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[34.168.184.9]) by smtp.gmail.com with UTF8SMTPSA id t13-20020a17090ae50d00b00277326038dasm868586pjy.39.2023.10.17.02.08.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Oct 2023 02:08:22 -0700 (PDT) From: jeffxu@chromium.org To: akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, sroettger@google.com, willy@infradead.org, gregkh@linuxfoundation.org, torvalds@linux-foundation.org Cc: jeffxu@google.com, jorgelo@chromium.org, groeck@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, surenb@google.com, alex.sierra@amd.com, apopple@nvidia.com, aneesh.kumar@linux.ibm.com, axelrasmussen@google.com, ben@decadent.org.uk, catalin.marinas@arm.com, david@redhat.com, dwmw@amazon.co.uk, ying.huang@intel.com, hughd@google.com, joey.gouly@arm.com, corbet@lwn.net, wangkefeng.wang@huawei.com, Liam.Howlett@oracle.com, lstoakes@gmail.com, mawupeng1@huawei.com, linmiaohe@huawei.com, namit@vmware.com, peterx@redhat.com, peterz@infradead.org, ryan.roberts@arm.com, shr@devkernel.io, vbabka@suse.cz, xiujianfeng@huawei.com, yu.ma@intel.com, zhangpeng362@huawei.com, dave.hansen@intel.com, luto@kernel.org, linux-hardening@vger.kernel.org Subject: [RFC PATCH v2 4/8] mseal: Check seal flag for mprotect(2) Date: Tue, 17 Oct 2023 09:08:11 +0000 Message-ID: <20231017090815.1067790-5-jeffxu@chromium.org> X-Mailer: git-send-email 2.42.0.655.g421f12c284-goog In-Reply-To: <20231017090815.1067790-1-jeffxu@chromium.org> References: <20231017090815.1067790-1-jeffxu@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Jeff Xu mprotect(2) changes protection of VMAs in the given address range. Sealing will prevent unintended mprotect call. What this patch does: When a mprotect(2) is invoked, if one of its VMAs has MM_SEAL_MPROTECT set from previous mseal(2) call, this mprotect(2) will fail, without any VMA modified. This patch is based on following: 1. do_mprotect_pkey() currently called in two places: SYSCALL_DEFINE3(mprotect,...) SYSCALL_DEFINE4(pkey_mprotect, ...) and not in any other places, therefore omit changing the signature of do_mprotect_pkey(), i.e. not passing checkSeals flag. 2. In do_mprotect_pkey(), calls can_modify_mm() before any update is made on the VMAs. Signed-off-by: Jeff Xu --- mm/mprotect.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/mprotect.c b/mm/mprotect.c index 130db91d3a8c..6321c4d0aa3f 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -753,6 +754,20 @@ static int do_mprotect_pkey(unsigned long start, size_t len, } } + /* + * do_mprotect_pkey() currently called from two places: + * SYSCALL_DEFINE3(mprotect,...) + * SYSCALL_DEFINE4(pkey_mprotect, ...) + * and not from other places. + * Therefore, omit changing the signature of do_mprotect_pkey(). + * Otherwise, we might need to add checkSeals and pass it + * from all callers of do_mprotect_pkey(). + */ + if (!can_modify_mm(current->mm, start, end, MM_SEAL_MPROTECT)) { + error = -EACCES; + goto out; + } + prev = vma_prev(&vmi); if (start > vma->vm_start) prev = vma;