projects/guix·blob python-team · refs

118 lines · 2.9 KiB

1Author: Raphael Geissert <[email protected]>
2Bug-Debian: https://bugs.debian.org/731860
3Description: Avoid directory traversal when extracting archives
4 by skipping over leading slashes and any prefix containing ".." components.
5Forwarded: yes
6
7--- a/lib/decode.c
8+++ b/lib/decode.c
9@@ -22,6 +22,36 @@
10 #endif
11
12
13+char *
14+safer_name_suffix (char const *file_name)
15+{
16+ char const *p, *t;
17+ p = t = file_name;
18+ while (*p == '/') t = ++p;
19+ while (*p)
20+ {
21+ while (p[0] == '.' && p[0] == p[1] && p[2] == '/')
22+ {
23+ p += 3;
24+ t = p;
25+ }
26+ /* advance pointer past the next slash */
27+ while (*p && (p++)[0] != '/');
28+ }
29+
30+ if (!*t)
31+ {
32+ t = ".";
33+ }
34+
35+ if (t != file_name)
36+ {
37+ /* TODO: warn somehow that the path was modified */
38+ }
39+ return (char*)t;
40+}
41+
42+
43 /* determine full path name */
44 char *
45 th_get_pathname(TAR *t)
46@@ -29,17 +59,17 @@ th_get_pathname(TAR *t)
47 static char filename[MAXPATHLEN];
48
49 if (t->th_buf.gnu_longname)
50- return t->th_buf.gnu_longname;
51+ return safer_name_suffix(t->th_buf.gnu_longname);
52
53 if (t->th_buf.prefix[0] != '\0')
54 {
55 snprintf(filename, sizeof(filename), "%.155s/%.100s",
56 t->th_buf.prefix, t->th_buf.name);
57- return filename;
58+ return safer_name_suffix(filename);
59 }
60
61 snprintf(filename, sizeof(filename), "%.100s", t->th_buf.name);
62- return filename;
63+ return safer_name_suffix(filename);
64 }
65
66
67--- a/lib/extract.c
68+++ b/lib/extract.c
69@@ -298,14 +298,14 @@ tar_extract_hardlink(TAR * t, char *real
70 if (mkdirhier(dirname(filename)) == -1)
71 return -1;
72 libtar_hashptr_reset(&hp);
73- if (libtar_hash_getkey(t->h, &hp, th_get_linkname(t),
74+ if (libtar_hash_getkey(t->h, &hp, safer_name_suffix(th_get_linkname(t)),
75 (libtar_matchfunc_t)libtar_str_match) != 0)
76 {
77 lnp = (char *)libtar_hashptr_data(&hp);
78 linktgt = &lnp[strlen(lnp) + 1];
79 }
80 else
81- linktgt = th_get_linkname(t);
82+ linktgt = safer_name_suffix(th_get_linkname(t));
83
84 #ifdef DEBUG
85 printf(" ==> extracting: %s (link to %s)\n", filename, linktgt);
86@@ -343,9 +343,9 @@ tar_extract_symlink(TAR *t, char *realna
87
88 #ifdef DEBUG
89 printf(" ==> extracting: %s (symlink to %s)\n",
90- filename, th_get_linkname(t));
91+ filename, safer_name_suffix(th_get_linkname(t)));
92 #endif
93- if (symlink(th_get_linkname(t), filename) == -1)
94+ if (symlink(safer_name_suffix(th_get_linkname(t)), filename) == -1)
95 {
96 #ifdef DEBUG
97 perror("symlink()");
98--- a/lib/internal.h
99+++ b/lib/internal.h
100@@ -15,3 +15,4 @@
101
102 #include <libtar.h>
103
104+char* safer_name_suffix(char const*);
105--- a/lib/output.c
106+++ b/lib/output.c
107@@ -123,9 +123,9 @@ th_print_long_ls(TAR *t)
108 else
109 printf(" link to ");
110 if ((t->options & TAR_GNU) && t->th_buf.gnu_longlink != NULL)
111- printf("%s", t->th_buf.gnu_longlink);
112+ printf("%s", safer_name_suffix(t->th_buf.gnu_longlink));
113 else
114- printf("%.100s", t->th_buf.linkname);
115+ printf("%.100s", safer_name_suffix(t->th_buf.linkname));
116 }
117
118 putchar('\n');