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Improve set_cpu_affinity() on NetBSD

By default, running libcpuid as regular user on NetBSD shows nothing: set_cpu_affinity() fails quietly so cpu_identify_all() is not able to get raw data.
This commit display a warning when an unallowed user try to set CPU affinity.
This commit is contained in:
The Tumultuous Unicorn Of Darkness 2024-07-27 13:25:08 +02:00
parent 3c37492b93
commit 2133c22052
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@ -526,6 +526,8 @@ static bool set_cpu_affinity(logical_cpu_t logical_cpu)
#endif /* defined __DragonFly__ */
#if defined __NetBSD__
#include <unistd.h>
#include <sys/sysctl.h>
#include <pthread.h>
#include <sched.h>
@ -553,9 +555,36 @@ static bool restore_cpu_affinity(void)
static bool set_cpu_affinity(logical_cpu_t logical_cpu)
{
cpuset_t *cpuset;
cpuset = cpuset_create();
cpuset_set((cpuid_t) logical_cpu, cpuset);
int result = -1;
size_t size = sizeof(result);
/* Note: pthread_setaffinity_np() always returns 0 even if the target logical CPU does not exist */
if (logical_cpu >= get_total_cpus())
return false;
/* Check if user is allowed to control CPU sets: https://man.netbsd.org/secmodel_extensions.9 */
if (getuid() != 0) {
if (sysctlbyname("security.models.extensions.user_set_cpu_affinity", &result, &size, NULL, 0)) {
warnf("failed to get sysctl value for security.models.extensions.user_set_cpu_affinity\n");
return false;
}
else if (result == 0) {
warnf("user is not allowed to control the CPU affinity: you may enable \"Non-superuser control of CPU sets\" by setting sysctl security.models.extensions.user_set_cpu_affinity=1\n");
return false;
}
}
cpuset_t *cpuset = cpuset_create();
if (cpuset == NULL) {
warnf("failed to create CPU set for logical CPU %u\n", logical_cpu);
return false;
}
if (cpuset_set((cpuid_t) logical_cpu, cpuset) < 0) {
warnf("failed to set CPU set for logical CPU %u\n", logical_cpu);
return false;
}
int ret = pthread_setaffinity_np(pthread_self(), cpuset_size(cpuset), cpuset);
cpuset_destroy(cpuset);
return ret == 0;