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// SPDX-License-Identifier: GPL-2.0
/*
* Capability utilities
*/
#include "cap.h"
#include "debug.h"
#include <errno.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>
#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3
bool perf_cap__capable(int cap, bool *used_root)
{
struct __user_cap_header_struct header = {
.version = _LINUX_CAPABILITY_VERSION_3,
.pid = 0,
};
struct __user_cap_data_struct data[MAX_LINUX_CAPABILITY_U32S] = {};
__u32 cap_val;
*used_root = false;
while (syscall(SYS_capget, &header, &data[0]) == -1) {
/* Retry, first attempt has set the header.version correctly. */
if (errno == EINVAL && header.version != _LINUX_CAPABILITY_VERSION_3 &&
header.version == _LINUX_CAPABILITY_VERSION_1)
continue;
pr_debug2("capget syscall failed (%s - %d) fall back on root check\n",
strerror(errno), errno);
*used_root = true;
return geteuid() == 0;
}
/* Extract the relevant capability bit. */
if (cap >= 32) {
if (header.version == _LINUX_CAPABILITY_VERSION_3) {
cap_val = data[1].effective;
} else {
/* Capability beyond 32 is requested but only 32 are supported. */
return false;
}
} else {
cap_val = data[0].effective;
}
return (cap_val & (1 << (cap & 0x1f))) != 0;
}
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