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AJvYcCUtK4th62oNcuZP75wOOrgurk/a57GVqV0PHY944RODUxgl8TX8o8JUQEno0jyO7uMD9Znc+VzgVw==@kvack.org X-Gm-Message-State: AOJu0YxhtUm4Z4ubX40xI+MXi+8WngTtusS7acx2/RWl+YGPD/3mPXbI ZyAoxYkNwYxF/wvCZ/k0z7sdUh8+GylhbR8o2xqI6xFmRvok5Sl2a0SO2h15oK0= X-Google-Smtp-Source: AGHT+IFZmP54aZT+PGhT0sMeks15kfczHLhKUFL1tfOl/r4KWZKd9Mj0XsQpQ7yVRv3lx6isgmniRg== X-Received: by 2002:a17:90b:4a42:b0:2e2:bad2:69ba with SMTP id 98e67ed59e1d1-2e2bad26afcmr3003723a91.14.1728518533102; Wed, 09 Oct 2024 17:02:13 -0700 (PDT) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e2d5f0b03bsm22252a91.34.2024.10.09.17.02.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Oct 2024 17:02:12 -0700 (PDT) Date: Wed, 9 Oct 2024 17:02:08 -0700 From: Deepak Gupta To: Lorenzo Stoakes Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , 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 , 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 Subject: Re: [PATCH v6 11/33] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Message-ID: References: <20241008-v5_user_cfi_series-v6-0-60d9fe073f37@rivosinc.com> <20241008-v5_user_cfi_series-v6-11-60d9fe073f37@rivosinc.com> <22972e7b-0844-4ebc-8d82-a0838b83c3a0@lucifer.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <22972e7b-0844-4ebc-8d82-a0838b83c3a0@lucifer.local> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 0AC2A160005 X-Stat-Signature: cjr3n8kfnu15hej6i9qwd4koeh149wrz X-Rspam-User: X-HE-Tag: 1728518533-688206 X-HE-Meta: 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 ktUF9E+O 1rdvv4pCTkRtjF9sKOJ6ieFuver8/b0xpkYW35GSb37zRTlkFa5f3m9M23U5yxN6Py6kBPZ7P0UJFMchCfzGGkbfZckG1qP6Jomh1mk4xnDSla/nA4soZS/zFmho1+ij1HRySTC7TYmDdK5RNgdKz7NCNiBmUhN5njmAGHtAybLGNGEgr9HLbxYGSOzdb9k2v8g4iXeixbWBymMzssGzW/pu/qoDk71H5bwo82/RDVkffg82ppW/P/wJYom8SUumhmkRSpsQQMn5DKVeB5ELtdcy/WUGqAClZllwxtADojinToPoPr8qojm3bqnz/GY9zzPPHzt4Pq8ZINomFmUti5F6TZ7z/xcw1D4tw7Ga2xbHO7DF48D/MoeYhpEPiumaMFkctsj6KfvjcOMREDygcZ5Makq3TO46+tDGcAI5qS3x3bxq/TsBa6NsIN6Gxng+RFzfrj+xsLHZTK4ZWRcC/DjdzXs426CxrBw7QHlXtLk+j8YaArKiT3lxHxoBProkl46/r9FUuedx+hCWsbVTu2MVbg7nh56JYGDkC5R7wkeafsJo= 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: On Wed, Oct 09, 2024 at 02:36:12PM +0100, Lorenzo Stoakes wrote: >On Tue, Oct 08, 2024 at 03:36:53PM -0700, Deepak Gupta wrote: >> `arch_calc_vm_prot_bits` is implemented on risc-v to return VM_READ | >> VM_WRITE if PROT_WRITE is specified. Similarly `riscv_sys_mmap` is >> updated to convert all incoming PROT_WRITE to (PROT_WRITE | PROT_READ). >> This is to make sure that any existing apps using PROT_WRITE still work. >> >> Earlier `protection_map[VM_WRITE]` used to pick read-write PTE encodings. >> Now `protection_map[VM_WRITE]` will always pick PAGE_SHADOWSTACK PTE >> encodings for shadow stack. Above changes ensure that existing apps >> continue to work because underneath kernel will be picking >> `protection_map[VM_WRITE|VM_READ]` PTE encodings. >> >> Signed-off-by: Deepak Gupta >> --- >> arch/riscv/include/asm/mman.h | 24 ++++++++++++++++++++++++ >> arch/riscv/include/asm/pgtable.h | 1 + >> arch/riscv/kernel/sys_riscv.c | 10 ++++++++++ >> arch/riscv/mm/init.c | 2 +- >> mm/mmap.c | 1 + >> 5 files changed, 37 insertions(+), 1 deletion(-) >> >> diff --git a/arch/riscv/include/asm/mman.h b/arch/riscv/include/asm/mman.h >> new file mode 100644 >> index 000000000000..ef9fedf32546 >> --- /dev/null >> +++ b/arch/riscv/include/asm/mman.h >> @@ -0,0 +1,24 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#ifndef __ASM_MMAN_H__ >> +#define __ASM_MMAN_H__ >> + >> +#include >> +#include >> +#include >> + >> +static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, >> + unsigned long pkey __always_unused) >> +{ >> + unsigned long ret = 0; >> + >> + /* >> + * If PROT_WRITE was specified, force it to VM_READ | VM_WRITE. >> + * Only VM_WRITE means shadow stack. >> + */ >> + if (prot & PROT_WRITE) >> + ret = (VM_READ | VM_WRITE); >> + return ret; >> +} >> +#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey) >> + >> +#endif /* ! __ASM_MMAN_H__ */ >> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h >> index e79f15293492..4948a1f18ae8 100644 >> --- a/arch/riscv/include/asm/pgtable.h >> +++ b/arch/riscv/include/asm/pgtable.h >> @@ -177,6 +177,7 @@ extern struct pt_alloc_ops pt_ops __meminitdata; >> #define PAGE_READ_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_EXEC) >> #define PAGE_WRITE_EXEC __pgprot(_PAGE_BASE | _PAGE_READ | \ >> _PAGE_EXEC | _PAGE_WRITE) >> +#define PAGE_SHADOWSTACK __pgprot(_PAGE_BASE | _PAGE_WRITE) >> >> #define PAGE_COPY PAGE_READ >> #define PAGE_COPY_EXEC PAGE_READ_EXEC >> diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c >> index d77afe05578f..43a448bf254b 100644 >> --- a/arch/riscv/kernel/sys_riscv.c >> +++ b/arch/riscv/kernel/sys_riscv.c >> @@ -7,6 +7,7 @@ >> >> #include >> #include >> +#include >> >> static long riscv_sys_mmap(unsigned long addr, unsigned long len, >> unsigned long prot, unsigned long flags, >> @@ -16,6 +17,15 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len, >> if (unlikely(offset & (~PAGE_MASK >> page_shift_offset))) >> return -EINVAL; >> >> + /* >> + * If PROT_WRITE is specified then extend that to PROT_READ >> + * protection_map[VM_WRITE] is now going to select shadow stack encodings. >> + * So specifying PROT_WRITE actually should select protection_map [VM_WRITE | VM_READ] >> + * If user wants to create shadow stack then they should use `map_shadow_stack` syscall. >> + */ >> + if (unlikely((prot & PROT_WRITE) && !(prot & PROT_READ))) >> + prot |= PROT_READ; >> + >> return ksys_mmap_pgoff(addr, len, prot, flags, fd, >> offset >> (PAGE_SHIFT - page_shift_offset)); >> } >> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c >> index 0e8c20adcd98..964810aeb405 100644 >> --- a/arch/riscv/mm/init.c >> +++ b/arch/riscv/mm/init.c >> @@ -326,7 +326,7 @@ pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); >> static const pgprot_t protection_map[16] = { >> [VM_NONE] = PAGE_NONE, >> [VM_READ] = PAGE_READ, >> - [VM_WRITE] = PAGE_COPY, >> + [VM_WRITE] = PAGE_SHADOWSTACK, >> [VM_WRITE | VM_READ] = PAGE_COPY, >> [VM_EXEC] = PAGE_EXEC, >> [VM_EXEC | VM_READ] = PAGE_READ_EXEC, >> diff --git a/mm/mmap.c b/mm/mmap.c >> index dd4b35a25aeb..b56f1e8cbfc6 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -47,6 +47,7 @@ >> #include >> #include >> #include >> +#include > >This seems benign enough, just wonder why you need it? I think leftover from previous versions. Will remove it. Don't think its needed here anymore. > >> >> #include >> #include >> >> -- >> 2.45.0 >>