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1// SPDX-License-Identifier: GPL-2.02/*3 * Capability utilities4 */5 6#include "cap.h"7#include "debug.h"8#include <errno.h>9#include <string.h>10#include <linux/capability.h>11#include <sys/syscall.h>12#include <unistd.h>13 14#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_315 16bool perf_cap__capable(int cap, bool *used_root)17{18 struct __user_cap_header_struct header = {19 .version = _LINUX_CAPABILITY_VERSION_3,20 .pid = 0,21 };22 struct __user_cap_data_struct data[MAX_LINUX_CAPABILITY_U32S] = {};23 __u32 cap_val;24 25 *used_root = false;26 while (syscall(SYS_capget, &header, &data[0]) == -1) {27 /* Retry, first attempt has set the header.version correctly. */28 if (errno == EINVAL && header.version != _LINUX_CAPABILITY_VERSION_3 &&29 header.version == _LINUX_CAPABILITY_VERSION_1)30 continue;31 32 pr_debug2("capget syscall failed (%s - %d) fall back on root check\n",33 strerror(errno), errno);34 *used_root = true;35 return geteuid() == 0;36 }37 38 /* Extract the relevant capability bit. */39 if (cap >= 32) {40 if (header.version == _LINUX_CAPABILITY_VERSION_3) {41 cap_val = data[1].effective;42 } else {43 /* Capability beyond 32 is requested but only 32 are supported. */44 return false;45 }46 } else {47 cap_val = data[0].effective;48 }49 return (cap_val & (1 << (cap & 0x1f))) != 0;50}51