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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: rspam07 X-Rspamd-Queue-Id: E55F616000D X-Stat-Signature: 4js5ftm6bzc8xx4zjky8g11iyo5wbatf X-Rspam-User: X-HE-Tag: 1728427124-201699 X-HE-Meta: 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 Icf26qL0 XbhoWMKaPhn/PYoNOBXE9kthcLr58shywjbln7YISPd0RduB/jBE/IobavXT70HMKeBHNRfNYDhX9oye+fGGGPgsmaoPs18RpGXKi8OFTVzpzxv87bPfUCV9/gKWWC5DrHqkkBQCnXJ2G70C3e1kl14KgybaAJbZtOpJK5dnTyZHURfPl2cN7R270Ls0WK+Aou1Nveaa785g1iQCLAiCnaAdgRwMnankYhP058eOCCkIYryxDgSh7uwuriF16ulOHj5BOrxbvco1Xv97jlg+PDGbNWmHJHtJNoAYx3hbd7B/slJyRQeEQHFlzG3kDito85vUQoQAHLTtKX3GS/LyGGGZ8/I0bEDyq6YOfYAR2kqwR6JXCaVnfcjMcAJkNMEKP3pocXG9iv+eswc3UPwR5BM2fGY6hIreExXXr23fQYI2N9N4x6PhEku8pt2YXH74L84a6n8r0Mb+DWJY= 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 0b3aff008c85..19ee8e7e23ee 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 6ac5e87b4c70..21ea2237efcf 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.envcfg |= ENVCFG_LPE; + else + task->thread.envcfg &= ~ENVCFG_LPE; + + csr_write(CSR_ENVCFG, task->thread.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; +}