1) When bpf_dump_raw_ok() == false and the kernel can provide >=1
func_info to the userspace, the current behavior is setting
the info.func_info_cnt to 0 instead of setting info.func_info
to 0.
It is different from the behavior in jited_func_lens/nr_jited_func_lens,
jited_ksyms/nr_jited_ksyms...etc.
This patch fixes it. (i.e. set func_info to 0 instead of
func_info_cnt to 0 when bpf_dump_raw_ok() == false).
2) When the userspace passed in info.func_info_cnt == 0, the kernel
will set the expected func_info size back to the
info.func_info_rec_size. It is a way for the userspace to learn
the kernel expected func_info_rec_size introduced in
commit 838e96904ff3 ("bpf: Introduce bpf_func_info").
An exception is the kernel expected size is not set when
func_info is not available for a bpf_prog. This makes the
returned info.func_info_rec_size has different values
depending on the returned value of info.func_info_cnt.
This patch sets the kernel expected size to info.func_info_rec_size
independent of the info.func_info_cnt.
3) The current logic only rejects invalid func_info_rec_size if
func_info_cnt is non zero. This patch also rejects invalid
nonzero info.func_info_rec_size and not equal to the kernel
expected size.
4) Set info.btf_id as long as prog->aux->btf != NULL. That will
setup the later copy_to_user() codes look the same as others
which then easier to understand and maintain.
prog->aux->btf is not NULL only if prog->aux->func_info_cnt > 0.
Breaking up info.btf_id from prog->aux->func_info_cnt is needed
for the later line info patch anyway.
A similar change is made to bpf_get_prog_name().
Fixes: 838e96904ff3 ("bpf: Introduce bpf_func_info")
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Acked-by: Yonghong Song <y...@fb.com>
---
kernel/bpf/core.c | 2 +-
kernel/bpf/syscall.c | 46 +++++++++++++++++++-------------------------
2 files changed, 21 insertions(+), 27 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index f93ed667546f..2a73fda1db5f 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -410,7 +410,7 @@ static void bpf_get_prog_name(const struct bpf_prog *prog,
char *sym)
sym = bin2hex(sym, prog->tag, sizeof(prog->tag));
/* prog->aux->name will be ignored if full btf name is available */
- if (prog->aux->btf) {
+ if (prog->aux->func_info_cnt) {
type = btf_type_by_id(prog->aux->btf,
prog->aux->func_info[prog->aux->func_idx].type_id);
func_name = btf_name_by_offset(prog->aux->btf, type->name_off);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4445d0d084d8..aa05aa38f4a8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2083,6 +2083,12 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
return -EFAULT;
}
+ if ((info.func_info_cnt || info.func_info_rec_size) &&
+ info.func_info_rec_size != sizeof(struct bpf_func_info))
+ return -EINVAL;
+
+ info.func_info_rec_size = sizeof(struct bpf_func_info);
+
if (!capable(CAP_SYS_ADMIN)) {
info.jited_prog_len = 0;
info.xlated_prog_len = 0;
@@ -2226,35 +2232,23 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog
*prog,
}
}
- if (prog->aux->btf) {
- u32 krec_size = sizeof(struct bpf_func_info);
- u32 ucnt, urec_size;
-
+ if (prog->aux->btf)
info.btf_id = btf_id(prog->aux->btf);
- ucnt = info.func_info_cnt;
- info.func_info_cnt = prog->aux->func_info_cnt;
- urec_size = info.func_info_rec_size;
- info.func_info_rec_size = krec_size;
- if (ucnt) {
- /* expect passed-in urec_size is what the kernel
expects */
- if (urec_size != info.func_info_rec_size)
- return -EINVAL;
-
- if (bpf_dump_raw_ok()) {
- char __user *user_finfo;
-
- user_finfo = u64_to_user_ptr(info.func_info);
- ucnt = min_t(u32, info.func_info_cnt, ucnt);
- if (copy_to_user(user_finfo,
prog->aux->func_info,
- krec_size * ucnt))
- return -EFAULT;
- } else {
- info.func_info_cnt = 0;
- }
+ ulen = info.func_info_cnt;
+ info.func_info_cnt = prog->aux->func_info_cnt;
+ if (info.func_info_cnt && ulen) {
+ if (bpf_dump_raw_ok()) {
+ char __user *user_finfo;
+
+ user_finfo = u64_to_user_ptr(info.func_info);
+ ulen = min_t(u32, info.func_info_cnt, ulen);
+ if (copy_to_user(user_finfo, prog->aux->func_info,
+ info.func_info_rec_size * ulen))
+ return -EFAULT;
+ } else {
+ info.func_info = 0;
}
- } else {
- info.func_info_cnt = 0;
}
done:
--
2.17.1
