diff options
-rw-r--r-- | tools/bpf/bpftool/feature.c | 85 |
1 files changed, 66 insertions, 19 deletions
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index f05e9e57b593..768bf77df886 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -758,11 +758,29 @@ static void section_misc(const char *define_prefix, __u32 ifindex) print_end_section(); } +#ifdef USE_LIBCAP +#define capability(c) { c, false, #c } +#define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", " +#endif + static int handle_perms(void) { #ifdef USE_LIBCAP - cap_value_t cap_list[1] = { CAP_SYS_ADMIN }; - bool has_sys_admin_cap = false; + struct { + cap_value_t cap; + bool set; + char name[14]; /* strlen("CAP_SYS_ADMIN") */ + } bpf_caps[] = { + capability(CAP_SYS_ADMIN), +#ifdef CAP_BPF + capability(CAP_BPF), + capability(CAP_NET_ADMIN), + capability(CAP_PERFMON), +#endif + }; + cap_value_t cap_list[ARRAY_SIZE(bpf_caps)]; + unsigned int i, nb_bpf_caps = 0; + bool cap_sys_admin_only = true; cap_flag_value_t val; int res = -1; cap_t caps; @@ -774,35 +792,64 @@ static int handle_perms(void) return -1; } - if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &val)) { - p_err("bug: failed to retrieve CAP_SYS_ADMIN status"); - goto exit_free; - } - if (val == CAP_SET) - has_sys_admin_cap = true; +#ifdef CAP_BPF + if (CAP_IS_SUPPORTED(CAP_BPF)) + cap_sys_admin_only = false; +#endif - if (!run_as_unprivileged && !has_sys_admin_cap) { - p_err("full feature probing requires CAP_SYS_ADMIN, run as root or use 'unprivileged'"); - goto exit_free; + for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) { + const char *cap_name = bpf_caps[i].name; + cap_value_t cap = bpf_caps[i].cap; + + if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) { + p_err("bug: failed to retrieve %s status: %s", cap_name, + strerror(errno)); + goto exit_free; + } + + if (val == CAP_SET) { + bpf_caps[i].set = true; + cap_list[nb_bpf_caps++] = cap; + } + + if (cap_sys_admin_only) + /* System does not know about CAP_BPF, meaning that + * CAP_SYS_ADMIN is the only capability required. We + * just checked it, break. + */ + break; } - if ((run_as_unprivileged && !has_sys_admin_cap) || - (!run_as_unprivileged && has_sys_admin_cap)) { + if ((run_as_unprivileged && !nb_bpf_caps) || + (!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) || + (!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) { /* We are all good, exit now */ res = 0; goto exit_free; } - /* if (run_as_unprivileged && has_sys_admin_cap), drop CAP_SYS_ADMIN */ + if (!run_as_unprivileged) { + if (cap_sys_admin_only) + p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'", + bpf_caps[0].name); + else + p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'", + capability_msg(bpf_caps, 0), + capability_msg(bpf_caps, 1), + capability_msg(bpf_caps, 2), + capability_msg(bpf_caps, 3)); + goto exit_free; + } - if (cap_set_flag(caps, CAP_EFFECTIVE, ARRAY_SIZE(cap_list), cap_list, + /* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */ + if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list, CAP_CLEAR)) { - p_err("bug: failed to clear CAP_SYS_ADMIN from capabilities"); + p_err("bug: failed to clear capabilities: %s", strerror(errno)); goto exit_free; } if (cap_set_proc(caps)) { - p_err("failed to drop CAP_SYS_ADMIN: %s", strerror(errno)); + p_err("failed to drop capabilities: %s", strerror(errno)); goto exit_free; } @@ -817,7 +864,7 @@ exit_free: return res; #else - /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN). + /* Detection assumes user has specific privileges. * We do not use libpcap so let's approximate, and restrict usage to * root user only. */ @@ -901,7 +948,7 @@ static int do_probe(int argc, char **argv) } } - /* Full feature detection requires CAP_SYS_ADMIN privilege. + /* Full feature detection requires specific privileges. * Let's approximate, and warn if user is not root. */ if (handle_perms()) |