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Date: Thu, 29 Aug 2019 06:04:42 +0000 From: Song Liu <songliubraving@...com> To: Alexei Starovoitov <ast@...nel.org> CC: Andy Lutomirski <luto@...capital.net>, "davem@...emloft.net" <davem@...emloft.net>, "peterz@...radead.org" <peterz@...radead.org>, "rostedt@...dmis.org" <rostedt@...dmis.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "bpf@...r.kernel.org" <bpf@...r.kernel.org>, Kernel Team <Kernel-team@...com>, "linux-api@...r.kernel.org" <linux-api@...r.kernel.org> Subject: Re: [PATCH v2 bpf-next 2/3] bpf: implement CAP_BPF > On Aug 28, 2019, at 10:12 PM, Alexei Starovoitov <ast@...nel.org> wrote: > [...] > diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c > index 44e2d640b088..91a7f25512ca 100644 > --- a/tools/testing/selftests/bpf/test_verifier.c > +++ b/tools/testing/selftests/bpf/test_verifier.c > @@ -805,10 +805,20 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type, > } > } > > +struct libcap { > + struct __user_cap_header_struct hdr; > + struct __user_cap_data_struct data[2]; > +}; > + I am confused by struct libcap. Why do we need it? > static int set_admin(bool admin) > { > cap_t caps; > - const cap_value_t cap_val = CAP_SYS_ADMIN; > + /* need CAP_BPF to load progs and CAP_NET_ADMIN to run networking progs, > + * and CAP_TRACING to create stackmap > + */ > + const cap_value_t cap_net_admin = CAP_NET_ADMIN; > + const cap_value_t cap_sys_admin = CAP_SYS_ADMIN; > + struct libcap *cap; > int ret = -1; > > caps = cap_get_proc(); > @@ -816,11 +826,26 @@ static int set_admin(bool admin) > perror("cap_get_proc"); > return -1; > } > - if (cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_val, > + cap = (struct libcap *)caps; > + if (cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_sys_admin, CAP_CLEAR)) { > + perror("cap_set_flag clear admin"); > + goto out; > + } > + if (cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap_net_admin, > admin ? CAP_SET : CAP_CLEAR)) { > - perror("cap_set_flag"); > + perror("cap_set_flag set_or_clear net"); > goto out; > } > + /* libcap is likely old and simply ignores CAP_BPF and CAP_TRACING, > + * so update effective bits manually > + */ > + if (admin) { > + cap->data[1].effective |= 1 << (38 /* CAP_BPF */ - 32); > + cap->data[1].effective |= 1 << (39 /* CAP_TRACING */ - 32); > + } else { > + cap->data[1].effective &= ~(1 << (38 - 32)); > + cap->data[1].effective &= ~(1 << (39 - 32)); > + } And why we do not need cap->data[0]? Thanks, Song
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