Yonghong Song c6f1bfe89a bpf: reject program if a __user tagged memory accessed in kernel way ... BPF verifier supports direct memory access for BPF_PROG_TYPE_TRACING type of bpf programs, e.g., a->b. If "a" is a pointer pointing to kernel memory, bpf verifier will allow user to write code in C like a->b and the verifier will translate it to a kernel load properly. If "a" is a pointer to user memory, it is expected that bpf developer should be bpf_probe_read_user() helper to get the value a->b. Without utilizing BTF __user tagging information, current verifier will assume that a->b is a kernel memory access and this may generate incorrect result. Now BTF contains __user information, it can check whether the pointer points to a user memory or not. If it is, the verifier can reject the program and force users to use bpf_probe_read_user() helper explicitly. In the future, we can easily extend btf_add_space for other address space tagging, for example, rcu/percpu etc. Signed-off-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/r/20220127154606.654961-1-yhs@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>		2022-01-27 12:03:46 -08:00
..
bpf_dummy_struct_ops.c	bpf: reject program if a __user tagged memory accessed in kernel way	2022-01-27 12:03:46 -08:00
Makefile	bpf: Add dummy BPF STRUCT_OPS for test purpose	2021-11-01 14:10:00 -07:00
test_run.c	bpf: Fix flexible_array.cocci warnings	2022-01-24 17:11:39 +01:00