From patchwork Wed Feb 19 10:01:52 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 13981876 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C504917A302; Wed, 19 Feb 2025 10:02:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739959344; cv=none; b=ngiDu7ZlwUFU905Jea0MeoMP119A7VTszBo2vIZ5dKYg/FLM4Ob0xyPgWbSI0Z78qS3/3Z0IdP37gpqKDjo0ZLIxxpwjKTxWsC9QN6SY8sLAJ5y6yvCPzXl3mXJ426Pk/aYBxMPXgvFLpO2o1RA4b2djIaWm1I4b54amkY6PqCY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739959344; c=relaxed/simple; bh=q41j+ox7rOuV1b/dMSn7KbOkJKy8kD1MpckFVr8+NFo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=tyliXUGVNMFyYJDZ+6jILmk2oPd0uWKr+ReBrA0ZXjGn8vseKQMO06ibKn9+Sylti1iyWnj2niTCs9YCK2WDGqBO8NbSSQcGNlSLaV80tzyroSpNJo8/nIg8bPPStV0ygroVlcUX+ASrQtYK2y1VzakQTPFgF3bKW6sFV8yB7eg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gc8CAVsl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gc8CAVsl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC24CC4CEEA; Wed, 19 Feb 2025 10:02:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739959344; bh=q41j+ox7rOuV1b/dMSn7KbOkJKy8kD1MpckFVr8+NFo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=gc8CAVslm3YtkEaUO3h60FqotlxMRKTDPL4NQmg5BVE3X3zGe//eKWCMv2Yc/SZ3B UYZuKYmhRD53oLwMY+eX0S/VXePYcjhFsUpnfGJnyZxUEc9aoudlSppBD+m5USZ/tG M+DgNtAm9rnWCruu2/yXvjntOvTr0jOd05W2Q5eWaNeFnpcfKu/oZ7IyekcXwKDg2p qJkI+vux6U8KdSsq7E39/bbaXCcX3OyI1O9ajUmMTHWMSk9m5z8Xg4QgGqJFTBCMVx vu4b0M8gc7EC8hGzJNIoYD6LJhoikaQPMVNIeSYERDcbp6VFMV3NKBg7zYNOrZieWd mHLddP309nYwg== From: Christian Brauner Date: Wed, 19 Feb 2025 11:01:52 +0100 Subject: [PATCH v3 4/4] selftests/ovl: add third selftest for "override_creds" Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250219-work-overlayfs-v3-4-46af55e4ceda@kernel.org> References: <20250219-work-overlayfs-v3-0-46af55e4ceda@kernel.org> In-Reply-To: <20250219-work-overlayfs-v3-0-46af55e4ceda@kernel.org> To: Miklos Szeredi , Amir Goldstein , Seth Forshee Cc: Gopal Kakivaya , linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christian Brauner X-Mailer: b4 0.15-dev-d23a9 X-Developer-Signature: v=1; a=openpgp-sha256; l=5035; i=brauner@kernel.org; h=from:subject:message-id; bh=q41j+ox7rOuV1b/dMSn7KbOkJKy8kD1MpckFVr8+NFo=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaRvXaN2c81Ur4bchKO/rK147iooJk9PEy1Y3VX+555a4 A7d49V+HaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABPh8GT477gs8JjJ4luvyk8e EH5err+q/vhN4bCdU/+UPDobJ/Fuszgjw6tv85jWH70cYSLdEXzZpliP4/ORHxUOwnuVP33j9Zl 1jw8A X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Add a simple test to verify that the new "override_creds" option works. Signed-off-by: Christian Brauner Reviewed-by: Amir Goldstein --- .../filesystems/overlayfs/set_layers_via_fds.c | 80 ++++++++++++++++++++++ tools/testing/selftests/filesystems/utils.c | 27 ++++++++ tools/testing/selftests/filesystems/utils.h | 1 + 3 files changed, 108 insertions(+) diff --git a/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c index 6b65e3610578..fd1e5d7c13a3 100644 --- a/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c +++ b/tools/testing/selftests/filesystems/overlayfs/set_layers_via_fds.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include @@ -442,4 +443,83 @@ TEST_F(set_layers_via_fds, set_override_creds_invalid) ASSERT_EQ(close(fd_userns2), 0); } +TEST_F(set_layers_via_fds, set_override_creds_nomknod) +{ + int fd_context, fd_tmpfs, fd_overlay; + int layer_fds[] = { [0 ... 3] = -EBADF }; + pid_t pid; + int pidfd; + + ASSERT_EQ(unshare(CLONE_NEWNS), 0); + ASSERT_EQ(sys_mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL), 0); + + fd_context = sys_fsopen("tmpfs", 0); + ASSERT_GE(fd_context, 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0); + fd_tmpfs = sys_fsmount(fd_context, 0, 0); + ASSERT_GE(fd_tmpfs, 0); + ASSERT_EQ(close(fd_context), 0); + + ASSERT_EQ(mkdirat(fd_tmpfs, "w", 0755), 0); + ASSERT_EQ(mkdirat(fd_tmpfs, "u", 0755), 0); + ASSERT_EQ(mkdirat(fd_tmpfs, "l1", 0755), 0); + ASSERT_EQ(mkdirat(fd_tmpfs, "l2", 0755), 0); + + layer_fds[0] = openat(fd_tmpfs, "w", O_DIRECTORY); + ASSERT_GE(layer_fds[0], 0); + + layer_fds[1] = openat(fd_tmpfs, "u", O_DIRECTORY); + ASSERT_GE(layer_fds[1], 0); + + layer_fds[2] = openat(fd_tmpfs, "l1", O_DIRECTORY); + ASSERT_GE(layer_fds[2], 0); + + layer_fds[3] = openat(fd_tmpfs, "l2", O_DIRECTORY); + ASSERT_GE(layer_fds[3], 0); + + ASSERT_EQ(sys_move_mount(fd_tmpfs, "", -EBADF, "/tmp", MOVE_MOUNT_F_EMPTY_PATH), 0); + ASSERT_EQ(close(fd_tmpfs), 0); + + fd_context = sys_fsopen("overlay", 0); + ASSERT_GE(fd_context, 0); + + ASSERT_NE(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir", NULL, layer_fds[2]), 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "workdir", NULL, layer_fds[0]), 0); + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "upperdir", NULL, layer_fds[1]), 0); + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[2]), 0); + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FD, "lowerdir+", NULL, layer_fds[3]), 0); + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "userxattr", NULL, 0), 0); + + pid = create_child(&pidfd, 0); + ASSERT_GE(pid, 0); + if (pid == 0) { + if (!cap_down(CAP_MKNOD)) + _exit(EXIT_FAILURE); + + if (!cap_down(CAP_SYS_ADMIN)) + _exit(EXIT_FAILURE); + + if (sys_fsconfig(fd_context, FSCONFIG_SET_FLAG, "override_creds", NULL, 0)) + _exit(EXIT_FAILURE); + + _exit(EXIT_SUCCESS); + } + ASSERT_EQ(sys_waitid(P_PID, pid, NULL, WEXITED), 0); + ASSERT_GE(close(pidfd), 0); + + ASSERT_EQ(sys_fsconfig(fd_context, FSCONFIG_CMD_CREATE, NULL, NULL, 0), 0); + + fd_overlay = sys_fsmount(fd_context, 0, 0); + ASSERT_GE(fd_overlay, 0); + + ASSERT_EQ(sys_move_mount(fd_overlay, "", -EBADF, "/set_layers_via_fds", MOVE_MOUNT_F_EMPTY_PATH), 0); + ASSERT_EQ(mknodat(fd_overlay, "dev-zero", S_IFCHR | 0644, makedev(1, 5)), -1); + ASSERT_EQ(errno, EPERM); + + ASSERT_EQ(close(fd_context), 0); + ASSERT_EQ(close(fd_overlay), 0); +} + TEST_HARNESS_MAIN diff --git a/tools/testing/selftests/filesystems/utils.c b/tools/testing/selftests/filesystems/utils.c index 0e8080bd0aea..e553c89c5b19 100644 --- a/tools/testing/selftests/filesystems/utils.c +++ b/tools/testing/selftests/filesystems/utils.c @@ -472,3 +472,30 @@ int caps_down(void) cap_free(caps); return fret; } + +/* cap_down - lower an effective cap */ +int cap_down(cap_value_t down) +{ + bool fret = false; + cap_t caps = NULL; + cap_value_t cap = down; + int ret = -1; + + caps = cap_get_proc(); + if (!caps) + goto out; + + ret = cap_set_flag(caps, CAP_EFFECTIVE, 1, &cap, 0); + if (ret) + goto out; + + ret = cap_set_proc(caps); + if (ret) + goto out; + + fret = true; + +out: + cap_free(caps); + return fret; +} diff --git a/tools/testing/selftests/filesystems/utils.h b/tools/testing/selftests/filesystems/utils.h index f35001a75f99..7f1df2a3e94c 100644 --- a/tools/testing/selftests/filesystems/utils.h +++ b/tools/testing/selftests/filesystems/utils.h @@ -24,6 +24,7 @@ extern int get_userns_fd(unsigned long nsid, unsigned long hostid, unsigned long range); extern int caps_down(void); +extern int cap_down(cap_value_t down); extern bool switch_ids(uid_t uid, gid_t gid);