Re: [PATCH 2/2] bpf samples: update tracex5 sample to use __seccomp_filter

[David Miller]

From: "Naveen N. Rao" 
Date: Sat, 24 Sep 2016 02:10:05 +0530

> seccomp_phase1() does not exist anymore. Instead, update sample to use
> __seccomp_filter(). While at it, set max locked memory to unlimited.
> 
> Signed-off-by: Naveen N. Rao 

Also applied to net-next, thanks.

Re: [PATCH 2/2] bpf samples: update tracex5 sample to use __seccomp_filter

[Alexei Starovoitov]

On Sat, Sep 24, 2016 at 02:10:05AM +0530, Naveen N. Rao wrote:
> seccomp_phase1() does not exist anymore. Instead, update sample to use
> __seccomp_filter(). While at it, set max locked memory to unlimited.
> 
> Signed-off-by: Naveen N. Rao 

Acked-by: Alexei Starovoitov 

[PATCH 2/2] bpf samples: update tracex5 sample to use __seccomp_filter

[Naveen N. Rao]

seccomp_phase1() does not exist anymore. Instead, update sample to use
__seccomp_filter(). While at it, set max locked memory to unlimited.

Signed-off-by: Naveen N. Rao 
---
I am not completely sure if __seccomp_filter is the right place to hook
in. This works for me though. Please review.

Thanks,
Naveen


 samples/bpf/tracex5_kern.c | 16 +++-
 samples/bpf/tracex5_user.c |  3 +++
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/samples/bpf/tracex5_kern.c b/samples/bpf/tracex5_kern.c
index f95f232..fd12d71 100644
--- a/samples/bpf/tracex5_kern.c
+++ b/samples/bpf/tracex5_kern.c
@@ -19,20 +19,18 @@ struct bpf_map_def SEC("maps") progs = {
.max_entries = 1024,
 };
 
-SEC("kprobe/seccomp_phase1")
+SEC("kprobe/__seccomp_filter")
 int bpf_prog1(struct pt_regs *ctx)
 {
-   struct seccomp_data sd;
-
-   bpf_probe_read(, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
+   int sc_nr = (int)PT_REGS_PARM1(ctx);
 
/* dispatch into next BPF program depending on syscall number */
-   bpf_tail_call(ctx, , sd.nr);
+   bpf_tail_call(ctx, , sc_nr);
 
/* fall through -> unknown syscall */
-   if (sd.nr >= __NR_getuid && sd.nr <= __NR_getsid) {
+   if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
-   bpf_trace_printk(fmt, sizeof(fmt), sd.nr);
+   bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
}
return 0;
 }
@@ -42,7 +40,7 @@ PROG(__NR_write)(struct pt_regs *ctx)
 {
struct seccomp_data sd;
 
-   bpf_probe_read(, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
+   bpf_probe_read(, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
if (sd.args[2] == 512) {
char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
bpf_trace_printk(fmt, sizeof(fmt),
@@ -55,7 +53,7 @@ PROG(__NR_read)(struct pt_regs *ctx)
 {
struct seccomp_data sd;
 
-   bpf_probe_read(, sizeof(sd), (void *)PT_REGS_PARM1(ctx));
+   bpf_probe_read(, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
if (sd.args[2] > 128 && sd.args[2] <= 1024) {
char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
bpf_trace_printk(fmt, sizeof(fmt),
diff --git a/samples/bpf/tracex5_user.c b/samples/bpf/tracex5_user.c
index a04dd3c..36b5925 100644
--- a/samples/bpf/tracex5_user.c
+++ b/samples/bpf/tracex5_user.c
@@ -6,6 +6,7 @@
 #include 
 #include "libbpf.h"
 #include "bpf_load.h"
+#include 
 
 /* install fake seccomp program to enable seccomp code path inside the kernel,
  * so that our kprobe attached to seccomp_phase1() can be triggered
@@ -27,8 +28,10 @@ int main(int ac, char **argv)
 {
FILE *f;
char filename[256];
+   struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+   setrlimit(RLIMIT_MEMLOCK, );
 
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
-- 
2.9.3