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Thu, 25 Jul 2024 16:46:47 -0700 (PDT) From: Deepak Gupta To: qemu-riscv@nongnu.org, qemu-devel@nongnu.org, jim.shu@sifive.com, andy.chiu@sifive.com, jesse.huang@sifive.com, kito.cheng@sifive.com Cc: palmer@dabbelt.com, Alistair.Francis@wdc.com, laurent@vivier.eu, bmeng.cn@gmail.com, liwei1518@gmail.com, dbarboza@ventanamicro.com, zhiwei_liu@linux.alibaba.com, Deepak Gupta Subject: [PATCH 18/24] linux-user/riscv: setup/teardown zicfiss shadow stack for qemu-user Date: Thu, 25 Jul 2024 16:46:07 -0700 Message-ID: <20240725234614.3850142-19-debug@rivosinc.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240725234614.3850142-1-debug@rivosinc.com> References: <20240725234614.3850142-1-debug@rivosinc.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::12b; envelope-from=debug@rivosinc.com; helo=mail-il1-x12b.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @rivosinc-com.20230601.gappssmtp.com) X-ZM-MESSAGEID: 1721951438792116601 Content-Type: text/plain; charset="utf-8" Implements shadow stack related prctls for qemu-user on riscv. Allocates shadow stack from host memory using `target_mmap` and tears down when user issues prctl to disable using `target_munmap`. Signed-off-by: Deepak Gupta Co-developed-by: Jesse Huang Co-developed-by: Jim Shu Co-developed-by: Andy Chiu --- linux-user/riscv/cpu_loop.c | 50 +++++++++++++++++++++++++++++++++ linux-user/riscv/target_cpu.h | 7 +++++ linux-user/riscv/target_prctl.h | 27 ++++++++++++++++++ target/riscv/cpu.c | 4 +++ target/riscv/cpu.h | 1 + 5 files changed, 89 insertions(+) diff --git a/linux-user/riscv/cpu_loop.c b/linux-user/riscv/cpu_loop.c index 52c49c2e42..22670b68e0 100644 --- a/linux-user/riscv/cpu_loop.c +++ b/linux-user/riscv/cpu_loop.c @@ -25,6 +25,7 @@ #include "signal-common.h" #include "elf.h" #include "semihosting/common-semi.h" +#include "user-mmap.h" =20 void cpu_loop(CPURISCVState *env) { @@ -94,6 +95,55 @@ void cpu_loop(CPURISCVState *env) } } =20 +#define ZICFISS_GUARD_SIZE (2UL * TARGET_PAGE_SIZE) +#define ZICFISS_STACK_SIZE (16UL * TARGET_PAGE_SIZE) +#define ZICFISS_THREAD_SIZE (ZICFISS_STACK_SIZE + ZICFISS_GUARD_SIZE) + +void zicfiss_shadow_stack_alloc(CPUArchState *env) +{ + uintptr_t new_base; + + /* SS page should be surrounded by two guard pages */ + new_base =3D (uintptr_t) target_mmap(0, ZICFISS_THREAD_SIZE, PROT_NONE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if ((intptr_t)new_base =3D=3D -1) { + perror("shadow stack alloc failure"); + exit(EXIT_FAILURE); + } + new_base +=3D TARGET_PAGE_SIZE; + int ret =3D mprotect((void *)new_base, ZICFISS_STACK_SIZE, + PROT_READ | PROT_WRITE); + if (ret =3D=3D -1) { + perror("shadow stack mprotect failure"); + exit(EXIT_FAILURE); + } + + env->ssp_base =3D new_base; + env->ssp =3D new_base + ZICFISS_STACK_SIZE; +} + +void zicfiss_shadow_stack_release(CPUArchState *env) +{ + abi_ulong mmap_base; + + if (env->ssp =3D=3D 0) { + perror("release empty shadow stack"); + exit(EXIT_FAILURE); + } + + /* It should match shadow stack allocation. */ + mmap_base =3D env->ssp_base - TARGET_PAGE_SIZE; + + int ret =3D target_munmap(mmap_base, ZICFISS_THREAD_SIZE); + if (ret =3D=3D -1) { + perror("shadow stack release failure"); + exit(EXIT_FAILURE); + } + + env->ssp_base =3D 0; + env->ssp =3D 0; +} + void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs) { CPUState *cpu =3D env_cpu(env); diff --git a/linux-user/riscv/target_cpu.h b/linux-user/riscv/target_cpu.h index 9c642367a3..bba54d93eb 100644 --- a/linux-user/riscv/target_cpu.h +++ b/linux-user/riscv/target_cpu.h @@ -1,6 +1,9 @@ #ifndef RISCV_TARGET_CPU_H #define RISCV_TARGET_CPU_H =20 +extern void zicfiss_shadow_stack_alloc(CPUArchState *env); +extern void zicfiss_shadow_stack_release(CPUArchState *env); + static inline void cpu_clone_regs_child(CPURISCVState *env, target_ulong n= ewsp, unsigned flags) { @@ -9,6 +12,10 @@ static inline void cpu_clone_regs_child(CPURISCVState *en= v, target_ulong newsp, } =20 env->gpr[xA0] =3D 0; + + if (flags & CLONE_VM) { + zicfiss_shadow_stack_alloc(env); + } } =20 static inline void cpu_clone_regs_parent(CPURISCVState *env, unsigned flag= s) diff --git a/linux-user/riscv/target_prctl.h b/linux-user/riscv/target_prct= l.h index d7f9f954c9..6293d61519 100644 --- a/linux-user/riscv/target_prctl.h +++ b/linux-user/riscv/target_prctl.h @@ -13,6 +13,33 @@ static abi_long do_prctl_cfi(CPUArchState *env, if (env_archcpu(env)->cfg.ext_zicfilp) { =20 switch (option) { + case PR_GET_SHADOW_STACK_STATUS: + abi_ulong bcfi_status =3D 0; + /* indirect branch tracking is enabled on the task or not */ + bcfi_status |=3D (env->ubcfien ? PR_INDIR_BR_LP_ENABLE : 0); + return copy_to_user(flag, &bcfi_status, sizeof(bcfi_status)) ?= \ + -EFAULT : 0; + + case PR_SET_SHADOW_STACK_STATUS: + /* if any other bit is set, its invalid param */ + if (flag & ~PR_SHADOW_STACK_ENABLE) { + return -TARGET_EINVAL; + } + + if ((flag & PR_SHADOW_STACK_ENABLE) + && (env->ssp =3D=3D 0 && !env->ubcfien)) { + zicfiss_shadow_stack_alloc(env); + } else { + zicfiss_shadow_stack_release(env); + } + env->ubcfien =3D (flag & PR_SHADOW_STACK_ENABLE); + tb_flush(env_cpu(env)); + return 0; + + /* locking not implemented (also not needed for qemu-user) yet */ + case PR_LOCK_SHADOW_STACK_STATUS: + return -TARGET_EINVAL; + case PR_GET_INDIR_BR_LP_STATUS: abi_ulong fcfi_status =3D 0; /* indirect branch tracking is enabled on the task or not */ diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index e1ff246c24..5a34eee10c 100644 --- a/target/riscv/cpu.c +++ b/target/riscv/cpu.c @@ -1001,6 +1001,10 @@ static void riscv_cpu_reset_hold(Object *obj, ResetT= ype type) /* on reset ssp is set to 0 */ env->ssp =3D 0; =20 +#ifdef CONFIG_USER_ONLY + env->ssp_base =3D 0; +#endif + /* * Bits 10, 6, 2 and 12 of mideleg are read only 1 when the Hypervisor * extension is enabled. diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index 82475490ab..af89fc1268 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -232,6 +232,7 @@ struct CPUArchState { uint32_t elf_flags; bool ufcfien; bool ubcfien; + target_ulong ssp_base; #endif =20 #ifndef CONFIG_USER_ONLY --=20 2.44.0