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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id f2sm7244500pfb.184.2020.07.24.14.36.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jul 2020 14:36:53 -0700 (PDT) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Scott Branden , Mimi Zohar , Luis Chamberlain , Jessica Yu , SeongJae Park , KP Singh , linux-efi@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 15/19] IMA: Add support for file reads without contents Date: Fri, 24 Jul 2020 14:36:36 -0700 Message-Id: <20200724213640.389191-16-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200724213640.389191-1-keescook@chromium.org> References: <20200724213640.389191-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Scott Branden When the kernel_read_file LSM hook is called with contents=false, IMA can appraise the file directly, without requiring a filled buffer. When such a buffer is available, though, IMA can continue to use it instead of forcing a double read here. Signed-off-by: Scott Branden Link: https://lore.kernel.org/lkml/20200706232309.12010-10-scott.branden@broadcom.com/ Signed-off-by: Kees Cook --- security/integrity/ima/ima_main.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index dc4f90660aa6..459e50526a12 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -613,11 +613,8 @@ void ima_post_path_mknod(struct dentry *dentry) int ima_read_file(struct file *file, enum kernel_read_file_id read_id, bool contents) { - /* Reject all partial reads during appraisal. */ - if (!contents) { - if (ima_appraise & IMA_APPRAISE_ENFORCE) - return -EACCES; - } + enum ima_hooks func; + u32 secid; /* * Do devices using pre-allocated memory run the risk of the @@ -626,7 +623,20 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id, * buffers? It may be desirable to include the buffer address * in this API and walk all the dma_map_single() mappings to check. */ - return 0; + + /* + * There will be a call made to ima_post_read_file() with + * a filled buffer, so we don't need to perform an extra + * read early here. + */ + if (contents) + return 0; + + /* Read entire file for all partial reads during appraisal. */ + func = read_idmap[read_id] ?: FILE_CHECK; + security_task_getsecid(current, &secid); + return process_measurement(file, current_cred(), secid, NULL, + 0, MAY_READ, func); } const int read_idmap[READING_MAX_ID] = { -- 2.25.1