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Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, Deepak Gupta X-Mailer: b4 0.14.0 X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: E26A68001E X-Stat-Signature: t3enkif7am1o33n4ja8ix5k4ggf3g6gy X-HE-Tag: 1727798874-854924 X-HE-Meta: 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 AMXUwQq3 UxY6p7+EVuwhztRelPwFnOlK+i8seiMO5mBTO18YmY1tpigHR42B92ja+tI4rM3JRkmfW0xNr8/CuhIPA2kZ3cyRpr1IXe2n1Kv2NzbCxBrQCbnyzXXOLEmjv+/0DeV+iyrCalaf+PxyKlu2fJUxs3j2LysxamHti1qugWoAZY/1VALRsKOPVd6FYuC19mKy1tCYUieruMT4A/d00u7VTfyMDs0Vc3jmfnC7sQExKcUkw6ADO9Zzm9ZR2fXySPBZkaOy3857I6w1c+4iMtHyonhj+4lROUN106N/y8iHs5cPDX3ogRd/rtiGIgI3ud+eJd86LobnTKwJrf+MjmS1XV/F5q/y87u9W1phWs+q687OxvzmpJ3CkMavk5ydADBTb+qTQYEh/7W5E7Y7omnFElZBvEXgonQUTxOwNrffxl7pRjSrQQWuo6BFWhjdz5FF20kg8bLEN/a0aCHot2GQX6bVG/Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: prctls implemented are: PR_SET_INDIR_BR_LP_STATUS, PR_GET_INDIR_BR_LP_STATUS and PR_LOCK_INDIR_BR_LP_STATUS. On trap entry, ELP state is recorded in sstatus image on stack and SR_ELP in CSR_STATUS is cleared. Signed-off-by: Deepak Gupta --- arch/riscv/include/asm/usercfi.h | 16 ++++++++- arch/riscv/kernel/entry.S | 2 +- arch/riscv/kernel/process.c | 5 +++ arch/riscv/kernel/usercfi.c | 76 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 97 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/usercfi.h b/arch/riscv/include/asm/usercfi.h index 52850a2c79cf..099204d0cd4a 100644 --- a/arch/riscv/include/asm/usercfi.h +++ b/arch/riscv/include/asm/usercfi.h @@ -16,7 +16,9 @@ struct kernel_clone_args; struct cfi_status { unsigned long ubcfi_en : 1; /* Enable for backward cfi. */ unsigned long ubcfi_locked : 1; - unsigned long rsvd : ((sizeof(unsigned long)*8) - 2); + unsigned long ufcfi_en : 1; /* Enable for forward cfi. Note that ELP goes in sstatus */ + unsigned long ufcfi_locked : 1; + unsigned long rsvd : ((sizeof(unsigned long)*8) - 4); unsigned long user_shdw_stk; /* Current user shadow stack pointer */ unsigned long shdw_stk_base; /* Base address of shadow stack */ unsigned long shdw_stk_size; /* size of shadow stack */ @@ -33,6 +35,10 @@ bool is_shstk_locked(struct task_struct *task); bool is_shstk_allocated(struct task_struct *task); void set_shstk_lock(struct task_struct *task); void set_shstk_status(struct task_struct *task, bool enable); +bool is_indir_lp_enabled(struct task_struct *task); +bool is_indir_lp_locked(struct task_struct *task); +void set_indir_lp_status(struct task_struct *task, bool enable); +void set_indir_lp_lock(struct task_struct *task); #define PR_SHADOW_STACK_SUPPORTED_STATUS_MASK (PR_SHADOW_STACK_ENABLE) @@ -58,6 +64,14 @@ void set_shstk_status(struct task_struct *task, bool enable); #define set_shstk_status(task, enable) +#define is_indir_lp_enabled(task) false + +#define is_indir_lp_locked(task) false + +#define set_indir_lp_status(task, enable) + +#define set_indir_lp_lock(task) + #endif /* CONFIG_RISCV_USER_CFI */ #endif /* __ASSEMBLY__ */ diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 8f7f477517e3..a1f258fd7bbc 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -143,7 +143,7 @@ SYM_CODE_START(handle_exception) * Disable the FPU/Vector to detect illegal usage of floating point * or vector in kernel space. */ - li t0, SR_SUM | SR_FS_VS + li t0, SR_SUM | SR_FS_VS | SR_ELP REG_L s0, TASK_TI_USER_SP(tp) csrrc s1, CSR_STATUS, t0 diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index f7dec532657f..5207f018415c 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -159,6 +159,11 @@ void start_thread(struct pt_regs *regs, unsigned long pc, set_shstk_status(current, false); set_shstk_base(current, 0, 0); set_active_shstk(current, 0); + /* + * disable indirect branch tracking on exec. + * libc will enable it later via prctl. + */ + set_indir_lp_status(current, false); #ifdef CONFIG_64BIT regs->status &= ~SR_UXL; diff --git a/arch/riscv/kernel/usercfi.c b/arch/riscv/kernel/usercfi.c index c77abe552c88..8da509afdbe9 100644 --- a/arch/riscv/kernel/usercfi.c +++ b/arch/riscv/kernel/usercfi.c @@ -69,6 +69,32 @@ void set_shstk_lock(struct task_struct *task) task->thread_info.user_cfi_state.ubcfi_locked = 1; } +bool is_indir_lp_enabled(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_en ? true : false; +} + +bool is_indir_lp_locked(struct task_struct *task) +{ + return task->thread_info.user_cfi_state.ufcfi_locked ? true : false; +} + +void set_indir_lp_status(struct task_struct *task, bool enable) +{ + task->thread_info.user_cfi_state.ufcfi_en = enable ? 1 : 0; + + if (enable) + task->thread_info.envcfg |= ENVCFG_LPE; + else + task->thread_info.envcfg &= ~ENVCFG_LPE; + + csr_write(CSR_ENVCFG, task->thread_info.envcfg); +} + +void set_indir_lp_lock(struct task_struct *task) +{ + task->thread_info.user_cfi_state.ufcfi_locked = 1; +} /* * If size is 0, then to be compatible with regular stack we want it to be as big as * regular stack. Else PAGE_ALIGN it and return back @@ -371,3 +397,53 @@ int arch_lock_shadow_stack_status(struct task_struct *task, return 0; } + +int arch_get_indir_br_lp_status(struct task_struct *t, unsigned long __user *status) +{ + unsigned long fcfi_status = 0; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is enabled on the task or not */ + fcfi_status |= (is_indir_lp_enabled(t) ? PR_INDIR_BR_LP_ENABLE : 0); + + return copy_to_user(status, &fcfi_status, sizeof(fcfi_status)) ? -EFAULT : 0; +} + +int arch_set_indir_br_lp_status(struct task_struct *t, unsigned long status) +{ + bool enable_indir_lp = false; + + if (!cpu_supports_indirect_br_lp_instr()) + return -EINVAL; + + /* indirect branch tracking is locked and further can't be modified by user */ + if (is_indir_lp_locked(t)) + return -EINVAL; + + /* Reject unknown flags */ + if (status & ~PR_INDIR_BR_LP_ENABLE) + return -EINVAL; + + enable_indir_lp = (status & PR_INDIR_BR_LP_ENABLE) ? true : false; + set_indir_lp_status(t, enable_indir_lp); + + return 0; +} + +int arch_lock_indir_br_lp_status(struct task_struct *task, + unsigned long arg) +{ + /* + * If indirect branch tracking is not supported or not enabled on task, + * nothing to lock here + */ + if (!cpu_supports_indirect_br_lp_instr() || + !is_indir_lp_enabled(task)) + return -EINVAL; + + set_indir_lp_lock(task); + + return 0; +}