]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/shared/base-filesystem.c
1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
11 #include "alloc-util.h"
12 #include "base-filesystem.h"
16 #include "nulstr-util.h"
17 #include "path-util.h"
18 #include "string-util.h"
19 #include "umask-util.h"
20 #include "user-util.h"
22 typedef struct BaseFilesystem
{
23 const char *dir
; /* directory or symlink to create */
25 const char *target
; /* if non-NULL create as symlink to this target */
26 const char *exists
; /* conditionalize this entry on existance of this file */
30 static const BaseFilesystem table
[] = {
31 { "bin", 0, "usr/bin\0", NULL
},
32 { "lib", 0, "usr/lib\0", NULL
},
33 { "root", 0755, NULL
, NULL
, true },
34 { "sbin", 0, "usr/sbin\0", NULL
},
35 { "usr", 0755, NULL
, NULL
},
36 { "var", 0755, NULL
, NULL
},
37 { "etc", 0755, NULL
, NULL
},
38 { "proc", 0755, NULL
, NULL
, true },
39 { "sys", 0755, NULL
, NULL
, true },
40 { "dev", 0755, NULL
, NULL
, true },
42 /* Various architecture ABIs define the path to the dynamic loader via the /lib64/ subdirectory of
43 * the root directory. When booting from an otherwise empty root file system (where only /usr/ has
44 * been mounted into) it is thus necessary to create a symlink pointing to the right subdirectory of
45 * /usr/ first — otherwise we couldn't invoke any dynamic binary. Let's detect this case here, and
46 * create the symlink as needed should it be missing. We prefer doing this consistently with Debian's
47 * multiarch logic, but support Fedora-style multilib too.*/
48 #if defined(__aarch64__)
49 /* aarch64 ELF ABI actually says dynamic loader is in /lib/, but Fedora puts it in /lib64/ anyway and
50 * just symlinks /lib/ld-linux-aarch64.so.1 to ../lib64/ld-linux-aarch64.so.1. For this to work
51 * correctly, /lib64/ must be symlinked to /usr/lib64/. */
52 { "lib64", 0, "usr/lib/aarch64-linux-gnu\0"
53 "usr/lib64\0", "ld-linux-aarch64.so.1" },
54 # define KNOW_LIB64_DIRS 1
55 #elif defined(__alpha__)
56 #elif defined(__arc__) || defined(__tilegx__)
57 #elif defined(__arm__)
58 /* No /lib64 on arm. The linker is /lib/ld-linux-armhf.so.3. */
59 # define KNOW_LIB64_DIRS 1
60 #elif defined(__i386__) || defined(__x86_64__)
61 { "lib64", 0, "usr/lib/x86_64-linux-gnu\0"
62 "usr/lib64\0", "ld-linux-x86-64.so.2" },
63 # define KNOW_LIB64_DIRS 1
64 #elif defined(__ia64__)
65 #elif defined(__m68k__)
67 # define KNOW_LIB64_DIRS 1
68 #elif defined(_MIPS_SIM)
69 # if _MIPS_SIM == _MIPS_SIM_ABI32
70 # elif _MIPS_SIM == _MIPS_SIM_NABI32
71 # elif _MIPS_SIM == _MIPS_SIM_ABI64
73 # error "Unknown MIPS ABI"
75 #elif defined(__powerpc__)
76 # if defined(__PPC64__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
77 { "lib64", 0, "usr/lib/powerpc64le-linux-gnu\0"
78 "usr/lib64\0", "ld64.so.2" },
79 # define KNOW_LIB64_DIRS 1
80 # elif defined(__powerpc64__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
81 /* powerpc64-linux-gnu */
83 /* powerpc-linux-gnu */
85 #elif defined(__riscv)
86 # if __riscv_xlen == 32
87 # elif __riscv_xlen == 64
88 /* Same situation as for aarch64 */
89 { "lib64", 0, "usr/lib/riscv64-linux-gnu\0"
90 "usr/lib64\0", "ld-linux-riscv64-lp64d.so.1" },
91 # define KNOW_LIB64_DIRS 1
93 # error "Unknown RISC-V ABI"
95 #elif defined(__s390__)
96 #elif defined(__s390x__)
97 #elif defined(__sparc__)
99 /* gcc doesn't allow pragma to be used within constructs, hence log about this separately below */
102 #ifndef KNOW_LIB64_DIRS
103 # pragma message "Please add an entry above specifying whether your architecture uses /lib64/, /lib32/, or no such links."
106 int base_filesystem_create(const char *root
, uid_t uid
, gid_t gid
) {
107 _cleanup_close_
int fd
= -1;
110 fd
= open(root
, O_RDONLY
|O_NONBLOCK
|O_DIRECTORY
|O_CLOEXEC
|O_NOFOLLOW
);
112 return log_error_errno(errno
, "Failed to open root file system: %m");
114 for (size_t i
= 0; i
< ELEMENTSOF(table
); i
++) {
115 if (faccessat(fd
, table
[i
].dir
, F_OK
, AT_SYMLINK_NOFOLLOW
) >= 0)
118 if (table
[i
].target
) {
119 const char *target
= NULL
, *s
;
121 /* check if one of the targets exists */
122 NULSTR_FOREACH(s
, table
[i
].target
) {
123 if (faccessat(fd
, s
, F_OK
, AT_SYMLINK_NOFOLLOW
) < 0)
126 /* check if a specific file exists at the target path */
127 if (table
[i
].exists
) {
128 _cleanup_free_
char *p
= NULL
;
130 p
= path_join(s
, table
[i
].exists
);
134 if (faccessat(fd
, p
, F_OK
, AT_SYMLINK_NOFOLLOW
) < 0)
145 if (symlinkat(target
, fd
, table
[i
].dir
) < 0) {
146 log_full_errno(IN_SET(errno
, EEXIST
, EROFS
) || table
[i
].ignore_failure
? LOG_DEBUG
: LOG_ERR
, errno
,
147 "Failed to create symlink at %s/%s: %m", root
, table
[i
].dir
);
149 if (IN_SET(errno
, EEXIST
, EROFS
) || table
[i
].ignore_failure
)
155 if (uid_is_valid(uid
) || gid_is_valid(gid
))
156 if (fchownat(fd
, table
[i
].dir
, uid
, gid
, AT_SYMLINK_NOFOLLOW
) < 0)
157 return log_error_errno(errno
, "Failed to chown symlink at %s/%s: %m", root
, table
[i
].dir
);
163 r
= mkdirat(fd
, table
[i
].dir
, table
[i
].mode
);
165 log_full_errno(IN_SET(errno
, EEXIST
, EROFS
) || table
[i
].ignore_failure
? LOG_DEBUG
: LOG_ERR
, errno
,
166 "Failed to create directory at %s/%s: %m", root
, table
[i
].dir
);
168 if (IN_SET(errno
, EEXIST
, EROFS
) || table
[i
].ignore_failure
)
174 if (uid
!= UID_INVALID
|| gid
!= UID_INVALID
)
175 if (fchownat(fd
, table
[i
].dir
, uid
, gid
, AT_SYMLINK_NOFOLLOW
) < 0)
176 return log_error_errno(errno
, "Failed to chown directory at %s/%s: %m", root
, table
[i
].dir
);