From bdab18633a302c82b5e5d5dbc4e38b0baf9c0837 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 20 Sep 2026 08:15:23 -0700 Subject: Merge tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull futex fix from Ingo Molnar: - Also allocate a default private futex hash on vfork() as well, to avoid races with (private) futex waiters (Peter Zijlstra) * tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Also allocate private hash on vfork() --- tools/perf/util/cap.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 tools/perf/util/cap.c (limited to 'tools/perf/util/cap.c') diff --git a/tools/perf/util/cap.c b/tools/perf/util/cap.c new file mode 100644 index 000000000..272bd8255 --- /dev/null +++ b/tools/perf/util/cap.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Capability utilities + */ + +#include "cap.h" +#include "debug.h" +#include +#include +#include +#include + +#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3 + +bool perf_cap__capable(int cap) +{ + 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; + + 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 (%m) fall back on root check\n"); + 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; +} -- cgit v1.3.1