From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- fs/Kconfig.binfmt | 210 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 210 insertions(+) create mode 100644 fs/Kconfig.binfmt (limited to 'fs/Kconfig.binfmt') diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt new file mode 100644 index 000000000..daeac4889 --- /dev/null +++ b/fs/Kconfig.binfmt @@ -0,0 +1,210 @@ +# SPDX-License-Identifier: GPL-2.0-only + +menu "Executable file formats" + +config BINFMT_ELF + bool "Kernel support for ELF binaries" + depends on MMU + select ELFCORE + default y + help + ELF (Executable and Linkable Format) is a format for libraries and + executables used across different architectures and operating + systems. Saying Y here will enable your kernel to run ELF binaries + and enlarge it by about 13 KB. ELF support under Linux has now all + but replaced the traditional Linux a.out formats (QMAGIC and ZMAGIC) + because it is portable (this does *not* mean that you will be able + to run executables from different architectures or operating systems + however) and makes building run-time libraries very easy. Many new + executables are distributed solely in ELF format. You definitely + want to say Y here. + + Information about ELF is contained in the ELF HOWTO available from + . + + If you find that after upgrading from Linux kernel 1.2 and saying Y + here, you still can't run any ELF binaries (they just crash), then + you'll have to install the newest ELF runtime libraries, including + ld.so (check the file for location and + latest version). + +config BINFMT_ELF_KUNIT_TEST + bool "Build KUnit tests for ELF binary support" if !KUNIT_ALL_TESTS + depends on KUNIT=y && BINFMT_ELF=y + default KUNIT_ALL_TESTS + help + This builds the ELF loader KUnit tests, which try to gather + prior bug fixes into a regression test collection. This is really + only needed for debugging. Note that with CONFIG_COMPAT=y, the + compat_binfmt_elf KUnit test is also created. + +config COMPAT_BINFMT_ELF + def_bool y + depends on COMPAT && BINFMT_ELF + select ELFCORE + +config ARCH_BINFMT_ELF_STATE + bool + +config ARCH_BINFMT_ELF_EXTRA_PHDRS + bool + +config ARCH_HAVE_ELF_PROT + bool + +config ARCH_USE_GNU_PROPERTY + bool + +config BINFMT_ELF_FDPIC + bool "Kernel support for FDPIC ELF binaries" + default y if !BINFMT_ELF + depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU) + select ELFCORE + help + ELF FDPIC binaries are based on ELF, but allow the individual load + segments of a binary to be located in memory independently of each + other. This makes this format ideal for use in environments where no + MMU is available as it still permits text segments to be shared, + even if data segments are not. + + It is also possible to run FDPIC ELF binaries on MMU linux also. + +config ELFCORE + bool + help + This option enables kernel/elfcore.o. + +config CORE_DUMP_DEFAULT_ELF_HEADERS + bool "Write ELF core dumps with partial segments" + default y + depends on BINFMT_ELF && ELF_CORE + help + ELF core dump files describe each memory mapping of the crashed + process, and can contain or omit the memory contents of each one. + The contents of an unmodified text mapping are omitted by default. + + For an unmodified text mapping of an ELF object, including just + the first page of the file in a core dump makes it possible to + identify the build ID bits in the file, without paying the i/o + cost and disk space to dump all the text. However, versions of + GDB before 6.7 are confused by ELF core dump files in this format. + + The core dump behavior can be controlled per process using + the /proc/PID/coredump_filter pseudo-file; this setting is + inherited. See Documentation/filesystems/proc.rst for details. + + This config option changes the default setting of coredump_filter + seen at boot time. If unsure, say Y. + +config BINFMT_SCRIPT + tristate "Kernel support for scripts starting with #!" + default y + help + Say Y here if you want to execute interpreted scripts starting with + #! followed by the path to an interpreter. + + You can build this support as a module; however, until that module + gets loaded, you cannot run scripts. Thus, if you want to load this + module from an initramfs, the portion of the initramfs before loading + this module must consist of compiled binaries only. + + Most systems will not boot if you say M or N here. If unsure, say Y. + +config ARCH_HAS_BINFMT_FLAT + bool + +config BINFMT_FLAT + bool "Kernel support for flat binaries" + depends on ARCH_HAS_BINFMT_FLAT + help + Support uClinux FLAT format binaries. + +config BINFMT_FLAT_ARGVP_ENVP_ON_STACK + bool + +config BINFMT_FLAT_OLD_ALWAYS_RAM + bool + +config BINFMT_FLAT_NO_DATA_START_OFFSET + bool + +config BINFMT_FLAT_OLD + bool "Enable support for very old legacy flat binaries" + depends on BINFMT_FLAT + help + Support decade old uClinux FLAT format binaries. Unless you know + you have some of those say N here. + +config BINFMT_ZFLAT + bool "Enable ZFLAT support" + depends on BINFMT_FLAT + select ZLIB_INFLATE + help + Support FLAT format compressed binaries + +config BINFMT_MISC + tristate "Kernel support for MISC binaries" + help + If you say Y here, it will be possible to plug wrapper-driven binary + formats into the kernel. You will like this especially when you use + programs that need an interpreter to run like Java, Python, .NET or + Emacs-Lisp. It's also useful if you often run DOS executables under + the Linux DOS emulator DOSEMU (read the DOSEMU-HOWTO, available from + ). Once you have + registered such a binary class with the kernel, you can start one of + those programs simply by typing in its name at a shell prompt; Linux + will automatically feed it to the correct interpreter. + + You can do other nice things, too. Read the file + to learn how to use this + feature, for information about how + to include Java support. and for + information about how to include Mono-based .NET support. + + To use binfmt_misc, you will need to mount it: + mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc + + You may say M here for module support and later load the module when + you have use for it; the module is called binfmt_misc. If you + don't know what to answer at this point, say Y. + +config BINFMT_MISC_BPF + bool "BPF-selected interpreters for misc binaries" + depends on BINFMT_MISC=y + depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF + help + Allow binfmt_misc binary type handlers to be implemented as bpf + struct_ops programs. Instead of matching a fixed magic and + redirecting to a fixed interpreter recorded at registration time + such handlers match binaries programmatically and compute the + interpreter to use per binary, e.g. relative to the location of + the binary itself. + + If you don't know what to answer at this point, say N. + +config COREDUMP + bool "Enable core dump support" if EXPERT + default y + help + This option enables support for performing core dumps. You almost + certainly want to say Y here. Not necessary on systems that never + need debugging or only ever run flawless code. + +config EXEC_KUNIT_TEST + bool "Build execve tests" if !KUNIT_ALL_TESTS + depends on KUNIT=y + default KUNIT_ALL_TESTS + help + This builds the exec KUnit tests, which tests boundary conditions + of various aspects of the exec internals. + +config ARCH_HAS_ELF_CORE_EFLAGS + bool + depends on BINFMT_ELF && ELF_CORE + default n + help + Select this option if the architecture makes use of the e_flags + field in the ELF header to store ABI or other architecture-specific + information that should be preserved in core dumps. + +endmenu -- cgit v1.3.1