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Biederman" , Alexander Viro Subject: [PATCH RESEND v2 02/18] block_dev: Check permissions towards block device inode when mounting Date: Mon, 4 Jan 2016 12:03:41 -0600 Message-Id: <1451930639-94331-3-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1451930639-94331-1-git-send-email-seth.forshee@canonical.com> References: <1451930639-94331-1-git-send-email-seth.forshee@canonical.com> X-TM-AS-MML: disable X-Mailman-Approved-At: Mon, 04 Jan 2016 13:14:22 -0500 X-BeenThere: selinux@tycho.nsa.gov X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Security-Enhanced Linux \(SELinux\) mailing list" List-Post: List-Help: Cc: Serge Hallyn , Seth Forshee , dm-devel@redhat.com, Miklos Szeredi , Richard Weinberger , linux-security-module@vger.kernel.org, linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, fuse-devel@lists.sourceforge.net, Austin S Hemmelgarn , linux-mtd@lists.infradead.org, selinux@tycho.nsa.gov, linux-fsdevel@vger.kernel.org MIME-Version: 1.0 Errors-To: selinux-bounces@tycho.nsa.gov Sender: "Selinux" X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Unprivileged users should not be able to mount block devices when they lack sufficient privileges towards the block device inode. Update blkdev_get_by_path() to validate that the user has the required access to the inode at the specified path. The check will be skipped for CAP_SYS_ADMIN, so privileged mounts will continue working as before. Signed-off-by: Seth Forshee Acked-by: Serge Hallyn --- fs/block_dev.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 3ebbde85d898..4fdb6ab59816 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1424,9 +1424,14 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, void *holder) { struct block_device *bdev; + int perm = 0; int err; - bdev = lookup_bdev(path, 0); + if (mode & FMODE_READ) + perm |= MAY_READ; + if (mode & FMODE_WRITE) + perm |= MAY_WRITE; + bdev = lookup_bdev(path, perm); if (IS_ERR(bdev)) return bdev;