diff mbox series

[bpf-next,2/6] bpf: verifier: Support KF_CHANGES_PKT flag

Message ID fc37530d6cf954c3ebd1173d2bdc6b731c733134.1671049840.git.dxu@dxuuu.xyz
State New
Headers
Series [bpf-next,1/6] ip: frags: Return actual error codes from ip_check_defrag() |

Commit Message

Daniel Xu Dec. 14, 2022, 11:25 p.m. UTC 
  KF_CHANGES_PKT indicates that the kfunc call may change packet data.
This is analogous to bpf_helper_changes_pkt_data().

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
---
 Documentation/bpf/kfuncs.rst | 7 +++++++
 include/linux/btf.h          | 1 +
 kernel/bpf/verifier.c        | 8 ++++++++
 3 files changed, 16 insertions(+)

Comments

kernel test robot Dec. 17, 2022, 6:08 p.m. UTC | #1 
Hi Daniel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Daniel-Xu/Support-defragmenting-IPv4-packets-in-BPF/20221215-072858
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/fc37530d6cf954c3ebd1173d2bdc6b731c733134.1671049840.git.dxu%40dxuuu.xyz
patch subject: [PATCH bpf-next 2/6] bpf: verifier: Support KF_CHANGES_PKT flag
reproduce:
        # https://github.com/intel-lab-lkp/linux/commit/ca42b5d5e5d93debd023634aca7e206550fee180
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Daniel-Xu/Support-defragmenting-IPv4-packets-in-BPF/20221215-072858
        git checkout ca42b5d5e5d93debd023634aca7e206550fee180
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        make htmldocs

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> Documentation/bpf/kfuncs.rst:204: WARNING: Title underline too short.

vim +204 Documentation/bpf/kfuncs.rst

   202	
   203	2.4.9 KF_CHANGES_PKT flag
 > 204	-----------------
   205
diff mbox series

Patch

diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
index 9fd7fb539f85..061ab392a02f 100644
--- a/Documentation/bpf/kfuncs.rst
+++ b/Documentation/bpf/kfuncs.rst
@@ -200,6 +200,13 @@  single argument which must be a trusted argument or a MEM_RCU pointer.
 The argument may have reference count of 0 and the kfunc must take this
 into consideration.
 
+2.4.9 KF_CHANGES_PKT flag
+-----------------
+
+The KF_CHANGES_PKT is used for kfuncs that may change packet data.
+After calls to such kfuncs, existing packet pointers will be invalidated
+and must be revalidated before the prog can access packet data.
+
 2.5 Registering the kfuncs
 --------------------------
 
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 5f628f323442..0575f530e40b 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -71,6 +71,7 @@ 
 #define KF_SLEEPABLE    (1 << 5) /* kfunc may sleep */
 #define KF_DESTRUCTIVE  (1 << 6) /* kfunc performs destructive actions */
 #define KF_RCU          (1 << 7) /* kfunc only takes rcu pointer arguments */
+#define KF_CHANGES_PKT  (1 << 8) /* kfunc may change packet data */
 
 /*
  * Return the name of the passed struct, if exists, or halt the build if for
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a5255a0dcbb6..0ac505cbd6ba 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8213,6 +8213,11 @@  static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
 	return meta->kfunc_flags & KF_RCU;
 }
 
+static bool is_kfunc_changes_pkt(struct bpf_kfunc_call_arg_meta *meta)
+{
+	return meta->kfunc_flags & KF_CHANGES_PKT;
+}
+
 static bool is_kfunc_arg_kptr_get(struct bpf_kfunc_call_arg_meta *meta, int arg)
 {
 	return arg == 0 && (meta->kfunc_flags & KF_KPTR_GET);
@@ -9313,6 +9318,9 @@  static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			mark_btf_func_reg_size(env, regno, t->size);
 	}
 
+	if (is_kfunc_changes_pkt(&meta))
+		clear_all_pkt_pointers(env);
+
 	return 0;
 }