> > +
> > + kill_litter_super(sb);
> > + kfree(opts);
> > +}
> > +
> > static struct file_system_type bpf_fs_type = {
> > .owner = THIS_MODULE,
> > .name = "bpf",
> > .init_fs_context = bpf_init_fs_context,
> > .parameters = bpf_fs_parameters,
> > - .kill_sb = kill_litter_super,
> > + .kill_sb = bpf_kill_super,
> > + .fs_flags = FS_USERNS_MOUNT,
> > };
> >
> > static int __init bpf_init(void)
>
>
