Commit 8d5da264 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf augmented_raw_syscalls: Support copying two string syscall args 

Starting with the renameat and renameat2 syscall, that both receive as
second and fourth parameters a pathname:

  # perf trace -e rename* mv one ANOTHER
  LLVM: dumping /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o
  mv: cannot stat 'one': No such file or directory
  renameat2(AT_FDCWD, "one", AT_FDCWD, "ANOTHER", RENAME_NOREPLACE) = -1 ENOENT (No such file or directory)
  #

Since the per CPU scratch buffer map has space for two maximum sized
pathnames, the verifier is satisfied that there will be no overrun.

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-x2uboyg5kx2wqeru288209b6@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent bf134ca6

tools/perf/builtin-trace.c

+2 −0
Original line number Diff line number Diff line
@@ -873,9 +873,11 @@ static struct syscall_fmt { 
	{ .name	    = "recvmsg",

	  .arg = { [2] = { .scnprintf = SCA_MSG_FLAGS, /* flags */ }, }, },

	{ .name	    = "renameat",

	  .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_renameat", },

	  .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },

		   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ }, }, },

	{ .name	    = "renameat2",

	  .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_renameat", },

	  .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },

		   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ },

		   [4] = { .scnprintf = SCA_RENAMEAT2_FLAGS, /* flags */ }, }, },

tools/perf/examples/bpf/augmented_raw_syscalls.c

+20 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ pid_filter(pids_filtered); 
struct augmented_args_filename {

       struct syscall_enter_args args;

       struct augmented_filename filename;

       struct augmented_filename filename2;

};



bpf_map(augmented_filename_map, PERCPU_ARRAY, int, struct augmented_args_filename, 1);
@@ -148,6 +149,25 @@ int sys_enter_openat(struct syscall_enter_args *args) 
	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);

}



SEC("!syscalls:sys_enter_renameat")

int sys_enter_renameat(struct syscall_enter_args *args)

{

	int key = 0;

	struct augmented_args_filename *augmented_args = bpf_map_lookup_elem(&augmented_filename_map, &key);

	const void *oldpath_arg = (const void *)args->args[1],

		   *newpath_arg = (const void *)args->args[3];

	unsigned int len = sizeof(augmented_args->args), oldpath_len;



        if (augmented_args == NULL)

                return 1; /* Failure: don't filter */



	oldpath_len = augmented_filename__read(&augmented_args->filename, oldpath_arg, sizeof(augmented_args->filename.value));

	len += oldpath_len + augmented_filename__read((void *)(&augmented_args->filename) + oldpath_len, newpath_arg, sizeof(augmented_args->filename.value));



	/* 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);

}



SEC("raw_syscalls:sys_enter")

int sys_enter(struct syscall_enter_args *args)

{

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