From 836b2fe544a5e9b5ce116622cb36fba33838c6fd Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 4 Sep 2026 01:33:23 -0700 Subject: selftests/bpf: Check that JMP32 pointer vs zero jumps are not predicted Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which the verifier used to skip, contains an out of bounds map value access, hence w/o the previous patch the program is accepted. See previous patch for detailed description. Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- tools/perf/util/cap.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 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..ac6d1d9a5 --- /dev/null +++ b/tools/perf/util/cap.c @@ -0,0 +1,48 @@ +// 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, 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 (%m) fall back on root check\n"); + *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; +} -- cgit v1.3.1