[PATCH 016/107] perf augmented_raw_syscalls: Augment sockaddr arg in 'connect'

Arnaldo Carvalho de Melo
2019-07-30T02:57:13Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

We already had a beautifier for an augmented sockaddr payload, but that
was when we were hooking on each syscalls:sys_enter_foo tracepoints,
since now we're almost doing that by doing a tail call from
raw_syscalls:sys_enter, its almost the same, we can reuse it straight
away.

# perf trace -e connec* ssh www.bla.com
connect(3</var/lib/sss/mc/passwd>, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(3</var/lib/sss/mc/passwd>, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(4<socket:[16604782]>, { .family: PF_LOCAL, path: /var/lib/sss/pipes/nss }, 0x6e) = 0
connect(7, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(7, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(5</etc/hosts>, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(5</etc/hosts>, { .family: PF_LOCAL, path: /var/run/nscd/socket }, 0x6e) = -1 ENOENT (No such file or directory)
connect(5</etc/hosts>, { .family: PF_INET, port: 53, addr: 192.168.44.1 }, 0x10) = 0
connect(5</etc/hosts>, { .family: PF_INET, port: 22, addr: 146.112.61.108 }, 0x10) = 0
connect(5</etc/hosts>, { .family: PF_INET6, port: 22, addr: ::ffff:146.112.61.108 }, 0x1c) = 0
^C#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-5xkrbcpjsgnr3zt1aqdd7nvc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
.../examples/bpf/augmented_raw_syscalls.c | 35 ++++++++++++++++---
1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index 77bb6a0edce3..d7a292d7ee2f 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -16,6 +16,7 @@

#include <unistd.h>
#include <linux/limits.h>
+#include <linux/socket.h>
#include <pid_filter.h>

/* bpf-output associated map */
@@ -69,10 +70,13 @@ pid_filter(pids_filtered);

struct augmented_args_payload {
struct syscall_enter_args args;
- struct {
- struct augmented_filename filename;
- struct augmented_filename filename2;
- };
+ union {
+ struct {
+ struct augmented_filename filename,
+ filename2;
+ };
+ struct sockaddr_storage saddr;
+ };
};

bpf_map(augmented_args_tmp, PERCPU_ARRAY, int, struct augmented_args_payload, 1);
@@ -112,11 +116,32 @@ int syscall_unaugmented(struct syscall_enter_args *args)
}

/*
- * This will be tail_called from SEC("raw_syscalls:sys_enter"), so will find in
+ * These will be tail_called from SEC("raw_syscalls:sys_enter"), so will find in
* augmented_args_tmp what was read by that raw_syscalls:sys_enter and go
* on from there, reading the first syscall arg as a string, i.e. open's
* filename.
*/
+SEC("!syscalls:sys_enter_connect")
+int sys_enter_connect(struct syscall_enter_args *args)
+{
+ int key = 0;
+ struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ const void *sockaddr_arg = (const void *)args->args[1];
+ unsigned int socklen = args->args[2];
+ unsigned int len = sizeof(augmented_args->args);
+
+ if (augmented_args == NULL)
+ return 1; /* Failure: don't filter */
+
+ if (socklen > sizeof(augmented_args->saddr))
+ socklen = sizeof(augmented_args->saddr);
+
+ probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
+
+ /* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
+ return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len + socklen);
+}
+
SEC("!syscalls:sys_enter_open")
int sys_enter_open(struct syscall_enter_args *args)
{
--
2.21.0