/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #include #include #include "alloc-util.h" #include "architecture.h" #include "base-filesystem.h" #include "errno-util.h" #include "fd-util.h" #include "log.h" #include "macro.h" #include "nulstr-util.h" #include "path-util.h" #include "string-util.h" #include "umask-util.h" #include "user-util.h" typedef struct BaseFilesystem { const char *dir; /* directory or symlink to create */ mode_t mode; const char *target; /* if non-NULL create as symlink to this target */ const char *exists; /* conditionalize this entry on existence of this file */ bool ignore_failure; } BaseFilesystem; static const BaseFilesystem table[] = { { "bin", 0, "usr/bin\0", NULL }, { "lib", 0, "usr/lib\0", NULL }, { "root", 0750, NULL, NULL, true }, { "sbin", 0, "usr/sbin\0", NULL }, { "usr", 0755, NULL, NULL }, { "var", 0755, NULL, NULL }, { "etc", 0755, NULL, NULL }, { "proc", 0555, NULL, NULL, true }, { "sys", 0555, NULL, NULL, true }, { "dev", 0555, NULL, NULL, true }, { "run", 0555, NULL, NULL, true }, /* We don't add /tmp/ here for now (even though it's necessary for regular operation), because we * want to support both cases where /tmp/ is a mount of its own (in which case we probably should set * the mode to 1555, to indicate that no one should write to it, not even root) and when it's part of * the rootfs (in which case we should set mode 1777), and we simply don't know what's right. */ /* Various architecture ABIs define the path to the dynamic loader via the /lib64/ subdirectory of * the root directory. When booting from an otherwise empty root file system (where only /usr/ has * been mounted into) it is thus necessary to create a symlink pointing to the right subdirectory of * /usr/ first — otherwise we couldn't invoke any dynamic binary. Let's detect this case here, and * create the symlink as needed should it be missing. We prefer doing this consistently with Debian's * multiarch logic, but support Fedora-style and Arch-style multilib too. */ #if defined(__aarch64__) /* aarch64 ELF ABI actually says dynamic loader is in /lib/, but Fedora puts it in /lib64/ anyway and * just symlinks /lib/ld-linux-aarch64.so.1 to ../lib64/ld-linux-aarch64.so.1. For this to work * correctly, /lib64/ must be symlinked to /usr/lib64/. */ { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-aarch64.so.1" }, # define KNOW_LIB64_DIRS 1 #elif defined(__alpha__) #elif defined(__arc__) || defined(__tilegx__) #elif defined(__arm__) /* No /lib64 on arm. The linker is /lib/ld-linux-armhf.so.3. */ # define KNOW_LIB64_DIRS 1 #elif defined(__i386__) || defined(__x86_64__) { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-x86-64.so.2" }, # define KNOW_LIB64_DIRS 1 #elif defined(__ia64__) #elif defined(__loongarch64) # define KNOW_LIB64_DIRS 1 # if defined(__loongarch_double_float) { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-loongarch-lp64d.so.1" }, # elif defined(__loongarch_single_float) { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-loongarch-lp64f.so.1" }, # elif defined(__loongarch_soft_float) { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-loongarch-lp64s.so.1" }, # else # error "Unknown LoongArch ABI" # endif #elif defined(__m68k__) /* No link needed. */ # define KNOW_LIB64_DIRS 1 #elif defined(_MIPS_SIM) # if _MIPS_SIM == _MIPS_SIM_ABI32 # elif _MIPS_SIM == _MIPS_SIM_NABI32 # elif _MIPS_SIM == _MIPS_SIM_ABI64 # else # error "Unknown MIPS ABI" # endif #elif defined(__powerpc__) # if defined(__PPC64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld64.so.2" }, # define KNOW_LIB64_DIRS 1 # elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ /* powerpc64-linux-gnu */ # else /* powerpc-linux-gnu */ # endif #elif defined(__riscv) # if __riscv_xlen == 32 # elif __riscv_xlen == 64 /* Same situation as for aarch64 */ { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-linux-riscv64-lp64d.so.1" }, # define KNOW_LIB64_DIRS 1 # else # error "Unknown RISC-V ABI" # endif #elif defined(__s390__) /* s390-linux-gnu */ #elif defined(__s390x__) { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" "usr/lib64\0" "usr/lib\0", "ld-lsb-s390x.so.3" }, # define KNOW_LIB64_DIRS 1 #elif defined(__sparc__) #endif /* gcc doesn't allow pragma to be used within constructs, hence log about this separately below */ }; #ifndef KNOW_LIB64_DIRS # pragma message "Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links." #endif int base_filesystem_create_fd(int fd, const char *root, uid_t uid, gid_t gid) { int r; assert(fd >= 0); assert(root); /* The "root" parameter is decoration only – it's only used as part of log messages */ for (size_t i = 0; i < ELEMENTSOF(table); i++) { if (faccessat(fd, table[i].dir, F_OK, AT_SYMLINK_NOFOLLOW) >= 0) continue; if (table[i].target) { /* Create as symlink? */ const char *target = NULL; /* check if one of the targets exists */ NULSTR_FOREACH(s, table[i].target) { if (faccessat(fd, s, F_OK, AT_SYMLINK_NOFOLLOW) < 0) continue; /* check if a specific file exists at the target path */ if (table[i].exists) { _cleanup_free_ char *p = NULL; p = path_join(s, table[i].exists); if (!p) return log_oom(); if (faccessat(fd, p, F_OK, AT_SYMLINK_NOFOLLOW) < 0) continue; } target = s; break; } if (!target) continue; r = RET_NERRNO(symlinkat(target, fd, table[i].dir)); } else { /* Create as directory. */ WITH_UMASK(0000) r = RET_NERRNO(mkdirat(fd, table[i].dir, table[i].mode)); } if (r < 0) { bool ignore = IN_SET(r, -EEXIST, -EROFS) || table[i].ignore_failure; log_full_errno(ignore ? LOG_DEBUG : LOG_ERR, r, "Failed to create %s/%s: %m", root, table[i].dir); if (ignore) continue; return r; } if (uid_is_valid(uid) || gid_is_valid(gid)) if (fchownat(fd, table[i].dir, uid, gid, AT_SYMLINK_NOFOLLOW) < 0) return log_error_errno(errno, "Failed to chown %s/%s: %m", root, table[i].dir); } return 0; } int base_filesystem_create(const char *root, uid_t uid, gid_t gid) { _cleanup_close_ int fd = -EBADF; fd = open(ASSERT_PTR(root), O_DIRECTORY|O_CLOEXEC); if (fd < 0) return log_error_errno(errno, "Failed to open root file system: %m"); return base_filesystem_create_fd(fd, root, uid, gid); }