nspawn: move uid shift/chown() code into shared/

6 files changed, 1 insertions, 544 deletions

diff --git a/src/nspawn/meson.build b/src/nspawn/meson.build
index 2a913b156d..26a7e7bfb9 100644
--- a/src/nspawn/meson.build
+++ b/src/nspawn/meson.build
@@ -7,7 +7,6 @@ libnspawn_core_sources = files(
         'nspawn-mount.c',
         'nspawn-network.c',
         'nspawn-oci.c',
-        'nspawn-patch-uid.c',
         'nspawn-register.c',
         'nspawn-seccomp.c',
         'nspawn-settings.c',
@@ -63,12 +62,6 @@ executables += [
         nspawn_test_template + {
                 'sources' : files('test-nspawn-util.c'),
         },
-        test_template + {
-                'sources' : files('test-patch-uid.c'),
-                'link_with' : nspawn_libs,
-                'dependencies' : libacl,
-                'type' : 'manual',
-        },
         nspawn_fuzz_template + {
                 'sources' : files('fuzz-nspawn-settings.c'),
         },
diff --git a/src/nspawn/nspawn-def.h b/src/nspawn/nspawn-def.h
deleted file mode 100644
index 32a20aabd5..0000000000
--- a/src/nspawn/nspawn-def.h
+++ /dev/null
@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-#pragma once
-
-#include <sys/types.h>
-
-/* While we are chmod()ing a directory tree, we set the top-level UID base to this "busy" base, so that we can always
- * recognize trees we are were chmod()ing recursively and got interrupted in */
-#define UID_BUSY_BASE ((uid_t) UINT32_C(0xFFFE0000))
-#define UID_BUSY_MASK ((uid_t) UINT32_C(0xFFFF0000))
diff --git a/src/nspawn/nspawn-patch-uid.c b/src/nspawn/nspawn-patch-uid.c
deleted file mode 100644
index b8918a2315..0000000000
--- a/src/nspawn/nspawn-patch-uid.c
+++ /dev/null
@@ -1,477 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-
-#include <fcntl.h>
-#include <sys/statvfs.h>
-#include <sys/vfs.h>
-#include <unistd.h>
-
-#include "acl-util.h"
-#include "dirent-util.h"
-#include "fd-util.h"
-#include "fileio.h"
-#include "fs-util.h"
-#include "missing_magic.h"
-#include "nspawn-def.h"
-#include "nspawn-patch-uid.h"
-#include "stat-util.h"
-#include "stdio-util.h"
-#include "string-util.h"
-#include "strv.h"
-#include "user-util.h"
-
-#if HAVE_ACL
-
-static int get_acl(int fd, const char *name, acl_type_t type, acl_t *ret) {
-        acl_t acl;
-
-        assert(fd >= 0);
-        assert(ret);
-
-        if (name) {
-                _cleanup_close_ int child_fd = -EBADF;
-
-                child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
-                if (child_fd < 0)
-                        return -errno;
-
-                acl = acl_get_file(FORMAT_PROC_FD_PATH(child_fd), type);
-        } else if (type == ACL_TYPE_ACCESS)
-                acl = acl_get_fd(fd);
-        else
-                acl = acl_get_file(FORMAT_PROC_FD_PATH(fd), type);
-        if (!acl)
-                return -errno;
-
-        *ret = acl;
-        return 0;
-}
-
-static int set_acl(int fd, const char *name, acl_type_t type, acl_t acl) {
-        int r;
-
-        assert(fd >= 0);
-        assert(acl);
-
-        if (name) {
-                _cleanup_close_ int child_fd = -EBADF;
-
-                child_fd = openat(fd, name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
-                if (child_fd < 0)
-                        return -errno;
-
-                r = acl_set_file(FORMAT_PROC_FD_PATH(child_fd), type, acl);
-        } else if (type == ACL_TYPE_ACCESS)
-                r = acl_set_fd(fd, acl);
-        else
-                r = acl_set_file(FORMAT_PROC_FD_PATH(fd), type, acl);
-        if (r < 0)
-                return -errno;
-
-        return 0;
-}
-
-static int shift_acl(acl_t acl, uid_t shift, acl_t *ret) {
-        _cleanup_(acl_freep) acl_t copy = NULL;
-        acl_entry_t i;
-        int r;
-
-        assert(acl);
-        assert(ret);
-
-        r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
-        if (r < 0)
-                return -errno;
-        while (r > 0) {
-                uid_t *old_uid, new_uid;
-                bool modify = false;
-                acl_tag_t tag;
-
-                if (acl_get_tag_type(i, &tag) < 0)
-                        return -errno;
-
-                if (IN_SET(tag, ACL_USER, ACL_GROUP)) {
-
-                        /* We don't distinguish here between uid_t and gid_t, let's make sure the compiler checks that
-                         * this is actually OK */
-                        assert_cc(sizeof(uid_t) == sizeof(gid_t));
-
-                        old_uid = acl_get_qualifier(i);
-                        if (!old_uid)
-                                return -errno;
-
-                        new_uid = shift | (*old_uid & UINT32_C(0xFFFF));
-                        if (!uid_is_valid(new_uid))
-                                return -EINVAL;
-
-                        modify = new_uid != *old_uid;
-                        if (modify && !copy) {
-                                int n;
-
-                                /* There's no copy of the ACL yet? if so, let's create one, and start the loop from the
-                                 * beginning, so that we copy all entries, starting from the first, this time. */
-
-                                n = acl_entries(acl);
-                                if (n < 0)
-                                        return -errno;
-
-                                copy = acl_init(n);
-                                if (!copy)
-                                        return -errno;
-
-                                /* Seek back to the beginning */
-                                r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
-                                if (r < 0)
-                                        return -errno;
-                                continue;
-                        }
-                }
-
-                if (copy) {
-                        acl_entry_t new_entry;
-
-                        if (acl_create_entry(&copy, &new_entry) < 0)
-                                return -errno;
-
-                        if (acl_copy_entry(new_entry, i) < 0)
-                                return -errno;
-
-                        if (modify)
-                                if (acl_set_qualifier(new_entry, &new_uid) < 0)
-                                        return -errno;
-                }
-
-                r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i);
-                if (r < 0)
-                        return -errno;
-        }
-
-        *ret = TAKE_PTR(copy);
-
-        return !!*ret;
-}
-
-static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) {
-        _cleanup_(acl_freep) acl_t acl = NULL, shifted = NULL;
-        bool changed = false;
-        int r;
-
-        assert(fd >= 0);
-        assert(st);
-
-        /* ACLs are not supported on symlinks, there's no point in trying */
-        if (S_ISLNK(st->st_mode))
-                return 0;
-
-        r = get_acl(fd, name, ACL_TYPE_ACCESS, &acl);
-        if (r == -EOPNOTSUPP)
-                return 0;
-        if (r < 0)
-                return r;
-
-        r = shift_acl(acl, shift, &shifted);
-        if (r < 0)
-                return r;
-        if (r > 0) {
-                r = set_acl(fd, name, ACL_TYPE_ACCESS, shifted);
-                if (r < 0)
-                        return r;
-
-                changed = true;
-        }
-
-        if (S_ISDIR(st->st_mode)) {
-                acl_free(acl);
-
-                if (shifted)
-                        acl_free(shifted);
-
-                acl = shifted = NULL;
-
-                r = get_acl(fd, name, ACL_TYPE_DEFAULT, &acl);
-                if (r < 0)
-                        return r;
-
-                r = shift_acl(acl, shift, &shifted);
-                if (r < 0)
-                        return r;
-                if (r > 0) {
-                        r = set_acl(fd, name, ACL_TYPE_DEFAULT, shifted);
-                        if (r < 0)
-                                return r;
-
-                        changed = true;
-                }
-        }
-
-        return changed;
-}
-
-#else
-
-static int patch_acls(int fd, const char *name, const struct stat *st, uid_t shift) {
-        return 0;
-}
-
-#endif
-
-static int patch_fd(int fd, const char *name, const struct stat *st, uid_t shift) {
-        uid_t new_uid;
-        gid_t new_gid;
-        bool changed = false;
-        int r;
-
-        assert(fd >= 0);
-        assert(st);
-
-        new_uid =         shift | (st->st_uid & UINT32_C(0xFFFF));
-        new_gid = (gid_t) shift | (st->st_gid & UINT32_C(0xFFFF));
-
-        if (!uid_is_valid(new_uid) || !gid_is_valid(new_gid))
-                return -EINVAL;
-
-        if (st->st_uid != new_uid || st->st_gid != new_gid) {
-                if (name)
-                        r = fchownat(fd, name, new_uid, new_gid, AT_SYMLINK_NOFOLLOW);
-                else
-                        r = fchown(fd, new_uid, new_gid);
-                if (r < 0)
-                        return -errno;
-
-                /* The Linux kernel alters the mode in some cases of chown(). Let's undo this. */
-                if (name) {
-                        if (!S_ISLNK(st->st_mode))
-                                r = fchmodat(fd, name, st->st_mode, 0);
-                        else /* Changing the mode of a symlink is not supported by Linux kernel. Don't bother. */
-                                r = 0;
-                } else
-                        r = fchmod(fd, st->st_mode);
-                if (r < 0)
-                        return -errno;
-
-                changed = true;
-        }
-
-        r = patch_acls(fd, name, st, shift);
-        if (r < 0)
-                return r;
-
-        return r > 0 || changed;
-}
-
-/*
- * Check if the filesystem is fully compatible with user namespaces or
- * UID/GID patching. Some filesystems in this list can be fully mounted inside
- * user namespaces, however their inodes may relate to host resources or only
- * valid in the global user namespace, therefore no patching should be applied.
- */
-static int is_fs_fully_userns_compatible(const struct statfs *sfs) {
-
-        assert(sfs);
-
-        return F_TYPE_EQUAL(sfs->f_type, BINFMTFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, CGROUP_SUPER_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, CGROUP2_SUPER_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, DEBUGFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, DEVPTS_SUPER_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, EFIVARFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, HUGETLBFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, MQUEUE_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, PROC_SUPER_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, PSTOREFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, SELINUX_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, SMACK_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, SECURITYFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, BPF_FS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, TRACEFS_MAGIC) ||
-               F_TYPE_EQUAL(sfs->f_type, SYSFS_MAGIC);
-}
-
-static int recurse_fd(int fd, bool donate_fd, const struct stat *st, uid_t shift, bool is_toplevel) {
-        _cleanup_closedir_ DIR *d = NULL;
-        bool changed = false;
-        struct statfs sfs;
-        int r;
-
-        assert(fd >= 0);
-
-        if (fstatfs(fd, &sfs) < 0)
-                return -errno;
-
-        /* We generally want to permit crossing of mount boundaries when patching the UIDs/GIDs. However, we probably
-         * shouldn't do this for /proc and /sys if that is already mounted into place. Hence, let's stop the recursion
-         * when we hit procfs, sysfs or some other special file systems. */
-
-        r = is_fs_fully_userns_compatible(&sfs);
-        if (r < 0)
-                goto finish;
-        if (r > 0) {
-                r = 0; /* don't recurse */
-                goto finish;
-        }
-
-        /* Also, if we hit a read-only file system, then don't bother, skip the whole subtree */
-        if ((sfs.f_flags & ST_RDONLY) ||
-            access_fd(fd, W_OK) == -EROFS)
-                goto read_only;
-
-        if (S_ISDIR(st->st_mode)) {
-                if (!donate_fd) {
-                        int copy;
-
-                        copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
-                        if (copy < 0) {
-                                r = -errno;
-                                goto finish;
-                        }
-
-                        fd = copy;
-                        donate_fd = true;
-                }
-
-                d = take_fdopendir(&fd);
-                if (!d) {
-                        r = -errno;
-                        goto finish;
-                }
-
-                FOREACH_DIRENT_ALL(de, d, r = -errno; goto finish) {
-                        struct stat fst;
-
-                        if (dot_or_dot_dot(de->d_name))
-                                continue;
-
-                        if (fstatat(dirfd(d), de->d_name, &fst, AT_SYMLINK_NOFOLLOW) < 0) {
-                                r = -errno;
-                                goto finish;
-                        }
-
-                        if (S_ISDIR(fst.st_mode)) {
-                                int subdir_fd;
-
-                                subdir_fd = openat(dirfd(d), de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
-                                if (subdir_fd < 0) {
-                                        r = -errno;
-                                        goto finish;
-
-                                }
-
-                                r = recurse_fd(subdir_fd, true, &fst, shift, false);
-                                if (r < 0)
-                                        goto finish;
-                                if (r > 0)
-                                        changed = true;
-
-                        } else {
-                                r = patch_fd(dirfd(d), de->d_name, &fst, shift);
-                                if (r < 0)
-                                        goto finish;
-                                if (r > 0)
-                                        changed = true;
-                        }
-                }
-        }
-
-        /* After we descended, also patch the directory itself. It's key to do this in this order so that the top-level
-         * directory is patched as very last object in the tree, so that we can use it as quick indicator whether the
-         * tree is properly chown()ed already. */
-        r = patch_fd(d ? dirfd(d) : fd, NULL, st, shift);
-        if (r == -EROFS)
-                goto read_only;
-        if (r > 0)
-                changed = true;
-
-        r = changed;
-        goto finish;
-
-read_only:
-        if (!is_toplevel) {
-                _cleanup_free_ char *name = NULL;
-
-                /* When we hit a ready-only subtree we simply skip it, but log about it. */
-                (void) fd_get_path(fd, &name);
-                log_debug("Skipping read-only file or directory %s.", strna(name));
-                r = changed;
-        }
-
-finish:
-        if (donate_fd)
-                safe_close(fd);
-
-        return r;
-}
-
-static int fd_patch_uid_internal(int fd, bool donate_fd, uid_t shift, uid_t range) {
-        struct stat st;
-        int r;
-
-        assert(fd >= 0);
-
-        /* Recursively adjusts the UID/GIDs of all files of a directory tree. This is used to automatically fix up an
-         * OS tree to the used user namespace UID range. Note that this automatic adjustment only works for UID ranges
-         * following the concept that the upper 16-bit of a UID identify the container, and the lower 16-bit are the actual
-         * UID within the container. */
-
-        if ((shift & 0xFFFF) != 0) {
-                /* We only support containers where the shift starts at a 2^16 boundary */
-                r = -EOPNOTSUPP;
-                goto finish;
-        }
-
-        if (shift == UID_BUSY_BASE) {
-                r = -EINVAL;
-                goto finish;
-        }
-
-        if (range != 0x10000) {
-                /* We only support containers with 16-bit UID ranges for the patching logic */
-                r = -EOPNOTSUPP;
-                goto finish;
-        }
-
-        if (fstat(fd, &st) < 0) {
-                r = -errno;
-                goto finish;
-        }
-
-        if ((uint32_t) st.st_uid >> 16 != (uint32_t) st.st_gid >> 16) {
-                /* We only support containers where the uid/gid container ID match */
-                r = -EBADE;
-                goto finish;
-        }
-
-        /* Try to detect if the range is already right. Of course, this a pretty drastic optimization, as we assume
-         * that if the top-level dir has the right upper 16-bit assigned, then everything below will have too... */
-        if (((uint32_t) (st.st_uid ^ shift) >> 16) == 0)
-                return 0;
-
-        /* Before we start recursively chowning, mark the top-level dir as "busy" by chowning it to the "busy"
-         * range. Should we be interrupted in the middle of our work, we'll see it owned by this user and will start
-         * chown()ing it again, unconditionally, as the busy UID is not a valid UID we'd everpick for ourselves. */
-
-        if ((st.st_uid & UID_BUSY_MASK) != UID_BUSY_BASE) {
-                if (fchown(fd,
-                           UID_BUSY_BASE | (st.st_uid & ~UID_BUSY_MASK),
-                           (gid_t) UID_BUSY_BASE | (st.st_gid & ~(gid_t) UID_BUSY_MASK)) < 0) {
-                        r = -errno;
-                        goto finish;
-                }
-        }
-
-        return recurse_fd(fd, donate_fd, &st, shift, true);
-
-finish:
-        if (donate_fd)
-                safe_close(fd);
-
-        return r;
-}
-
-int path_patch_uid(const char *path, uid_t shift, uid_t range) {
-        int fd;
-
-        fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
-        if (fd < 0)
-                return -errno;
-
-        return fd_patch_uid_internal(fd, true, shift, range);
-}
diff --git a/src/nspawn/nspawn-patch-uid.h b/src/nspawn/nspawn-patch-uid.h
deleted file mode 100644
index 5c7349bc73..0000000000
--- a/src/nspawn/nspawn-patch-uid.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-
-#pragma once
-
-#include <sys/types.h>
-
-int path_patch_uid(const char *path, uid_t shift, uid_t range);
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index dddb3c5747..c2f232ae79 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -74,7 +74,6 @@
 #include "nspawn-mount.h"
 #include "nspawn-network.h"
 #include "nspawn-oci.h"
-#include "nspawn-patch-uid.h"
 #include "nspawn-register.h"
 #include "nspawn-seccomp.h"
 #include "nspawn-settings.h"
@@ -97,6 +96,7 @@
 #include "rlimit-util.h"
 #include "rm-rf.h"
 #include "seccomp-util.h"
+#include "shift-uid.h"
 #include "signal-util.h"
 #include "socket-util.h"
 #include "stat-util.h"
diff --git a/src/nspawn/test-patch-uid.c b/src/nspawn/test-patch-uid.c
deleted file mode 100644
index f8f44b0b0b..0000000000
--- a/src/nspawn/test-patch-uid.c
+++ /dev/null
@@ -1,43 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-
-#include <stdlib.h>
-
-#include "log.h"
-#include "nspawn-patch-uid.h"
-#include "user-util.h"
-#include "string-util.h"
-#include "tests.h"
-
-int main(int argc, char *argv[]) {
-        uid_t shift, range;
-        int r;
-
-        test_setup_logging(LOG_DEBUG);
-
-        if (argc != 4) {
-                log_error("Expected PATH SHIFT RANGE parameters.");
-                return EXIT_FAILURE;
-        }
-
-        r = parse_uid(argv[2], &shift);
-        if (r < 0) {
-                log_error_errno(r, "Failed to parse UID shift %s.", argv[2]);
-                return EXIT_FAILURE;
-        }
-
-        r = parse_gid(argv[3], &range);
-        if (r < 0) {
-                log_error_errno(r, "Failed to parse UID range %s.", argv[3]);
-                return EXIT_FAILURE;
-        }
-
-        r = path_patch_uid(argv[1], shift, range);
-        if (r < 0) {
-                log_error_errno(r, "Failed to patch directory tree: %m");
-                return EXIT_FAILURE;
-        }
-
-        log_info("Changed: %s", yes_no(r));
-
-        return EXIT_SUCCESS;
-}