tar: correctly skip (and warn about) pax headers.

plug memory leak. save 50 bytes.
Wooohooo! we finally can unpack kernel tarballs!

diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index b785d631d383c1e23d70d9ac96801c72ef6ccde8..583f6f81175852b911a32f02e98ffb671921d0ac 100644 (file)
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -40,11 +40,12 @@ static unsigned long long getOctal(char *str, int len)
                bb_error_msg_and_die("corrupted octal value in tar header");
        return v;
 }
+#define GET_OCTAL(a) getOctal((a), sizeof(a))
 
 void BUG_tar_header_size(void);
 char get_header_tar(archive_handle_t *archive_handle)
 {
-       static int end = 0;
+       static int end;
 
        file_header_t *file_header = archive_handle->file_header;
        struct {
@@ -69,18 +70,17 @@ 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 = 1 };
-#endif
 
        if (sizeof(tar) != 512)
                BUG_tar_header_size();
+ again:
 
        /* Align header */
        data_align(archive_handle, 512);
 
+ again_after_align:
+
        xread(archive_handle->src_fd, &tar, 512);
        archive_handle->offset += 512;
 
@@ -121,13 +121,12 @@ 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
+       /* 0 is reserved for high perf file, treat as normal file */
+       if (!tar.typeflag) tar.typeflag = '0';
+       parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');
 
        /* getOctal trashes subsequent field, therefore we call it
         * on fields in reverse order */
-#define GET_OCTAL(a) getOctal((a), sizeof(a))
        if (tar.devmajor[0]) {
                unsigned minor = GET_OCTAL(tar.devminor);
                unsigned major = GET_OCTAL(tar.devmajor);
@@ -147,8 +146,8 @@ char get_header_tar(archive_handle_t *archive_handle)
        file_header->uid = GET_OCTAL(tar.uid);
        /* Set bits 0-11 of the files mode */
        file_header->mode = 07777 & GET_OCTAL(tar.mode);
-#undef GET_OCTAL
 
+       file_header->name = NULL;
        if (!longname && parse_names) {
                /* we trash mode[0] here, it's ok */
                tar.name[sizeof(tar.name)] = '\0';
@@ -158,6 +157,7 @@ char get_header_tar(archive_handle_t *archive_handle)
                        file_header->name = concat_path_file(tar.prefix, tar.name);
                } else
                        file_header->name = xstrdup(tar.name);
+               /* FIXME: add check for /../ attacks */
        }
 
        /* Set bits 12-15 of the files mode */
@@ -168,8 +168,7 @@ char get_header_tar(archive_handle_t *archive_handle)
                file_header->mode |= S_IFREG;
                break;
        case '7':
-               /* Reserved for high performance files, treat as normal file */
-       case 0:
+       /* case 0: */
        case '0':
 #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
                if (last_char_is(file_header->name, '/')) {
@@ -195,18 +194,24 @@ char get_header_tar(archive_handle_t *archive_handle)
                break;
 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
        case 'L':
-               /* paranoia: tar with several consecutive longnames */
+               /* free: paranoia: tar with several consecutive longnames */
                free(longname);
+               /* For paranoia reasons we allocate extra NUL char */
                longname = xzalloc(file_header->size + 1);
+               /* We read ASCIZ string, including NUL */
                xread(archive_handle->src_fd, longname, file_header->size);
                archive_handle->offset += file_header->size;
-               return get_header_tar(archive_handle);
+               /* return get_header_tar(archive_handle); */
+               /* gcc 4.1.1 didn't optimize it into jump */
+               /* so we will do it ourself, this also saves stack */
+               goto again;
        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;
-               return get_header_tar(archive_handle);
+               /* return get_header_tar(archive_handle); */
+               goto again;
        case 'D':       /* GNU dump dir */
        case 'M':       /* Continuation of multi volume archive */
        case 'N':       /* Old GNU for names > 100 characters */
@@ -214,11 +219,19 @@ char get_header_tar(archive_handle_t *archive_handle)
        case 'V':       /* Volume header */
 #endif
        case 'g':       /* pax global header */
-       case 'x':       /* pax extended header */
-               bb_error_msg("ignoring extension type %c", tar.typeflag);
-               break;
+       case 'x': {     /* pax extended header */
+               off_t sz;
+               bb_error_msg("warning: skipping header '%c'", tar.typeflag);
+               sz = (file_header->size + 511) & ~(off_t)511;
+               archive_handle->offset += sz;
+               sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
+               while (sz--)
+                       xread(archive_handle->src_fd, &tar, 512);
+               /* return get_header_tar(archive_handle); */
+               goto again_after_align;
+       }
        default:
-               bb_error_msg("unknown typeflag: 0x%x", tar.typeflag);
+               bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
        }
 
 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
@@ -246,10 +259,12 @@ char get_header_tar(archive_handle_t *archive_handle)
                llist_add_to(&(archive_handle->passed), file_header->name);
        } else {
                data_skip(archive_handle);
+               free(file_header->name);
        }
        archive_handle->offset += file_header->size;
 
        free(file_header->link_name);
+       /* Do not free(file_header->name)! */
 
        return EXIT_SUCCESS;
 }

diff --git a/archival/tar.c b/archival/tar.c
index bf6786f0a14c79af8ec4f913488d22f39cff9e3b..48a1c34cd2bce16ec80fc56de7d3789b7712b883 100644 (file)
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -768,7 +768,7 @@ int tar_main(int argc, char **argv)
        if (verboseFlag) tar_handle->action_header = header_verbose_list;
        if (verboseFlag == 1) tar_handle->action_header = header_list;
 
-       if ((opt & OPT_EXTRACT) && tar_handle->action_data != data_extract_to_stdout)
+       if (opt & OPT_EXTRACT)
                tar_handle->action_data = data_extract_all;
 
        if (opt & OPT_2STDOUT)