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[35.204.162.40]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5e4c3fb6067sm6248635a12.50.2025.03.02.21.09.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 02 Mar 2025 21:09:39 -0800 (PST) From: jeffxu@chromium.org To: akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, torvalds@linux-foundation.org, vbabka@suse.cz, lorenzo.stoakes@oracle.com, Liam.Howlett@Oracle.com, adhemerval.zanella@linaro.org, oleg@redhat.com, avagin@gmail.com, benjamin@sipsolutions.net Cc: linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, jorgelo@chromium.org, sroettger@google.com, hch@lst.de, ojeda@kernel.org, thomas.weissschuh@linutronix.de, adobriyan@gmail.com, johannes@sipsolutions.net, pedro.falcato@gmail.com, hca@linux.ibm.com, willy@infradead.org, anna-maria@linutronix.de, mark.rutland@arm.com, linus.walleij@linaro.org, Jason@zx2c4.com, deller@gmx.de, rdunlap@infradead.org, davem@davemloft.net, peterx@redhat.com, f.fainelli@gmail.com, gerg@kernel.org, dave.hansen@linux.intel.com, mingo@kernel.org, ardb@kernel.org, mhocko@suse.com, 42.hyeyoo@gmail.com, peterz@infradead.org, ardb@google.com, enh@google.com, rientjes@google.com, groeck@chromium.org, mpe@ellerman.id.au, aleksandr.mikhalitsyn@canonical.com, mike.rapoport@gmail.com, Jeff Xu , Kees Cook Subject: [PATCH v8 6/7] mseal sysmap: update mseal.rst Date: Mon, 3 Mar 2025 05:09:20 +0000 Message-ID: <20250303050921.3033083-7-jeffxu@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog In-Reply-To: <20250303050921.3033083-1-jeffxu@google.com> References: <20250303050921.3033083-1-jeffxu@google.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Jeff Xu Update memory sealing documentation to include details about system mappings. Signed-off-by: Jeff Xu Reviewed-by: Kees Cook Reviewed-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett --- Documentation/userspace-api/mseal.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/userspace-api/mseal.rst b/Documentation/userspace-api/mseal.rst index 41102f74c5e2..76e10938302a 100644 --- a/Documentation/userspace-api/mseal.rst +++ b/Documentation/userspace-api/mseal.rst @@ -130,6 +130,26 @@ Use cases - Chrome browser: protect some security sensitive data structures. +- System mappings: + The system mappings are created by the kernel and includes vdso, vvar, + vvar_vclock, vectors (arm compact-mode), sigpage (arm compact-mode), uprobes. + + Those system mappings are readonly only or execute only, memory sealing can + protect them from ever changing to writable or unmmap/remapped as different + attributes. This is useful to mitigate memory corruption issues where a + corrupted pointer is passed to a memory management system. + + If supported by an architecture (CONFIG_ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS), + the CONFIG_MSEAL_SYSTEM_MAPPINGS seals all system mappings of this + architecture. + + The following architectures currently support this feature: x86-64 and arm64. + + WARNING: This feature breaks programs which rely on relocating + or unmapping system mappings. Known broken software at the time + of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore + this config can't be enabled universally. + When not to use mseal ===================== Applications can apply sealing to any virtual memory region from userspace,