From: Hao Luo <haoluo@google.com>
To: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
KP Singh <kpsingh@kernel.org>, Shakeel Butt <shakeelb@google.com>,
Joe Burton <jevburton.kernel@gmail.com>,
Tejun Heo <tj@kernel.org>,
joshdon@google.com, sdf@google.com, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v1 1/9] bpf: Add mkdir, rmdir, unlink syscalls for prog_bpf_syscall
Date: Thu, 3 Mar 2022 10:56:53 -0800 [thread overview]
Message-ID: <CA+khW7gAEL+yBmXjWO28ns5hU4oHVZrEArfepuOfy6Q1y7VDKQ@mail.gmail.com> (raw)
In-Reply-To: <7e862b1c-7818-6759-caf1-962598d2c8b3@fb.com>
On Wed, Mar 2, 2022 at 12:55 PM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 2/25/22 3:43 PM, Hao Luo wrote:
> > This patch allows bpf_syscall prog to perform some basic filesystem
> > operations: create, remove directories and unlink files. Three bpf
> > helpers are added for this purpose. When combined with the following
> > patches that allow pinning and getting bpf objects from bpf prog,
> > this feature can be used to create directory hierarchy in bpffs that
> > help manage bpf objects purely using bpf progs.
> >
> > The added helpers subject to the same permission checks as their syscall
> > version. For example, one can not write to a read-only file system;
> > The identity of the current process is checked to see whether it has
> > sufficient permission to perform the operations.
> >
> > Only directories and files in bpffs can be created or removed by these
> > helpers. But it won't be too hard to allow these helpers to operate
> > on files in other filesystems, if we want.
> >
> > Signed-off-by: Hao Luo <haoluo@google.com>
> > ---
> > include/linux/bpf.h | 1 +
> > include/uapi/linux/bpf.h | 26 +++++
> > kernel/bpf/inode.c | 9 +-
> > kernel/bpf/syscall.c | 177 +++++++++++++++++++++++++++++++++
> > tools/include/uapi/linux/bpf.h | 26 +++++
> > 5 files changed, 236 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index f19abc59b6cd..fce5e26179f5 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -1584,6 +1584,7 @@ int bpf_link_new_fd(struct bpf_link *link);
> > struct file *bpf_link_new_file(struct bpf_link *link, int *reserved_fd);
> > struct bpf_link *bpf_link_get_from_fd(u32 ufd);
> >
> > +bool bpf_path_is_bpf_dir(const struct path *path);
> > int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
> > int bpf_obj_get_user(const char __user *pathname, int flags);
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index afe3d0d7f5f2..a5dbc794403d 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -5086,6 +5086,29 @@ union bpf_attr {
> > * Return
> > * 0 on success, or a negative error in case of failure. On error
> > * *dst* buffer is zeroed out.
> > + *
> > + * long bpf_mkdir(const char *pathname, int pathname_sz, u32 mode)
>
> Can we make pathname_sz to be u32 instead of int? pathname_sz should
> never be negative any way.
>
> Also, I think it is a good idea to add 'u64 flags' parameter for all
> three helpers, so we have room in the future to tune for new use cases.
>
SG. Will make this change.
Actually, I think I need to cap patthname_sz from above, to ensure
pathname_sz isn't too big. Is that necessary? I see there are other
helpers that don't have this type of check.
> > + * Description
> > + * Attempts to create a directory name *pathname*. The argument
> > + * *pathname_sz* specifies the length of the string *pathname*.
> > + * The argument *mode* specifies the mode for the new directory. It
> > + * is modified by the process's umask. It has the same semantic as
> > + * the syscall mkdir(2).
> > + * Return
> > + * 0 on success, or a negative error in case of failure.
> > + *
> > + * long bpf_rmdir(const char *pathname, int pathname_sz)
> > + * Description
> > + * Deletes a directory, which must be empty.
> > + * Return
> > + * 0 on sucess, or a negative error in case of failure.
> > + *
> > + * long bpf_unlink(const char *pathname, int pathname_sz)
> > + * Description
> > + * Deletes a name and possibly the file it refers to. It has the
> > + * same semantic as the syscall unlink(2).
> > + * Return
> > + * 0 on success, or a negative error in case of failure.
> > */
> > #define __BPF_FUNC_MAPPER(FN) \
> > FN(unspec), \
> > @@ -5280,6 +5303,9 @@ union bpf_attr {
> > FN(xdp_load_bytes), \
> > FN(xdp_store_bytes), \
> > FN(copy_from_user_task), \
> > + FN(mkdir), \
> > + FN(rmdir), \
> > + FN(unlink), \
> > /* */
> >
> > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> [...]
next prev parent reply other threads:[~2022-03-03 18:57 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-25 23:43 [PATCH bpf-next v1 0/9] Extend cgroup interface with bpf Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 1/9] bpf: Add mkdir, rmdir, unlink syscalls for prog_bpf_syscall Hao Luo
2022-02-27 5:18 ` Kumar Kartikeya Dwivedi
2022-02-28 22:10 ` Hao Luo
2022-03-02 19:34 ` Alexei Starovoitov
2022-03-03 18:50 ` Hao Luo
2022-03-04 18:37 ` Hao Luo
2022-03-05 23:47 ` Alexei Starovoitov
2022-03-08 21:08 ` Hao Luo
2022-03-02 20:55 ` Yonghong Song
2022-03-03 18:56 ` Hao Luo [this message]
2022-03-03 19:13 ` Yonghong Song
2022-03-03 19:15 ` Hao Luo
2022-03-12 3:46 ` Al Viro
2022-03-14 17:07 ` Hao Luo
2022-03-14 23:10 ` Al Viro
2022-03-15 17:27 ` Hao Luo
2022-03-15 18:59 ` Alexei Starovoitov
2022-03-15 19:03 ` Alexei Starovoitov
2022-03-15 19:00 ` Al Viro
2022-03-15 19:47 ` Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 2/9] bpf: Add BPF_OBJ_PIN and BPF_OBJ_GET in the bpf_sys_bpf helper Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 3/9] selftests/bpf: tests mkdir, rmdir, unlink and pin in syscall Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 4/9] bpf: Introduce sleepable tracepoints Hao Luo
2022-03-02 19:41 ` Alexei Starovoitov
2022-03-03 19:37 ` Hao Luo
2022-03-03 19:59 ` Alexei Starovoitov
2022-03-02 21:23 ` Yonghong Song
2022-03-02 21:30 ` Alexei Starovoitov
2022-03-03 1:08 ` Yonghong Song
2022-03-03 2:29 ` Alexei Starovoitov
2022-03-03 19:43 ` Hao Luo
2022-03-03 20:02 ` Alexei Starovoitov
2022-03-03 20:04 ` Alexei Starovoitov
2022-03-03 22:06 ` Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 5/9] cgroup: Sleepable cgroup tracepoints Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 6/9] libbpf: Add sleepable tp_btf Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 7/9] bpf: Lift permission check in __sys_bpf when called from kernel Hao Luo
2022-03-02 20:01 ` Alexei Starovoitov
2022-03-03 19:14 ` Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 8/9] bpf: Introduce cgroup iter Hao Luo
2022-02-26 2:32 ` kernel test robot
2022-02-26 2:32 ` kernel test robot
2022-02-26 2:53 ` kernel test robot
2022-03-02 21:59 ` Yonghong Song
2022-03-03 20:02 ` Hao Luo
2022-03-02 22:45 ` Kumar Kartikeya Dwivedi
2022-03-03 2:03 ` Yonghong Song
2022-03-03 3:03 ` Kumar Kartikeya Dwivedi
2022-03-03 4:00 ` Alexei Starovoitov
2022-03-03 7:33 ` Yonghong Song
2022-03-03 8:13 ` Kumar Kartikeya Dwivedi
2022-03-03 21:52 ` Hao Luo
2022-02-25 23:43 ` [PATCH bpf-next v1 9/9] selftests/bpf: Tests using sleepable tracepoints to monitor cgroup events Hao Luo
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