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Kumar Kartikeya Dwivedi 97e6d7dab1 bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access 
The commit being fixed was aiming to disallow users from incorrectly
obtaining writable pointer to memory that is only meant to be read. This
is enforced now using a MEM_RDONLY flag.

For instance, in case of global percpu variables, when the BTF type is
not struct (e.g. bpf_prog_active), the verifier marks register type as
PTR_TO_MEM | MEM_RDONLY from bpf_this_cpu_ptr or bpf_per_cpu_ptr
helpers. However, when passing such pointer to kfunc, global funcs, or
BPF helpers, in check_helper_mem_access, there is no expectation
MEM_RDONLY flag will be set, hence it is checked as pointer to writable
memory. Later, verifier sets up argument type of global func as
PTR_TO_MEM | PTR_MAYBE_NULL, so user can use a global func to get around
the limitations imposed by this flag.

This check will also cover global non-percpu variables that may be
introduced in kernel BTF in future.

Also, we update the log message for PTR_TO_BUF case to be similar to
PTR_TO_MEM case, so that the reason for error is clear to user.

Fixes: 34d3a78c68 ("bpf: Make per_cpu_ptr return rdonly PTR_TO_MEM.")
Reviewed-by: Hao Luo <haoluo@google.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220319080827.73251-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-04-06 10:32:12 -07:00
arch bpf, arm64: Sign return address for JITed code 2022-04-06 00:04:22 +02:00
block ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
certs KEYS: Introduce link restriction for machine keys 2022-03-08 13:55:52 +02:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation Networking fixes for 5.18-rc1 and rethook patches. 2022-03-31 11:23:31 -07:00
drivers Networking fixes for 5.18-rc1 and rethook patches. 2022-03-31 11:23:31 -07:00
fs fs: fix fd table size alignment properly 2022-03-29 23:29:18 -07:00
include bpf: Correct the comment for BTF kind bitfield 2022-04-03 17:06:52 -07:00
init Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access 2022-04-06 10:32:12 -07:00
lib bpf, tests: Add load store test case for tail call 2022-04-01 00:27:52 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: page_alloc: validate buddy before check its migratetype. 2022-03-30 15:45:43 -07:00
net net: netfilter: Reports ct direction in CT lookup helpers for XDP and TC-BPF 2022-04-06 09:58:30 -07:00
samples samples: bpf: Fix linking xdp_router_ipv4 after migration 2022-04-04 14:45:06 -07:00
scripts Driver core changes for 5.18-rc1 2022-03-28 12:41:28 -07:00
security ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
sound xen: branch for v5.18-rc1 2022-03-28 14:32:39 -07:00
tools selftests/bpf: Use bpf_num_possible_cpus() in per-cpu map allocations 2022-04-06 10:15:53 -07:00
usr reiserfs_xattr.h: add linux/reiserfs_xattr.h to UAPI compile-test coverage 2022-02-17 09:09:38 +01:00
virt KVM: compat: riscv: Prevent KVM_COMPAT from being selected 2022-03-11 19:02:15 +05:30
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap Char/Misc and other driver updates for 5.18-rc1 2022-03-28 12:27:35 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.18-rc1 and rethook patches. 2022-03-31 11:23:31 -07:00
Makefile array-bounds updates for v5.18-rc1 2022-03-26 12:30:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.