113 lines
3.3 KiB
Diff
113 lines
3.3 KiB
Diff
Author: Raphael Geissert <geissert@debian.org>
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Bug-Debian: https://bugs.debian.org/731860
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Description: Avoid directory traversal when extracting archives
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by skipping over leading slashes and any prefix containing ".." components.
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Forwarded: yes
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--- a/lib/decode.c
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+++ b/lib/decode.c
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@@ -22,13 +22,42 @@
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# include <string.h>
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#endif
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+char *
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+safer_name_suffix (char const *file_name)
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+{
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+ char const *p, *t;
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+ p = t = file_name;
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+ while (*p == '/') t = ++p;
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+ while (*p)
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+ {
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+ while (p[0] == '.' && p[0] == p[1] && p[2] == '/')
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+ {
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+ p += 3;
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+ t = p;
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+ }
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+ /* advance pointer past the next slash */
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+ while (*p && (p++)[0] != '/');
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+ }
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+
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+ if (!*t)
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+ {
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+ t = ".";
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+ }
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+
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+ if (t != file_name)
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+ {
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+ /* TODO: warn somehow that the path was modified */
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+ }
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+ return (char*)t;
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+}
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+
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/* determine full path name */
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char *
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th_get_pathname(TAR *t)
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{
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if (t->th_buf.gnu_longname)
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- return t->th_buf.gnu_longname;
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+ return safer_name_suffix(t->th_buf.gnu_longname);
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/* allocate the th_pathname buffer if not already */
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if (t->th_pathname == NULL)
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@@ -51,7 +80,7 @@ th_get_pathname(TAR *t)
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}
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/* will be deallocated in tar_close() */
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- return t->th_pathname;
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+ return safer_name_suffix(t->th_pathname);
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}
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--- a/lib/extract.c
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+++ b/lib/extract.c
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@@ -298,14 +298,14 @@ tar_extract_hardlink(TAR * t, char *real
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if (mkdirhier(dirname(filename)) == -1)
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return -1;
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libtar_hashptr_reset(&hp);
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- if (libtar_hash_getkey(t->h, &hp, th_get_linkname(t),
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+ if (libtar_hash_getkey(t->h, &hp, safer_name_suffix(th_get_linkname(t)),
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(libtar_matchfunc_t)libtar_str_match) != 0)
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{
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lnp = (char *)libtar_hashptr_data(&hp);
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linktgt = &lnp[strlen(lnp) + 1];
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}
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else
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- linktgt = th_get_linkname(t);
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+ linktgt = safer_name_suffix(th_get_linkname(t));
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#ifdef DEBUG
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printf(" ==> extracting: %s (link to %s)\n", filename, linktgt);
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@@ -343,9 +343,9 @@ tar_extract_symlink(TAR *t, char *realna
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#ifdef DEBUG
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printf(" ==> extracting: %s (symlink to %s)\n",
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- filename, th_get_linkname(t));
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+ filename, safer_name_suffix(th_get_linkname(t)));
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#endif
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- if (symlink(th_get_linkname(t), filename) == -1)
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+ if (symlink(safer_name_suffix(th_get_linkname(t)), filename) == -1)
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{
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#ifdef DEBUG
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perror("symlink()");
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--- a/lib/internal.h
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+++ b/lib/internal.h
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@@ -21,3 +21,4 @@
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#define TLS_THREAD
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#endif
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+char* safer_name_suffix(char const*);
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--- a/lib/output.c
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+++ b/lib/output.c
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@@ -123,9 +123,9 @@ th_print_long_ls(TAR *t)
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else
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printf(" link to ");
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if ((t->options & TAR_GNU) && t->th_buf.gnu_longlink != NULL)
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- printf("%s", t->th_buf.gnu_longlink);
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+ printf("%s", safer_name_suffix(t->th_buf.gnu_longlink));
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else
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- printf("%.100s", t->th_buf.linkname);
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+ printf("%.100s", safer_name_suffix(t->th_buf.linkname));
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}
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putchar('\n');
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