From c162cde9eaf50b92de5277df3e48c93349bf45a3 Mon Sep 17 00:00:00 2001 From: 6eanut Date: Thu, 22 Jan 2026 04:23:38 +0000 Subject: executor, sys/linux, pkg: enable syzos for riscv64 This patch enables syzos for riscv64 and implements the corresponding pseudo syscalls. Pseudo syscalls: - syz_kvm_setup_syzos_vm - syz_kvm_add_vcpu - syz_kvm_assert_syzos_uexit Syzos guest support: - guest_uexit - guest_execute_code - guest_handle_csrr and guest_handle_csrw Test seeds: - riscv64-syz_kvm_setup_syzos_vm - riscv64-syz_kvm_setup_syzos_vm-csrr - riscv64-syz_kvm_setup_syzos_vm-csrw --- sys/linux/dev_kvm.txt | 2 +- sys/linux/dev_kvm_riscv64.txt | 56 ++++++++++++++++++++++ sys/linux/test/riscv64-syz_kvm_setup_syzos_vm | 35 ++++++++++++++ sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrr | 21 ++++++++ sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrw | 22 +++++++++ 5 files changed, 135 insertions(+), 1 deletion(-) create mode 100644 sys/linux/test/riscv64-syz_kvm_setup_syzos_vm create mode 100644 sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrr create mode 100644 sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrw (limited to 'sys/linux') diff --git a/sys/linux/dev_kvm.txt b/sys/linux/dev_kvm.txt index a3d646efb..3b4a6b04d 100644 --- a/sys/linux/dev_kvm.txt +++ b/sys/linux/dev_kvm.txt @@ -644,7 +644,7 @@ kvm_regs_arm64_extra = 0x603000000013c01b, 0x603000000013c01f, 0x603000000013c02 # For riscv64, the following ids are computed from arch/riscv/include/uapi/asm/kvm.h and arch/riscv/include/uapi/asm/ptrace.h . kvm_regs_riscv64_config = 0x8030000000100000, 0x8030000000100001, 0x8030000000100002, 0x8030000000100003, 0x8030000000100004, 0x8030000000100005, 0x8030000000100006, 0x8030000000100007 kvm_regs_riscv64_core = 0x8030000000200000, 0x8030000000200001, 0x8030000000200002, 0x8030000000200003, 0x8030000000200004, 0x8030000000200005, 0x8030000000200006, 0x8030000000200007, 0x8030000000200008, 0x8030000000200009, 0x803000000020000a, 0x803000000020000b, 0x803000000020000c, 0x803000000020000d, 0x803000000020000e, 0x803000000020000f, 0x8030000000200010, 0x8030000000200011, 0x8030000000200012, 0x8030000000200013, 0x8030000000200014, 0x8030000000200015, 0x8030000000200016, 0x8030000000200017, 0x8030000000200018, 0x8030000000200019, 0x803000000020001a, 0x803000000020001b, 0x803000000020001c, 0x803000000020001d, 0x803000000020001e, 0x803000000020001f, 0x8030000000200020 -kvm_regs_riscv64_csr = 0x8030000000300000, 0x8030000000300001, 0x8030000000300002, 0x8030000000300003, 0x8030000000300004, 0x8030000000300005, 0x8030000000300006, 0x8030000000300007, 0x8030000000300008 +kvm_regs_riscv64_csr = 0x8030000000300000, 0x8030000000300001, 0x8030000000300002, 0x8030000000300003, 0x8030000000300004, 0x8030000000300005, 0x8030000000300006, 0x8030000000300007, 0x8030000000300008, 0x8030000000300009, 0x803000000030000a kvm_regs_riscv64_aia_csr = 0x8030000003010000, 0x8030000003010001, 0x8030000003010002, 0x8030000003010003, 0x8030000003010004, 0x8030000003010005, 0x8030000003010006 kvm_regs_riscv64_smstateen_csr = 0x8030000003020000 kvm_regs_riscv64_timer = 0x8030000004000000, 0x8030000004000001, 0x8030000004000002, 0x8030000004000003 diff --git a/sys/linux/dev_kvm_riscv64.txt b/sys/linux/dev_kvm_riscv64.txt index 5e7e508a9..9c1dea7d9 100644 --- a/sys/linux/dev_kvm_riscv64.txt +++ b/sys/linux/dev_kvm_riscv64.txt @@ -32,4 +32,60 @@ kvm_text_riscv64 { size len[text, intptr] } +# kvm_syz_vm is a VM handler used by syzos-related pseudo-syscalls. It is actually an opaque pointer under the hood. +resource kvm_syz_vm$riscv64[int64] + +# Map the given memory into the VM and set up syzos there. +syz_kvm_setup_syzos_vm$riscv64(fd fd_kvmvm, usermem vma[1024]) kvm_syz_vm$riscv64 + +# Create a VCPU inside a kvm_syz_vm VM. +# Prohibit flattening the input arguments, so that it is easier to reason about them. +syz_kvm_add_vcpu$riscv64(vm kvm_syz_vm$riscv64, text ptr[in, kvm_text_syzos_riscv64], opts ptr[in, array[kvm_setup_opt_riscv64, 1]], nopt len[opts]) fd_kvmcpu (no_squash) + +kvm_text_syzos_riscv64 { + typ const[0, intptr] + text ptr[in, array[syzos_api_call$riscv64, 1:32]] + size bytesize[text, int64] +} + +type syzos_api$riscv64[NUM, PAYLOAD] { + call const[NUM, int64] + size bytesize[parent, int64] + payload PAYLOAD +} + +syzos_api_code$riscv64 { + insns text[riscv64] + ret const[0x8067, int32] +} [packed] + +syzos_api_csrr { + arg_reg riscv64_csr_or_any +} + +syzos_api_csrw { + arg_reg riscv64_csr_or_any + arg_value int64 +} + +riscv64_csr_or_any [ + valid flags[riscv64_csr, int64] + any int64 +] + +# Table 5 in https://docs.riscv.org/reference/isa/_attachments/riscv-privileged.pdf . +# Currently, only 11 CSRS are supported in Linux-6.19. See +# https://elixir.bootlin.com/linux/v6.19-rc5/source/arch/riscv/include/uapi/asm/kvm.h#L75 . +riscv64_csr = 0x100, 0x104, 0x105, 0x140, 0x141, 0x142, 0x143, 0x144, 0x180, 0x106, 0x10a + +syzos_api_call$riscv64 [ + uexit syzos_api$riscv64[0, intptr] + code syzos_api$riscv64[10, syzos_api_code$riscv64] + csrr syzos_api$riscv64[100, syzos_api_csrr] + csrw syzos_api$riscv64[101, syzos_api_csrw] +] [varlen] + +# Test assertions, will not be used by the fuzzer. syz_kvm_assert_reg$riscv64(fd fd_kvmcpu, reg int64, value int64) (no_generate) +syz_kvm_assert_syzos_uexit$riscv64(cpufd fd_kvmcpu, run kvm_run_ptr, exitcode int64) (no_generate) +syz_kvm_assert_syzos_kvm_exit$riscv64(run kvm_run_ptr, exitcode int64) (no_generate) diff --git a/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm new file mode 100644 index 000000000..5942f1b9f --- /dev/null +++ b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm @@ -0,0 +1,35 @@ +# +# requires: arch=riscv64 -threaded +# + +r0 = openat$kvm(0, &AUTO='/dev/kvm\x00', 0x0, 0x0) +r1 = ioctl$KVM_CREATE_VM(r0, AUTO, 0x0) +r2 = syz_kvm_setup_syzos_vm$riscv64(r1, &(0x7f0000c00000/0x400000)=nil) + +# Perform two uexits. The first one is done via a code blob: +# lui a0, 0x40000 +# addi a0, a0, 0x100 # a0 = RISCV64_ADDR_UEXIT +# sd zero, 0(a0) +# ret +# The second uexit is done via a syzos API command that sets uexit exit code to 0xaaaa. +# +r3 = syz_kvm_add_vcpu$riscv64(r2, &AUTO={0x0, &AUTO=[@code={AUTO, AUTO, {"370500401305051023300500", 0x00008067}}, @uexit={AUTO, AUTO, 0xaaaa}], AUTO}, 0x0, 0x0) + +r4 = ioctl$KVM_GET_VCPU_MMAP_SIZE(r0, AUTO) +r5 = mmap$KVM_VCPU(&(0x7f0000009000/0x1000)=nil, r4, 0x3, 0x1, r3, 0x0) + +# Run till the first uexit. +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$riscv64(r3, r5, 0x0) +# Run till the second uexit. +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$riscv64(r3, r5, 0xaaaa) +# Run till the end of guest_main(). 0xffffffffffffffff is UEXIT_END. +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +# Ensure that exit reason is KVM_EXIT_MMIO and uexit code is UEXIT_END. +# +syz_kvm_assert_syzos_kvm_exit$riscv64(r5, 0x6) +syz_kvm_assert_syzos_uexit$riscv64(r3, r5, 0xffffffffffffffff) diff --git a/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrr b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrr new file mode 100644 index 000000000..77ea424df --- /dev/null +++ b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrr @@ -0,0 +1,21 @@ +# +# requires: arch=riscv64 -threaded +# + +# This test verifies that SYZOS can safely execute CSR access instructions +# inside a RISC-V KVM guest. +# +r0 = openat$kvm(0, &AUTO='/dev/kvm\x00', 0x0, 0x0) +r1 = ioctl$KVM_CREATE_VM(r0, AUTO, 0x0) +r2 = syz_kvm_setup_syzos_vm$riscv64(r1, &(0x7f0000c00000/0x400000)=nil) + +# Number 0x140 is sscratch (encode). +# +r3 = syz_kvm_add_vcpu$riscv64(r2, &AUTO={0x0, &AUTO=[@csrr={AUTO, AUTO, {@valid=0x140}}], AUTO}, 0x0, 0x0) +r4 = ioctl$KVM_GET_VCPU_MMAP_SIZE(r0, AUTO) +r5 = mmap$KVM_VCPU(&(0x7f0000009000/0x1000)=nil, r4, 0x3, 0x1, r3, 0x0) + +# Run till end of guest_main(). +# +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$riscv64(r3, r5, 0xffffffffffffffff) diff --git a/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrw b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrw new file mode 100644 index 000000000..38fdd4929 --- /dev/null +++ b/sys/linux/test/riscv64-syz_kvm_setup_syzos_vm-csrw @@ -0,0 +1,22 @@ +# +# requires: arch=riscv64 -threaded +# + +# This test verifies that writing a supervisor CSR from the guest is +# correctly reflected in the KVM vCPU state. +# +r0 = openat$kvm(0, &AUTO='/dev/kvm\x00', 0x0, 0x0) +r1 = ioctl$KVM_CREATE_VM(r0, AUTO, 0x0) +r2 = syz_kvm_setup_syzos_vm$riscv64(r1, &(0x7f0000c00000/0x400000)=nil) + +# Number 0x140 is sscratch (encode). +# +r3 = syz_kvm_add_vcpu$riscv64(r2, &AUTO={0x0, &AUTO=[@csrw={AUTO, AUTO, {@valid=0x140, 0xfefefee0}}], AUTO}, 0x0, 0x0) +r4 = ioctl$KVM_GET_VCPU_MMAP_SIZE(r0, AUTO) +r5 = mmap$KVM_VCPU(&(0x7f0000009000/0x1000)=nil, r4, 0x3, 0x1, r3, 0x0) +ioctl$KVM_RUN(r3, AUTO, 0x0) +syz_kvm_assert_syzos_uexit$riscv64(r3, r5, 0xffffffffffffffff) + +# ID 0x8030000003000003 is sscratch (kvm reg id). +# +syz_kvm_assert_reg$riscv64(r3, 0x8030000003000003, 0xfefefee0) -- cgit mrf-deployment