linux-kernel - [PATCH v3 2/3] perf bpf filter: Add uid and gid terms

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Message-Id: <20240524205227.244375-3-irogers@google.com>
Date: Fri, 24 May 2024 13:52:26 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Changbin Du <changbin.du@...wei.com>, 
	Yang Jihong <yangjihong1@...wei.com>, Andrii Nakryiko <andrii@...nel.org>, 
	John Fastabend <john.fastabend@...il.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH v3 2/3] perf bpf filter: Add uid and gid terms

Allow the BPF filter to use the uid and gid terms determined by the
bpf_get_current_uid_gid BPF helper. For example, the following will
record the cpu-clock event system wide discarding samples that don't
belong to the current user.

$ perf record -e cpu-clock --filter "uid == $(id -u)" -a sleep 0.1

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/Documentation/perf-record.txt     | 2 +-
 tools/perf/util/bpf-filter.c                 | 5 +++++
 tools/perf/util/bpf-filter.l                 | 2 ++
 tools/perf/util/bpf_skel/sample-filter.h     | 3 +++
 tools/perf/util/bpf_skel/sample_filter.bpf.c | 4 ++++
 5 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 6015fdd08fb6..059bc40c5ee1 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -200,7 +200,7 @@ OPTIONS
 	  ip, id, tid, pid, cpu, time, addr, period, txn, weight, phys_addr,
 	  code_pgsz, data_pgsz, weight1, weight2, weight3, ins_lat, retire_lat,
 	  p_stage_cyc, mem_op, mem_lvl, mem_snoop, mem_remote, mem_lock,
-	  mem_dtlb, mem_blk, mem_hops
+	  mem_dtlb, mem_blk, mem_hops, uid, gid
 
 	The <operator> can be one of:
 	  ==, !=, >, >=, <, <=, &
diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c
index f10148623a8e..04f98b6bb291 100644
--- a/tools/perf/util/bpf-filter.c
+++ b/tools/perf/util/bpf-filter.c
@@ -63,6 +63,11 @@ static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *
 	    (evsel->core.attr.sample_type & (1 << (expr->term - PBF_TERM_SAMPLE_START))))
 		return 0;
 
+	if (expr->term == PBF_TERM_UID || expr->term == PBF_TERM_GID) {
+		/* Not dependent on the sample_type as computed from a BPF helper. */
+		return 0;
+	}
+
 	if (expr->op == PBF_OP_GROUP_BEGIN) {
 		struct perf_bpf_filter_expr *group;
 
diff --git a/tools/perf/util/bpf-filter.l b/tools/perf/util/bpf-filter.l
index 62c959813466..2a7c839f3fae 100644
--- a/tools/perf/util/bpf-filter.l
+++ b/tools/perf/util/bpf-filter.l
@@ -95,6 +95,8 @@ mem_lock	{ return sample_part(PBF_TERM_DATA_SRC, 5); }
 mem_dtlb	{ return sample_part(PBF_TERM_DATA_SRC, 6); }
 mem_blk		{ return sample_part(PBF_TERM_DATA_SRC, 7); }
 mem_hops	{ return sample_part(PBF_TERM_DATA_SRC, 8); }
+uid		{ return sample(PBF_TERM_UID); }
+gid		{ return sample(PBF_TERM_GID); }
 
 "=="		{ return operator(PBF_OP_EQ); }
 "!="		{ return operator(PBF_OP_NEQ); }
diff --git a/tools/perf/util/bpf_skel/sample-filter.h b/tools/perf/util/bpf_skel/sample-filter.h
index 25f780022951..350efa121026 100644
--- a/tools/perf/util/bpf_skel/sample-filter.h
+++ b/tools/perf/util/bpf_skel/sample-filter.h
@@ -47,6 +47,9 @@ enum perf_bpf_filter_term {
 	PBF_TERM_CODE_PAGE_SIZE	= PBF_TERM_SAMPLE_START + 23, /* SAMPLE_CODE_PAGE_SIZE = 1U << 23 */
 	PBF_TERM_WEIGHT_STRUCT	= PBF_TERM_SAMPLE_START + 24, /* SAMPLE_WEIGHT_STRUCT = 1U << 24 */
 	PBF_TERM_SAMPLE_END	= PBF_TERM_WEIGHT_STRUCT,
+	/* Terms computed from BPF helpers. */
+	PBF_TERM_UID,
+	PBF_TERM_GID,
 };
 
 /* BPF map entry for filtering */
diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c
index 5ac1778ff66e..f59985101973 100644
--- a/tools/perf/util/bpf_skel/sample_filter.bpf.c
+++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c
@@ -140,6 +140,10 @@ static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx,
 		}
 		/* return the whole word */
 		return kctx->data->data_src.val;
+	case PBF_TERM_UID:
+		return bpf_get_current_uid_gid() & 0xFFFFFFFF;
+	case PBF_TERM_GID:
+		return bpf_get_current_uid_gid() >> 32;
 	case PBF_TERM_NONE:
 	case __PBF_UNUSED_TERM4:
 	case __PBF_UNUSED_TERM5:
-- 
2.45.1.288.g0e0cd299f1-goog