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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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.. | ||
compat_vdso | ||
pi | ||
probes | ||
vdso | ||
.gitignore | ||
acpi.c | ||
alternative.c | ||
asm-offsets.c | ||
cacheinfo.c | ||
cfi.c | ||
compat_signal.c | ||
compat_syscall_table.c | ||
cpu-hotplug.c | ||
cpu.c | ||
cpu_ops.c | ||
cpu_ops_sbi.c | ||
cpu_ops_spinwait.c | ||
cpufeature.c | ||
crash_core.c | ||
crash_dump.c | ||
crash_save_regs.S | ||
efi-header.S | ||
efi.c | ||
elf_kexec.c | ||
entry.S | ||
fpu.S | ||
ftrace.c | ||
head.h | ||
head.S | ||
hibernate-asm.S | ||
hibernate.c | ||
image-vars.h | ||
irq.c | ||
jump_label.c | ||
kexec_relocate.S | ||
kgdb.c | ||
machine_kexec.c | ||
machine_kexec_file.c | ||
Makefile | ||
mcount-dyn.S | ||
mcount.S | ||
module-sections.c | ||
module.c | ||
patch.c | ||
perf_callchain.c | ||
perf_regs.c | ||
process.c | ||
ptrace.c | ||
reset.c | ||
riscv_ksyms.c | ||
sbi-ipi.c | ||
sbi.c | ||
setup.c | ||
signal.c | ||
smp.c | ||
smpboot.c | ||
soc.c | ||
stacktrace.c | ||
suspend.c | ||
suspend_entry.S | ||
sys_riscv.c | ||
syscall_table.c | ||
time.c | ||
traps.c | ||
traps_misaligned.c | ||
vdso.c | ||
vector.c | ||
vmlinux-xip.lds.S | ||
vmlinux.lds.S |