diff --git a/compel/arch/aarch64/src/lib/include/uapi/asm/infect-types.h b/compel/arch/aarch64/src/lib/include/uapi/asm/infect-types.h index 39aed4ac5..e11f2910f 100644 --- a/compel/arch/aarch64/src/lib/include/uapi/asm/infect-types.h +++ b/compel/arch/aarch64/src/lib/include/uapi/asm/infect-types.h @@ -2,6 +2,7 @@ #define UAPI_COMPEL_ASM_TYPES_H__ #include +#include #include #include #include @@ -17,8 +18,18 @@ typedef struct user_pt_regs user_regs_struct_t; +/* + * GCS (Guarded Control Stack) + */ +struct user_gcs { + __u64 features_enabled; + __u64 features_locked; + __u64 gcspr_el0; +}; + struct user_fpregs_struct { struct user_fpsimd_state fpstate; + struct user_gcs gcs; }; typedef struct user_fpregs_struct user_fpregs_struct_t; @@ -43,4 +54,7 @@ typedef struct user_fpregs_struct user_fpregs_struct_t; __NR_##syscall; \ }) +extern bool __compel_host_supports_gcs(void); +#define compel_host_supports_gcs __compel_host_supports_gcs + #endif /* UAPI_COMPEL_ASM_TYPES_H__ */ diff --git a/compel/arch/aarch64/src/lib/include/uapi/asm/sigframe.h b/compel/arch/aarch64/src/lib/include/uapi/asm/sigframe.h index a3528500d..7efee528f 100644 --- a/compel/arch/aarch64/src/lib/include/uapi/asm/sigframe.h +++ b/compel/arch/aarch64/src/lib/include/uapi/asm/sigframe.h @@ -10,11 +10,20 @@ /* Copied from the kernel header arch/arm64/include/uapi/asm/sigcontext.h */ #define FPSIMD_MAGIC 0x46508001 +#define GCS_MAGIC 0x47435300 typedef struct fpsimd_context fpu_state_t; +struct gcs_context { + struct _aarch64_ctx head; + __u64 gcspr; + __u64 features_enabled; + __u64 reserved; +}; + struct aux_context { struct fpsimd_context fpsimd; + struct gcs_context gcs; /* additional context to be added before "end" */ struct _aarch64_ctx end; }; @@ -63,6 +72,7 @@ struct cr_sigcontext { #define RT_SIGFRAME_AUX_CONTEXT(rt_sigframe) ((struct aux_context *)&(RT_SIGFRAME_SIGCONTEXT(rt_sigframe)->__reserved)) #define RT_SIGFRAME_FPU(rt_sigframe) (&RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)->fpsimd) #define RT_SIGFRAME_OFFSET(rt_sigframe) 0 +#define RT_SIGFRAME_GCS(rt_sigframe) (&RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)->gcs) #define rt_sigframe_erase_sigset(sigframe) memset(&sigframe->uc.uc_sigmask, 0, sizeof(k_rtsigset_t)) #define rt_sigframe_copy_sigset(sigframe, from) memcpy(&sigframe->uc.uc_sigmask, from, sizeof(k_rtsigset_t)) diff --git a/compel/arch/aarch64/src/lib/infect.c b/compel/arch/aarch64/src/lib/infect.c index 503616df7..0f74a023a 100644 --- a/compel/arch/aarch64/src/lib/infect.c +++ b/compel/arch/aarch64/src/lib/infect.c @@ -2,8 +2,8 @@ #include #include #include +#include #include -#include #include #include "common/page.h" @@ -13,6 +13,8 @@ #include "infect.h" #include "infect-priv.h" #include "asm/breakpoints.h" +#include "asm/gcs-types.h" +#include unsigned __page_size = 0; unsigned __page_shift = 0; @@ -33,12 +35,32 @@ static inline void __always_unused __check_code_syscall(void) BUILD_BUG_ON(!is_log2(sizeof(code_syscall))); } +bool __compel_host_supports_gcs(void) +{ + unsigned long hwcap = getauxval(AT_HWCAP); + return (hwcap & HWCAP_GCS) != 0; +} + +static bool __compel_gcs_enabled(struct user_gcs *gcs) +{ + if (!compel_host_supports_gcs()) + return false; + + if (gcs->features_enabled & PR_SHADOW_STACK_ENABLE) + return true; + + return false; +} + int sigreturn_prep_regs_plain(struct rt_sigframe *sigframe, user_regs_struct_t *regs, user_fpregs_struct_t *fpregs) { struct fpsimd_context *fpsimd = RT_SIGFRAME_FPU(sigframe); + struct gcs_context *gcs = RT_SIGFRAME_GCS(sigframe); memcpy(sigframe->uc.uc_mcontext.regs, regs->regs, sizeof(regs->regs)); + pr_debug("sigreturn_prep_regs_plain: sp %lx pc %lx\n", (long)regs->sp, (long)regs->pc); + sigframe->uc.uc_mcontext.sp = regs->sp; sigframe->uc.uc_mcontext.pc = regs->pc; sigframe->uc.uc_mcontext.pstate = regs->pstate; @@ -51,6 +73,19 @@ int sigreturn_prep_regs_plain(struct rt_sigframe *sigframe, user_regs_struct_t * fpsimd->head.magic = FPSIMD_MAGIC; fpsimd->head.size = sizeof(*fpsimd); + if (__compel_gcs_enabled(&fpregs->gcs)) { + gcs->head.magic = GCS_MAGIC; + gcs->head.size = sizeof(*gcs); + gcs->reserved = 0; + gcs->gcspr = fpregs->gcs.gcspr_el0 - 8; + gcs->features_enabled = fpregs->gcs.features_enabled; + + pr_debug("sigframe gcspr=%llx features_enabled=%llx\n", fpregs->gcs.gcspr_el0 - 8, fpregs->gcs.features_enabled); + } else { + pr_debug("sigframe gcspr=[disabled]\n"); + memset(gcs, 0, sizeof(*gcs)); + } + return 0; } @@ -81,6 +116,8 @@ int compel_get_task_regs(pid_t pid, user_regs_struct_t *regs, user_fpregs_struct goto err; } + memset(&ext_regs->gcs, 0, sizeof(ext_regs->gcs)); + ret = save(pid, arg, regs, ext_regs); err: return ret; diff --git a/compel/include/uapi/infect.h b/compel/include/uapi/infect.h index 1f61876ff..d21c261b7 100644 --- a/compel/include/uapi/infect.h +++ b/compel/include/uapi/infect.h @@ -192,6 +192,14 @@ void compel_set_thread_ip(struct parasite_thread_ctl *tctl, uint64_t v); extern void compel_get_stack(struct parasite_ctl *ctl, void **rstack, void **r_thread_stack); +#ifndef compel_host_supports_gcs +static inline bool compel_host_supports_gcs(void) +{ + return false; +} +#define compel_host_supports_gcs +#endif + #ifndef compel_shstk_enabled static inline bool compel_shstk_enabled(user_fpregs_struct_t *ext_regs) {