1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Author: Aleksa Sarai <cyphar@cyphar.com> |
4 | * Copyright (C) 2018-2019 SUSE LLC. |
5 | */ |
6 | |
7 | #define _GNU_SOURCE |
8 | #include <errno.h> |
9 | #include <fcntl.h> |
10 | #include <stdbool.h> |
11 | #include <string.h> |
12 | #include <syscall.h> |
13 | #include <limits.h> |
14 | |
15 | #include "helpers.h" |
16 | |
17 | bool needs_openat2(const struct open_how *how) |
18 | { |
19 | return how->resolve != 0; |
20 | } |
21 | |
22 | int raw_openat2(int dfd, const char *path, void *how, size_t size) |
23 | { |
24 | int ret = syscall(__NR_openat2, dfd, path, how, size); |
25 | return ret >= 0 ? ret : -errno; |
26 | } |
27 | |
28 | int sys_openat2(int dfd, const char *path, struct open_how *how) |
29 | { |
30 | return raw_openat2(dfd, path, how, size: sizeof(*how)); |
31 | } |
32 | |
33 | int sys_openat(int dfd, const char *path, struct open_how *how) |
34 | { |
35 | int ret = openat(dfd, path, how->flags, how->mode); |
36 | return ret >= 0 ? ret : -errno; |
37 | } |
38 | |
39 | int sys_renameat2(int olddirfd, const char *oldpath, |
40 | int newdirfd, const char *newpath, unsigned int flags) |
41 | { |
42 | int ret = syscall(__NR_renameat2, olddirfd, oldpath, |
43 | newdirfd, newpath, flags); |
44 | return ret >= 0 ? ret : -errno; |
45 | } |
46 | |
47 | int touchat(int dfd, const char *path) |
48 | { |
49 | int fd = openat(dfd, path, O_CREAT, 0700); |
50 | if (fd >= 0) |
51 | close(fd); |
52 | return fd; |
53 | } |
54 | |
55 | char *fdreadlink(int fd) |
56 | { |
57 | char *target, *tmp; |
58 | |
59 | E_asprintf(&tmp, "/proc/self/fd/%d" , fd); |
60 | |
61 | target = malloc(PATH_MAX); |
62 | if (!target) |
63 | ksft_exit_fail_msg(msg: "fdreadlink: malloc failed\n" ); |
64 | memset(target, 0, PATH_MAX); |
65 | |
66 | E_readlink(tmp, target, PATH_MAX); |
67 | free(tmp); |
68 | return target; |
69 | } |
70 | |
71 | bool fdequal(int fd, int dfd, const char *path) |
72 | { |
73 | char *fdpath, *dfdpath, *other; |
74 | bool cmp; |
75 | |
76 | fdpath = fdreadlink(fd); |
77 | dfdpath = fdreadlink(fd: dfd); |
78 | |
79 | if (!path) |
80 | E_asprintf(&other, "%s" , dfdpath); |
81 | else if (*path == '/') |
82 | E_asprintf(&other, "%s" , path); |
83 | else |
84 | E_asprintf(&other, "%s/%s" , dfdpath, path); |
85 | |
86 | cmp = !strcmp(fdpath, other); |
87 | |
88 | free(fdpath); |
89 | free(dfdpath); |
90 | free(other); |
91 | return cmp; |
92 | } |
93 | |
94 | bool openat2_supported = false; |
95 | |
96 | void __attribute__((constructor)) init(void) |
97 | { |
98 | struct open_how how = {}; |
99 | int fd; |
100 | |
101 | BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0); |
102 | |
103 | /* Check openat2(2) support. */ |
104 | fd = sys_openat2(dfd: AT_FDCWD, path: "." , how: &how); |
105 | openat2_supported = (fd >= 0); |
106 | |
107 | if (fd >= 0) |
108 | close(fd); |
109 | } |
110 | |