[PATCH 7/9] riscv: bpf: Avoid breaking W^X

Jisheng Zhang
2021-03-29T18:31:17Z

From: Jisheng Zhang <jszhang@kernel.org>

We allocate Non-executable pages, then call bpf_jit_binary_lock_ro()
to enable executable permission after mapping them read-only. This is
to prepare for STRICT_MODULE_RWX in following patch.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
arch/riscv/net/bpf_jit_core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c
index d8da819290b7..0d5099f0dac8 100644
--- a/arch/riscv/net/bpf_jit_core.c
+++ b/arch/riscv/net/bpf_jit_core.c
@@ -152,6 +152,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
bpf_flush_icache(jit_data->header, ctx->insns + ctx->ninsns);

if (!prog->is_func || extra_pass) {
+ bpf_jit_binary_lock_ro(header);
out_offset:
kfree(ctx->offset);
kfree(jit_data);
@@ -169,7 +170,7 @@ void *bpf_jit_alloc_exec(unsigned long size)
{
return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START,
BPF_JIT_REGION_END, GFP_KERNEL,
- PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+ PAGE_KERNEL, 0, NUMA_NO_NODE,
__builtin_return_address(0));
}

--
2.31.0