diff options
| -rw-r--r-- | src/basic/mountpoint-util.c | 28 | ||||
| -rw-r--r-- | src/test/test-mountpoint-util.c | 32 | ||||
| -rw-r--r-- | src/test/test-path-util.c | 7 |
3 files changed, 60 insertions, 7 deletions
diff --git a/src/basic/mountpoint-util.c b/src/basic/mountpoint-util.c index 8bed96069f..a6602ad539 100644 --- a/src/basic/mountpoint-util.c +++ b/src/basic/mountpoint-util.c @@ -132,6 +132,29 @@ static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *ret_mn return safe_atoi(p, ret_mnt_id); } +static bool filename_possibly_with_slash_suffix(const char *s) { + const char *slash, *copied; + + /* Checks whether the specified string is either file name, or a filename with a suffix of + * slashes. But nothing else. + * + * this is OK: foo, bar, foo/, bar/, foo//, bar/// + * this is not OK: "", "/", "/foo", "foo/bar", ".", ".." … */ + + slash = strchr(s, '/'); + if (!slash) + return filename_is_valid(s); + + if (slash - s > FILENAME_MAX) /* We want to allocate on the stack below, hence do a size check first */ + return false; + + if (slash[strspn(slash, "/")] != 0) /* Check that the suffix consist only of one or more slashes */ + return false; + + copied = strndupa(s, slash - s); + return filename_is_valid(copied); +} + int fd_is_mount_point(int fd, const char *filename, int flags) { _cleanup_free_ struct file_handle *h = NULL, *h_parent = NULL; int mount_id = -1, mount_id_parent = -1; @@ -144,6 +167,11 @@ int fd_is_mount_point(int fd, const char *filename, int flags) { assert(filename); assert((flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH)) == 0); + /* Insist that the specified filename is actually a filename, and not a path, i.e. some inode further + * up or down the tree then immediately below the specified directory fd. */ + if (!filename_possibly_with_slash_suffix(filename)) + return -EINVAL; + /* First we will try statx()' STATX_ATTR_MOUNT_ROOT attribute, which is our ideal API, available * since kernel 5.8. * diff --git a/src/test/test-mountpoint-util.c b/src/test/test-mountpoint-util.c index 287488b7c1..47fde5cb2c 100644 --- a/src/test/test-mountpoint-util.c +++ b/src/test/test-mountpoint-util.c @@ -256,6 +256,37 @@ static void test_path_is_mount_point(void) { assert_se(rm_rf(tmp_dir, REMOVE_ROOT|REMOVE_PHYSICAL) == 0); } +static void test_fd_is_mount_point(void) { + _cleanup_close_ int fd = -1; + + log_info("/* %s */", __func__); + + fd = open("/", O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY); + assert_se(fd >= 0); + + /* Not allowed, since "/" is a path, not a plain filename */ + assert_se(fd_is_mount_point(fd, "/", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, ".", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "./", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "..", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "../", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "/proc", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "/proc/", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "proc/sys", 0) == -EINVAL); + assert_se(fd_is_mount_point(fd, "proc/sys/", 0) == -EINVAL); + + /* This one definitely is a mount point */ + assert_se(fd_is_mount_point(fd, "proc", 0) > 0); + assert_se(fd_is_mount_point(fd, "proc/", 0) > 0); + + /* /root's entire raison d'etre is to be on the root file system (i.e. not in /home/ which might be + * split off), so that the user can always log in, so it cannot be a mount point unless the system is + * borked. Let's allow for it to be missing though. */ + assert_se(IN_SET(fd_is_mount_point(fd, "root", 0), -ENOENT, 0)); + assert_se(IN_SET(fd_is_mount_point(fd, "root/", 0), -ENOENT, 0)); +} + int main(int argc, char *argv[]) { test_setup_logging(LOG_DEBUG); @@ -279,6 +310,7 @@ int main(int argc, char *argv[]) { test_mnt_id(); test_path_is_mount_point(); + test_fd_is_mount_point(); return 0; } diff --git a/src/test/test-path-util.c b/src/test/test-path-util.c index f4f8d0550b..cb91a1a979 100644 --- a/src/test/test-path-util.c +++ b/src/test/test-path-util.c @@ -6,7 +6,6 @@ #include "alloc-util.h" #include "fd-util.h" #include "macro.h" -#include "mountpoint-util.h" #include "path-util.h" #include "rm-rf.h" #include "stat-util.h" @@ -40,8 +39,6 @@ static void test_path_simplify(const char *in, const char *out, const char *out_ } static void test_path(void) { - _cleanup_close_ int fd = -1; - log_info("/* %s */", __func__); test_path_compare("/goo", "/goo", 0); @@ -80,10 +77,6 @@ static void test_path(void) { assert_se(streq(basename("/aa///file..."), "file...")); assert_se(streq(basename("file.../"), "")); - fd = open("/", O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY); - assert_se(fd >= 0); - assert_se(fd_is_mount_point(fd, "/", 0) > 0); - test_path_simplify("aaa/bbb////ccc", "aaa/bbb/ccc", "aaa/bbb/ccc"); test_path_simplify("//aaa/.////ccc", "/aaa/./ccc", "/aaa/ccc"); test_path_simplify("///", "/", "/"); |