From: Dmitrii Banshchikov <me@ubique.spb.ru>
To: bpf@vger.kernel.org
Cc: Dmitrii Banshchikov <me@ubique.spb.ru>,
ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
john.fastabend@gmail.com, kpsingh@kernel.org,
netdev@vger.kernel.org, tglx@linutronix.de, rdna@fb.com
Subject: [PATCH bpf v2 2/2] selftests/bpf: Add tests for restricted helpers
Date: Sat, 13 Nov 2021 18:22:27 +0400 [thread overview]
Message-ID: <20211113142227.566439-3-me@ubique.spb.ru> (raw)
In-Reply-To: <20211113142227.566439-1-me@ubique.spb.ru>
This patch adds tests that bpf_ktime_get_coarse_ns(), bpf_timer_* and
bpf_spin_lock()/bpf_spin_unlock() helpers are forbidden in tracing progs
as their use there may result in various locking issues.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
---
.../bpf/prog_tests/helper_restricted.c | 33 +++
.../bpf/progs/test_helper_restricted.c | 123 +++++++++++
tools/testing/selftests/bpf/test_verifier.c | 46 +++-
.../bpf/verifier/helper_restricted.c | 196 ++++++++++++++++++
4 files changed, 397 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/helper_restricted.c
create mode 100644 tools/testing/selftests/bpf/progs/test_helper_restricted.c
create mode 100644 tools/testing/selftests/bpf/verifier/helper_restricted.c
diff --git a/tools/testing/selftests/bpf/prog_tests/helper_restricted.c b/tools/testing/selftests/bpf/prog_tests/helper_restricted.c
new file mode 100644
index 000000000000..e1de5f80c3b2
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/helper_restricted.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "test_helper_restricted.skel.h"
+
+void test_helper_restricted(void)
+{
+ int prog_i = 0, prog_cnt;
+ int duration = 0;
+
+ do {
+ struct test_helper_restricted *test;
+ int maybeOK;
+
+ test = test_helper_restricted__open();
+ if (!ASSERT_OK_PTR(test, "open"))
+ return;
+
+ prog_cnt = test->skeleton->prog_cnt;
+
+ for (int j = 0; j < prog_cnt; ++j) {
+ struct bpf_program *prog = *test->skeleton->progs[j].prog;
+
+ maybeOK = bpf_program__set_autoload(prog, prog_i == j);
+ ASSERT_OK(maybeOK, "set autoload");
+ }
+
+ maybeOK = test_helper_restricted__load(test);
+ CHECK(!maybeOK, test->skeleton->progs[prog_i].name, "helper isn't restricted");
+
+ test_helper_restricted__destroy(test);
+ } while (++prog_i < prog_cnt);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_helper_restricted.c b/tools/testing/selftests/bpf/progs/test_helper_restricted.c
new file mode 100644
index 000000000000..68d64c365f90
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_helper_restricted.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <time.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct timer {
+ struct bpf_timer t;
+};
+
+struct lock {
+ struct bpf_spin_lock l;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, struct timer);
+} timers SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, struct lock);
+} locks SEC(".maps");
+
+static int timer_cb(void *map, int *key, struct timer *timer)
+{
+ return 0;
+}
+
+static void timer_work(void)
+{
+ struct timer *timer;
+ const int key = 0;
+
+ timer = bpf_map_lookup_elem(&timers, &key);
+ if (timer) {
+ bpf_timer_init(&timer->t, &timers, CLOCK_MONOTONIC);
+ bpf_timer_set_callback(&timer->t, timer_cb);
+ bpf_timer_start(&timer->t, 10E9, 0);
+ bpf_timer_cancel(&timer->t);
+ }
+}
+
+static void spin_lock_work(void)
+{
+ const int key = 0;
+ struct lock *lock;
+
+ lock = bpf_map_lookup_elem(&locks, &key);
+ if (lock) {
+ bpf_spin_lock(&lock->l);
+ bpf_spin_unlock(&lock->l);
+ }
+}
+
+SEC("raw_tp/sys_enter")
+int raw_tp_timer(void *ctx)
+{
+ timer_work();
+
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int tp_timer(void *ctx)
+{
+ timer_work();
+
+ return 0;
+}
+
+SEC("kprobe/sys_nanosleep")
+int kprobe_timer(void *ctx)
+{
+ timer_work();
+
+ return 0;
+}
+
+SEC("perf_event")
+int perf_event_timer(void *ctx)
+{
+ timer_work();
+
+ return 0;
+}
+
+SEC("raw_tp/sys_enter")
+int raw_tp_spin_lock(void *ctx)
+{
+ spin_lock_work();
+
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_nanosleep")
+int tp_spin_lock(void *ctx)
+{
+ spin_lock_work();
+
+ return 0;
+}
+
+SEC("kprobe/sys_nanosleep")
+int kprobe_spin_lock(void *ctx)
+{
+ spin_lock_work();
+
+ return 0;
+}
+
+SEC("perf_event")
+int perf_event_spin_lock(void *ctx)
+{
+ spin_lock_work();
+
+ return 0;
+}
+
+const char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 25afe423b3f0..465ef3f112c0 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -92,6 +92,7 @@ struct bpf_test {
int fixup_map_event_output[MAX_FIXUPS];
int fixup_map_reuseport_array[MAX_FIXUPS];
int fixup_map_ringbuf[MAX_FIXUPS];
+ int fixup_map_timer[MAX_FIXUPS];
/* Expected verifier log output for result REJECT or VERBOSE_ACCEPT.
* Can be a tab-separated sequence of expected strings. An empty string
* means no log verification.
@@ -604,8 +605,15 @@ static int create_cgroup_storage(bool percpu)
* int cnt;
* struct bpf_spin_lock l;
* };
+ * struct bpf_timer {
+ * __u64 :64;
+ * __u64 :64;
+ * } __attribute__((aligned(8)));
+ * struct timer {
+ * struct bpf_timer t;
+ * };
*/
-static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l";
+static const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l\0bpf_timer\0timer\0t";
static __u32 btf_raw_types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
@@ -616,6 +624,11 @@ static __u32 btf_raw_types[] = {
BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
+ /* struct bpf_timer */ /* [4] */
+ BTF_TYPE_ENC(25, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0), 16),
+ /* struct timer */ /* [5] */
+ BTF_TYPE_ENC(35, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 16),
+ BTF_MEMBER_ENC(41, 4, 0), /* struct bpf_timer t; */
};
static int load_btf(void)
@@ -696,6 +709,29 @@ static int create_sk_storage_map(void)
return fd;
}
+static int create_map_timer(void)
+{
+ struct bpf_create_map_attr attr = {
+ .name = "test_map",
+ .map_type = BPF_MAP_TYPE_ARRAY,
+ .key_size = 4,
+ .value_size = 16,
+ .max_entries = 1,
+ .btf_key_type_id = 1,
+ .btf_value_type_id = 5,
+ };
+ int fd, btf_fd;
+
+ btf_fd = load_btf();
+ if (btf_fd < 0)
+ return -1;
+ attr.btf_fd = btf_fd;
+ fd = bpf_create_map_xattr(&attr);
+ if (fd < 0)
+ printf("Failed to create map with timer\n");
+ return fd;
+}
+
static char bpf_vlog[UINT_MAX >> 8];
static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
@@ -722,6 +758,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
int *fixup_map_event_output = test->fixup_map_event_output;
int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
int *fixup_map_ringbuf = test->fixup_map_ringbuf;
+ int *fixup_map_timer = test->fixup_map_timer;
if (test->fill_helper) {
test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -907,6 +944,13 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
fixup_map_ringbuf++;
} while (*fixup_map_ringbuf);
}
+ if (*fixup_map_timer) {
+ map_fds[21] = create_map_timer();
+ do {
+ prog[*fixup_map_timer].imm = map_fds[21];
+ fixup_map_timer++;
+ } while (*fixup_map_timer);
+ }
}
struct libcap {
diff --git a/tools/testing/selftests/bpf/verifier/helper_restricted.c b/tools/testing/selftests/bpf/verifier/helper_restricted.c
new file mode 100644
index 000000000000..a067b7098b97
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/helper_restricted.c
@@ -0,0 +1,196 @@
+{
+ "bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_KPROBE",
+ .insns = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "unknown func bpf_ktime_get_coarse_ns",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+ "bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+ .insns = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "unknown func bpf_ktime_get_coarse_ns",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+ "bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+ .insns = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "unknown func bpf_ktime_get_coarse_ns",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+ "bpf_ktime_get_coarse_ns is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+ .insns = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ktime_get_coarse_ns),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "unknown func bpf_ktime_get_coarse_ns",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},
+{
+ "bpf_timer_init isn restricted in BPF_PROG_TYPE_KPROBE",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_LD_MAP_FD(BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_3, 1),
+ BPF_EMIT_CALL(BPF_FUNC_timer_init),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_timer = { 3, 8 },
+ .errstr = "tracing progs cannot use bpf_timer yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+ "bpf_timer_init is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_LD_MAP_FD(BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_3, 1),
+ BPF_EMIT_CALL(BPF_FUNC_timer_init),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_timer = { 3, 8 },
+ .errstr = "tracing progs cannot use bpf_timer yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+ "bpf_timer_init is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_LD_MAP_FD(BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_3, 1),
+ BPF_EMIT_CALL(BPF_FUNC_timer_init),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_timer = { 3, 8 },
+ .errstr = "tracing progs cannot use bpf_timer yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+ "bpf_timer_init is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_LD_MAP_FD(BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_3, 1),
+ BPF_EMIT_CALL(BPF_FUNC_timer_init),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_timer = { 3, 8 },
+ .errstr = "tracing progs cannot use bpf_timer yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},
+{
+ "bpf_spin_lock is forbidden in BPF_PROG_TYPE_KPROBE",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_spin_lock = { 3 },
+ .errstr = "tracing progs cannot use bpf_spin_lock yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_KPROBE,
+},
+{
+ "bpf_spin_lock is forbidden in BPF_PROG_TYPE_TRACEPOINT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_spin_lock = { 3 },
+ .errstr = "tracing progs cannot use bpf_spin_lock yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_TRACEPOINT,
+},
+{
+ "bpf_spin_lock is forbidden in BPF_PROG_TYPE_PERF_EVENT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_spin_lock = { 3 },
+ .errstr = "tracing progs cannot use bpf_spin_lock yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_PERF_EVENT,
+},
+{
+ "bpf_spin_lock is forbidden in BPF_PROG_TYPE_RAW_TRACEPOINT",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+ BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+ BPF_EMIT_CALL(BPF_FUNC_spin_lock),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_spin_lock = { 3 },
+ .errstr = "tracing progs cannot use bpf_spin_lock yet",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT,
+},
--
2.25.1
next prev parent reply other threads:[~2021-11-13 14:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-13 14:22 [PATCH bpf v2 0/2] Forbid bpf_ktime_get_coarse_ns and bpf_timer_* in tracing progs Dmitrii Banshchikov
2021-11-13 14:22 ` [PATCH bpf v2 1/2] bpf: " Dmitrii Banshchikov
2021-11-16 2:02 ` Thomas Gleixner
2021-11-16 4:44 ` Alexei Starovoitov
2021-11-13 14:22 ` Dmitrii Banshchikov [this message]
2021-11-14 18:38 ` [PATCH bpf v2 0/2] " Alexei Starovoitov
2021-11-16 2:18 ` Thomas Gleixner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211113142227.566439-3-me@ubique.spb.ru \
--to=me@ubique.spb.ru \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=john.fastabend@gmail.com \
--cc=kafai@fb.com \
--cc=kpsingh@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=rdna@fb.com \
--cc=songliubraving@fb.com \
--cc=tglx@linutronix.de \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.