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

Date: Tue, 16 Jul 2019 14:55:57 -0300

Subject: perf augmented_raw_syscalls: Support copying two string syscall args

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Git-commit: 8d5da2649d8211e63c5f65ccf8945f2c46a9c0b8

Patch-mainline: v5.4-rc1

References: jsc#SLE-13661

​

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

Signed-off-by: Tony Jones <tonyj@suse.de>

---

 tools/perf/builtin-trace.c                       |  2 ++

 tools/perf/examples/bpf/augmented_raw_syscalls.c | 20 ++++++++++++++++++++

 2 files changed, 22 insertions(+)

​

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c

index a681b8c2ee4e..c64f7c99db15 100644

--- a/tools/perf/builtin-trace.c

+++ b/tools/perf/builtin-trace.c

@@ -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 */ }, }, },

diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c

index ce308b9a317c..df52d92e1c69 100644

--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c

+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c

@@ -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)

 {

​

​