From a615a850ee820848b2d464973855148e55c8c92f Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@google.com>
Date: Fri, 19 Jan 2024 08:07:06 -0800
Subject: [PATCH] Pass the correct user ID to SetProcessProfilesCached()
SetProcessProfilesCached() can only set cgroup attributes in the v2
cgroup hierarchy if it is passed the correct user ID. Hence this CL.
This CL makes SetProcessProfilesCached() apply IO controller cgroup
attributes for processes with a user ID that is not zero.
Bug: 320456702
Bug: 213617178
Change-Id: I84d072c14ff01422560c241a69cb9f4e02c47e74
Signed-off-by: Bart Van Assche <bvanassche@google.com>
---
core/jni/android_util_Process.cpp | 33 ++++++++++++++++++++++++++++++-
1 file changed, 32 insertions(+), 1 deletion(-)
diff --git a/core/jni/android_util_Process.cpp b/core/jni/android_util_Process.cpp
index 7af69f2dff08..6a640a5ab23b 100644
--- a/core/jni/android_util_Process.cpp
+++ b/core/jni/android_util_Process.cpp
@@ -28,6 +28,7 @@
#include <meminfo/sysmeminfo.h>
#include <processgroup/processgroup.h>
#include <processgroup/sched_policy.h>
+#include <android-base/logging.h>
#include <android-base/unique_fd.h>
#include <algorithm>
@@ -232,6 +233,31 @@ void android_os_Process_setThreadGroupAndCpuset(JNIEnv* env, jobject clazz, int
}
}
+// Look up the user ID of a process in /proc/${pid}/status. The Uid: line is present in
+// /proc/${pid}/status since at least kernel v2.5.
+static int uid_from_pid(int pid)
+{
+ int uid = -1;
+ std::array<char, 64> path;
+ int res = snprintf(path.data(), path.size(), "/proc/%d/status", pid);
+ if (res < 0 || res >= static_cast<int>(path.size())) {
+ DCHECK(false);
+ return uid;
+ }
+ FILE* f = fopen(path.data(), "r");
+ if (!f) {
+ return uid;
+ }
+ char line[256];
+ while (fgets(line, sizeof(line), f)) {
+ if (sscanf(line, "Uid: %d", &uid) == 1) {
+ break;
+ }
+ }
+ fclose(f);
+ return uid;
+}
+
void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jint grp)
{
ALOGV("%s pid=%d grp=%" PRId32, __func__, pid, grp);
@@ -275,7 +301,12 @@ void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jin
}
}
- if (!SetProcessProfilesCached(0, pid, {get_cpuset_policy_profile_name((SchedPolicy)grp)}))
+ const int uid = uid_from_pid(pid);
+ if (uid < 0) {
+ signalExceptionForGroupError(env, ESRCH, pid);
+ return;
+ }
+ if (!SetProcessProfilesCached(uid, pid, {get_cpuset_policy_profile_name((SchedPolicy)grp)}))
signalExceptionForGroupError(env, errno ? errno : EPERM, pid);
}
--
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