From 2af87fa2776c8125a587a9b0c2c4fae3bf921ff7 Mon Sep 17 00:00:00 2001 From: Connor Behan Date: Mon, 27 Jan 2014 14:42:09 +0200 Subject: [PATCH] Detect tarbombs while extracting * src/common.h (one_top_level_option): New global. (one_top_level): New global. * src/extract.c (extr_init): If one_top_level_option is set, determine the name one_top_level that might have to be prepended. (extract_archive): If one_top_level_option is set, prepend one_top_level to all names that don't already start with it. * src/tar.c (ONE_TOP_LEVEL_OPTION): New contant. (options): New option --one-top-level. (parse_opt): Handle this option. (decode_options): Make it conflict with --absolute-names. --- NEWS | 8 +++++++ doc/tar.texi | 11 ++++++++++ src/common.h | 4 ++++ src/extract.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++ src/tar.c | 11 ++++++++++ 5 files changed, 93 insertions(+) diff --git a/NEWS b/NEWS index ced28e0..44b2e37 100644 --- a/NEWS +++ b/NEWS @@ -42,6 +42,14 @@ version 1.27.1 - Sergey Poznyakoff, 2013-11-17 * Fix extracting sparse members from star archives. +* The --one-top-level option. + +This new command line option tells tar that the working directory +(or the one passed to -C) should not be populated with more than one +name directly under it. Instead, a newly created subdirectory is +used whose name is equal to the archive name without the extension. +For example, foo.tar.gz would be extracted to foo. + version 1.27 - Sergey Poznyakoff, 2013-10-05 diff --git a/doc/tar.texi b/doc/tar.texi index 424617c..ece40f4 100644 --- a/doc/tar.texi +++ b/doc/tar.texi @@ -3086,6 +3086,17 @@ Used when creating an archive. Prevents @command{tar} from recursing into directories that are on different file systems from the current directory. +@opsummary{one-top-level} +@item --one-top-level +Tells @command{tar} to create a new directory beneath the extraction directory +(or the one passed to @option{-C}) and use it to guard against tarbombs. The +name of the new directory will be equal to the name of the archive with the +extension stripped off. If any archive names (after transformations from +@option{--transform} and @option{--strip-components}) do not already begin with +it, the new directory will be prepended to the names immediately before +extraction. Recognized extensions are @samp{.tar}, @samp{.taz}, @samp{.tbz}, +@samp{.tb2}, @samp{.tgz}, @samp{.tlz} and @samp{.txz}. + @opsummary{overwrite} @item --overwrite diff --git a/src/common.h b/src/common.h index 8f8a337..365379a 100644 --- a/src/common.h +++ b/src/common.h @@ -235,6 +235,10 @@ GLOBAL bool numeric_owner_option; GLOBAL bool one_file_system_option; +/* Create a top-level directory for extracting based on the archive name. */ +GLOBAL bool one_top_level_option; +GLOBAL char *one_top_level; + /* Specified value to be put into tar file in place of stat () results, or just null and -1 if such an override should not take place. */ GLOBAL char const *owner_name_option; diff --git a/src/extract.c b/src/extract.c index 9b6b7f9..b6fdbbb 100644 --- a/src/extract.c +++ b/src/extract.c @@ -191,6 +191,35 @@ extr_init (void) umask (newdir_umask); /* restore the kernel umask */ current_umask = newdir_umask; } + + /* If the user wants to guarantee that everything is under one directory, + determine its name now and let it be created later. */ + if (one_top_level_option) + { + int i; + char *base = base_name (archive_name_array[0]); + + for (i = strlen (base) - 1; i > 2; i--) + if (!strncmp (base + i - 3, ".tar", 4) || + !strncmp (base + i - 3, ".taz", 4) || + !strncmp (base + i - 3, ".tbz", 4) || + !strncmp (base + i - 3, ".tb2", 4) || + !strncmp (base + i - 3, ".tgz", 4) || + !strncmp (base + i - 3, ".tlz", 4) || + !strncmp (base + i - 3, ".txz", 4)) break; + + if (i <= 3) + { + one_top_level_option = false; + free (base); + return; + } + + one_top_level = xmalloc (i - 2); + strncpy (one_top_level, base, i - 3); + one_top_level[i - 3] = '\0'; + free (base); + } } /* Use fchmod if possible, fchmodat otherwise. */ @@ -1578,6 +1607,33 @@ prepare_to_extract (char const *file_name, int typeflag, tar_extractor_t *fun) return 1; } +void +maybe_prepend_name (char **file_name) +{ + int i; + + for (i = 0; i < strlen (*file_name); i++) + if (!ISSLASH ((*file_name)[i]) && (*file_name)[i] != '.') break; + + if (i == strlen (*file_name)) + return; + + if (!strncmp (*file_name + i, one_top_level, strlen (one_top_level))) + { + int pos = i + strlen (one_top_level); + if (ISSLASH ((*file_name)[pos]) || (*file_name)[pos] == '\0') return; + } + + char *new_name = xmalloc (strlen (one_top_level) + strlen (*file_name) + 2); + + strcpy (new_name, one_top_level); + strcat (new_name, "/"); + strcat (new_name, *file_name); + + free (*file_name); + *file_name = new_name; +} + /* Extract a file from the archive. */ void extract_archive (void) @@ -1628,6 +1684,9 @@ extract_archive (void) typeflag = sparse_member_p (¤t_stat_info) ? GNUTYPE_SPARSE : current_header->header.typeflag; + if (one_top_level_option) + maybe_prepend_name (¤t_stat_info.file_name); + if (prepare_to_extract (current_stat_info.file_name, typeflag, &fun)) { if (fun && (*fun) (current_stat_info.file_name, typeflag) diff --git a/src/tar.c b/src/tar.c index 979bf59..0dfa9c1 100644 --- a/src/tar.c +++ b/src/tar.c @@ -319,6 +319,7 @@ enum OCCURRENCE_OPTION, OLD_ARCHIVE_OPTION, ONE_FILE_SYSTEM_OPTION, + ONE_TOP_LEVEL_OPTION, OVERWRITE_DIR_OPTION, OVERWRITE_OPTION, OWNER_OPTION, @@ -489,6 +490,9 @@ static struct argp_option options[] = { {"keep-directory-symlink", KEEP_DIRECTORY_SYMLINK_OPTION, 0, 0, N_("preserve existing symlinks to directories when extracting"), GRID+1 }, + {"one-top-level", ONE_TOP_LEVEL_OPTION, 0, 0, + N_("create a subdirectory to avoid having loose files extracted"), + GRID+1 }, #undef GRID #define GRID 40 @@ -1441,6 +1445,10 @@ parse_opt (int key, char *arg, struct argp_state *state) one_file_system_option = true; break; + case ONE_TOP_LEVEL_OPTION: + one_top_level_option = true; + break; + case 'l': check_links_option = 1; break; @@ -2393,6 +2401,9 @@ decode_options (int argc, char **argv) subcommand_string (subcommand_option))); } + if (one_top_level_option && absolute_names_option) + USAGE_ERROR ((0, 0, _("--one-top-level cannot be used with --absolute-names"))); + if (archive_names == 0) { /* If no archive file name given, try TAPE from the environment, or -- 2.43.0