1 // SPDX-License-Identifier: GPL-2.0
2 #include "util/copyfile.h"
3 #include "util/namespaces.h"
4 #include <internal/lib.h>
5 #include <sys/mman.h>
6 #include <sys/stat.h>
7 #include <errno.h>
8 #include <fcntl.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <unistd.h>
13 
slow_copyfile(const char * from,const char * to,struct nsinfo * nsi)14 static int slow_copyfile(const char *from, const char *to, struct nsinfo *nsi)
15 {
16 	int err = -1;
17 	char *line = NULL;
18 	size_t n;
19 	FILE *from_fp, *to_fp;
20 	struct nscookie nsc;
21 
22 	nsinfo__mountns_enter(nsi, &nsc);
23 	from_fp = fopen(from, "r");
24 	nsinfo__mountns_exit(&nsc);
25 	if (from_fp == NULL)
26 		goto out;
27 
28 	to_fp = fopen(to, "w");
29 	if (to_fp == NULL)
30 		goto out_fclose_from;
31 
32 	while (getline(&line, &n, from_fp) > 0)
33 		if (fputs(line, to_fp) == EOF)
34 			goto out_fclose_to;
35 	err = 0;
36 out_fclose_to:
37 	fclose(to_fp);
38 	free(line);
39 out_fclose_from:
40 	fclose(from_fp);
41 out:
42 	return err;
43 }
44 
copyfile_offset(int ifd,loff_t off_in,int ofd,loff_t off_out,u64 size)45 int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size)
46 {
47 	void *ptr;
48 	loff_t pgoff;
49 
50 	pgoff = off_in & ~(page_size - 1);
51 	off_in -= pgoff;
52 
53 	ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff);
54 	if (ptr == MAP_FAILED)
55 		return -1;
56 
57 	while (size) {
58 		ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out);
59 		if (ret < 0 && errno == EINTR)
60 			continue;
61 		if (ret <= 0)
62 			break;
63 
64 		size -= ret;
65 		off_in += ret;
66 		off_out += ret;
67 	}
68 	munmap(ptr, off_in + size);
69 
70 	return size ? -1 : 0;
71 }
72 
copyfile_mode_ns(const char * from,const char * to,mode_t mode,struct nsinfo * nsi)73 static int copyfile_mode_ns(const char *from, const char *to, mode_t mode,
74 			    struct nsinfo *nsi)
75 {
76 	int fromfd, tofd;
77 	struct stat st;
78 	int err;
79 	char *tmp = NULL, *ptr = NULL;
80 	struct nscookie nsc;
81 
82 	nsinfo__mountns_enter(nsi, &nsc);
83 	err = stat(from, &st);
84 	nsinfo__mountns_exit(&nsc);
85 	if (err)
86 		goto out;
87 	err = -1;
88 
89 	/* extra 'x' at the end is to reserve space for '.' */
90 	if (asprintf(&tmp, "%s.XXXXXXx", to) < 0) {
91 		tmp = NULL;
92 		goto out;
93 	}
94 	ptr = strrchr(tmp, '/');
95 	if (!ptr)
96 		goto out;
97 	ptr = memmove(ptr + 1, ptr, strlen(ptr) - 1);
98 	*ptr = '.';
99 
100 	tofd = mkstemp(tmp);
101 	if (tofd < 0)
102 		goto out;
103 
104 	if (st.st_size == 0) { /* /proc? do it slowly... */
105 		err = slow_copyfile(from, tmp, nsi);
106 		if (!err && fchmod(tofd, mode))
107 			err = -1;
108 		goto out_close_to;
109 	}
110 
111 	if (fchmod(tofd, mode))
112 		goto out_close_to;
113 
114 	nsinfo__mountns_enter(nsi, &nsc);
115 	fromfd = open(from, O_RDONLY);
116 	nsinfo__mountns_exit(&nsc);
117 	if (fromfd < 0)
118 		goto out_close_to;
119 
120 	err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size);
121 
122 	close(fromfd);
123 out_close_to:
124 	close(tofd);
125 	if (!err)
126 		err = link(tmp, to);
127 	unlink(tmp);
128 out:
129 	free(tmp);
130 	return err;
131 }
132 
copyfile_ns(const char * from,const char * to,struct nsinfo * nsi)133 int copyfile_ns(const char *from, const char *to, struct nsinfo *nsi)
134 {
135 	return copyfile_mode_ns(from, to, 0755, nsi);
136 }
137 
copyfile_mode(const char * from,const char * to,mode_t mode)138 int copyfile_mode(const char *from, const char *to, mode_t mode)
139 {
140 	return copyfile_mode_ns(from, to, mode, NULL);
141 }
142 
copyfile(const char * from,const char * to)143 int copyfile(const char *from, const char *to)
144 {
145 	return copyfile_mode(from, to, 0755);
146 }
147