[tip: perf/core] trace/bpf_trace: Open access for CAP_PERFMON privileged process

[tip-bot2 for Alexey Budankov]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     031258da05956646c5606023ab0abe10a7e68ea1
Gitweb:        https://git.kernel.org/tip/031258da05956646c5606023ab0abe10a7e68ea1
Author:        Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
AuthorDate:    Thu, 02 Apr 2020 11:48:54 +03:00
Committer:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Thu, 16 Apr 2020 12:19:08 -03:00

trace/bpf_trace: Open access for CAP_PERFMON privileged process

Open access to bpf_trace monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without the
rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the
credentials and makes operation more secure.

CAP_PERFMON implements the principle of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
principle of least privilege: A security design principle that states
that a process or program be granted only those privileges (e.g.,
capabilities) necessary to accomplish its legitimate function, and only
for the time that such privileges are actually required)

For backward compatibility reasons access to bpf_trace monitoring
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure bpf_trace monitoring is discouraged with respect to
CAP_PERFMON capability.

Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
Reviewed-by: James Morris <jamorris@xxxxxxxxxxxxxxxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Igor Lubashev <ilubashe@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Serge Hallyn <serge@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-man@xxxxxxxxxxxxxxx
Cc: linux-security-module@xxxxxxxxxxxxxxx
Cc: selinux@xxxxxxxxxxxxxxx
Link: http://lore.kernel.org/lkml/c0a0ae47-8b6e-ff3e-416b-3cd1faaf71c0@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 kernel/trace/bpf_trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca17967..d7d8800 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1468,7 +1468,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
 	u32 *ids, prog_cnt, ids_len;
 	int ret;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!perfmon_capable())
 		return -EPERM;
 	if (event->attr.type != PERF_TYPE_TRACEPOINT)
 		return -EINVAL;