bpf, docs: Rename bpf_lsm.rst to prog_lsm.rst

This allows for documentation relating to BPF Program Types to be
matched by the glob pattern prog_* for inclusion in a sphinx toctree

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/49fe0f370a2b28500c1b60f1fdb6fb7ec90de28a.1636749493.git.dave@dtucker.co.uk

diff --git a/Documentation/bpf/bpf_lsm.rst b/Documentation/bpf/bpf_lsm.rst
deleted file mode 100644 (file)
index 0dc3fb0..0000000
--- a/Documentation/bpf/bpf_lsm.rst
+++ /dev/null
@@ -1,143 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0+
-.. Copyright (C) 2020 Google LLC.
-
-================
-LSM BPF Programs
-================
-
-These BPF programs allow runtime instrumentation of the LSM hooks by privileged
-users to implement system-wide MAC (Mandatory Access Control) and Audit
-policies using eBPF.
-
-Structure
----------
-
-The example shows an eBPF program that can be attached to the ``file_mprotect``
-LSM hook:
-
-.. c:function:: int file_mprotect(struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot);
-
-Other LSM hooks which can be instrumented can be found in
-``include/linux/lsm_hooks.h``.
-
-eBPF programs that use Documentation/bpf/btf.rst do not need to include kernel
-headers for accessing information from the attached eBPF program's context.
-They can simply declare the structures in the eBPF program and only specify
-the fields that need to be accessed.
-
-.. code-block:: c
-
-       struct mm_struct {
-               unsigned long start_brk, brk, start_stack;
-       } __attribute__((preserve_access_index));
-
-       struct vm_area_struct {
-               unsigned long start_brk, brk, start_stack;
-               unsigned long vm_start, vm_end;
-               struct mm_struct *vm_mm;
-       } __attribute__((preserve_access_index));
-
-
-.. note:: The order of the fields is irrelevant.
-
-This can be further simplified (if one has access to the BTF information at
-build time) by generating the ``vmlinux.h`` with:
-
-.. code-block:: console
-
-       # bpftool btf dump file <path-to-btf-vmlinux> format c > vmlinux.h
-
-.. note:: ``path-to-btf-vmlinux`` can be ``/sys/kernel/btf/vmlinux`` if the
-         build environment matches the environment the BPF programs are
-         deployed in.
-
-The ``vmlinux.h`` can then simply be included in the BPF programs without
-requiring the definition of the types.
-
-The eBPF programs can be declared using the``BPF_PROG``
-macros defined in `tools/lib/bpf/bpf_tracing.h`_. In this
-example:
-
-       * ``"lsm/file_mprotect"`` indicates the LSM hook that the program must
-         be attached to
-       * ``mprotect_audit`` is the name of the eBPF program
-
-.. code-block:: c
-
-       SEC("lsm/file_mprotect")
-       int BPF_PROG(mprotect_audit, struct vm_area_struct *vma,
-                    unsigned long reqprot, unsigned long prot, int ret)
-       {
-               /* ret is the return value from the previous BPF program
-                * or 0 if it's the first hook.
-                */
-               if (ret != 0)
-                       return ret;
-
-               int is_heap;
-
-               is_heap = (vma->vm_start >= vma->vm_mm->start_brk &&
-                          vma->vm_end <= vma->vm_mm->brk);
-
-               /* Return an -EPERM or write information to the perf events buffer
-                * for auditing
-                */
-               if (is_heap)
-                       return -EPERM;
-       }
-
-The ``__attribute__((preserve_access_index))`` is a clang feature that allows
-the BPF verifier to update the offsets for the access at runtime using the
-Documentation/bpf/btf.rst information. Since the BPF verifier is aware of the
-types, it also validates all the accesses made to the various types in the
-eBPF program.
-
-Loading
--------
-
-eBPF programs can be loaded with the :manpage:`bpf(2)` syscall's
-``BPF_PROG_LOAD`` operation:
-
-.. code-block:: c
-
-       struct bpf_object *obj;
-
-       obj = bpf_object__open("./my_prog.o");
-       bpf_object__load(obj);
-
-This can be simplified by using a skeleton header generated by ``bpftool``:
-
-.. code-block:: console
-
-       # bpftool gen skeleton my_prog.o > my_prog.skel.h
-
-and the program can be loaded by including ``my_prog.skel.h`` and using
-the generated helper, ``my_prog__open_and_load``.
-
-Attachment to LSM Hooks
------------------------
-
-The LSM allows attachment of eBPF programs as LSM hooks using :manpage:`bpf(2)`
-syscall's ``BPF_RAW_TRACEPOINT_OPEN`` operation or more simply by
-using the libbpf helper ``bpf_program__attach_lsm``.
-
-The program can be detached from the LSM hook by *destroying* the ``link``
-link returned by ``bpf_program__attach_lsm`` using ``bpf_link__destroy``.
-
-One can also use the helpers generated in ``my_prog.skel.h`` i.e.
-``my_prog__attach`` for attachment and ``my_prog__destroy`` for cleaning up.
-
-Examples
---------
-
-An example eBPF program can be found in
-`tools/testing/selftests/bpf/progs/lsm.c`_ and the corresponding
-userspace code in `tools/testing/selftests/bpf/prog_tests/test_lsm.c`_
-
-.. Links
-.. _tools/lib/bpf/bpf_tracing.h:
-   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/lib/bpf/bpf_tracing.h
-.. _tools/testing/selftests/bpf/progs/lsm.c:
-   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/progs/lsm.c
-.. _tools/testing/selftests/bpf/prog_tests/test_lsm.c:
-   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/prog_tests/test_lsm.c

diff --git a/Documentation/bpf/prog_lsm.rst b/Documentation/bpf/prog_lsm.rst
new file mode 100644 (file)
index 0000000..0dc3fb0
--- /dev/null
+++ b/Documentation/bpf/prog_lsm.rst
@@ -0,0 +1,143 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2020 Google LLC.
+
+================
+LSM BPF Programs
+================
+
+These BPF programs allow runtime instrumentation of the LSM hooks by privileged
+users to implement system-wide MAC (Mandatory Access Control) and Audit
+policies using eBPF.
+
+Structure
+---------
+
+The example shows an eBPF program that can be attached to the ``file_mprotect``
+LSM hook:
+
+.. c:function:: int file_mprotect(struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot);
+
+Other LSM hooks which can be instrumented can be found in
+``include/linux/lsm_hooks.h``.
+
+eBPF programs that use Documentation/bpf/btf.rst do not need to include kernel
+headers for accessing information from the attached eBPF program's context.
+They can simply declare the structures in the eBPF program and only specify
+the fields that need to be accessed.
+
+.. code-block:: c
+
+       struct mm_struct {
+               unsigned long start_brk, brk, start_stack;
+       } __attribute__((preserve_access_index));
+
+       struct vm_area_struct {
+               unsigned long start_brk, brk, start_stack;
+               unsigned long vm_start, vm_end;
+               struct mm_struct *vm_mm;
+       } __attribute__((preserve_access_index));
+
+
+.. note:: The order of the fields is irrelevant.
+
+This can be further simplified (if one has access to the BTF information at
+build time) by generating the ``vmlinux.h`` with:
+
+.. code-block:: console
+
+       # bpftool btf dump file <path-to-btf-vmlinux> format c > vmlinux.h
+
+.. note:: ``path-to-btf-vmlinux`` can be ``/sys/kernel/btf/vmlinux`` if the
+         build environment matches the environment the BPF programs are
+         deployed in.
+
+The ``vmlinux.h`` can then simply be included in the BPF programs without
+requiring the definition of the types.
+
+The eBPF programs can be declared using the``BPF_PROG``
+macros defined in `tools/lib/bpf/bpf_tracing.h`_. In this
+example:
+
+       * ``"lsm/file_mprotect"`` indicates the LSM hook that the program must
+         be attached to
+       * ``mprotect_audit`` is the name of the eBPF program
+
+.. code-block:: c
+
+       SEC("lsm/file_mprotect")
+       int BPF_PROG(mprotect_audit, struct vm_area_struct *vma,
+                    unsigned long reqprot, unsigned long prot, int ret)
+       {
+               /* ret is the return value from the previous BPF program
+                * or 0 if it's the first hook.
+                */
+               if (ret != 0)
+                       return ret;
+
+               int is_heap;
+
+               is_heap = (vma->vm_start >= vma->vm_mm->start_brk &&
+                          vma->vm_end <= vma->vm_mm->brk);
+
+               /* Return an -EPERM or write information to the perf events buffer
+                * for auditing
+                */
+               if (is_heap)
+                       return -EPERM;
+       }
+
+The ``__attribute__((preserve_access_index))`` is a clang feature that allows
+the BPF verifier to update the offsets for the access at runtime using the
+Documentation/bpf/btf.rst information. Since the BPF verifier is aware of the
+types, it also validates all the accesses made to the various types in the
+eBPF program.
+
+Loading
+-------
+
+eBPF programs can be loaded with the :manpage:`bpf(2)` syscall's
+``BPF_PROG_LOAD`` operation:
+
+.. code-block:: c
+
+       struct bpf_object *obj;
+
+       obj = bpf_object__open("./my_prog.o");
+       bpf_object__load(obj);
+
+This can be simplified by using a skeleton header generated by ``bpftool``:
+
+.. code-block:: console
+
+       # bpftool gen skeleton my_prog.o > my_prog.skel.h
+
+and the program can be loaded by including ``my_prog.skel.h`` and using
+the generated helper, ``my_prog__open_and_load``.
+
+Attachment to LSM Hooks
+-----------------------
+
+The LSM allows attachment of eBPF programs as LSM hooks using :manpage:`bpf(2)`
+syscall's ``BPF_RAW_TRACEPOINT_OPEN`` operation or more simply by
+using the libbpf helper ``bpf_program__attach_lsm``.
+
+The program can be detached from the LSM hook by *destroying* the ``link``
+link returned by ``bpf_program__attach_lsm`` using ``bpf_link__destroy``.
+
+One can also use the helpers generated in ``my_prog.skel.h`` i.e.
+``my_prog__attach`` for attachment and ``my_prog__destroy`` for cleaning up.
+
+Examples
+--------
+
+An example eBPF program can be found in
+`tools/testing/selftests/bpf/progs/lsm.c`_ and the corresponding
+userspace code in `tools/testing/selftests/bpf/prog_tests/test_lsm.c`_
+
+.. Links
+.. _tools/lib/bpf/bpf_tracing.h:
+   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/lib/bpf/bpf_tracing.h
+.. _tools/testing/selftests/bpf/progs/lsm.c:
+   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/progs/lsm.c
+.. _tools/testing/selftests/bpf/prog_tests/test_lsm.c:
+   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/tools/testing/selftests/bpf/prog_tests/test_lsm.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4c74516e4353f832908d964b744eb77edf682015..25a59950042def0185f1bbfd2cf7507585a55556 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3559,7 +3559,7 @@ R:        Florent Revest <revest@chromium.org>
 R:     Brendan Jackman <jackmanb@chromium.org>
 L:     bpf@vger.kernel.org
 S:     Maintained
-F:     Documentation/bpf/bpf_lsm.rst
+F:     Documentation/bpf/prog_lsm.rst
 F:     include/linux/bpf_lsm.h
 F:     kernel/bpf/bpf_lsm.c
 F:     security/bpf/