On Wed, 2022-04-20 at 20:39 -0700, Andrii Nakryiko wrote:
> Allow attaching BTF-aware TRACING programs, previously attachable only
> through BPF_RAW_TRACEPOINT_OPEN command, through LINK_CREATE command:
> - BTF-aware raw tracepoints (tp_btf in libbpf lingo);
> - fentry/fexit/fmod_ret programs;
> - BPF LSM programs.
>
> This change converges all bpf_link-based attachments under LINK_CREATE
> command allowing to further extend the API with features like BPF
> cookie
> under "multiplexed" link_create section of bpf_attr.
>
> Non-BTF-aware raw tracepoints are left under BPF_RAW_TRACEPOINT_OPEN,
> but there is nothing preventing opening them up to LINK_CREATE as well.
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Reviewed-by: Kuifeng Lee <kuifeng@xxxxxx>
LGTM
> ---
> kernel/bpf/syscall.c | 110 ++++++++++++++++++++++---------------------
> 1 file changed, 56 insertions(+), 54 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index e9621cfa09f2..e9e3e49c0eb7 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -3030,66 +3030,45 @@ static int bpf_perf_link_attach(const union
> bpf_attr *attr, struct bpf_prog *pro
> }
> #endif /* CONFIG_PERF_EVENTS */
>
> -#define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd
> -
> -static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> +static int bpf_raw_tp_link_attach(struct bpf_prog *prog,
> + const char __user *user_tp_name)
> {
> struct bpf_link_primer link_primer;
> struct bpf_raw_tp_link *link;
> struct bpf_raw_event_map *btp;
> - struct bpf_prog *prog;
> const char *tp_name;
> char buf[128];
> int err;
>
> - if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN))
> - return -EINVAL;
> -
> - prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);
> - if (IS_ERR(prog))
> - return PTR_ERR(prog);
> -
> switch (prog->type) {
> case BPF_PROG_TYPE_TRACING:
> case BPF_PROG_TYPE_EXT:
> case BPF_PROG_TYPE_LSM:
> - if (attr->raw_tracepoint.name) {
> + if (user_tp_name)
> /* The attach point for this category of
> programs
> * should be specified via btf_id during
> program load.
> */
> - err = -EINVAL;
> - goto out_put_prog;
> - }
> + return -EINVAL;
> if (prog->type == BPF_PROG_TYPE_TRACING &&
> prog->expected_attach_type == BPF_TRACE_RAW_TP) {
> tp_name = prog->aux->attach_func_name;
> break;
> }
> - err = bpf_tracing_prog_attach(prog, 0, 0);
> - if (err >= 0)
> - return err;
> - goto out_put_prog;
> + return bpf_tracing_prog_attach(prog, 0, 0);
> case BPF_PROG_TYPE_RAW_TRACEPOINT:
> case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
> - if (strncpy_from_user(buf,
> - u64_to_user_ptr(attr-
> >raw_tracepoint.name),
> - sizeof(buf) - 1) < 0) {
> - err = -EFAULT;
> - goto out_put_prog;
> - }
> + if (strncpy_from_user(buf, user_tp_name, sizeof(buf) -
> 1) < 0)
> + return -EFAULT;
> buf[sizeof(buf) - 1] = 0;
> tp_name = buf;
> break;
> default:
> - err = -EINVAL;
> - goto out_put_prog;
> + return -EINVAL;
> }
>
> btp = bpf_get_raw_tracepoint(tp_name);
> - if (!btp) {
> - err = -ENOENT;
> - goto out_put_prog;
> - }
> + if (!btp)
> + return -ENOENT;
>
> link = kzalloc(sizeof(*link), GFP_USER);
> if (!link) {
> @@ -3116,11 +3095,29 @@ static int bpf_raw_tracepoint_open(const union
> bpf_attr *attr)
>
> out_put_btp:
> bpf_put_raw_tracepoint(btp);
> -out_put_prog:
> - bpf_prog_put(prog);
> return err;
> }
>
> +#define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd
> +
> +static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> +{
> + struct bpf_prog *prog;
> + int fd;
> +
> + if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN))
> + return -EINVAL;
> +
> + prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);
> + if (IS_ERR(prog))
> + return PTR_ERR(prog);
> +
> + fd = bpf_raw_tp_link_attach(prog, u64_to_user_ptr(attr-
> >raw_tracepoint.name));
> + if (fd < 0)
> + bpf_prog_put(prog);
> + return fd;
> +}
> +
> static int bpf_prog_attach_check_attach_type(const struct bpf_prog
> *prog,
> enum bpf_attach_type
> attach_type)
> {
> @@ -3189,7 +3186,13 @@ attach_type_to_prog_type(enum bpf_attach_type
> attach_type)
> case BPF_CGROUP_SETSOCKOPT:
> return BPF_PROG_TYPE_CGROUP_SOCKOPT;
> case BPF_TRACE_ITER:
> + case BPF_TRACE_RAW_TP:
> + case BPF_TRACE_FENTRY:
> + case BPF_TRACE_FEXIT:
> + case BPF_MODIFY_RETURN:
> return BPF_PROG_TYPE_TRACING;
> + case BPF_LSM_MAC:
> + return BPF_PROG_TYPE_LSM;
> case BPF_SK_LOOKUP:
> return BPF_PROG_TYPE_SK_LOOKUP;
> case BPF_XDP:
> @@ -4246,21 +4249,6 @@ static int bpf_map_do_batch(const union bpf_attr
> *attr,
> return err;
> }
>
> -static int tracing_bpf_link_attach(const union bpf_attr *attr,
> bpfptr_t uattr,
> - struct bpf_prog *prog)
> -{
> - if (attr->link_create.attach_type != prog-
> >expected_attach_type)
> - return -EINVAL;
> -
> - if (prog->expected_attach_type == BPF_TRACE_ITER)
> - return bpf_iter_link_attach(attr, uattr, prog);
> - else if (prog->type == BPF_PROG_TYPE_EXT)
> - return bpf_tracing_prog_attach(prog,
> - attr-
> >link_create.target_fd,
> - attr-
> >link_create.target_btf_id);
> - return -EINVAL;
> -}
> -
> #define BPF_LINK_CREATE_LAST_FIELD link_create.kprobe_multi.cookies
> static int link_create(union bpf_attr *attr, bpfptr_t uattr)
> {
> @@ -4282,15 +4270,13 @@ static int link_create(union bpf_attr *attr,
> bpfptr_t uattr)
>
> switch (prog->type) {
> case BPF_PROG_TYPE_EXT:
> - ret = tracing_bpf_link_attach(attr, uattr, prog);
> - goto out;
> + break;
> case BPF_PROG_TYPE_PERF_EVENT:
> case BPF_PROG_TYPE_TRACEPOINT:
> if (attr->link_create.attach_type != BPF_PERF_EVENT) {
> ret = -EINVAL;
> goto out;
> }
> - ptype = prog->type;
> break;
> case BPF_PROG_TYPE_KPROBE:
> if (attr->link_create.attach_type != BPF_PERF_EVENT &&
> @@ -4298,7 +4284,6 @@ static int link_create(union bpf_attr *attr,
> bpfptr_t uattr)
> ret = -EINVAL;
> goto out;
> }
> - ptype = prog->type;
> break;
> default:
> ptype = attach_type_to_prog_type(attr-
> >link_create.attach_type);
> @@ -4309,7 +4294,7 @@ static int link_create(union bpf_attr *attr,
> bpfptr_t uattr)
> break;
> }
>
> - switch (ptype) {
> + switch (prog->type) {
> case BPF_PROG_TYPE_CGROUP_SKB:
> case BPF_PROG_TYPE_CGROUP_SOCK:
> case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
> @@ -4319,8 +4304,25 @@ static int link_create(union bpf_attr *attr,
> bpfptr_t uattr)
> case BPF_PROG_TYPE_CGROUP_SOCKOPT:
> ret = cgroup_bpf_link_attach(attr, prog);
> break;
> + case BPF_PROG_TYPE_EXT:
> + ret = bpf_tracing_prog_attach(prog,
> + attr-
> >link_create.target_fd,
> + attr-
> >link_create.target_btf_id);
> + break;
> + case BPF_PROG_TYPE_LSM:
> case BPF_PROG_TYPE_TRACING:
> - ret = tracing_bpf_link_attach(attr, uattr, prog);
> + if (attr->link_create.attach_type != prog-
> >expected_attach_type) {
> + ret = -EINVAL;
> + goto out;
> + }
> + if (prog->expected_attach_type == BPF_TRACE_RAW_TP)
> + ret = bpf_raw_tp_link_attach(prog, NULL);
> + else if (prog->expected_attach_type == BPF_TRACE_ITER)
> + ret = bpf_iter_link_attach(attr, uattr, prog);
> + else
> + ret = bpf_tracing_prog_attach(prog,
> + attr-
> >link_create.target_fd,
> + attr-
> >link_create.target_btf_id);
> break;
> case BPF_PROG_TYPE_FLOW_DISSECTOR:
> case BPF_PROG_TYPE_SK_LOOKUP:
