From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cyril Hrubis Date: Mon, 4 Mar 2019 13:30:09 +0100 Subject: [LTP] [PATCH v2] Add ltp pivot_root test In-Reply-To: <20190304122639.GA90147@google.com> References: <20190301185534.37513-1-paullawrence@google.com> <20190304122639.GA90147@google.com> Message-ID: <20190304123009.GA27682@rei.lan> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it Hi! > > +#include > > +#include > > +#include > > +#include > This include is not available on systems without libcap-devel or similar > installed. I suggest you compile this test conditional. A similar > mechanism is implemented for libaio-devel (HAVE_LIBAIO). We already have configure check for libcap in place so that has to be done is to include config.h and add some #ifdef HAVE_LIBCAP guards around the code that includes and the test. > > +#include > > +#include > > + > > +#include "tst_test.h" > > + > > +static const char* chroot_dir = "chroot"; > > +static const char* new_root = "/new_root"; > > +static const char* put_old = "/new_root/put_old"; > > + > > +// Test consists of a series of steps that allow pivot_root to succeed, which is > > +// run when param is NORMAL. All other values tweak one of the steps to induce > > +// a failure, and check the errno is as expected. > > +#define NORMAL 0 > > + > > +// EBUSY > > +// new_root or put_old are on the current root file system > > +#define NEW_ROOT_ON_CURRENT_ROOT 1 > > + > > +// EINVAL > > +// put_old is not underneath new_root > > +// Note: if put_old and new_root are on the same fs, > > +// pivot_root fails with EBUSY before testing reachability We are prefering to use /* */ for comments. > > +#define PUT_OLD_NOT_UNDERNEATH_NEW_ROOT 2 > > + > > +static const char* put_old_fs = "/put_old_fs"; > > +static const char* put_old_bad = "/put_old_fs/put_old"; > Even though these constants belong to this define, I would move them up > to have all string constants defined in a single place. > > > + > > +// ENOTDIR > > +// new_root or put_old is not a directory > > +#define PUT_OLD_NOT_DIR 3 > > + > > +// EPERM > > +// The calling process does not have the CAP_SYS_ADMIN capability. > > +#define NO_CAP_SYS_ADMIN 4 > > + > > +#define TEST_COUNT 5 > == ARRAY_SIZE(expected_error) ... and can be defined directly in the > tst_test struct. > > > + > > +static int expected_error[] = { > > + 0, > > + EBUSY, > > + EINVAL, > > + ENOTDIR, > > + EPERM, > > +}; > Maybe you are able to combine the defines, the documentation and this array > into one array of testcase structs. > (see e.g. testcases/kernel/syscalls/umount/umount02.c) > That would be a bit more descriptive and easier to add more test cases. > > > + > > +static void drop_cap_sys_admin(void) { > braces > > > + cap_value_t cap_value[] = { CAP_SYS_ADMIN }; > > + cap_t cap = cap_get_proc(); > > + if (!cap) > > + tst_brk(TFAIL | TERRNO, "cap_get_proc failed"); > > + > > + if (cap_set_flag(cap, CAP_EFFECTIVE, 1, cap_value, CAP_CLEAR)) > > + tst_brk(TFAIL | TERRNO, "cap_set_flag failed"); > > + > > + if (cap_set_proc(cap)) > > + tst_brk(TFAIL | TERRNO, "cap_set_proc failed"); > > +} > > + > > +#ifdef HAVE_UNSHARE > > +static void run(unsigned int param) > 'param' is a bit bit generic, how about 'testcase' ? > > > +{ > > + // Work in child process - needed to undo unshare and chroot > > + if (SAFE_FORK()) { > > + tst_reap_children(); > > + return; > > + } > > + > > + // pivot_root requires no shared mounts exist in process namespace > > + TEST(unshare(CLONE_NEWNS | CLONE_FS)); > > + if (TST_RET == -1) > > + tst_brk(TFAIL | TERRNO, "unshare failed"); > > + > > + // Create an initial root dir. pivot_root doesn't work if the initial root > > + // dir is a initramfs, so use chroot to create a safe environment > > + SAFE_MOUNT("none", "/", NULL, MS_REC|MS_PRIVATE, NULL); > > + SAFE_MOUNT("none", chroot_dir, "tmpfs", 0, 0); > > + SAFE_CHROOT(chroot_dir); > > + > > + // Create our new root location > > + SAFE_MKDIR(new_root, 0777); > > + > > + // pivot_root only works if new_root is a mount point, so mount a tmpfs > > + // unless testing for that fail mode > > + if (param != NEW_ROOT_ON_CURRENT_ROOT) > > + SAFE_MOUNT("none", new_root, "tmpfs", 0, 0); > > + > > + // Create put_old under new_root, unless testing for that specific fail > > + // mode > > + const char* actual_put_old = NULL; > > + if (param == PUT_OLD_NOT_UNDERNEATH_NEW_ROOT) { > > + actual_put_old = put_old_bad; > > + SAFE_MKDIR(put_old_fs, 0777); > > + SAFE_MOUNT("none", put_old_fs, "tmpfs", 0, 0); > > + SAFE_MKDIR(put_old_bad, 0777); > > + } else { > > + actual_put_old = put_old; > > + > > + // put_old must be a directory for success > > + if (param == PUT_OLD_NOT_DIR) > > + SAFE_CREAT(put_old, 0777); > > + else > > + SAFE_MKDIR(put_old, 0777); > > + } > > + > > + if (param == NO_CAP_SYS_ADMIN) > > + drop_cap_sys_admin(); > > + > > + // Test the syscall > > + TEST(syscall(__NR_pivot_root, new_root, actual_put_old)); > > + > > + // If NORMAL it should have succeeded > > + if (param == NORMAL) { > > + if (TST_RET) { > > + tst_res(TFAIL | TERRNO, "pivot_root failed"); > > + exit(TBROK); > > + } else { > > + tst_res(TPASS, "pivot_root succeeded"); > > + exit(TPASS); > > + } > > + } > > + > > + // pivot_root is expected to fail > > + if (TST_RET == 0) { > > + tst_res(TFAIL, "pivot_root succeeded unexpectedly"); > > + exit(TBROK); > > + } > > + > > + // Check error code is correct > > + if (errno != expected_error[param]) { > > + tst_res(TFAIL | TERRNO, "pivot_root failed with wrong errno"); > > + exit(TBROK); > > + } > > + > > + tst_res(TPASS, "pivot_root failed as expected with %s", > > + strerror(errno)); > > + exit(TPASS); > > +} > > + > > +#else > > +static void run(void) > > +{ > > + tst_brk(TCONF, NULL, "unshare is undefined."); > > +} > > +#endif > > + > > +static void setup(void) > > +{ > > + SAFE_MKDIR(chroot_dir, 0777); > > +} > > + > > +static struct tst_test test = { > > + .test = run, > > + .tcnt = TEST_COUNT, > > + .needs_tmpdir = 1, > > + .needs_root = 1, > > + .forks_child = 1, > > + .setup = setup, > > +}; > > -- > > 2.21.0.352.gf09ad66450-goog > > Thanks for addressing all the previous comments! > > -- > Cheers, > Matthias > > > -- > Mailing list info: https://lists.linux.it/listinfo/ltp -- Cyril Hrubis chrubis@suse.cz