Rev 24 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 24 | magnus | 1 | Author: Raphael Geissert <geissert@debian.org> |
| 2 | Bug-Debian: https://bugs.debian.org/731860 |
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| 3 | Description: Avoid directory traversal when extracting archives |
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| 4 | by skipping over leading slashes and any prefix containing ".." components. |
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| 5 | Forwarded: yes |
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| 6 | |||
| 7 | --- a/lib/decode.c |
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| 8 | +++ b/lib/decode.c |
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| 9 | @@ -21,13 +21,42 @@ |
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| 10 | # include <string.h> |
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| 11 | #endif |
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| 12 | |||
| 13 | +char * |
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| 14 | +safer_name_suffix (char const *file_name) |
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| 15 | +{ |
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| 16 | + char const *p, *t; |
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| 17 | + p = t = file_name; |
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| 18 | + while (*p == '/') t = ++p; |
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| 19 | + while (*p) |
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| 20 | + { |
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| 21 | + while (p[0] == '.' && p[0] == p[1] && p[2] == '/') |
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| 22 | + { |
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| 23 | + p += 3; |
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| 24 | + t = p; |
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| 25 | + } |
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| 26 | + /* advance pointer past the next slash */ |
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| 27 | + while (*p && (p++)[0] != '/'); |
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| 28 | + } |
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| 29 | + |
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| 30 | + if (!*t) |
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| 31 | + { |
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| 32 | + t = "."; |
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| 33 | + } |
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| 34 | + |
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| 35 | + if (t != file_name) |
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| 36 | + { |
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| 37 | + /* TODO: warn somehow that the path was modified */ |
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| 38 | + } |
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| 39 | + return (char*)t; |
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| 40 | +} |
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| 41 | + |
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| 42 | |||
| 43 | /* determine full path name */ |
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| 44 | char * |
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| 45 | th_get_pathname(TAR *t) |
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| 46 | { |
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| 47 | if (t->th_buf.gnu_longname) |
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| 48 | - return t->th_buf.gnu_longname; |
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| 49 | + return safer_name_suffix(t->th_buf.gnu_longname); |
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| 50 | |||
| 51 | size_t pathlen = |
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| 52 | strlen(t->th_buf.prefix) + strlen(t->th_buf.name) + 2; |
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| 53 | @@ -43,12 +72,12 @@ th_get_pathname(TAR *t) |
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| 54 | |||
| 55 | if (t->th_buf.prefix[0] == '\0') |
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| 56 | { |
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| 57 | - snprintf(t->th_pathname, pathlen, "%.100s", t->th_buf.name); |
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| 58 | + snprintf(t->th_pathname, pathlen, "%.100s", safer_name_suffix(t->th_buf.name)); |
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| 59 | } |
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| 60 | else |
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| 61 | { |
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| 62 | snprintf(t->th_pathname, pathlen, "%.155s/%.100s", |
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| 63 | - t->th_buf.prefix, t->th_buf.name); |
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| 64 | + t->th_buf.prefix, safer_name_suffix(t->th_buf.name)); |
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| 65 | } |
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| 66 | |||
| 67 | /* will be deallocated in tar_close() */ |
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| 68 | --- a/lib/extract.c |
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| 69 | +++ b/lib/extract.c |
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| 70 | @@ -298,14 +298,14 @@ tar_extract_hardlink(TAR * t, char *real |
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| 71 | if (mkdirhier(dirname(filename)) == -1) |
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| 72 | return -1; |
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| 73 | libtar_hashptr_reset(&hp); |
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| 74 | - if (libtar_hash_getkey(t->h, &hp, th_get_linkname(t), |
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| 75 | + if (libtar_hash_getkey(t->h, &hp, safer_name_suffix(th_get_linkname(t)), |
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| 76 | (libtar_matchfunc_t)libtar_str_match) != 0) |
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| 77 | { |
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| 78 | lnp = (char *)libtar_hashptr_data(&hp); |
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| 79 | linktgt = &lnp[strlen(lnp) + 1]; |
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| 80 | } |
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| 81 | else |
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| 82 | - linktgt = th_get_linkname(t); |
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| 83 | + linktgt = safer_name_suffix(th_get_linkname(t)); |
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| 84 | |||
| 85 | #ifdef DEBUG |
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| 86 | printf(" ==> extracting: %s (link to %s)\n", filename, linktgt); |
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| 87 | @@ -343,9 +343,9 @@ tar_extract_symlink(TAR *t, char *realna |
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| 88 | |||
| 89 | #ifdef DEBUG |
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| 90 | printf(" ==> extracting: %s (symlink to %s)\n", |
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| 91 | - filename, th_get_linkname(t)); |
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| 92 | + filename, safer_name_suffix(th_get_linkname(t))); |
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| 93 | #endif |
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| 94 | - if (symlink(th_get_linkname(t), filename) == -1) |
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| 95 | + if (symlink(safer_name_suffix(th_get_linkname(t)), filename) == -1) |
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| 96 | { |
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| 97 | #ifdef DEBUG |
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| 98 | perror("symlink()"); |
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| 99 | --- a/lib/internal.h |
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| 100 | +++ b/lib/internal.h |
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| 101 | @@ -21,3 +21,4 @@ |
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| 102 | #define TLS_THREAD |
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| 103 | #endif |
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| 104 | |||
| 105 | +char* safer_name_suffix(char const*); |