Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel…

…/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2023-05-16

We've added 57 non-merge commits during the last 19 day(s) which contain
a total of 63 files changed, 3293 insertions(+), 690 deletions(-).

The main changes are:

1) Add precision propagation to verifier for subprogs and callbacks,
   from Andrii Nakryiko.

2) Improve BPF's {g,s}setsockopt() handling with wrong option lengths,
   from Stanislav Fomichev.

3) Utilize pahole v1.25 for the kernel's BTF generation to filter out
   inconsistent function prototypes, from Alan Maguire.

4) Various dyn-pointer verifier improvements to relax restrictions,
   from Daniel Rosenberg.

5) Add a new bpf_task_under_cgroup() kfunc for designated task,
   from Feng Zhou.

6) Unblock tests for arm64 BPF CI after ftrace supporting direct call,
   from Florent Revest.

7) Add XDP hint kfunc metadata for RX hash/timestamp for igc,
   from Jesper Dangaard Brouer.

8) Add several new dyn-pointer kfuncs to ease their usability,
   from Joanne Koong.

9) Add in-depth LRU internals description and dot function graph,
   from Joe Stringer.

10) Fix KCSAN report on bpf_lru_list when accessing node->ref,
    from Martin KaFai Lau.

11) Only dump unprivileged_bpf_disabled log warning upon write,
    from Kui-Feng Lee.

12) Extend test_progs to directly passing allow/denylist file,
    from Stephen Veiss.

13) Fix BPF trampoline memleak upon failure attaching to fentry,
    from Yafang Shao.

14) Fix emitting struct bpf_tcp_sock type in vmlinux BTF,
    from Yonghong Song.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (57 commits)
  bpf: Fix memleak due to fentry attach failure
  bpf: Remove bpf trampoline selector
  bpf, arm64: Support struct arguments in the BPF trampoline
  bpftool: JIT limited misreported as negative value on aarch64
  bpf: fix calculation of subseq_idx during precision backtracking
  bpf: Remove anonymous union in bpf_kfunc_call_arg_meta
  bpf: Document EFAULT changes for sockopt
  selftests/bpf: Correctly handle optlen > 4096
  selftests/bpf: Update EFAULT {g,s}etsockopt selftests
  bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen
  libbpf: fix offsetof() and container_of() to work with CO-RE
  bpf: Address KCSAN report on bpf_lru_list
  bpf: Add --skip_encoding_btf_inconsistent_proto, --btf_gen_optimized to pahole flags for v1.25
  selftests/bpf: Accept mem from dynptr in helper funcs
  bpf: verifier: Accept dynptr mem as mem in helpers
  selftests/bpf: Check overflow in optional buffer
  selftests/bpf: Test allowing NULL buffer in dynptr slice
  bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)
  selftests/bpf: Add testcase for bpf_task_under_cgroup
  bpf: Add bpf_task_under_cgroup() kfunc
  ...
====================

Link: https://lore.kernel.org/r/20230515225603.27027-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/bpf/kfuncs.rst

@@ -100,7 +100,7 @@ Hence, whenever a constant scalar argument is accepted by a kfunc which is not a
 size parameter, and the value of the constant matters for program safety, __k
 suffix should be used.
 
-2.2.2 __uninit Annotation
+2.2.3 __uninit Annotation
 -------------------------
 
 This annotation is used to indicate that the argument will be treated as
@@ -117,6 +117,27 @@ Here, the dynptr will be treated as an uninitialized dynptr. Without this
 annotation, the verifier will reject the program if the dynptr passed in is
 not initialized.
 
+2.2.4 __opt Annotation
+-------------------------
+
+This annotation is used to indicate that the buffer associated with an __sz or __szk
+argument may be null. If the function is passed a nullptr in place of the buffer,
+the verifier will not check that length is appropriate for the buffer. The kfunc is
+responsible for checking if this buffer is null before using it.
+
+An example is given below::
+
+        __bpf_kfunc void *bpf_dynptr_slice(..., void *buffer__opt, u32 buffer__szk)
+        {
+        ...
+        }
+
+Here, the buffer may be null. If buffer is not null, it at least of size buffer_szk.
+Either way, the returned buffer is either NULL, or of size buffer_szk. Without this
+annotation, the verifier will reject the program if a null pointer is passed in with
+a nonzero size.
+
+
 .. _BPF_kfunc_nodef:
 
 2.3 Using an existing kernel function

Documentation/bpf/llvm_reloc.rst

@@ -48,7 +48,7 @@ the code with ``llvm-objdump -dr test.o``::
       14:       0f 10 00 00 00 00 00 00 r0 += r1
       15:       95 00 00 00 00 00 00 00 exit
 
-There are four relations in the above for four ``LD_imm64`` instructions.
+There are four relocations in the above for four ``LD_imm64`` instructions.
 The following ``llvm-readelf -r test.o`` shows the binary values of the four
 relocations::
 
@@ -79,14 +79,16 @@ The following is the symbol table with ``llvm-readelf -s test.o``::
 The 6th entry is global variable ``g1`` with value 0.
 
 Similarly, the second relocation is at ``.text`` offset ``0x18``, instruction 3,
-for global variable ``g2`` which has a symbol value 4, the offset
-from the start of ``.data`` section.
-
-The third and fourth relocations refers to static variables ``l1``
-and ``l2``. From ``.rel.text`` section above, it is not clear
-which symbols they really refers to as they both refers to
+has a type of ``R_BPF_64_64`` and refers to entry 7 in the symbol table.
+The second relocation resolves to global variable ``g2`` which has a symbol
+value 4. The symbol value represents the offset from the start of ``.data``
+section where the initial value of the global variable ``g2`` is stored.
+
+The third and fourth relocations refer to static variables ``l1``
+and ``l2``. From the ``.rel.text`` section above, it is not clear
+to which symbols they really refer as they both refer to
 symbol table entry 4, symbol ``sec``, which has ``STT_SECTION`` type
-and represents a section. So for static variable or function,
+and represents a section. So for a static variable or function,
 the section offset is written to the original insn
 buffer, which is called ``A`` (addend). Looking at
 above insn ``7`` and ``11``, they have section offset ``8`` and ``12``.

Documentation/bpf/map_hash.rst

@@ -1,5 +1,6 @@
 .. SPDX-License-Identifier: GPL-2.0-only
 .. Copyright (C) 2022 Red Hat, Inc.
+.. Copyright (C) 2022-2023 Isovalent, Inc.
 
 ===============================================
 BPF_MAP_TYPE_HASH, with PERCPU and LRU Variants
@@ -29,7 +30,16 @@ will automatically evict the least recently used entries when the hash
 table reaches capacity. An LRU hash maintains an internal LRU list that
 is used to select elements for eviction. This internal LRU list is
 shared across CPUs but it is possible to request a per CPU LRU list with
-the ``BPF_F_NO_COMMON_LRU`` flag when calling ``bpf_map_create``.
+the ``BPF_F_NO_COMMON_LRU`` flag when calling ``bpf_map_create``.  The
+following table outlines the properties of LRU maps depending on the a
+map type and the flags used to create the map.
+
+======================== ========================= ================================
+Flag                     ``BPF_MAP_TYPE_LRU_HASH`` ``BPF_MAP_TYPE_LRU_PERCPU_HASH``
+======================== ========================= ================================
+**BPF_F_NO_COMMON_LRU**  Per-CPU LRU, global map   Per-CPU LRU, per-cpu map
+**!BPF_F_NO_COMMON_LRU** Global LRU, global map    Global LRU, per-cpu map
+======================== ========================= ================================
 
 Usage
 =====
@@ -206,3 +216,44 @@ Userspace walking the map elements from the map declared above:
                     cur_key = &next_key;
             }
     }
+
+Internals
+=========
+
+This section of the document is targeted at Linux developers and describes
+aspects of the map implementations that are not considered stable ABI. The
+following details are subject to change in future versions of the kernel.
+
+``BPF_MAP_TYPE_LRU_HASH`` and variants
+--------------------------------------
+
+Updating elements in LRU maps may trigger eviction behaviour when the capacity
+of the map is reached. There are various steps that the update algorithm
+attempts in order to enforce the LRU property which have increasing impacts on
+other CPUs involved in the following operation attempts:
+
+- Attempt to use CPU-local state to batch operations
+- Attempt to fetch free nodes from global lists
+- Attempt to pull any node from a global list and remove it from the hashmap
+- Attempt to pull any node from any CPU's list and remove it from the hashmap
+
+This algorithm is described visually in the following diagram. See the
+description in commit 3a08c2fd7634 ("bpf: LRU List") for a full explanation of
+the corresponding operations:
+
+.. kernel-figure::  map_lru_hash_update.dot
+   :alt:    Diagram outlining the LRU eviction steps taken during map update.
+
+   LRU hash eviction during map update for ``BPF_MAP_TYPE_LRU_HASH`` and
+   variants. See the dot file source for kernel function name code references.
+
+Map updates start from the oval in the top right "begin ``bpf_map_update()``"
+and progress through the graph towards the bottom where the result may be
+either a successful update or a failure with various error codes. The key in
+the top right provides indicators for which locks may be involved in specific
+operations. This is intended as a visual hint for reasoning about how map
+contention may impact update operations, though the map type and flags may
+impact the actual contention on those locks, based on the logic described in
+the table above. For instance, if the map is created with type
+``BPF_MAP_TYPE_LRU_PERCPU_HASH`` and flags ``BPF_F_NO_COMMON_LRU`` then all map
+properties would be per-cpu.

Documentation/bpf/map_lru_hash_update.dot

@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2022-2023 Isovalent, Inc.
+digraph {
+  node [colorscheme=accent4,style=filled] # Apply colorscheme to all nodes
+  graph [splines=ortho, nodesep=1]
+
+  subgraph cluster_key {
+    label = "Key\n(locks held during operation)";
+    rankdir = TB;
+
+    remote_lock [shape=rectangle,fillcolor=4,label="remote CPU LRU lock"]
+    hash_lock [shape=rectangle,fillcolor=3,label="hashtab lock"]
+    lru_lock [shape=rectangle,fillcolor=2,label="LRU lock"]
+    local_lock [shape=rectangle,fillcolor=1,label="local CPU LRU lock"]
+    no_lock [shape=rectangle,label="no locks held"]
+  }
+
+  begin [shape=oval,label="begin\nbpf_map_update()"]
+
+  // Nodes below with an 'fn_' prefix are roughly labeled by the C function
+  // names that initiate the corresponding logic in kernel/bpf/bpf_lru_list.c.
+  // Number suffixes and errno suffixes handle subsections of the corresponding
+  // logic in the function as of the writing of this dot.
+
+  // cf. __local_list_pop_free() / bpf_percpu_lru_pop_free()
+  local_freelist_check [shape=diamond,fillcolor=1,
+    label="Local freelist\nnode available?"];
+  use_local_node [shape=rectangle,
+    label="Use node owned\nby this CPU"]
+
+  // cf. bpf_lru_pop_free()
+  common_lru_check [shape=diamond,
+    label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];
+
+  fn_bpf_lru_list_pop_free_to_local [shape=rectangle,fillcolor=2,
+    label="Flush local pending,
+    Rotate Global list, move
+    LOCAL_FREE_TARGET
+    from global -> local"]
+  // Also corresponds to:
+  // fn__local_list_flush()
+  // fn_bpf_lru_list_rotate()
+  fn___bpf_lru_node_move_to_free[shape=diamond,fillcolor=2,
+    label="Able to free\nLOCAL_FREE_TARGET\nnodes?"]
+
+  fn___bpf_lru_list_shrink_inactive [shape=rectangle,fillcolor=3,
+    label="Shrink inactive list
+      up to remaining
+      LOCAL_FREE_TARGET
+      (global LRU -> local)"]
+  fn___bpf_lru_list_shrink [shape=diamond,fillcolor=2,
+    label="> 0 entries in\nlocal free list?"]
+  fn___bpf_lru_list_shrink2 [shape=rectangle,fillcolor=2,
+    label="Steal one node from
+      inactive, or if empty,
+      from active global list"]
+  fn___bpf_lru_list_shrink3 [shape=rectangle,fillcolor=3,
+    label="Try to remove\nnode from hashtab"]
+
+  local_freelist_check2 [shape=diamond,label="Htab removal\nsuccessful?"]
+  common_lru_check2 [shape=diamond,
+    label="Map created with\ncommon LRU?\n(!BPF_F_NO_COMMON_LRU)"];
+
+  subgraph cluster_remote_lock {
+    label = "Iterate through CPUs\n(start from current)";
+    style = dashed;
+    rankdir=LR;
+
+    local_freelist_check5 [shape=diamond,fillcolor=4,
+      label="Steal a node from\nper-cpu freelist?"]
+    local_freelist_check6 [shape=rectangle,fillcolor=4,
+      label="Steal a node from
+        (1) Unreferenced pending, or
+        (2) Any pending node"]
+    local_freelist_check7 [shape=rectangle,fillcolor=3,
+      label="Try to remove\nnode from hashtab"]
+    fn_htab_lru_map_update_elem [shape=diamond,
+      label="Stole node\nfrom remote\nCPU?"]
+    fn_htab_lru_map_update_elem2 [shape=diamond,label="Iterated\nall CPUs?"]
+    // Also corresponds to:
+    // use_local_node()
+    // fn__local_list_pop_pending()
+  }
+
+  fn_bpf_lru_list_pop_free_to_local2 [shape=rectangle,
+    label="Use node that was\nnot recently referenced"]
+  local_freelist_check4 [shape=rectangle,
+    label="Use node that was\nactively referenced\nin global list"]
+  fn_htab_lru_map_update_elem_ENOMEM [shape=oval,label="return -ENOMEM"]
+  fn_htab_lru_map_update_elem3 [shape=rectangle,
+    label="Use node that was\nactively referenced\nin (another?) CPU's cache"]
+  fn_htab_lru_map_update_elem4 [shape=rectangle,fillcolor=3,
+    label="Update hashmap\nwith new element"]
+  fn_htab_lru_map_update_elem5 [shape=oval,label="return 0"]
+  fn_htab_lru_map_update_elem_EBUSY [shape=oval,label="return -EBUSY"]
+  fn_htab_lru_map_update_elem_EEXIST [shape=oval,label="return -EEXIST"]
+  fn_htab_lru_map_update_elem_ENOENT [shape=oval,label="return -ENOENT"]
+
+  begin -> local_freelist_check
+  local_freelist_check -> use_local_node [xlabel="Y"]
+  local_freelist_check -> common_lru_check [xlabel="N"]
+  common_lru_check -> fn_bpf_lru_list_pop_free_to_local [xlabel="Y"]
+  common_lru_check -> fn___bpf_lru_list_shrink_inactive [xlabel="N"]
+  fn_bpf_lru_list_pop_free_to_local -> fn___bpf_lru_node_move_to_free
+  fn___bpf_lru_node_move_to_free ->
+    fn_bpf_lru_list_pop_free_to_local2 [xlabel="Y"]
+  fn___bpf_lru_node_move_to_free ->
+    fn___bpf_lru_list_shrink_inactive [xlabel="N"]
+  fn___bpf_lru_list_shrink_inactive -> fn___bpf_lru_list_shrink
+  fn___bpf_lru_list_shrink -> fn_bpf_lru_list_pop_free_to_local2 [xlabel = "Y"]
+  fn___bpf_lru_list_shrink -> fn___bpf_lru_list_shrink2 [xlabel="N"]
+  fn___bpf_lru_list_shrink2 -> fn___bpf_lru_list_shrink3
+  fn___bpf_lru_list_shrink3 -> local_freelist_check2
+  local_freelist_check2 -> local_freelist_check4 [xlabel = "Y"]
+  local_freelist_check2 -> common_lru_check2 [xlabel = "N"]
+  common_lru_check2 -> local_freelist_check5 [xlabel = "Y"]
+  common_lru_check2 -> fn_htab_lru_map_update_elem_ENOMEM [xlabel = "N"]
+  local_freelist_check5 -> fn_htab_lru_map_update_elem [xlabel = "Y"]
+  local_freelist_check5 -> local_freelist_check6 [xlabel = "N"]
+  local_freelist_check6 -> local_freelist_check7
+  local_freelist_check7 -> fn_htab_lru_map_update_elem
+
+  fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem3 [xlabel = "Y"]
+  fn_htab_lru_map_update_elem -> fn_htab_lru_map_update_elem2  [xlabel = "N"]
+  fn_htab_lru_map_update_elem2 ->
+    fn_htab_lru_map_update_elem_ENOMEM [xlabel = "Y"]
+  fn_htab_lru_map_update_elem2 -> local_freelist_check5 [xlabel = "N"]
+  fn_htab_lru_map_update_elem3 -> fn_htab_lru_map_update_elem4
+
+  use_local_node -> fn_htab_lru_map_update_elem4
+  fn_bpf_lru_list_pop_free_to_local2 -> fn_htab_lru_map_update_elem4
+  local_freelist_check4 -> fn_htab_lru_map_update_elem4
+
+  fn_htab_lru_map_update_elem4 -> fn_htab_lru_map_update_elem5 [headlabel="Success"]
+  fn_htab_lru_map_update_elem4 ->
+    fn_htab_lru_map_update_elem_EBUSY [xlabel="Hashtab lock failed"]
+  fn_htab_lru_map_update_elem4 ->
+    fn_htab_lru_map_update_elem_EEXIST [xlabel="BPF_EXIST set and\nkey already exists"]
+  fn_htab_lru_map_update_elem4 ->
+    fn_htab_lru_map_update_elem_ENOENT [headlabel="BPF_NOEXIST set\nand no such entry"]
+
+  // Create invisible pad nodes to line up various nodes
+  pad0 [style=invis]
+  pad1 [style=invis]
+  pad2 [style=invis]
+  pad3 [style=invis]
+  pad4 [style=invis]
+
+  // Line up the key with the top of the graph
+  no_lock -> local_lock [style=invis]
+  local_lock -> lru_lock [style=invis]
+  lru_lock -> hash_lock [style=invis]
+  hash_lock -> remote_lock [style=invis]
+  remote_lock -> local_freelist_check5 [style=invis]
+  remote_lock -> fn___bpf_lru_list_shrink [style=invis]
+
+  // Line up return code nodes at the bottom of the graph
+  fn_htab_lru_map_update_elem -> pad0 [style=invis]
+  pad0 -> pad1 [style=invis]
+  pad1 -> pad2 [style=invis]
+  //pad2-> fn_htab_lru_map_update_elem_ENOMEM [style=invis]
+  fn_htab_lru_map_update_elem4 -> pad3 [style=invis]
+  pad3 -> fn_htab_lru_map_update_elem5  [style=invis]
+  pad3 -> fn_htab_lru_map_update_elem_EBUSY  [style=invis]
+  pad3 -> fn_htab_lru_map_update_elem_EEXIST  [style=invis]
+  pad3 -> fn_htab_lru_map_update_elem_ENOENT  [style=invis]
+
+  // Reduce diagram width by forcing some nodes to appear above others
+  local_freelist_check4 -> fn_htab_lru_map_update_elem3 [style=invis]
+  common_lru_check2 -> pad4 [style=invis]
+  pad4 -> local_freelist_check5 [style=invis]
+}

Documentation/bpf/prog_cgroup_sockopt.rst

@@ -98,10 +98,65 @@ can access only the first ``PAGE_SIZE`` of that data. So it has to options:
   indicates that the kernel should use BPF's trimmed ``optval``.
 
 When the BPF program returns with the ``optlen`` greater than
-``PAGE_SIZE``, the userspace will receive ``EFAULT`` errno.
+``PAGE_SIZE``, the userspace will receive original kernel
+buffers without any modifications that the BPF program might have
+applied.
 
 Example
 =======
 
+Recommended way to handle BPF programs is as follows:
+
+.. code-block:: c
+
+	SEC("cgroup/getsockopt")
+	int getsockopt(struct bpf_sockopt *ctx)
+	{
+		/* Custom socket option. */
+		if (ctx->level == MY_SOL && ctx->optname == MY_OPTNAME) {
+			ctx->retval = 0;
+			optval[0] = ...;
+			ctx->optlen = 1;
+			return 1;
+		}
+
+		/* Modify kernel's socket option. */
+		if (ctx->level == SOL_IP && ctx->optname == IP_FREEBIND) {
+			ctx->retval = 0;
+			optval[0] = ...;
+			ctx->optlen = 1;
+			return 1;
+		}
+
+		/* optval larger than PAGE_SIZE use kernel's buffer. */
+		if (ctx->optlen > PAGE_SIZE)
+			ctx->optlen = 0;
+
+		return 1;
+	}
+
+	SEC("cgroup/setsockopt")
+	int setsockopt(struct bpf_sockopt *ctx)
+	{
+		/* Custom socket option. */
+		if (ctx->level == MY_SOL && ctx->optname == MY_OPTNAME) {
+			/* do something */
+			ctx->optlen = -1;
+			return 1;
+		}
+
+		/* Modify kernel's socket option. */
+		if (ctx->level == SOL_IP && ctx->optname == IP_FREEBIND) {
+			optval[0] = ...;
+			return 1;
+		}
+
+		/* optval larger than PAGE_SIZE use kernel's buffer. */
+		if (ctx->optlen > PAGE_SIZE)
+			ctx->optlen = 0;
+
+		return 1;
+	}
+
 See ``tools/testing/selftests/bpf/progs/sockopt_sk.c`` for an example
 of BPF program that handles socket options.