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Instead of duplicating the same code for each architecture, move
the CFI type hash variables for BPF function types and related
helper functions to generic CFI code, and allow architectures to
override the function definitions if needed.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20250801001004.1859976-7-samitolvanen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The riscv BPF JIT doesn't emit proper kCFI prologues for BPF programs
and struct_ops trampolines when CONFIG_CFI_CLANG is enabled.
This causes CFI failures when calling BPF programs and can even crash
the kernel due to invalid memory accesses.
Example crash:
root@rv-selftester:~/bpf# ./test_progs -a dummy_st_ops
Unable to handle kernel paging request at virtual address ffffffff78204ffc
Oops [#1]
Modules linked in: bpf_testmod(OE) [....]
CPU: 3 PID: 356 Comm: test_progs Tainted: P OE 6.8.0-rc1 #1
Hardware name: riscv-virtio,qemu (DT)
epc : bpf_struct_ops_test_run+0x28c/0x5fc
ra : bpf_struct_ops_test_run+0x26c/0x5fc
epc : ffffffff82958010 ra : ffffffff82957ff0 sp : ff200000007abc80
gp : ffffffff868d6218 tp : ff6000008d87b840 t0 : 000000000000000f
t1 : 0000000000000000 t2 : 000000002005793e s0 : ff200000007abcf0
s1 : ff6000008a90fee0 a0 : 0000000000000000 a1 : 0000000000000000
a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000
a5 : ffffffff868dba26 a6 : 0000000000000001 a7 : 0000000052464e43
s2 : 00007ffffc0a95f0 s3 : ff6000008a90fe80 s4 : ff60000084c24c00
s5 : ffffffff78205000 s6 : ff60000088750648 s7 : ff20000000035008
s8 : fffffffffffffff4 s9 : ffffffff86200610 s10: 0000000000000000
s11: 0000000000000000 t3 : ffffffff8483dc30 t4 : ffffffff8483dc10
t5 : ffffffff8483dbf0 t6 : ffffffff8483dbd0
status: 0000000200000120 badaddr: ffffffff78204ffc cause: 000000000000000d
[<ffffffff82958010>] bpf_struct_ops_test_run+0x28c/0x5fc
[<ffffffff805083ee>] bpf_prog_test_run+0x170/0x548
[<ffffffff805029c8>] __sys_bpf+0x2d2/0x378
[<ffffffff804ff570>] __riscv_sys_bpf+0x5c/0x120
[<ffffffff8000e8fe>] syscall_handler+0x62/0xe4
[<ffffffff83362df6>] do_trap_ecall_u+0xc6/0x27c
[<ffffffff833822c4>] ret_from_exception+0x0/0x64
Code: b603 0109 b683 0189 b703 0209 8493 0609 157d 8d65 (a303) ffca
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Fatal exception
SMP: stopping secondary CPUs
Implement proper kCFI prologues for the BPF programs and callbacks and
drop __nocfi for riscv64. Fix the trampoline generation code to emit kCFI
prologue when a struct_ops trampoline is being prepared.
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20240303170207.82201-2-puranjay12@gmail.com
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Normal include order is that linux/foo.h should include asm/foo.h, CFI has it
the wrong way around.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20231215092707.231038174@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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With CONFIG_CFI_CLANG, the compiler injects a type preamble immediately
before each function and a check to validate the target function type
before indirect calls:
; type preamble
.word <id>
function:
...
; indirect call check
lw t1, -4(a0)
lui t2, <hi20>
addiw t2, t2, <lo12>
beq t1, t2, .Ltmp0
ebreak
.Ltmp0:
jarl a0
Implement error handling code for the ebreak traps emitted for the
checks. This produces the following oops on a CFI failure (generated
using lkdtm):
[ 21.177245] CFI failure at lkdtm_indirect_call+0x22/0x32 [lkdtm]
(target: lkdtm_increment_int+0x0/0x18 [lkdtm]; expected type: 0x3ad55aca)
[ 21.178483] Kernel BUG [#1]
[ 21.178671] Modules linked in: lkdtm
[ 21.179037] CPU: 1 PID: 104 Comm: sh Not tainted
6.3.0-rc6-00037-g37d5ec6297ab #1
[ 21.179511] Hardware name: riscv-virtio,qemu (DT)
[ 21.179818] epc : lkdtm_indirect_call+0x22/0x32 [lkdtm]
[ 21.180106] ra : lkdtm_CFI_FORWARD_PROTO+0x48/0x7c [lkdtm]
[ 21.180426] epc : ffffffff01387092 ra : ffffffff01386f14 sp : ff20000000453cf0
[ 21.180792] gp : ffffffff81308c38 tp : ff6000000243f080 t0 : ff20000000453b78
[ 21.181157] t1 : 000000003ad55aca t2 : 000000007e0c52a5 s0 : ff20000000453d00
[ 21.181506] s1 : 0000000000000001 a0 : ffffffff0138d170 a1 : ffffffff013870bc
[ 21.181819] a2 : b5fea48dd89aa700 a3 : 0000000000000001 a4 : 0000000000000fff
[ 21.182169] a5 : 0000000000000004 a6 : 00000000000000b7 a7 : 0000000000000000
[ 21.182591] s2 : ff20000000453e78 s3 : ffffffffffffffea s4 : 0000000000000012
[ 21.183001] s5 : ff600000023c7000 s6 : 0000000000000006 s7 : ffffffff013882a0
[ 21.183653] s8 : 0000000000000008 s9 : 0000000000000002 s10: ffffffff0138d878
[ 21.184245] s11: ffffffff0138d878 t3 : 0000000000000003 t4 : 0000000000000000
[ 21.184591] t5 : ffffffff8133df08 t6 : ffffffff8133df07
[ 21.184858] status: 0000000000000120 badaddr: 0000000000000000
cause: 0000000000000003
[ 21.185415] [<ffffffff01387092>] lkdtm_indirect_call+0x22/0x32 [lkdtm]
[ 21.185772] [<ffffffff01386f14>] lkdtm_CFI_FORWARD_PROTO+0x48/0x7c [lkdtm]
[ 21.186093] [<ffffffff01383552>] lkdtm_do_action+0x22/0x34 [lkdtm]
[ 21.186445] [<ffffffff0138350c>] direct_entry+0x128/0x13a [lkdtm]
[ 21.186817] [<ffffffff8033ed8c>] full_proxy_write+0x58/0xb2
[ 21.187352] [<ffffffff801d4fe8>] vfs_write+0x14c/0x33a
[ 21.187644] [<ffffffff801d5328>] ksys_write+0x64/0xd4
[ 21.187832] [<ffffffff801d53a6>] sys_write+0xe/0x1a
[ 21.188171] [<ffffffff80003996>] ret_from_syscall+0x0/0x2
[ 21.188595] Code: 0513 0f65 a303 ffc5 53b7 7e0c 839b 2a53 0363 0073 (9002) 9582
[ 21.189178] ---[ end trace 0000000000000000 ]---
[ 21.189590] Kernel panic - not syncing: Fatal exception
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com> # ISA bits
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20230710183544.999540-12-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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