tar: fix and sanitize handling of long filenames/linknames

(GNU extensions 'K' and 'L').
We correctly handle them when untarring now, but unfortunately
we still don't use them when tarring! That stupid 100 char limit
is still there!
The biggest problem is that we don't support 'pax' tar format.
Linux kernel tarballs are in this format... shame

diff --git a/archival/libunarchive/get_header_ar.c b/archival/libunarchive/get_header_ar.c
index b91c6f97d76e99a618c3ef5cd3aeaaa7967c220f..0d040e30b5e24e5aaa2ebedfe264efe5dd2a9c92 100644 (file)
--- a/archival/libunarchive/get_header_ar.c
+++ b/archival/libunarchive/get_header_ar.c
@@ -88,7 +88,7 @@ char get_header_ar(archive_handle_t *archive_handle)
 #endif
        } else {
                /* short filenames */
-              typed->name = xstrndup(ar.formatted.name, 16);
+               typed->name = xstrndup(ar.formatted.name, 16);
        }
 
        typed->name[strcspn(typed->name, " /")] = '\0';

diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index 68f7b2b9b1fb28c06744f8735ce8b6491e777449..0fb14e8e49c5b72f7e4889f92fe0b713ed96b8a1 100644 (file)
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -14,9 +14,14 @@
 #include "libbb.h"
 #include "unarchive.h"
 
-#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
-static char *longname = NULL;
-static char *linkname = NULL;
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+static char *longname;
+static char *linkname;
+#else
+enum {
+       longname = 0,
+       linkname = 0,
+};
 #endif
 
 /* NB: _DESTROYS_ str[len] character! */
@@ -64,6 +69,11 @@ char get_header_tar(archive_handle_t *archive_handle)
        } tar;
        char *cp;
        int sum, i;
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+       int parse_names;
+#else
+       enum { parse_names = 0 };
+#endif
 
        if (sizeof(tar) != 512)
                BUG_tar_header_size();
@@ -93,7 +103,7 @@ char get_header_tar(archive_handle_t *archive_handle)
         * 0's are for the old tar format
         */
        if (strncmp(tar.magic, "ustar", 5) != 0) {
-#ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
+#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
                if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
 #endif
                        bb_error_msg_and_die("invalid tar magic");
@@ -111,6 +121,10 @@ char get_header_tar(archive_handle_t *archive_handle)
                bb_error_msg_and_die("invalid tar header checksum");
        }
 
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+       parse_names = (tar.typeflag != 'L' && tar.typeflag != 'K');
+#endif
+
        /* getOctal trashes subsequent field, therefore we call it
         * on fields in reverse order */
 #define GET_OCTAL(a) getOctal((a), sizeof(a))
@@ -119,27 +133,24 @@ char get_header_tar(archive_handle_t *archive_handle)
                unsigned major = GET_OCTAL(tar.devmajor);
                file_header->device = makedev(major, minor);
        }
+       file_header->link_name = NULL;
+       if (!linkname && parse_names && tar.linkname[0]) {
+               /* we trash magic[0] here, it's ok */
+               tar.linkname[sizeof(tar.linkname)] = '\0';
+               file_header->link_name = xstrdup(tar.linkname);
+               /* FIXME: what if we have non-link object with link_name? */
+               /* Will link_name be free()ed? */
+       }
        file_header->mtime = GET_OCTAL(tar.mtime);
        file_header->size = GET_OCTAL(tar.size);
        file_header->gid = GET_OCTAL(tar.gid);
        file_header->uid = GET_OCTAL(tar.uid);
-       file_header->link_name = !tar.linkname[0] ? NULL :
-                       xstrndup(tar.linkname, sizeof(tar.linkname));
        /* Set bits 0-11 of the files mode */
        file_header->mode = 07777 & GET_OCTAL(tar.mode);
 #undef GET_OCTAL
 
-#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
-       if (longname) {
-               file_header->name = longname;
-               longname = NULL;
-       }
-       else if (linkname) {
-               file_header->name = linkname;
-               linkname = NULL;
-       } else
-#endif
-       {       /* we trash mode[0] here, it's ok */
+       if (!longname && parse_names) {
+               /* we trash mode[0] here, it's ok */
                tar.name[sizeof(tar.name)] = '\0';
                if (tar.prefix[0])
                        file_header->name = concat_path_file(tar.prefix, tar.name);
@@ -148,6 +159,7 @@ char get_header_tar(archive_handle_t *archive_handle)
        }
 
        /* Set bits 12-15 of the files mode */
+       /* (typeflag was not trashed because chksum does not use getOctal) */
        switch (tar.typeflag) {
        /* busybox identifies hard links as being regular files with 0 size and a link name */
        case '1':
@@ -157,7 +169,7 @@ char get_header_tar(archive_handle_t *archive_handle)
                /* Reserved for high performance files, treat as normal file */
        case 0:
        case '0':
-#ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
+#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
                if (last_char_is(file_header->name, '/')) {
                        file_header->mode |= S_IFDIR;
                } else
@@ -179,17 +191,19 @@ char get_header_tar(archive_handle_t *archive_handle)
        case '6':
                file_header->mode |= S_IFIFO;
                break;
-#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
        case 'L':
+               /* paranoia: tar with several consecutive longnames */
+               free(longname);
                longname = xzalloc(file_header->size + 1);
                xread(archive_handle->src_fd, longname, file_header->size);
                archive_handle->offset += file_header->size;
                return get_header_tar(archive_handle);
        case 'K':
+               free(linkname);
                linkname = xzalloc(file_header->size + 1);
                xread(archive_handle->src_fd, linkname, file_header->size);
                archive_handle->offset += file_header->size;
-               file_header->name = linkname;
                return get_header_tar(archive_handle);
        case 'D':       /* GNU dump dir */
        case 'M':       /* Continuation of multi volume archive */
@@ -205,6 +219,17 @@ char get_header_tar(archive_handle_t *archive_handle)
                bb_error_msg("unknown typeflag: 0x%x", tar.typeflag);
        }
 
+#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+       if (longname) {
+               file_header->name = longname;
+               longname = NULL;
+       }
+       if (linkname) {
+               file_header->link_name = linkname;
+               linkname = NULL;
+       }
+#endif
+
        /* Strip trailing '/' in directories */
        /* Must be done after mode is set as '/' is used to check if its a directory */
        cp = last_char_is(file_header->name, '/');

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index e6f4e3a48883ed2915b1c405dab21264aeb3f901..1dbd7521b91368d6d838d19980d2f24736b39f82 100644 (file)
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -74,6 +74,7 @@ char * xstrndup(const char *s, int n)
        if (ENABLE_DEBUG && s == NULL)
                bb_error_msg_and_die("xstrndup bug");
 
+       /* TODO: think about xstrndup("abc", 10000)!!! */
        t = xmalloc(++n);
 
        return safe_strncpy(t,s,n);