linux-stable.git/include/linux/bpf.h, branch v6.8.4 Linux kernel stable tree bpf: Relax tracing prog recursive attach rules 2024-01-05T04:31:34+00:00 Dmitrii Dolgov 9erthalion6@gmail.com 2024-01-03T19:05:44+00:00 19bfcdf9498aa968ea293417fbbc39e523527ca8 Currently, it's not allowed to attach an fentry/fexit prog to another one fentry/fexit. At the same time it's not uncommon to see a tracing program with lots of logic in use, and the attachment limitation prevents usage of fentry/fexit for performance analysis (e.g. with "bpftool prog profile" command) in this case. An example could be falcosecurity libs project that uses tp_btf tracing programs. Following the corresponding discussion [1], the reason for that is to avoid tracing progs call cycles without introducing more complex solutions. But currently it seems impossible to load and attach tracing programs in a way that will form such a cycle. The limitation is coming from the fact that attach_prog_fd is specified at the prog load (thus making it impossible to attach to a program loaded after it in this way), as well as tracing progs not implementing link_detach. Replace "no same type" requirement with verification that no more than one level of attachment nesting is allowed. In this way only one fentry/fexit program could be attached to another fentry/fexit to cover profiling use case, and still no cycle could be formed. To implement, add a new field into bpf_prog_aux to track nested attachment for tracing programs. [1]: https://lore.kernel.org/bpf/20191108064039.2041889-16-ast@kernel.org/ Acked-by: Jiri Olsa <olsajiri@gmail.com> Acked-by: Song Liu <song@kernel.org> Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> Link: https://lore.kernel.org/r/20240103190559.14750-2-9erthalion6@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Currently, it's not allowed to attach an fentry/fexit prog to another
one fentry/fexit. At the same time it's not uncommon to see a tracing
program with lots of logic in use, and the attachment limitation
prevents usage of fentry/fexit for performance analysis (e.g. with
"bpftool prog profile" command) in this case. An example could be
falcosecurity libs project that uses tp_btf tracing programs.

Following the corresponding discussion [1], the reason for that is to
avoid tracing progs call cycles without introducing more complex
solutions. But currently it seems impossible to load and attach tracing
programs in a way that will form such a cycle. The limitation is coming
from the fact that attach_prog_fd is specified at the prog load (thus
making it impossible to attach to a program loaded after it in this
way), as well as tracing progs not implementing link_detach.

Replace "no same type" requirement with verification that no more than
one level of attachment nesting is allowed. In this way only one
fentry/fexit program could be attached to another fentry/fexit to cover
profiling use case, and still no cycle could be formed. To implement,
add a new field into bpf_prog_aux to track nested attachment for tracing
programs.

[1]: https://lore.kernel.org/bpf/20191108064039.2041889-16-ast@kernel.org/

Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-2-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: move subprog call logic back to verifier.c 2023-12-20T02:06:46+00:00 Andrii Nakryiko andrii@kernel.org 2023-12-15T01:13:28+00:00 c5a7244759b1eeacc59d0426fb73859afa942d0d Subprog call logic in btf_check_subprog_call() currently has both a lot of BTF parsing logic (which is, presumably, what justified putting it into btf.c), but also a bunch of register state checks, some of each utilize deep verifier logic helpers, necessarily exported from verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(), and check_mem_reg(). Going forward, btf_check_subprog_call() will have a minimum of BTF-related logic, but will get more internal verifier logic related to register state manipulation. So move it into verifier.c to minimize amount of verifier-specific logic exposed to btf.c. We do this move before refactoring btf_check_func_arg_match() to preserve as much history post-refactoring as possible. No functional changes. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Subprog call logic in btf_check_subprog_call() currently has both a lot
of BTF parsing logic (which is, presumably, what justified putting it
into btf.c), but also a bunch of register state checks, some of each
utilize deep verifier logic helpers, necessarily exported from
verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(),
and check_mem_reg().

Going forward, btf_check_subprog_call() will have a minimum of
BTF-related logic, but will get more internal verifier logic related to
register state manipulation. So move it into verifier.c to minimize
amount of verifier-specific logic exposed to btf.c.

We do this move before refactoring btf_check_func_arg_match() to
preserve as much history post-refactoring as possible.

No functional changes.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: reuse btf_prepare_func_args() check for main program BTF validation 2023-12-20T02:06:46+00:00 Andrii Nakryiko andrii@kernel.org 2023-12-15T01:13:26+00:00 5eccd2db42d77e3570619c32d39e39bf486607cf Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args() logic to validate "trustworthiness" of main BPF program's BTF information, if it is present. We ignored results of original BTF check anyway, often times producing confusing and ominously-sounding "reg type unsupported for arg#0 function" message, which has no apparent effect on program correctness and verification process. All the -EFAULT returning sanity checks are already performed in check_btf_info_early(), so there is zero reason to have this duplication of logic between btf_check_subprog_call() and btf_check_subprog_arg_match(). Dropping btf_check_subprog_arg_match() simplifies btf_check_func_arg_match() further removing `bool processing_call` flag. One subtle bit that was done by btf_check_subprog_arg_match() was potentially marking main program's BTF as unreliable. We do this explicitly now with a dedicated simple check, preserving the original behavior, but now based on well factored btf_prepare_func_args() logic. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args()
logic to validate "trustworthiness" of main BPF program's BTF information,
if it is present.

We ignored results of original BTF check anyway, often times producing
confusing and ominously-sounding "reg type unsupported for arg#0
function" message, which has no apparent effect on program correctness
and verification process.

All the -EFAULT returning sanity checks are already performed in
check_btf_info_early(), so there is zero reason to have this duplication
of logic between btf_check_subprog_call() and btf_check_subprog_arg_match().
Dropping btf_check_subprog_arg_match() simplifies
btf_check_func_arg_match() further removing `bool processing_call` flag.

One subtle bit that was done by btf_check_subprog_arg_match() was
potentially marking main program's BTF as unreliable. We do this
explicitly now with a dedicated simple check, preserving the original
behavior, but now based on well factored btf_prepare_func_args() logic.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: abstract away global subprog arg preparation logic from reg state setup 2023-12-20T02:06:46+00:00 Andrii Nakryiko andrii@kernel.org 2023-12-15T01:13:25+00:00 4ba1d0f23414135e4f426dae4cb5cdc2ce246f89 btf_prepare_func_args() is used to understand expectations and restrictions on global subprog arguments. But current implementation is hard to extend, as it intermixes BTF-based func prototype parsing and interpretation logic with setting up register state at subprog entry. Worse still, those registers are not completely set up inside btf_prepare_func_args(), requiring some more logic later in do_check_common(). Like calling mark_reg_unknown() and similar initialization operations. This intermixing of BTF interpretation and register state setup is problematic. First, it causes duplication of BTF parsing logic for global subprog verification (to set up initial state of global subprog) and global subprog call sites analysis (when we need to check that whatever is being passed into global subprog matches expectations), performed in btf_check_subprog_call(). Given we want to extend global func argument with tags later, this duplication is problematic. So refactor btf_prepare_func_args() to do only BTF-based func proto and args parsing, returning high-level argument "expectations" only, with no regard to specifics of register state. I.e., if it's a context argument, instead of setting register state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as "an argument specification" for further processing inside do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc. This allows to reuse btf_prepare_func_args() in following patches at global subprog call site analysis time. It also keeps register setup code consistently in one place, do_check_common(). Besides all this, we cache this argument specs information inside env->subprog_info, eliminating the need to redo these potentially expensive BTF traversals, especially if BPF program's BTF is big and/or there are lots of global subprog calls. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
btf_prepare_func_args() is used to understand expectations and
restrictions on global subprog arguments. But current implementation is
hard to extend, as it intermixes BTF-based func prototype parsing and
interpretation logic with setting up register state at subprog entry.

Worse still, those registers are not completely set up inside
btf_prepare_func_args(), requiring some more logic later in
do_check_common(). Like calling mark_reg_unknown() and similar
initialization operations.

This intermixing of BTF interpretation and register state setup is
problematic. First, it causes duplication of BTF parsing logic for global
subprog verification (to set up initial state of global subprog) and
global subprog call sites analysis (when we need to check that whatever
is being passed into global subprog matches expectations), performed in
btf_check_subprog_call().

Given we want to extend global func argument with tags later, this
duplication is problematic. So refactor btf_prepare_func_args() to do
only BTF-based func proto and args parsing, returning high-level
argument "expectations" only, with no regard to specifics of register
state. I.e., if it's a context argument, instead of setting register
state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as
"an argument specification" for further processing inside
do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc.

This allows to reuse btf_prepare_func_args() in following patches at
global subprog call site analysis time. It also keeps register setup
code consistently in one place, do_check_common().

Besides all this, we cache this argument specs information inside
env->subprog_info, eliminating the need to redo these potentially
expensive BTF traversals, especially if BPF program's BTF is big and/or
there are lots of global subprog calls.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Revert BPF token-related functionality 2023-12-19T16:23:03+00:00 Andrii Nakryiko andrii@kernel.org 2023-12-19T15:37:35+00:00 d17aff807f845cf93926c28705216639c7279110 This patch includes the following revert (one conflicting BPF FS patch and three token patch sets, represented by merge commits): - revert 0f5d5454c723 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'"; - revert 750e785796bb "bpf: Support uid and gid when mounting bpffs"; - revert 733763285acf "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'"; - revert c35919dcce28 "Merge branch 'bpf-token-and-bpf-fs-based-delegation'". Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org> 
This patch includes the following revert (one  conflicting BPF FS
patch and three token patch sets, represented by merge commits):
  - revert 0f5d5454c723 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'";
  - revert 750e785796bb "bpf: Support uid and gid when mounting bpffs";
  - revert 733763285acf "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'";
  - revert c35919dcce28 "Merge branch 'bpf-token-and-bpf-fs-based-delegation'".

Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2023-12-19T00:46:08+00:00 Jakub Kicinski kuba@kernel.org 2023-12-19T00:46:07+00:00 c49b292d031e385abf764ded32cd953c77e73f2d Alexei Starovoitov says: ==================== pull-request: bpf-next 2023-12-18 This PR is larger than usual and contains changes in various parts of the kernel. The main changes are: 1) Fix kCFI bugs in BPF, from Peter Zijlstra. End result: all forms of indirect calls from BPF into kernel and from kernel into BPF work with CFI enabled. This allows BPF to work with CONFIG_FINEIBT=y. 2) Introduce BPF token object, from Andrii Nakryiko. It adds an ability to delegate a subset of BPF features from privileged daemon (e.g., systemd) through special mount options for userns-bound BPF FS to a trusted unprivileged application. The design accommodates suggestions from Christian Brauner and Paul Moore. Example: $ sudo mkdir -p /sys/fs/bpf/token $ sudo mount -t bpf bpffs /sys/fs/bpf/token \ -o delegate_cmds=prog_load:MAP_CREATE \ -o delegate_progs=kprobe \ -o delegate_attachs=xdp 3) Various verifier improvements and fixes, from Andrii Nakryiko, Andrei Matei. - Complete precision tracking support for register spills - Fix verification of possibly-zero-sized stack accesses - Fix access to uninit stack slots - Track aligned STACK_ZERO cases as imprecise spilled registers. It improves the verifier "instructions processed" metric from single digit to 50-60% for some programs. - Fix verifier retval logic 4) Support for VLAN tag in XDP hints, from Larysa Zaremba. 5) Allocate BPF trampoline via bpf_prog_pack mechanism, from Song Liu. End result: better memory utilization and lower I$ miss for calls to BPF via BPF trampoline. 6) Fix race between BPF prog accessing inner map and parallel delete, from Hou Tao. 7) Add bpf_xdp_get_xfrm_state() kfunc, from Daniel Xu. It allows BPF interact with IPSEC infra. The intent is to support software RSS (via XDP) for the upcoming ipsec pcpu work. Experiments on AWS demonstrate single tunnel pcpu ipsec reaching line rate on 100G ENA nics. 8) Expand bpf_cgrp_storage to support cgroup1 non-attach, from Yafang Shao. 9) BPF file verification via fsverity, from Song Liu. It allows BPF progs get fsverity digest. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (164 commits) bpf: Ensure precise is reset to false in __mark_reg_const_zero() selftests/bpf: Add more uprobe multi fail tests bpf: Fail uprobe multi link with negative offset selftests/bpf: Test the release of map btf s390/bpf: Fix indirect trampoline generation selftests/bpf: Temporarily disable dummy_struct_ops test on s390 x86/cfi,bpf: Fix bpf_exception_cb() signature bpf: Fix dtor CFI cfi: Add CFI_NOSEAL() x86/cfi,bpf: Fix bpf_struct_ops CFI x86/cfi,bpf: Fix bpf_callback_t CFI x86/cfi,bpf: Fix BPF JIT call cfi: Flip headers selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test selftests/bpf: Add test for abnormal cnt during multi-uprobe attachment bpf: Limit the number of kprobes when attaching program to multiple kprobes bpf: Limit the number of uprobes when attaching program to multiple uprobes bpf: xdp: Register generic_kfunc_set with XDP programs selftests/bpf: utilize string values for delegate_xxx mount options ... ==================== Link: https://lore.kernel.org/r/20231219000520.34178-1-alexei.starovoitov@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Alexei Starovoitov says:

====================
pull-request: bpf-next 2023-12-18

This PR is larger than usual and contains changes in various parts
of the kernel.

The main changes are:

1) Fix kCFI bugs in BPF, from Peter Zijlstra.

End result: all forms of indirect calls from BPF into kernel
and from kernel into BPF work with CFI enabled. This allows BPF
to work with CONFIG_FINEIBT=y.

2) Introduce BPF token object, from Andrii Nakryiko.

It adds an ability to delegate a subset of BPF features from privileged
daemon (e.g., systemd) through special mount options for userns-bound
BPF FS to a trusted unprivileged application. The design accommodates
suggestions from Christian Brauner and Paul Moore.

Example:
$ sudo mkdir -p /sys/fs/bpf/token
$ sudo mount -t bpf bpffs /sys/fs/bpf/token \
             -o delegate_cmds=prog_load:MAP_CREATE \
             -o delegate_progs=kprobe \
             -o delegate_attachs=xdp

3) Various verifier improvements and fixes, from Andrii Nakryiko, Andrei Matei.

 - Complete precision tracking support for register spills
 - Fix verification of possibly-zero-sized stack accesses
 - Fix access to uninit stack slots
 - Track aligned STACK_ZERO cases as imprecise spilled registers.
   It improves the verifier "instructions processed" metric from single
   digit to 50-60% for some programs.
 - Fix verifier retval logic

4) Support for VLAN tag in XDP hints, from Larysa Zaremba.

5) Allocate BPF trampoline via bpf_prog_pack mechanism, from Song Liu.

End result: better memory utilization and lower I$ miss for calls to BPF
via BPF trampoline.

6) Fix race between BPF prog accessing inner map and parallel delete,
from Hou Tao.

7) Add bpf_xdp_get_xfrm_state() kfunc, from Daniel Xu.

It allows BPF interact with IPSEC infra. The intent is to support
software RSS (via XDP) for the upcoming ipsec pcpu work.
Experiments on AWS demonstrate single tunnel pcpu ipsec reaching
line rate on 100G ENA nics.

8) Expand bpf_cgrp_storage to support cgroup1 non-attach, from Yafang Shao.

9) BPF file verification via fsverity, from Song Liu.

It allows BPF progs get fsverity digest.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (164 commits)
  bpf: Ensure precise is reset to false in __mark_reg_const_zero()
  selftests/bpf: Add more uprobe multi fail tests
  bpf: Fail uprobe multi link with negative offset
  selftests/bpf: Test the release of map btf
  s390/bpf: Fix indirect trampoline generation
  selftests/bpf: Temporarily disable dummy_struct_ops test on s390
  x86/cfi,bpf: Fix bpf_exception_cb() signature
  bpf: Fix dtor CFI
  cfi: Add CFI_NOSEAL()
  x86/cfi,bpf: Fix bpf_struct_ops CFI
  x86/cfi,bpf: Fix bpf_callback_t CFI
  x86/cfi,bpf: Fix BPF JIT call
  cfi: Flip headers
  selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment
  selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test
  selftests/bpf: Add test for abnormal cnt during multi-uprobe attachment
  bpf: Limit the number of kprobes when attaching program to multiple kprobes
  bpf: Limit the number of uprobes when attaching program to multiple uprobes
  bpf: xdp: Register generic_kfunc_set with XDP programs
  selftests/bpf: utilize string values for delegate_xxx mount options
  ...
====================

Link: https://lore.kernel.org/r/20231219000520.34178-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
x86/cfi,bpf: Fix bpf_exception_cb() signature 2023-12-16T00:25:55+00:00 Alexei Starovoitov alexei.starovoitov@gmail.com 2023-12-15T09:12:23+00:00 852486b35f344887786d63250946dd921a05d7e8 As per the earlier patches, BPF sub-programs have bpf_callback_t signature and CFI expects callers to have matching signature. This is violated by bpf_prog_aux::bpf_exception_cb(). [peterz: Changelog] Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=R-dExk-uHtfOLtoLxQ1XxEpqEA@mail.gmail.com Link: https://lore.kernel.org/r/20231215092707.910319166@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
As per the earlier patches, BPF sub-programs have bpf_callback_t
signature and CFI expects callers to have matching signature. This is
violated by bpf_prog_aux::bpf_exception_cb().

[peterz: Changelog]
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=R-dExk-uHtfOLtoLxQ1XxEpqEA@mail.gmail.com
Link: https://lore.kernel.org/r/20231215092707.910319166@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
x86/cfi,bpf: Fix bpf_struct_ops CFI 2023-12-16T00:25:55+00:00 Peter Zijlstra peterz@infradead.org 2023-12-15T09:12:20+00:00 2cd3e3772e41377f32d6eea643e0590774e9187c BPF struct_ops uses __arch_prepare_bpf_trampoline() to write trampolines for indirect function calls. These tramplines much have matching CFI. In order to obtain the correct CFI hash for the various methods, add a matching structure that contains stub functions, the compiler will generate correct CFI which we can pilfer for the trampolines. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
BPF struct_ops uses __arch_prepare_bpf_trampoline() to write
trampolines for indirect function calls. These tramplines much have
matching CFI.

In order to obtain the correct CFI hash for the various methods, add a
matching structure that contains stub functions, the compiler will
generate correct CFI which we can pilfer for the trampolines.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
x86/cfi,bpf: Fix BPF JIT call 2023-12-16T00:25:55+00:00 Peter Zijlstra peterz@infradead.org 2023-12-15T09:12:18+00:00 4f9087f16651aca4a5f32da840a53f6660f0579a The current BPF call convention is __nocfi, except when it calls !JIT things, then it calls regular C functions. It so happens that with FineIBT the __nocfi and C calling conventions are incompatible. Specifically __nocfi will call at func+0, while FineIBT will have endbr-poison there, which is not a valid indirect target. Causing #CP. Notably this only triggers on IBT enabled hardware, which is probably why this hasn't been reported (also, most people will have JIT on anyway). Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for x86. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
The current BPF call convention is __nocfi, except when it calls !JIT things,
then it calls regular C functions.

It so happens that with FineIBT the __nocfi and C calling conventions are
incompatible. Specifically __nocfi will call at func+0, while FineIBT will have
endbr-poison there, which is not a valid indirect target. Causing #CP.

Notably this only triggers on IBT enabled hardware, which is probably why this
hasn't been reported (also, most people will have JIT on anyway).

Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for
x86.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Support uid and gid when mounting bpffs 2023-12-13T23:37:42+00:00 Jie Jiang jiejiang@chromium.org 2023-12-12T09:39:23+00:00 750e785796bb72423b97cac21ecd0fa3b3b65610 Parse uid and gid in bpf_parse_param() so that they can be passed in as the `data` parameter when mount() bpffs. This will be useful when we want to control which user/group has the control to the mounted bpffs, otherwise a separate chown() call will be needed. Signed-off-by: Jie Jiang <jiejiang@chromium.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Mike Frysinger <vapier@chromium.org> Acked-by: Christian Brauner <brauner@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231212093923.497838-1-jiejiang@chromium.org 
Parse uid and gid in bpf_parse_param() so that they can be passed in as
the `data` parameter when mount() bpffs. This will be useful when we
want to control which user/group has the control to the mounted bpffs,
otherwise a separate chown() call will be needed.

Signed-off-by: Jie Jiang <jiejiang@chromium.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Mike Frysinger <vapier@chromium.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231212093923.497838-1-jiejiang@chromium.org