redonkable/alistair23-linux
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Daniel Borkmann b2a5212fb6 bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier 
Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the
very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on
archs with overlapping address ranges.

While the helpers have been addressed through work in 6ae08ae3de ("bpf: Add
probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need
an option for bpf_trace_printk() as well to fix it.

Similarly as with the helpers, force users to make an explicit choice by adding
%pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding
strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS.
The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended
for other objects aside strings that are probed and printed under tracing, and
reused out of other facilities like bpf_seq_printf() or BTF based type printing.

Existing behavior of %s for current users is still kept working for archs where it
is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.
For archs not having this property we fall-back to pick probing under KERNEL_DS as
a sensible default.

Fixes: 8d3b7dce86 ("bpf: add support for %s specifier to bpf_trace_printk()")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-15 08:10:36 -07:00
arch bpf: Restrict bpf_probe_read{, str}() only to archs where they work 2020-05-15 08:10:36 -07:00
block block: remove the bd_openers checks in blk_drop_partitions 2020-04-30 10:25:43 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
Documentation bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier 2020-05-15 08:10:36 -07:00
drivers net: phy: fix aneg restart in phy_ethtool_set_eee 2020-05-13 15:21:59 -07:00
fs for-5.7-rc3-tag 2020-05-03 11:30:08 -07:00
include security: Fix the default value of secid_to_secctx hook 2020-05-14 12:46:34 -07:00
init bpf: Restrict bpf_probe_read{, str}() only to archs where they work 2020-05-15 08:10:36 -07:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-10 15:36:22 -07:00
kernel bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier 2020-05-15 08:10:36 -07:00
lib bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier 2020-05-15 08:10:36 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm: check that mm is still valid in madvise() 2020-04-24 13:28:03 -07:00
net tipc: fix failed service subscription deletion 2020-05-13 12:33:19 -07:00
samples samples: bpf: Fix build error 2020-05-14 12:37:39 -07:00
scripts GCC 10 fixes for gcc-plugins 2020-05-04 11:20:32 -07:00
security selinux/stable-5.7 PR 20200430 2020-04-30 16:35:45 -07:00
sound sound fixes for 5.7-rc4 2020-05-01 11:05:28 -07:00
tools selftests/bpf: Enforce returning 0 for fentry/fexit programs 2020-05-14 12:53:53 -07:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt KVM: Pass kvm_init()'s opaque param to additional arch funcs 2020-03-31 10:48:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-04-18 13:49:33 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.mailmap mailmap: Add Sedat Dilek (replacement for expired email address) 2020-04-11 09:28:34 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: add Karsten Graul as S390 NETWORK DRIVERS maintainer 2020-05-13 12:14:51 -07:00
Makefile Linux 5.7-rc4 2020-05-03 14:56:04 -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.