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pping: Various minor fixes

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Perform various fixes and tweaks:
- Rename several defines to make them more informative
- Remove unrolling of loop in BPF programs
- Reuse defines for program sections between userspace and kernel
  space programs
- Perform fork+exec to run bpf_egress_loader script instead of
  system()
- Add comment to copied scripts indicating I've modified them
- Add pping.h and pping_helpers.h as dependencies in Makefile

Also, add a brief description of what PPing is and how it works to
README

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>
This commit is contained in:
Simon Sundberg
2021-01-26 18:34:23 +01:00
parent 71c6458712
commit 7410d5cc2c
10 changed files with 184 additions and 107 deletions
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152
pping/pping.c
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@@ -3,7 +3,6 @@
#include <bpf/libbpf.h>
#include <linux/if_link.h>
#include <net/if.h> // For if_nametoindex
//#include <linux/err.h> // For IS_ERR_OR_NULL macro // use libbpf_get_error instead
#include <arpa/inet.h> // For inet_ntoa and ntohs
#include <stdio.h>
@@ -14,28 +13,31 @@
#include <stdbool.h>
#include <signal.h> // For detecting Ctrl-C
#include <sys/resource.h> // For setting rlmit
#include <sys/wait.h>
#include <time.h>
#include <pthread.h>
#include "pping.h" //key and value structs for the ts_start map
#define BILLION 1000000000UL
#define MILLION 1000000UL
#define NS_PER_SECOND 1000000000UL
#define NS_PER_MS 1000000UL
#define TCBPF_LOADER_SCRIPT "./bpf_egress_loader.sh"
#define PINNED_DIR "/sys/fs/bpf/tc/globals"
#define PPING_XDP_OBJ "pping_kern_xdp.o"
#define XDP_PROG_SEC "xdp"
#define PPING_TCBPF_OBJ "pping_kern_tc.o"
#define TCBPF_PROG_SEC "pping_egress"
#define XDP_FLAGS XDP_FLAGS_UPDATE_IF_NOEXIST
#define MAP_NAME "ts_start"
#define MAP_CLEANUP_INTERVAL 1 * BILLION // Clean timestamp map once per second
#define PERF_BUFFER_NAME "rtt_events"
#define TS_MAP "ts_start"
#define MAP_CLEANUP_INTERVAL 1 * NS_PER_SECOND // Clean timestamp map once per second
#define TIMESTAMP_LIFETIME 10 * NS_PER_SECOND // Clear out entries from ts_start if they're over 10 seconds
#define PERF_BUFFER "rtt_events"
#define PERF_BUFFER_PAGES 64 // Related to the perf-buffer size?
#define PERF_POLL_TIMEOUT_MS 100
#define RMEMLIM 512UL << 20 /* 512 MBs */
#define MAX_COMMAND_LEN 1024
#define MAX_PATH_LEN 1024
#define TIMESTAMP_LIFETIME 10 * BILLION // Clear out entries from ts_start if they're over 10 seconds
/*
* BPF implementation of pping using libbpf
@@ -50,6 +52,7 @@
* (together with the related flow) and printed out
*/
// Structure to contain arguments for clean_map (for passing to pthread_create)
struct map_cleanup_args {
int map_fd;
__u64 max_age_ns;
@@ -97,6 +100,7 @@ static int xdp_attach(struct bpf_object *obj, const char *sec, int ifindex,
prog = bpf_object__find_program_by_title(obj, sec);
else
prog = bpf_program__next(NULL, obj);
prog_fd = bpf_program__fd(prog);
if (prog_fd < 0) {
fprintf(stderr, "Could not find program to attach\n");
@@ -105,6 +109,7 @@ static int xdp_attach(struct bpf_object *obj, const char *sec, int ifindex,
if (force) // detach current (if any) xdp-program first
xdp_detach(ifindex, xdp_flags);
err = bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags);
if (err < 0) {
fprintf(stderr, "Failed loading xdp-program on interface %d\n",
@@ -114,21 +119,76 @@ static int xdp_attach(struct bpf_object *obj, const char *sec, int ifindex,
return 0;
}
static int tc_bpf_load(const char *bpf_object, const char *section,
const char *interface)
{
int status;
int ret = -1;
pid_t pid = fork();
if (pid < 0)
return -errno;
if (pid == 0) {
execl(TCBPF_LOADER_SCRIPT, TCBPF_LOADER_SCRIPT,
"--dev", interface, "--obj", bpf_object,
"--sec", section, NULL);
return -errno;
}
else { //pid > 0
waitpid(pid, &status, 0);
if (WIFEXITED(status))
ret = WEXITSTATUS(status);
return ret;
}
}
static int tc_bpf_clear(const char *interface)
{
int status;
int ret = -1;
pid_t pid = fork();
if (pid < 0)
return -errno;
if (pid == 0) {
execl(TCBPF_LOADER_SCRIPT, TCBPF_LOADER_SCRIPT,
"--dev", interface, "--remove", NULL);
return -errno;
}
else { //pid > 0
waitpid(pid, &status, 0);
if (WIFEXITED(status))
ret = WEXITSTATUS(status);
return ret;
}
}
/*
* Returns time of CLOCK_MONOTONIC as nanoseconds in a single __u64.
* On failure, the value 0 is returned (and errno will be set).
*/
static __u64 get_time_ns(clockid_t clockid)
{
struct timespec t;
if (clock_gettime(clockid, &t) != 0) // CLOCK_BOOTTIME if using bpf_get_ktime_boot_ns
return 0;
return (__u64)t.tv_sec * BILLION + (__u64)t.tv_nsec;
return (__u64)t.tv_sec * NS_PER_SECOND + (__u64)t.tv_nsec;
}
static int remove_old_entries_from_map(int map_fd, __u64 max_age)
static int clean_map(int map_fd, __u64 max_age)
{
int removed = 0, entries = 0;
int removed = 0;
struct ts_key key, prev_key = { 0 };
struct ts_timestamp value;
bool delete_prev = false;
__u64 now_nsec = get_time_ns(CLOCK_MONOTONIC);
int entries = 0; // Just for debug
__u64 duration; // Just for debug
if (now_nsec == 0)
return -errno;
@@ -153,9 +213,9 @@ static int remove_old_entries_from_map(int map_fd, __u64 max_age)
bpf_map_delete_elem(map_fd, &prev_key);
removed++;
}
__u64 duration = get_time_ns(CLOCK_MONOTONIC) - now_nsec;
duration = get_time_ns(CLOCK_MONOTONIC) - now_nsec;
printf("Gone through %d entries and removed %d of them in %llu.%09llu s\n",
entries, removed, duration / BILLION, duration % BILLION);
entries, removed, duration / NS_PER_SECOND, duration % NS_PER_SECOND);
return removed;
}
@@ -163,10 +223,11 @@ static void *periodic_map_cleanup(void *args)
{
struct map_cleanup_args *argp = args;
struct timespec interval;
interval.tv_sec = MAP_CLEANUP_INTERVAL / BILLION;
interval.tv_nsec = MAP_CLEANUP_INTERVAL % BILLION;
interval.tv_sec = MAP_CLEANUP_INTERVAL / NS_PER_SECOND;
interval.tv_nsec = MAP_CLEANUP_INTERVAL % NS_PER_SECOND;
while (keep_running) {
remove_old_entries_from_map(argp->map_fd, argp->max_age_ns);
clean_map(argp->map_fd, argp->max_age_ns);
nanosleep(&interval, NULL);
}
pthread_exit(NULL);
@@ -178,9 +239,10 @@ static void handle_rtt_event(void *ctx, int cpu, void *data, __u32 data_size)
struct in_addr saddr, daddr;
saddr.s_addr = e->flow.saddr;
daddr.s_addr = e->flow.daddr;
// inet_ntoa is deprecated, will switch to inet_ntop when adding IPv6 support
printf("%llu.%06llu ms %s:%d+", e->rtt / MILLION,
e->rtt % MILLION, inet_ntoa(daddr), ntohs(e->flow.dport));
printf("%llu.%06llu ms %s:%d+", e->rtt / NS_PER_MS,
e->rtt % NS_PER_MS, inet_ntoa(daddr), ntohs(e->flow.dport));
printf("%s:%d\n", inet_ntoa(saddr), ntohs(e->flow.sport));
}
@@ -191,17 +253,10 @@ static void handle_missed_rtt_event(void *ctx, int cpu, __u64 lost_cnt)
int main(int argc, char *argv[])
{
if (argc < 2) {
printf("Usage: ./pping_user <dev>\n");
return EXIT_FAILURE;
}
int err = 0;
int ifindex = 0;
bool xdp_attached = false;
bool tc_attached = false;
char tc_cmd[MAX_COMMAND_LEN];
char map_path[MAX_PATH_LEN];
struct bpf_object *obj = NULL;
@@ -213,12 +268,17 @@ int main(int argc, char *argv[])
struct perf_buffer *pb = NULL;
struct perf_buffer_opts pb_opts;
// TODO - better argument parsing (more relevant as featureas are added)
if (argc < 2) {
printf("Usage: ./pping_user <dev>\n");
return EXIT_FAILURE;
}
// Increase rlimit
err = set_rlimit(RMEMLIM);
err = set_rlimit(RLIM_INFINITY);
if (err) {
fprintf(stderr, "Could not set rlimit to %ld bytes: %s\n",
RMEMLIM, strerror(-err));
fprintf(stderr, "Could not set rlimit to infinity: %s\n",
strerror(-err));
goto cleanup;
}
@@ -240,15 +300,14 @@ int main(int argc, char *argv[])
}
// Get map here to allow for unpinning at cleanup
map = bpf_object__find_map_by_name(obj, MAP_NAME);
map = bpf_object__find_map_by_name(obj, TS_MAP);
err = libbpf_get_error(map);
if (err) {
fprintf(stderr, "Could not find map %s in %s: %s\n",
MAP_NAME, PPING_XDP_OBJ, strerror(err));
TS_MAP, PPING_XDP_OBJ, strerror(err));
map = NULL;
}
err = bpf_object__load(obj);
if (err) {
fprintf(stderr, "Failed loading XDP program: %s\n",
@@ -264,27 +323,26 @@ int main(int argc, char *argv[])
}
xdp_attached = true;
//Load tc-bpf section on interface egress
snprintf(tc_cmd, MAX_COMMAND_LEN, "%s --dev %s --obj %s --sec %s",
TCBPF_LOADER_SCRIPT, argv[1], PPING_TCBPF_OBJ, TCBPF_PROG_SEC);
err = system(tc_cmd);
// Load tc-bpf section on interface egress
err = tc_bpf_load(PPING_TCBPF_OBJ, TCBPF_PROG_SEC, argv[1]);
if (err) {
fprintf(stderr,
"Could not load section %s of %s on interface %s: %s\n",
TCBPF_PROG_SEC, PPING_TCBPF_OBJ, argv[1],
strerror(err));
strerror(-err));
goto cleanup;
}
tc_attached = true;
// Set up the periodical map cleaning
clean_args.max_age_ns = TIMESTAMP_LIFETIME;
clean_args.map_fd = bpf_map__fd(map);
if (clean_args.map_fd < 0) {
fprintf(stderr, "Could not get file descriptor of map %s in object %s: %s\n",
MAP_NAME, PPING_XDP_OBJ, strerror(-clean_args.map_fd));
TS_MAP, PPING_XDP_OBJ, strerror(-clean_args.map_fd));
goto cleanup;
}
clean_args.max_age_ns = TIMESTAMP_LIFETIME;
err = pthread_create(&tid, NULL, periodic_map_cleanup, &clean_args);
if (err) {
fprintf(stderr,
@@ -298,13 +356,13 @@ int main(int argc, char *argv[])
pb_opts.lost_cb = handle_missed_rtt_event;
pb = perf_buffer__new(bpf_object__find_map_fd_by_name(obj,
PERF_BUFFER_NAME),
PERF_BUFFER),
PERF_BUFFER_PAGES, &pb_opts);
err = libbpf_get_error(pb);
if (err) {
pb = NULL;
fprintf(stderr, "Failed to open perf buffer %s: %s\n",
PERF_BUFFER_NAME, strerror(err));
PERF_BUFFER, strerror(err));
goto cleanup;
}
@@ -326,7 +384,7 @@ cleanup:
perf_buffer__free(pb);
if (map && bpf_map__is_pinned(map)) {
snprintf(map_path, sizeof(map_path), "%s/%s",
PINNED_DIR, MAP_NAME);
PINNED_DIR, TS_MAP);
err = bpf_map__unpin(map, map_path);
if (err) {
fprintf(stderr,
@@ -343,13 +401,11 @@ cleanup:
}
}
if (tc_attached) {
snprintf(tc_cmd, MAX_COMMAND_LEN, "%s --dev %s --remove",
TCBPF_LOADER_SCRIPT, argv[1]);
err = system(tc_cmd);
err = tc_bpf_clear(argv[1]); //system(tc_cmd);
if (err) {
fprintf(stderr,
"Failed removing tc-bpf program from interface %s: %s\n",
argv[1], strerror(err));
argv[1], strerror(-err));
}
}