rtllib_process_action() is only called in one place with management
frames. Frame is passed over to rtllib_get_payload() which passes it to
rtllib_get_hdrlen(). In rtllib_get_hdrlen() all management frames
return with hdrlen = RTLLIB_3ADDR_LEN. Therefore the switch in
rtllib_get_payload() is useless and dead code. The condition act == NULL
cannot occur and can also be removed. Then rtllib_hdr_2addr is not used
anymore and can be removed as well.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/3ef288fb819f50da3eb9291522067babaa57f532.1694546301.git.philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When "switch (WLAN_FC_GET_STYPE(le16_to_cpu(header->frame_ctl)))" results
in "case RTLLIB_STYPE_BEACON:" there is no need to calculate this again
inside "case" and when a frame is a beacon there is no need to print the
frame identifier again as it is explicit.
Same for PROBE RESPONSE and PROBE REQUEST. Remove dead code.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/f3c8deddac66d11c41ba720e4048aba37e41e885.1694546300.git.philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Remove unsupported mode IW_MODE_ADHOC because this mode is only partially
coded in the driver.
rtllib_rx_mgt() can only handle probe requests in IW_MODE_ADHOC and no
authentication or association frames.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20230827132704.GA12506@matrix-ESPRIMO-P710
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
- Fix kernel-devel RPM and linux-headers Deb package
- Fix too long argument list error in 'make modules_install'
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Merge tag 'kbuild-fixes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada:
- Fix kernel-devel RPM and linux-headers Deb package
- Fix too long argument list error in 'make modules_install'
* tag 'kbuild-fixes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: avoid long argument lists in make modules_install
kbuild: fix kernel-devel RPM package and linux-headers Deb package
Commit 408579cd62 ("mm: Update do_vmi_align_munmap() return
semantics") seems to have updated one of the callers of do_vmi_munmap()
incorrectly: it used to check for the error case (which didn't
change: negative means error).
That commit changed the check to the success case (which did change:
before that commit, 0 was success, and 1 was "success and lock
downgraded". After the change, it's always 0 for success, and the lock
will have been released if requested).
This didn't change any actual VM behavior _except_ for memory accounting
when 'VM_ACCOUNT' was set on the vma. Which made the wrong return value
test fairly subtle, since everything continues to work.
Or rather - it continues to work but the "Committed memory" accounting
goes all wonky (Committed_AS value in /proc/meminfo), and depending on
settings that then causes problems much much later as the VM relies on
bogus statistics for its heuristics.
Revert that one line of the change back to the original logic.
Fixes: 408579cd62 ("mm: Update do_vmi_align_munmap() return semantics")
Reported-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Reported-bisected-and-tested-by: Michael Labiuk <michael.labiuk@virtuozzo.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/all/1694366957@msgid.manchmal.in-ulm.de/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
16 small(ish) fixes all in drivers. The major fixes are in pm8001
(fixes MSI-X issue going back to its origin), the qla2xxx endianness
fix, which fixes a bug on big endian and the lpfc ones which can cause
an oops on module removal without them.
Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI fixes from James Bottomley:
"16 small(ish) fixes all in drivers.
The major fixes are in pm8001 (fixes MSI-X issue going back to its
origin), the qla2xxx endianness fix, which fixes a bug on big endian
and the lpfc ones which can cause an oops on module removal without
them"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: lpfc: Prevent use-after-free during rmmod with mapped NVMe rports
scsi: lpfc: Early return after marking final NLP_DROPPED flag in dev_loss_tmo
scsi: lpfc: Fix the NULL vs IS_ERR() bug for debugfs_create_file()
scsi: target: core: Fix target_cmd_counter leak
scsi: pm8001: Setup IRQs on resume
scsi: pm80xx: Avoid leaking tags when processing OPC_INB_SET_CONTROLLER_CONFIG command
scsi: pm80xx: Use phy-specific SAS address when sending PHY_START command
scsi: ufs: core: Poll HCS.UCRDY before issuing a UIC command
scsi: ufs: core: Move __ufshcd_send_uic_cmd() outside host_lock
scsi: qedf: Add synchronization between I/O completions and abort
scsi: target: Replace strlcpy() with strscpy()
scsi: qla2xxx: Fix NULL vs IS_ERR() bug for debugfs_create_dir()
scsi: qla2xxx: Use raw_smp_processor_id() instead of smp_processor_id()
scsi: qla2xxx: Correct endianness for rqstlen and rsplen
scsi: ppa: Fix accidentally reversed conditions for 16-bit and 32-bit EPP
scsi: megaraid_sas: Fix deadlock on firmware crashdump
- Fix link power management transitions to disallow unsupported
states (Niklas).
- A small string handling fix for the sata_mv driver (Christophe).
- Clear port pending interrupts before reset, as per AHCI
specifications (Szuying). Followup fixes for this one are to not
clear ATA_PFLAG_EH_PENDING in ata_eh_reset() to allow EH to
continue on with other actions recorded with error interrupts
triggered before EH completes. A~Nd an additional fix to avoid
thawing a port twice in EH (Niklas).
- Small code style fixes in the pata_parport driver to silence the
build bot as it keeps complaining about bad indentation (me).
- A fix for the recent CDL code to avoid fetching sense data for
successful commands when not necessary for correct operation
(Niklas).
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Merge tag 'ata-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata
Pull ata fixes from Damien Le Moal:
- Fix link power management transitions to disallow unsupported states
(Niklas)
- A small string handling fix for the sata_mv driver (Christophe)
- Clear port pending interrupts before reset, as per AHCI
specifications (Szuying).
Followup fixes for this one are to not clear ATA_PFLAG_EH_PENDING in
ata_eh_reset() to allow EH to continue on with other actions recorded
with error interrupts triggered before EH completes. And an
additional fix to avoid thawing a port twice in EH (Niklas)
- Small code style fixes in the pata_parport driver to silence the
build bot as it keeps complaining about bad indentation (me)
- A fix for the recent CDL code to avoid fetching sense data for
successful commands when not necessary for correct operation (Niklas)
* tag 'ata-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
ata: libata-core: fetch sense data for successful commands iff CDL enabled
ata: libata-eh: do not thaw the port twice in ata_eh_reset()
ata: libata-eh: do not clear ATA_PFLAG_EH_PENDING in ata_eh_reset()
ata: pata_parport: Fix code style issues
ata: libahci: clear pending interrupt status
ata: sata_mv: Fix incorrect string length computation in mv_dump_mem()
ata: libata: disallow dev-initiated LPM transitions to unsupported states
Here is a single USB fix for a much-reported regression for 6.6-rc1.
It resolves a crash in the typec debugfs code for many systems. It's
been in linux-next with no reported issues, and many people have
reported it resolving their problem with 6.6-rc1.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fix from Greg KH:
"Here is a single USB fix for a much-reported regression for 6.6-rc1.
It resolves a crash in the typec debugfs code for many systems. It's
been in linux-next with no reported issues, and many people have
reported it resolving their problem with 6.6-rc1"
* tag 'usb-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
usb: typec: ucsi: Fix NULL pointer dereference
Here is a single driver core fix for a much-reported-by-sysbot issue
that showed up in 6.6-rc1. It's been submitted by many people, all in
the same way, so it obviously fixes things for them all.
Also in here is a single documentation update adding riscv to the
embargoed hardware document in case there are any future issues with
that processor family.
Both of these have been in linux-next with no reported problems.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core fixes from Greg KH:
"Here is a single driver core fix for a much-reported-by-sysbot issue
that showed up in 6.6-rc1. It's been submitted by many people, all in
the same way, so it obviously fixes things for them all.
Also in here is a single documentation update adding riscv to the
embargoed hardware document in case there are any future issues with
that processor family.
Both of these have been in linux-next with no reported problems"
* tag 'driver-core-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
Documentation: embargoed-hardware-issues.rst: Add myself for RISC-V
driver core: return an error when dev_set_name() hasn't happened
Here is a single patch for 6.6-rc2 that reverts a 6.5 change for the
comedi subsystem that has ended up being incorrect and caused drivers
that were working for people to be unable to be able to be selected to
build at all. To fix this, the Kconfig change needs to be reverted and
a future set of fixes for the ioport dependancies will show up in
6.7-rc1 (there's no rush for them.)
This has been in linux-next with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc fix from Greg KH:
"Here is a single patch for 6.6-rc2 that reverts a 6.5 change for the
comedi subsystem that has ended up being incorrect and caused drivers
that were working for people to be unable to be able to be selected to
build at all.
To fix this, the Kconfig change needs to be reverted and a future set
of fixes for the ioport dependancies will show up in 6.7-rc1 (there's
no rush for them.)
This has been in linux-next with no reported issues"
* tag 'char-misc-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
Revert "comedi: add HAS_IOPORT dependencies"
are converted now. Thanks Uwe, this marks the end of a long conversion
process. Other than that, we have a few Kconfig updates and driver
bugfixes.
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Merge tag 'i2c-for-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c fixes from Wolfram Sang:
"The main thing is the removal of 'probe_new' because all i2c client
drivers are converted now. Thanks Uwe, this marks the end of a long
conversion process.
Other than that, we have a few Kconfig updates and driver bugfixes"
* tag 'i2c-for-6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: cadence: Fix the kernel-doc warnings
i2c: aspeed: Reset the i2c controller when timeout occurs
i2c: I2C_MLXCPLD on ARM64 should depend on ACPI
i2c: Make I2C_ATR invisible
i2c: Drop legacy callback .probe_new()
w1: ds2482: Switch back to use struct i2c_driver's .probe()
Kumar Kartikeya Dwivedi says:
====================
Exceptions - 1/2
This series implements the _first_ part of the runtime and verifier
support needed to enable BPF exceptions. Exceptions thrown from programs
are processed as an immediate exit from the program, which unwinds all
the active stack frames until the main stack frame, and returns to the
BPF program's caller. The ability to perform this unwinding safely
allows the program to test conditions that are always true at runtime
but which the verifier has no visibility into.
Thus, it also reduces verification effort by safely terminating
redundant paths that can be taken within a program.
The patches to perform runtime resource cleanup during the
frame-by-frame unwinding will be posted as a follow-up to this set.
It must be noted that exceptions are not an error handling mechanism for
unlikely runtime conditions, but a way to safely terminate the execution
of a program in presence of conditions that should never occur at
runtime. They are meant to serve higher-level primitives such as program
assertions.
The following kfuncs and macros are introduced:
Assertion macros are also introduced, please see patch 13 for their
documentation.
/* Description
* Throw a BPF exception from the program, immediately terminating its
* execution and unwinding the stack. The supplied 'cookie' parameter
* will be the return value of the program when an exception is thrown,
* and the default exception callback is used. Otherwise, if an exception
* callback is set using the '__exception_cb(callback)' declaration tag
* on the main program, the 'cookie' parameter will be the callback's only
* input argument.
*
* Thus, in case of default exception callback, 'cookie' is subjected to
* constraints on the program's return value (as with R0 on exit).
* Otherwise, the return value of the marked exception callback will be
* subjected to the same checks.
*
* Note that throwing an exception with lingering resources (locks,
* references, etc.) will lead to a verification error.
*
* Note that callbacks *cannot* call this helper.
* Returns
* Never.
* Throws
* An exception with the specified 'cookie' value.
*/
extern void bpf_throw(u64 cookie) __ksym;
/* This macro must be used to mark the exception callback corresponding to the
* main program. For example:
*
* int exception_cb(u64 cookie) {
* return cookie;
* }
*
* SEC("tc")
* __exception_cb(exception_cb)
* int main_prog(struct __sk_buff *ctx) {
* ...
* return TC_ACT_OK;
* }
*
* Here, exception callback for the main program will be 'exception_cb'. Note
* that this attribute can only be used once, and multiple exception callbacks
* specified for the main program will lead to verification error.
*/
\#define __exception_cb(name) __attribute__((btf_decl_tag("exception_callback:" #name)))
As such, a program can only install an exception handler once for the
lifetime of a BPF program, and this handler cannot be changed at
runtime. The purpose of the handler is to simply interpret the cookie
value supplied by the bpf_throw call, and execute user-defined logic
corresponding to it. The primary purpose of allowing a handler is to
control the return value of the program. The default handler returns the
cookie value passed to bpf_throw when an exception is thrown.
Fixing the handler for the lifetime of the program eliminates tricky and
expensive handling in case of runtime changes of the handler callback
when programs begin to nest, where it becomes more complex to save and
restore the active handler at runtime.
This version of offline unwinding based BPF exceptions is truly zero
overhead, with the exception of generation of a default callback which
contains a few instructions to return a default return value (0) when no
exception callback is supplied by the user.
Callbacks are disallowed from throwing BPF exceptions for now, since
such exceptions need to cross the callback helper boundary (and
therefore must care about unwinding kernel state), however it is
possible to lift this restriction in the future follow-up.
Exceptions terminate propogating at program boundaries, hence both
BPF_PROG_TYPE_EXT and tail call targets return to their caller context
the return value of the exception callback, in the event that they throw
an exception. Thus, exceptions do not cross extension or tail call
boundary.
However, this is mostly an implementation choice, and can be changed to
suit more user-friendly semantics.
Changelog:
----------
v2 -> v3
v2: https://lore.kernel.org/bpf/20230809114116.3216687-1-memxor@gmail.com
* Add Dave's Acked-by.
* Address all comments from Alexei.
* Use bpf_is_subprog to check for main prog in bpf_stack_walker.
* Drop accidental leftover hunk in libbpf patch.
* Split libbpf patch's refactoring to aid review
* Disable fentry/fexit in addition to freplace for exception cb.
* Add selftests for fentry/fexit/freplace on exception cb and main prog.
* Use btf_find_by_name_kind in bpf_find_exception_callback_insn_off (Martin)
* Split KASAN patch into two to aid backporting (Andrey)
* Move exception callback append step to bpf_object__reloacte (Andrii)
* Ensure that the exception callback name is unique (Andrii)
* Keep ASM implementation of assertion macros instead of C, as it does
not achieve intended results for bpf_assert_range and other cases.
v1 -> v2
v1: https://lore.kernel.org/bpf/20230713023232.1411523-1-memxor@gmail.com
* Address all comments from Alexei.
* Fix a few bugs and corner cases in the implementations found during
testing. Also add new selftests for these cases.
* Reinstate patch to consider ksym.end part of the program (but
reworked to cover other corner cases).
* Implement new style of tagging exception callbacks, add libbpf
support for the new declaration tag.
* Limit support to 64-bit integer types for assertion macros. The
compiler ends up performing shifts or bitwise and operations when
finally making use of the value, which defeats the purpose of the
macro. On noalu32 mode, the shifts may also happen before use,
hurting reliability.
* Comprehensively test assertion macros and their side effects on the
verifier state, register bounds, etc.
* Fix a KASAN false positive warning.
RFC v1 -> v1
RFC v1: https://lore.kernel.org/bpf/20230405004239.1375399-1-memxor@gmail.com
* Completely rework the unwinding infrastructure to use offline
unwinding support.
* Remove the runtime exception state and program rewriting code.
* Make bpf_set_exception_callback idempotent to avoid vexing
synchronization and state clobbering issues in presence of program
nesting.
* Disable bpf_throw within callback functions, for now.
* Allow bpf_throw in tail call programs and extension programs,
removing limitations of rewrite based unwinding.
* Expand selftests.
====================
Link: https://lore.kernel.org/r/20230912233214.1518551-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add selftests to cover success and failure cases of API usage, runtime
behavior and invariants that need to be maintained for implementation
correctness.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-18-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add macros implementing an 'assert' statement primitive using macros,
built on top of the BPF exceptions support introduced in previous
patches.
The bpf_assert_*_with variants allow supplying a value which can the be
inspected within the exception handler to signify the assert statement
that led to the program being terminated abruptly, or be returned by the
default exception handler.
Note that only 64-bit scalar values are supported with these assertion
macros, as during testing I found other cases quite unreliable in
presence of compiler shifts/manipulations extracting the value of the
right width from registers scrubbing the verifier's bounds information
and knowledge about the value in the register.
Thus, it is easier to reliably support this feature with only the full
register width, and support both signed and unsigned variants.
The bpf_assert_range is interesting in particular, which clamps the
value in the [begin, end] (both inclusive) range within verifier state,
and emits a check for the same at runtime.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-17-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support to libbpf to append exception callbacks when loading a
program. The exception callback is found by discovering the declaration
tag 'exception_callback:<value>' and finding the callback in the value
of the tag.
The process is done in two steps. First, for each main program, the
bpf_object__sanitize_and_load_btf function finds and marks its
corresponding exception callback as defined by the declaration tag on
it. Second, bpf_object__reloc_code is modified to append the indicated
exception callback at the end of the instruction iteration (since
exception callback will never be appended in that loop, as it is not
directly referenced).
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-16-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor bpf_object__append_subprog_code out of bpf_object__reloc_code
to be able to reuse it to append subprog related code for the exception
callback to the main program.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-15-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kfunc code to handle KF_ARG_PTR_TO_CALLBACK does not check the reg
type before using reg->subprogno. This can accidently permit invalid
pointers from being passed into callback helpers (e.g. silently from
different paths). Likewise, reg->subprogno from the per-register type
union may not be meaningful either. We need to reject any other type
except PTR_TO_FUNC.
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Fixes: 5d92ddc3de ("bpf: Add callback validation to kfunc verifier logic")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-14-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
During testing, it was discovered that extensions to exception callbacks
had no checks, upon running a testcase, the kernel ended up running off
the end of a program having final call as bpf_throw, and hitting int3
instructions.
The reason is that while the default exception callback would have reset
the stack frame to return back to the main program's caller, the
replacing extension program will simply return back to bpf_throw, which
will instead return back to the program and the program will continue
execution, now in an undefined state where anything could happen.
The way to support extensions to an exception callback would be to mark
the BPF_PROG_TYPE_EXT main subprog as an exception_cb, and prevent it
from calling bpf_throw. This would make the JIT produce a prologue that
restores saved registers and reset the stack frame. But let's not do
that until there is a concrete use case for this, and simply disallow
this for now.
Similar issues will exist for fentry and fexit cases, where trampoline
saves data on the stack when invoking exception callback, which however
will then end up resetting the stack frame, and on return, the fexit
program will never will invoked as the return address points to the main
program's caller in the kernel. Instead of additional complexity and
back and forth between the two stacks to enable such a use case, simply
forbid it.
One key point here to note is that currently X86_TAIL_CALL_OFFSET didn't
require any modifications, even though we emit instructions before the
corresponding endbr64 instruction. This is because we ensure that a main
subprog never serves as an exception callback, and therefore the
exception callback (which will be a global subprog) can never serve as
the tail call target, eliminating any discrepancies. However, once we
support a BPF_PROG_TYPE_EXT to also act as an exception callback, it
will end up requiring change to the tail call offset to account for the
extra instructions. For simplicitly, tail calls could be disabled for
such targets.
Noting the above, it appears better to wait for a concrete use case
before choosing to permit extension programs to replace exception
callbacks.
As a precaution, we disable fentry and fexit for exception callbacks as
well.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-13-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that bpf_throw kfunc is the first such call instruction that has
noreturn semantics within the verifier, this also kicks in dead code
elimination in unprecedented ways. For one, any instruction following
a bpf_throw call will never be marked as seen. Moreover, if a callchain
ends up throwing, any instructions after the call instruction to the
eventually throwing subprog in callers will also never be marked as
seen.
The tempting way to fix this would be to emit extra 'int3' instructions
which bump the jited_len of a program, and ensure that during runtime
when a program throws, we can discover its boundaries even if the call
instruction to bpf_throw (or to subprogs that always throw) is emitted
as the final instruction in the program.
An example of such a program would be this:
do_something():
...
r0 = 0
exit
foo():
r1 = 0
call bpf_throw
r0 = 0
exit
bar(cond):
if r1 != 0 goto pc+2
call do_something
exit
call foo
r0 = 0 // Never seen by verifier
exit //
main(ctx):
r1 = ...
call bar
r0 = 0
exit
Here, if we do end up throwing, the stacktrace would be the following:
bpf_throw
foo
bar
main
In bar, the final instruction emitted will be the call to foo, as such,
the return address will be the subsequent instruction (which the JIT
emits as int3 on x86). This will end up lying outside the jited_len of
the program, thus, when unwinding, we will fail to discover the return
address as belonging to any program and end up in a panic due to the
unreliable stack unwinding of BPF programs that we never expect.
To remedy this case, make bpf_prog_ksym_find treat IP == ksym.end as
part of the BPF program, so that is_bpf_text_address returns true when
such a case occurs, and we are able to unwind reliably when the final
instruction ends up being a call instruction.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-12-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We require access to this kasan helper in BPF code in the next patch
where we have to unpoison the task stack when we unwind and reset the
stack frame from bpf_throw, and it never really unpoisons the poisoned
stack slots on entry when compiler instrumentation is generated by
CONFIG_KASAN_STACK and inline instrumentation is supported.
Also, remove the declaration from mm/kasan/kasan.h as we put it in the
header file kasan.h.
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-10-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In case of the default exception callback, change the behavior of
bpf_throw, where the passed cookie value is no longer ignored, but
is instead the return value of the default exception callback. As
such, we need to place restrictions on the value being passed into
bpf_throw in such a case, only allowing those permitted by the
check_return_code function.
Thus, bpf_throw can now control the return value of the program from
each call site without having the user install a custom exception
callback just to override the return value when an exception is thrown.
We also modify the hidden subprog instructions to now move BPF_REG_1 to
BPF_REG_0, so as to set the return value before exit in the default
callback.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-9-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since exception callbacks are not referenced using bpf_pseudo_func and
bpf_pseudo_call instructions, check_cfg traversal will never explore
instructions of the exception callback. Even after adding the subprog,
the program will then fail with a 'unreachable insn' error.
We thus need to begin walking from the start of the exception callback
again in check_cfg after a complete CFG traversal finishes, so as to
explore the CFG rooted at the exception callback.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
By default, the subprog generated by the verifier to handle a thrown
exception hardcodes a return value of 0. To allow user-defined logic
and modification of the return value when an exception is thrown,
introduce the 'exception_callback:' declaration tag, which marks a
callback as the default exception handler for the program.
The format of the declaration tag is 'exception_callback:<value>', where
<value> is the name of the exception callback. Each main program can be
tagged using this BTF declaratiion tag to associate it with an exception
callback. In case the tag is absent, the default callback is used.
As such, the exception callback cannot be modified at runtime, only set
during verification.
Allowing modification of the callback for the current program execution
at runtime leads to issues when the programs begin to nest, as any
per-CPU state maintaing this information will have to be saved and
restored. We don't want it to stay in bpf_prog_aux as this takes a
global effect for all programs. An alternative solution is spilling
the callback pointer at a known location on the program stack on entry,
and then passing this location to bpf_throw as a parameter.
However, since exceptions are geared more towards a use case where they
are ideally never invoked, optimizing for this use case and adding to
the complexity has diminishing returns.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch splits the check_btf_info's check_btf_func check into two
separate phases. The first phase sets up the BTF and prepares
func_info, but does not perform any validation of required invariants
for subprogs just yet. This is left to the second phase, which happens
where check_btf_info executes currently, and performs the line_info and
CO-RE relocation.
The reason to perform this split is to obtain the userspace supplied
func_info information before we perform the add_subprog call, where we
would now require finding and adding subprogs that may not have a
bpf_pseudo_call or bpf_pseudo_func instruction in the program.
We require this as we want to enable userspace to supply exception
callbacks that can override the default hidden subprogram generated by
the verifier (which performs a hardcoded action). In such a case, the
exception callback may never be referenced in an instruction, but will
still be suitably annotated (by way of BTF declaration tags). For
finding this exception callback, we would require the program's BTF
information, and the supplied func_info information which maps BTF type
IDs to subprograms.
Since the exception callback won't actually be referenced through
instructions, later checks in check_cfg and do_check_subprogs will not
verify the subprog. This means that add_subprog needs to add them in the
add_subprog_and_kfunc phase before we move forward, which is why the BTF
and func_info are required at that point.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch implements BPF exceptions, and introduces a bpf_throw kfunc
to allow programs to throw exceptions during their execution at runtime.
A bpf_throw invocation is treated as an immediate termination of the
program, returning back to its caller within the kernel, unwinding all
stack frames.
This allows the program to simplify its implementation, by testing for
runtime conditions which the verifier has no visibility into, and assert
that they are true. In case they are not, the program can simply throw
an exception from the other branch.
BPF exceptions are explicitly *NOT* an unlikely slowpath error handling
primitive, and this objective has guided design choices of the
implementation of the them within the kernel (with the bulk of the cost
for unwinding the stack offloaded to the bpf_throw kfunc).
The implementation of this mechanism requires use of add_hidden_subprog
mechanism introduced in the previous patch, which generates a couple of
instructions to move R1 to R0 and exit. The JIT then rewrites the
prologue of this subprog to take the stack pointer and frame pointer as
inputs and reset the stack frame, popping all callee-saved registers
saved by the main subprog. The bpf_throw function then walks the stack
at runtime, and invokes this exception subprog with the stack and frame
pointers as parameters.
Reviewers must take note that currently the main program is made to save
all callee-saved registers on x86_64 during entry into the program. This
is because we must do an equivalent of a lightweight context switch when
unwinding the stack, therefore we need the callee-saved registers of the
caller of the BPF program to be able to return with a sane state.
Note that we have to additionally handle r12, even though it is not used
by the program, because when throwing the exception the program makes an
entry into the kernel which could clobber r12 after saving it on the
stack. To be able to preserve the value we received on program entry, we
push r12 and restore it from the generated subprogram when unwinding the
stack.
For now, bpf_throw invocation fails when lingering resources or locks
exist in that path of the program. In a future followup, bpf_throw will
be extended to perform frame-by-frame unwinding to release lingering
resources for each stack frame, removing this limitation.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce support in the verifier for generating a subprogram and
include it as part of a BPF program dynamically after the do_check phase
is complete. The first user will be the next patch which generates
default exception callbacks if none are set for the program. The phase
of invocation will be do_misc_fixups. Note that this is an internal
verifier function, and should be used with instruction blocks which
uphold the invariants stated in check_subprogs.
Since these subprogs are always appended to the end of the instruction
sequence of the program, it becomes relatively inexpensive to do the
related adjustments to the subprog_info of the program. Only the fake
exit subprogram is shifted forward, making room for our new subprog.
This is useful to insert a new subprogram, get it JITed, and obtain its
function pointer. The next patch will use this functionality to insert a
default exception callback which will be invoked after unwinding the
stack.
Note that these added subprograms are invisible to userspace, and never
reported in BPF_OBJ_GET_INFO_BY_ID etc. For now, only a single
subprogram is supported, but more can be easily supported in the future.
To this end, two function counts are introduced now, the existing
func_cnt, and real_func_cnt, the latter including hidden programs. This
allows us to conver the JIT code to use the real_func_cnt for management
of resources while syscall path continues working with existing
func_cnt.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The plumbing for offline unwinding when we throw an exception in
programs would require walking the stack, hence introduce a new
arch_bpf_stack_walk function. This is provided when the JIT supports
exceptions, i.e. bpf_jit_supports_exceptions is true. The arch-specific
code is really minimal, hence it should be straightforward to extend
this support to other architectures as well, as it reuses the logic of
arch_stack_walk, but allowing access to unwind_state data.
Once the stack pointer and frame pointer are known for the main subprog
during the unwinding, we know the stack layout and location of any
callee-saved registers which must be restored before we return back to
the kernel. This handling will be added in the subsequent patches.
Note that while we primarily unwind through BPF frames, which are
effectively CONFIG_UNWINDER_FRAME_POINTER, we still need one of this or
CONFIG_UNWINDER_ORC to be able to unwind through the bpf_throw frame
from which we begin walking the stack. We also require both sp and bp
(stack and frame pointers) from the unwind_state structure, which are
only available when one of these two options are enabled.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We would like to know whether a bpf_prog corresponds to the main prog or
one of the subprogs. The current JIT implementations simply check this
using the func_idx in bpf_prog->aux->func_idx. When the index is 0, it
belongs to the main program, otherwise it corresponds to some
subprogram.
This will also be necessary to halt exception propagation while walking
the stack when an exception is thrown, so we add a simple helper
function to check this, named bpf_is_subprog, and convert existing JIT
implementations to also make use of it.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Aananth V says:
====================
tcp: new TCP_INFO stats for RTO events
The 2023 SIGCOMM paper "Improving Network Availability with Protective
ReRoute" has indicated Linux TCP's RTO-triggered txhash rehashing can
effectively reduce application disruption during outages. To better
measure the efficacy of this feature, this patch set adds three more
detailed stats during RTO recovery and exports via TCP_INFO.
Applications and monitoring systems can leverage this data to measure
the network path diversity and end-to-end repair latency during network
outages to improve their network infrastructure.
Patch 1 fixes a bug in TFO SYNACK that we encountered while testing
these new metrics.
Patch 2 adds the new metrics to tcp_sock and tcp_info.
v2: Addressed feedback from a check bot in patch 2 by removing the
inline keyword from the tcp_update_rto_time and tcp_update_rto_stats
functions. Changed a comment in include/net/tcp.h to fit under 80 words.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The 2023 SIGCOMM paper "Improving Network Availability with Protective
ReRoute" has indicated Linux TCP's RTO-triggered txhash rehashing can
effectively reduce application disruption during outages. To better
measure the efficacy of this feature, this patch adds three more
detailed stats during RTO recovery and exports via TCP_INFO.
Applications and monitoring systems can leverage this data to measure
the network path diversity and end-to-end repair latency during network
outages to improve their network infrastructure.
The following counters are added to tcp_sock in order to track RTO
events over the lifetime of a TCP socket.
1. u16 total_rto - Counts the total number of RTO timeouts.
2. u16 total_rto_recoveries - Counts the total number of RTO recoveries.
3. u32 total_rto_time - Counts the total time spent (ms) in RTO
recoveries. (time spent in CA_Loss and
CA_Recovery states)
To compute total_rto_time, we add a new u32 rto_stamp field to
tcp_sock. rto_stamp records the start timestamp (ms) of the last RTO
recovery (CA_Loss).
Corresponding fields are also added to the tcp_info struct.
Signed-off-by: Aananth V <aananthv@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
For passive TCP Fast Open sockets that had SYN/ACK timeout and did not
send more data in SYN_RECV, upon receiving the final ACK in 3WHS, the
congestion state may awkwardly stay in CA_Loss mode unless the CA state
was undone due to TCP timestamp checks. However, if
tcp_rcv_synrecv_state_fastopen() decides not to undo, then we should
enter CA_Open, because at that point we have received an ACK covering
the retransmitted SYNACKs. Currently, the icsk_ca_state is only set to
CA_Open after we receive an ACK for a data-packet. This is because
tcp_ack does not call tcp_fastretrans_alert (and tcp_process_loss) if
!prior_packets
Note that tcp_process_loss() calls tcp_try_undo_recovery(), so having
tcp_rcv_synrecv_state_fastopen() decide that if we're in CA_Loss we
should call tcp_try_undo_recovery() is consistent with that, and
low risk.
Fixes: dad8cea7ad ("tcp: fix TFO SYNACK undo to avoid double-timestamp-undo")
Signed-off-by: Aananth V <aananthv@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
