Merge pull request #8822 from fbuihuu/rfc-tmpfiles-safe-upstream

Make tmpfiles safe

src/basic/btrfs-util.c

@@ -116,8 +116,25 @@ int btrfs_is_subvol(const char *path) {
         return btrfs_is_subvol_fd(fd);
 }
 
-int btrfs_subvol_make(const char *path) {
+int btrfs_subvol_make_fd(int fd, const char *subvolume) {
         struct btrfs_ioctl_vol_args args = {};
+        int r;
+
+        assert(subvolume);
+
+        r = validate_subvolume_name(subvolume);
+        if (r < 0)
+                return r;
+
+        strncpy(args.name, subvolume, sizeof(args.name)-1);
+
+        if (ioctl(fd, BTRFS_IOC_SUBVOL_CREATE, &args) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int btrfs_subvol_make(const char *path) {
         _cleanup_close_ int fd = -1;
         const char *subvolume;
         int r;
@@ -132,12 +149,7 @@ int btrfs_subvol_make(const char *path) {
         if (fd < 0)
                 return fd;
 
-        strncpy(args.name, subvolume, sizeof(args.name)-1);
-
-        if (ioctl(fd, BTRFS_IOC_SUBVOL_CREATE, &args) < 0)
-                return -errno;
-
-        return 0;
+        return btrfs_subvol_make_fd(fd, subvolume);
 }
 
 int btrfs_subvol_set_read_only_fd(int fd, bool b) {

src/basic/btrfs-util.h

@@ -65,6 +65,7 @@ int btrfs_resize_loopback_fd(int fd, uint64_t size, bool grow_only);
 int btrfs_resize_loopback(const char *path, uint64_t size, bool grow_only);
 
 int btrfs_subvol_make(const char *path);
+int btrfs_subvol_make_fd(int fd, const char *subvolume);
 
 int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, BtrfsSnapshotFlags flags);
 int btrfs_subvol_snapshot(const char *old_path, const char *new_path, BtrfsSnapshotFlags flags);

src/basic/fileio.c

@@ -1319,8 +1319,7 @@ int tempfn_random_child(const char *p, const char *extra, char **ret) {
                 r = tmp_dir(&p);
                 if (r < 0)
                         return r;
-        } else if (isempty(p))
-                return -EINVAL;
+        }
 
         extra = strempty(extra);
 
@@ -1328,7 +1327,10 @@ int tempfn_random_child(const char *p, const char *extra, char **ret) {
         if (!t)
                 return -ENOMEM;
 
-        x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
+        if (isempty(p))
+                x = stpcpy(stpcpy(t, ".#"), extra);
+        else
+                x = stpcpy(stpcpy(stpcpy(t, p), "/.#"), extra);
 
         u = random_u64();
         for (i = 0; i < 16; i++) {

src/basic/fs-util.c

@@ -435,6 +435,31 @@ int mkfifo_atomic(const char *path, mode_t mode) {
         return 0;
 }
 
+int mkfifoat_atomic(int dirfd, const char *path, mode_t mode) {
+        _cleanup_free_ char *t = NULL;
+        int r;
+
+        assert(path);
+
+        if (path_is_absolute(path))
+                return mkfifo_atomic(path, mode);
+
+        /* We're only interested in the (random) filename.  */
+        r = tempfn_random_child("", NULL, &t);
+        if (r < 0)
+                return r;
+
+        if (mkfifoat(dirfd, t, mode) < 0)
+                return -errno;
+
+        if (renameat(dirfd, t, dirfd, path) < 0) {
+                unlink_noerrno(t);
+                return -errno;
+        }
+
+        return 0;
+}
+
 int get_files_in_directory(const char *path, char ***list) {
         _cleanup_closedir_ DIR *d = NULL;
         struct dirent *de;
@@ -670,7 +695,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
         if (!original_root && !ret && (flags & (CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_OPEN|CHASE_STEP)) == CHASE_OPEN) {
                 /* Shortcut the CHASE_OPEN case if the caller isn't interested in the actual path and has no root set
                  * and doesn't care about any of the other special features we provide either. */
-                r = open(path, O_PATH|O_CLOEXEC);
+                r = open(path, O_PATH|O_CLOEXEC|((flags & CHASE_NOFOLLOW) ? O_NOFOLLOW : 0));
                 if (r < 0)
                         return -errno;
 
@@ -825,7 +850,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                     fd_is_fs_type(child, AUTOFS_SUPER_MAGIC) > 0)
                         return -EREMOTE;
 
-                if (S_ISLNK(st.st_mode)) {
+                if (S_ISLNK(st.st_mode) && !((flags & CHASE_NOFOLLOW) && isempty(todo))) {
                         char *joined;
 
                         _cleanup_free_ char *destination = NULL;

src/basic/fs-util.h

@@ -42,6 +42,7 @@ int symlink_idempotent(const char *from, const char *to);
 int symlink_atomic(const char *from, const char *to);
 int mknod_atomic(const char *path, mode_t mode, dev_t dev);
 int mkfifo_atomic(const char *path, mode_t mode);
+int mkfifoat_atomic(int dir_fd, const char *path, mode_t mode);
 
 int get_files_in_directory(const char *path, char ***list);
 
@@ -72,6 +73,7 @@ enum {
         CHASE_OPEN        = 1 << 4, /* If set, return an O_PATH object to the final component */
         CHASE_TRAIL_SLASH = 1 << 5, /* If set, any trailing slash will be preserved */
         CHASE_STEP        = 1 << 6, /* If set, just execute a single step of the normalization */
+        CHASE_NOFOLLOW    = 1 << 7, /* Only valid with CHASE_OPEN: when the path's right-most component refers to symlink return O_PATH fd of the symlink, rather than following it. */
 };
 
 /* How many iterations to execute before returning -ELOOP */

src/basic/label.h

@@ -12,6 +12,7 @@ typedef enum LabelFixFlags {
 int label_fix(const char *path, LabelFixFlags flags);
 
 int mkdir_label(const char *path, mode_t mode);
+int mkdirat_label(int dirfd, const char *path, mode_t mode);
 int symlink_label(const char *old_path, const char *new_path);
 
 int btrfs_subvol_make_label(const char *path);

src/basic/mkdir-label.c

@@ -28,6 +28,23 @@ int mkdir_label(const char *path, mode_t mode) {
         return mac_smack_fix(path, 0);
 }
 
+int mkdirat_label(int dirfd, const char *path, mode_t mode) {
+        int r;
+
+        assert(path);
+
+        r = mac_selinux_create_file_prepare_at(dirfd, path, S_IFDIR);
+        if (r < 0)
+                return r;
+
+        r = mkdirat_errno_wrapper(dirfd, path, mode);
+        mac_selinux_create_file_clear();
+        if (r < 0)
+                return r;
+
+        return mac_smack_fix_at(dirfd, path, 0);
+}
+
 int mkdir_safe_label(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags) {
         return mkdir_safe_internal(path, mode, uid, gid, flags, mkdir_label);
 }

src/basic/mkdir.c

@@ -80,6 +80,12 @@ int mkdir_errno_wrapper(const char *pathname, mode_t mode) {
         return 0;
 }
 
+int mkdirat_errno_wrapper(int dirfd, const char *pathname, mode_t mode) {
+        if (mkdirat(dirfd, pathname, mode) < 0)
+                return -errno;
+        return 0;
+}
+
 int mkdir_safe(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags) {
         return mkdir_safe_internal(path, mode, uid, gid, flags, mkdir_errno_wrapper);
 }

src/basic/mkdir.h

@@ -9,6 +9,7 @@ typedef enum MkdirFlags {
 } MkdirFlags;
 
 int mkdir_errno_wrapper(const char *pathname, mode_t mode);
+int mkdirat_errno_wrapper(int dirfd, const char *pathname, mode_t mode);
 int mkdir_safe(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
 int mkdir_parents(const char *path, mode_t mode);
 int mkdir_p(const char *path, mode_t mode);

src/basic/path-util.c

@@ -110,10 +110,7 @@ int path_make_absolute_cwd(const char *p, char **ret) {
                 if (r < 0)
                         return r;
 
-                if (endswith(cwd, "/"))
-                        c = strjoin(cwd, p);
-                else
-                        c = strjoin(cwd, "/", p);
+                c = path_join(NULL, cwd, p);
         }
         if (!c)
                 return -ENOMEM;

src/basic/selinux-util.c

@@ -316,47 +316,88 @@ char* mac_selinux_free(char *label) {
         return NULL;
 }
 
-int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
+#if HAVE_SELINUX
+static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode) {
+        _cleanup_freecon_ char *filecon = NULL;
+        _cleanup_free_ char *path = NULL;
+        int r;
+
+        assert(abspath);
+        assert(path_is_absolute(abspath));
+
+        r = selabel_lookup_raw(label_hnd, &filecon, abspath, mode);
+        if (r < 0) {
+                /* No context specified by the policy? Proceed without setting it. */
+                if (errno == ENOENT)
+                        return 0;
+
+                log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", abspath);
+        } else {
+                if (setfscreatecon_raw(filecon) >= 0)
+                        return 0; /* Success! */
+
+                log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, abspath);
+        }
+
+        if (security_getenforce() > 0)
+                return -errno;
+
+        return 0;
+}
+#endif
+
+int mac_selinux_create_file_prepare_at(int dirfd, const char *path, mode_t mode) {
+        int r = 0;
 
 #if HAVE_SELINUX
-        _cleanup_freecon_ char *filecon = NULL;
-        int r;
+        _cleanup_free_ char *abspath = NULL;
+        _cleanup_close_ int fd = -1;
 
         assert(path);
 
         if (!label_hnd)
                 return 0;
 
-        if (path_is_absolute(path))
-                r = selabel_lookup_raw(label_hnd, &filecon, path, mode);
-        else {
-                _cleanup_free_ char *newpath = NULL;
+        if (!path_is_absolute(path)) {
+                _cleanup_free_ char *p = NULL;
 
-                r = path_make_absolute_cwd(path, &newpath);
+                if (dirfd == AT_FDCWD)
+                        r = safe_getcwd(&p);
+                else
+                        r = fd_get_path(dirfd, &p);
                 if (r < 0)
                         return r;
 
-                r = selabel_lookup_raw(label_hnd, &filecon, newpath, mode);
+                abspath = path_join(NULL, p, path);
+                if (!abspath)
+                        return -ENOMEM;
+
+                path = abspath;
         }
 
-        if (r < 0) {
-                /* No context specified by the policy? Proceed without setting it. */
-                if (errno == ENOENT)
-                        return 0;
-
-                log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", path);
-        } else {
-                if (setfscreatecon_raw(filecon) >= 0)
-                        return 0; /* Success! */
-
-                log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, path);
-        }
-
-        if (security_getenforce() > 0)
-                return -errno;
-
+        r = selinux_create_file_prepare_abspath(path, mode);
 #endif
-        return 0;
+        return r;
+}
+
+int mac_selinux_create_file_prepare(const char *path, mode_t mode) {
+        int r = 0;
+
+#if HAVE_SELINUX
+        _cleanup_free_ char *abspath = NULL;
+
+        assert(path);
+
+        if (!label_hnd)
+                return 0;
+
+        r = path_make_absolute_cwd(path, &abspath);
+        if (r < 0)
+                return r;
+
+        r = selinux_create_file_prepare_abspath(abspath, mode);
+#endif
+        return r;
 }
 
 void mac_selinux_create_file_clear(void) {

src/basic/selinux-util.h

@@ -23,6 +23,7 @@ int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *
 char* mac_selinux_free(char *label);
 
 int mac_selinux_create_file_prepare(const char *path, mode_t mode);
+int mac_selinux_create_file_prepare_at(int dirfd, const char *path, mode_t mode);
 void mac_selinux_create_file_clear(void);
 
 int mac_selinux_create_socket_prepare(const char *label);

src/basic/smack-util.c

@@ -122,43 +122,20 @@ int mac_smack_apply_pid(pid_t pid, const char *label) {
         return r;
 }
 
-int mac_smack_fix(const char *path, LabelFixFlags flags) {
+static int smack_fix_fd(int fd , const char *abspath, LabelFixFlags flags) {
         char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
-        _cleanup_close_ int fd = -1;
         const char *label;
         struct stat st;
         int r;
 
-        assert(path);
+        /* The caller should have done the sanity checks. */
+        assert(abspath);
+        assert(path_is_absolute(abspath));
 
-        if (!mac_smack_use())
+        /* Path must be in /dev. */
+        if (!path_startswith(abspath, "/dev"))
                 return 0;
 
-        /* Path must be in /dev. Note that this check is pretty sloppy, as we might be called with non-normalized paths
-         * and hence not detect all cases of /dev. */
-
-        if (path_is_absolute(path)) {
-                if (!path_startswith(path, "/dev"))
-                        return 0;
-        } else {
-                _cleanup_free_ char *cwd = NULL;
-
-                r = safe_getcwd(&cwd);
-                if (r < 0)
-                        return r;
-
-                if (!path_startswith(cwd, "/dev"))
-                        return 0;
-        }
-
-        fd = open(path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
-        if (fd < 0) {
-                if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
-                        return 0;
-
-                return -errno;
-        }
-
         if (fstat(fd, &st) < 0)
                 return -errno;
 
@@ -196,12 +173,62 @@ int mac_smack_fix(const char *path, LabelFixFlags flags) {
                     streq(old_label, label))
                         return 0;
 
-                return log_debug_errno(r, "Unable to fix SMACK label of %s: %m", path);
+                return log_debug_errno(r, "Unable to fix SMACK label of %s: %m", abspath);
         }
 
         return 0;
 }
 
+int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
+        _cleanup_free_ char *p = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(path);
+
+        if (!mac_smack_use())
+                return 0;
+
+        fd = openat(dirfd, path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+        if (fd < 0) {
+                if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+                        return 0;
+
+                return -errno;
+        }
+
+        r = fd_get_path(fd, &p);
+        if (r < 0)
+                return r;
+
+        return smack_fix_fd(fd, p, flags);
+}
+
+int mac_smack_fix(const char *path, LabelFixFlags flags) {
+        _cleanup_free_ char *abspath = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(path);
+
+        if (!mac_smack_use())
+                return 0;
+
+        r = path_make_absolute_cwd(path, &abspath);
+        if (r < 0)
+                return r;
+
+        fd = open(abspath, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+        if (fd < 0) {
+                if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
+                        return 0;
+
+                return -errno;
+        }
+
+        return smack_fix_fd(fd, abspath, flags);
+}
+
 int mac_smack_copy(const char *dest, const char *src) {
         int r = 0;
         _cleanup_free_ char *label = NULL;
@@ -249,6 +276,10 @@ int mac_smack_fix(const char *path, LabelFixFlags flags) {
         return 0;
 }
 
+int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags) {
+        return 0;
+}
+
 int mac_smack_copy(const char *dest, const char *src) {
         return 0;
 }

src/basic/smack-util.h

@@ -30,6 +30,7 @@ typedef enum SmackAttr {
 bool mac_smack_use(void);
 
 int mac_smack_fix(const char *path, LabelFixFlags flags);
+int mac_smack_fix_at(int dirfd, const char *path, LabelFixFlags flags);
 
 const char* smack_attr_to_string(SmackAttr i) _const_;
 SmackAttr smack_attr_from_string(const char *s) _pure_;

src/basic/stat-util.c

@@ -45,6 +45,17 @@ int is_dir(const char* path, bool follow) {
         return !!S_ISDIR(st.st_mode);
 }
 
+int is_dir_fd(int fd) {
+        struct stat st;
+        int r;
+
+        r = fstat(fd, &st);
+        if (r < 0)
+                return -errno;
+
+        return !!S_ISDIR(st.st_mode);
+}
+
 int is_device_node(const char *path) {
         struct stat info;
 

src/basic/stat-util.h

@@ -12,6 +12,7 @@
 
 int is_symlink(const char *path);
 int is_dir(const char *path, bool follow);
+int is_dir_fd(int fd);
 int is_device_node(const char *path);
 
 int dir_is_empty(const char *path);