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0c443a8800
The header provides _MIPS_SIM_ABI32 and friends. Glibc indirectly includes the header through sys/syscall.h or unistd.h, but let's explicitly include the header where we use _MIPS_SIM_ABI32 and friends.
223 lines
10 KiB
C
223 lines
10 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <syslog.h>
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#include <unistd.h>
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#ifdef ARCH_MIPS
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#include <asm/sgidefs.h>
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#endif
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#include "alloc-util.h"
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#include "base-filesystem.h"
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#include "errno-util.h"
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#include "fd-util.h"
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#include "log.h"
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#include "nulstr-util.h"
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#include "path-util.h"
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#include "umask-util.h"
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#include "user-util.h"
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typedef enum BaseFilesystemFlags {
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BASE_FILESYSTEM_IGNORE_ON_FAILURE = 1 << 0,
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BASE_FILESYSTEM_EMPTY_MARKER = 1 << 1, /* If this is missing, then we are booting on an empty filesystem - see comment below */
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BASE_FILESYSTEM_EMPTY_ONLY = 1 << 2, /* If booting on an empty filesystem create this, otherwise skip it - see comment below */
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} BaseFilesystemFlags;
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typedef struct BaseFilesystem {
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const char *dir; /* directory or symlink to create */
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mode_t mode;
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const char *target; /* if non-NULL create as symlink to this target */
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const char *exists; /* conditionalize this entry on existence of this file */
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BaseFilesystemFlags flags; /* various modifiers for behaviour on creation */
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} BaseFilesystem;
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/* Note that as entries are processed in order, entries with BASE_FILESYSTEM_EMPTY_MARKER must be listed
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* before entries with BASE_FILESYSTEM_EMPTY_ONLY. */
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static const BaseFilesystem table[] = {
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{ "bin", 0, "usr/bin\0", NULL, BASE_FILESYSTEM_EMPTY_MARKER },
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{ "lib", 0, "usr/lib\0", NULL, BASE_FILESYSTEM_EMPTY_MARKER },
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{ "root", 0750, NULL, NULL, BASE_FILESYSTEM_IGNORE_ON_FAILURE },
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{ "sbin", 0, "usr/sbin\0", NULL, BASE_FILESYSTEM_EMPTY_MARKER },
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{ "usr", 0755, NULL, NULL },
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{ "var", 0755, NULL, NULL },
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{ "etc", 0755, NULL, NULL },
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{ "proc", 0555, NULL, NULL, BASE_FILESYSTEM_IGNORE_ON_FAILURE },
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{ "sys", 0555, NULL, NULL, BASE_FILESYSTEM_IGNORE_ON_FAILURE },
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{ "dev", 0555, NULL, NULL, BASE_FILESYSTEM_IGNORE_ON_FAILURE },
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{ "run", 0555, NULL, NULL, BASE_FILESYSTEM_IGNORE_ON_FAILURE },
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/* We don't add /tmp/ here for now (even though it's necessary for regular operation), because we
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* want to support both cases where /tmp/ is a mount of its own (in which case we probably should set
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* the mode to 1555, to indicate that no one should write to it, not even root) and when it's part of
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* the rootfs (in which case we should set mode 1777), and we simply don't know what's right. */
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/* Various architecture ABIs define the path to the dynamic loader via the /lib64/ subdirectory of
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* the root directory. When booting from an otherwise empty root file system (where only /usr/ has
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* been mounted into) it is thus necessary to create a symlink pointing to the right subdirectory of
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* /usr/ first — otherwise we couldn't invoke any dynamic binary. Let's detect this case here, and
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* create the symlink as needed should it be missing. We prefer doing this consistently with Debian's
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* multiarch logic, but support Fedora-style and Arch-style multilib too. */
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#if defined(__aarch64__)
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/* aarch64 ELF ABI actually says dynamic loader is in /lib/, but Fedora puts it in /lib64/ anyway and
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* just symlinks /lib/ld-linux-aarch64.so.1 to ../lib64/ld-linux-aarch64.so.1. For this to work
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* correctly, /lib64/ must be symlinked to /usr/lib64/. On the flip side, we must not create /lib64/
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* on Debian and derivatives as they expect the target to be different from what Fedora et al. use,
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* which is problematic for example when nspawn from some other distribution boots a Debian
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* container with only /usr/, so we only create this symlink when at least one other symlink is
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* missing, and let the image builder/package manager worry about not creating incomplete persistent
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* filesystem hierarchies instead. The key purpose of this code is to ensure we can bring up a system
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* with a volatile root filesystem after all. */
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-aarch64.so.1", BASE_FILESYSTEM_EMPTY_ONLY },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__alpha__)
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#elif defined(__arc__) || defined(__tilegx__)
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#elif defined(__arm__)
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/* No /lib64 on arm. The linker is /lib/ld-linux-armhf.so.3. */
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# define KNOW_LIB64_DIRS 1
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#elif defined(__i386__) || defined(__x86_64__)
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-x86-64.so.2" },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__ia64__)
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#elif defined(__loongarch_lp64)
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# define KNOW_LIB64_DIRS 1
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# if defined(__loongarch_double_float)
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-loongarch-lp64d.so.1" },
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# elif defined(__loongarch_single_float)
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-loongarch-lp64f.so.1" },
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# elif defined(__loongarch_soft_float)
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-loongarch-lp64s.so.1" },
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# else
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# error "Unknown LoongArch ABI"
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# endif
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#elif defined(__m68k__)
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/* No link needed. */
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# define KNOW_LIB64_DIRS 1
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#elif defined(_MIPS_SIM)
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# if _MIPS_SIM == _MIPS_SIM_ABI32
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# elif _MIPS_SIM == _MIPS_SIM_NABI32
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# elif _MIPS_SIM == _MIPS_SIM_ABI64
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# else
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# error "Unknown MIPS ABI"
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# endif
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#elif defined(__powerpc__)
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# if defined(__PPC64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld64.so.2" },
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# define KNOW_LIB64_DIRS 1
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# elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
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/* powerpc64-linux-gnu */
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# else
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/* powerpc-linux-gnu */
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# endif
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#elif defined(__riscv)
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# if __riscv_xlen == 32
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# elif __riscv_xlen == 64
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/* Same situation as for aarch64 */
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-linux-riscv64-lp64d.so.1", BASE_FILESYSTEM_EMPTY_ONLY },
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# define KNOW_LIB64_DIRS 1
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# else
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# error "Unknown RISC-V ABI"
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# endif
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#elif defined(__s390x__)
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/* Same situation as for aarch64 */
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{ "lib64", 0, "usr/lib64\0"
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"usr/lib\0", "ld-lsb-s390x.so.3", BASE_FILESYSTEM_EMPTY_ONLY },
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# define KNOW_LIB64_DIRS 1
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#elif defined(__s390__)
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/* s390-linux-gnu */
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#elif defined(__sparc__)
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#endif
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/* gcc doesn't allow pragma to be used within constructs, hence log about this separately below */
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};
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#ifndef KNOW_LIB64_DIRS
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# pragma message "Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links."
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#endif
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int base_filesystem_create_fd(int fd, const char *root, uid_t uid, gid_t gid) {
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bool empty_fs = false;
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int r;
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assert(fd >= 0);
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assert(root);
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/* The "root" parameter is decoration only – it's only used as part of log messages */
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FOREACH_ELEMENT(i, table) {
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if (FLAGS_SET(i->flags, BASE_FILESYSTEM_EMPTY_ONLY) && !empty_fs)
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continue;
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if (faccessat(fd, i->dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0)
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continue;
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if (FLAGS_SET(i->flags, BASE_FILESYSTEM_EMPTY_MARKER))
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empty_fs = true;
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if (i->target) { /* Create as symlink? */
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const char *target = NULL;
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/* check if one of the targets exists */
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NULSTR_FOREACH(s, i->target) {
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if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
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continue;
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/* check if a specific file exists at the target path */
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if (i->exists) {
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_cleanup_free_ char *p = NULL;
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p = path_join(s, i->exists);
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if (!p)
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return log_oom();
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if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0)
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continue;
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}
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target = s;
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break;
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}
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if (!target)
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continue;
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r = RET_NERRNO(symlinkat(target, fd, i->dir));
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} else {
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/* Create as directory. */
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WITH_UMASK(0000)
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r = RET_NERRNO(mkdirat(fd, i->dir, i->mode));
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}
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if (r < 0) {
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bool ignore = IN_SET(r, -EEXIST, -EROFS) || FLAGS_SET(i->flags, BASE_FILESYSTEM_IGNORE_ON_FAILURE);
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log_full_errno(ignore ? LOG_DEBUG : LOG_ERR, r,
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"Failed to create %s/%s: %m", root, i->dir);
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if (ignore)
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continue;
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return r;
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}
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if (uid_is_valid(uid) || gid_is_valid(gid))
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if (fchownat(fd, i->dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
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return log_error_errno(errno, "Failed to chown %s/%s: %m", root, i->dir);
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}
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return 0;
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}
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int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
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_cleanup_close_ int fd = -EBADF;
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fd = open(ASSERT_PTR(root), O_DIRECTORY|O_CLOEXEC);
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if (fd < 0)
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return log_error_errno(errno, "Failed to open root file system: %m");
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return base_filesystem_create_fd(fd, root, uid, gid);
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}
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