Commit 4b82b181a26c ("bpf: Allow pre-ordering for bpf cgroup progs")
introduced BPF_F_PREORDER to request pre-order execution across the
cgroup hierarchy. Furthermore, attachments legitimately use combinations
such as BPF_F_ALLOW_MULTI | BPF_F_PREORDER.With BPF_PROG_QUERY reporting the per-program BPF_F_PREORDER attribute, bpftool's exact-match formatter falls back to "unknown(40)" when BPF_F_PREORDER is present alone, or "unknown(42)" when combined with BPF_F_ALLOW_MULTI. Additionally, do_attach() only accepts "multi" and "override", rejecting "preorder" with "unknown option". Before: $ bpftool cgroup show <cg> 1234 cgroup_inet_ingress unknown(42) test_prog $ bpftool cgroup attach <cg> cgroup_inet_ingress id 5678 multi preorder Error: unknown option: preorder After: $ bpftool cgroup show <cg> 1234 cgroup_inet_ingress multi,preorder test_prog $ bpftool cgroup attach <cg> cgroup_inet_ingress id 5678 multi preorder (attaches successfully) Refactor the attach flags formatter to use a bitmask formatter that outputs comma-separated flag names while preserving unrecognized bits as "unknown(...)". Also accept "preorder" in do_attach(), and update bpftool-cgroup.rst, usage help, and bash completion. Signed-off-by: Hui Su <[email protected]> --- .../bpftool/Documentation/bpftool-cgroup.rst | 9 ++- tools/bpf/bpftool/bash-completion/bpftool | 2 +- tools/bpf/bpftool/cgroup.c | 55 +++++++++++++------ 3 files changed, 45 insertions(+), 21 deletions(-) diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst index e8185596a759..8ec2546c0b8e 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst @@ -45,7 +45,7 @@ CGROUP COMMANDS | **cgroup_unix_recvmsg** | **cgroup_sysctl** | | **cgroup_getsockopt** | **cgroup_setsockopt** | | **cgroup_inet_sock_release** } -| *ATTACH_FLAGS* := { **multi** | **override** } +| *ATTACH_FLAGS* := { **multi** | **override** | **preorder** } DESCRIPTION =========== @@ -75,10 +75,13 @@ bpftool cgroup attach *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*] Attach program *PROG* to the cgroup *CGROUP* with attach type *ATTACH_TYPE* and optional *ATTACH_FLAGS*. - *ATTACH_FLAGS* can be one of: **override** if a sub-cgroup installs some + *ATTACH_FLAGS* can include: **override** if a sub-cgroup installs some bpf program, the program in this cgroup yields to sub-cgroup program; **multi** if a sub-cgroup installs some bpf program, that cgroup program - gets run in addition to the program in this cgroup. + gets run in addition to the program in this cgroup; + **preorder** requests that this program executes before programs attached + further down the cgroup hierarchy during evaluation. **preorder** can be + combined with **multi**. Only one program is allowed to be attached to a cgroup with no attach flags or the **override** flag. Attaching another program will release old diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool index 75cbcb512eba..819757d7a360 100644 --- a/tools/bpf/bpftool/bash-completion/bpftool +++ b/tools/bpf/bpftool/bash-completion/bpftool @@ -1057,7 +1057,7 @@ _bpftool() attach|detach) local BPFTOOL_CGROUP_ATTACH_TYPES="$(bpftool feature list_builtins attach_types 2>/dev/null | \ grep '^cgroup_')" - local ATTACH_FLAGS='multi override' + local ATTACH_FLAGS='multi override preorder' # Check for $prev = $command first if [ $prev = $command ]; then _filedir diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index ce69d1e5468e..aec1281c95d8 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -56,7 +56,7 @@ static const int cgroup_attach_types[] = { }; #define HELP_SPEC_ATTACH_FLAGS \ - "ATTACH_FLAGS := { multi | override }" + "ATTACH_FLAGS := { multi | override | preorder }" #define HELP_SPEC_ATTACH_TYPES \ " ATTACH_TYPE := { cgroup_inet_ingress | cgroup_inet_egress |\n" \ @@ -269,6 +269,39 @@ static int show_effective_bpf_progs(int cgroup_fd, enum bpf_attach_type type, return 0; } +static const char *format_attach_flags(__u32 attach_flags, char *buf, size_t sz) +{ + static const struct { + __u32 flag; + const char *name; + } flags[] = { + { BPF_F_ALLOW_MULTI, "multi" }, + { BPF_F_ALLOW_OVERRIDE, "override" }, + { BPF_F_PREORDER, "preorder" }, + }; + size_t len = 0; + size_t i; + int n; + + buf[0] = '\0'; + for (i = 0; i < ARRAY_SIZE(flags); i++) { + if (attach_flags & flags[i].flag) { + n = snprintf(buf + len, sz - len, "%s%s", + len ? "," : "", flags[i].name); + if (n < 0 || (size_t)n >= sz - len) + return buf; + len += n; + attach_flags &= ~flags[i].flag; + } + } + + if (attach_flags) + snprintf(buf + len, sz - len, "%sunknown(%x)", + len ? "," : "", attach_flags); + + return buf; +} + static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, int level) { @@ -276,7 +309,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, __u32 prog_attach_flags[1024] = {0}; const char *attach_flags_str; __u32 prog_ids[1024] = {0}; - char buf[32]; + char buf[64]; __u32 iter; int ret; @@ -296,21 +329,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, __u32 attach_flags; attach_flags = prog_attach_flags[iter] ?: p.attach_flags; - - switch (attach_flags) { - case BPF_F_ALLOW_MULTI: - attach_flags_str = "multi"; - break; - case BPF_F_ALLOW_OVERRIDE: - attach_flags_str = "override"; - break; - case 0: - attach_flags_str = ""; - break; - default: - snprintf(buf, sizeof(buf), "unknown(%x)", attach_flags); - attach_flags_str = buf; - } + attach_flags_str = format_attach_flags(attach_flags, buf, sizeof(buf)); show_bpf_prog(prog_ids[iter], type, attach_flags_str, level); @@ -593,6 +612,8 @@ static int do_attach(int argc, char **argv) attach_flags |= BPF_F_ALLOW_MULTI; } else if (is_prefix(argv[i], "override")) { attach_flags |= BPF_F_ALLOW_OVERRIDE; + } else if (is_prefix(argv[i], "preorder")) { + attach_flags |= BPF_F_PREORDER; } else { p_err("unknown option: %s", argv[i]); goto exit_cgroup; -- 2.55.0
