From: Johannes Berg <johannes.b...@intel.com>
It took me quite some time to figure out how this was linked,
so in order to save the next person the effort of finding it
add a comment in __bpf_prog_run() that indicates what exactly
determines that a program can access the ctx == skb.
Signed-off-by: Johannes Berg <johannes.b...@intel.com>
---
kernel/bpf/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index f45827e205d3..b4f1cb0c5ac7 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1162,12 +1162,12 @@ static unsigned int __bpf_prog_run(void *ctx, const
struct bpf_insn *insn)
LD_ABS_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + imm32)) */
off = IMM;
load_word:
- /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are
- * only appearing in the programs where ctx ==
- * skb. All programs keep 'ctx' in regs[BPF_REG_CTX]
- * == BPF_R6, bpf_convert_filter() saves it in BPF_R6,
- * internal BPF verifier will check that BPF_R6 ==
- * ctx.
+ /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are only
+ * appearing in the programs where ctx == skb
+ * (see may_access_skb() in the verifier). All programs
+ * keep 'ctx' in regs[BPF_REG_CTX] == BPF_R6,
+ * bpf_convert_filter() saves it in BPF_R6, internal BPF
+ * verifier will check that BPF_R6 == ctx.
*
* BPF_ABS and BPF_IND are wrappers of function calls,
* so they scratch BPF_R1-BPF_R5 registers, preserve
--
2.11.0
