| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <stdbool.h> |
| #include <stdlib.h> |
| #include <sys/stat.h> |
| #include <syslog.h> |
| #include <unistd.h> |
| |
| #include "alloc-util.h" |
| #include "architecture.h" |
| #include "base-filesystem.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", 0755, NULL, NULL, true }, |
| { "sys", 0755, NULL, NULL, true }, |
| { "dev", 0755, NULL, NULL, true }, |
| |
| /* 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 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", "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", "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", "ld-linux-loongarch-lp64d.so.1" }, |
| # elif defined(__loongarch_single_float) |
| { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" |
| "usr/lib64\0", "ld-linux-loongarch-lp64f.so.1" }, |
| # elif defined(__loongarch_soft_float) |
| { "lib64", 0, "usr/lib/"LIB_ARCH_TUPLE"\0" |
| "usr/lib64\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", "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", "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", "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(const char *root, uid_t uid, gid_t gid) { |
| _cleanup_close_ int fd = -EBADF; |
| int r; |
| |
| fd = open(root, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW); |
| if (fd < 0) |
| return log_error_errno(errno, "Failed to open root file system: %m"); |
| |
| 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) { |
| 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; |
| |
| if (symlinkat(target, fd, table[i].dir) < 0) { |
| log_full_errno(IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno, |
| "Failed to create symlink at %s/%s: %m", root, table[i].dir); |
| |
| if (IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure) |
| continue; |
| |
| return -errno; |
| } |
| |
| 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 symlink at %s/%s: %m", root, table[i].dir); |
| |
| continue; |
| } |
| |
| WITH_UMASK(0000) |
| r = mkdirat(fd, table[i].dir, table[i].mode); |
| if (r < 0) { |
| log_full_errno(IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure ? LOG_DEBUG : LOG_ERR, errno, |
| "Failed to create directory at %s/%s: %m", root, table[i].dir); |
| |
| if (IN_SET(errno, EEXIST, EROFS) || table[i].ignore_failure) |
| continue; |
| |
| return -errno; |
| } |
| |
| 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 directory at %s/%s: %m", root, table[i].dir); |
| } |
| |
| return 0; |
| } |
