From 59357157706d47c365b2227739e17daba3607526 Mon Sep 17 00:00:00 2001 From: Alessandro Ghedini <alessandro@ghedini.me> Date: Sun, 1 Mar 2015 12:07:45 +0100 Subject: [PATCH] Add ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS option This fixes a directory traversal in the cpio tool. --- cpio/bsdcpio.1 | 3 ++- cpio/cpio.c | 2 ++ libarchive/archive.h | 2 ++ libarchive/archive_write_disk.3 | 3 +++ libarchive/archive_write_disk_posix.c | 14 +++++++++++--- libarchive/test/test_write_disk_secure.c | 23 +++++++++++++++++++++++ 6 files changed, 43 insertions(+), 4 deletions(-) diff --git a/cpio/bsdcpio.1 b/cpio/bsdcpio.1 index f966aa0..e52546e 100644 --- a/cpio/bsdcpio.1 +++ b/cpio/bsdcpio.1 @@ -156,7 +156,8 @@ See above for description. .It Fl Fl insecure (i and p mode only) Disable security checks during extraction or copying. -This allows extraction via symbolic links and path names containing +This allows extraction via symbolic links, absolute paths, +and path names containing .Sq .. in the name. .It Fl J , Fl Fl xz diff --git a/cpio/cpio.c b/cpio/cpio.c index 0acde11..b267e9b 100644 --- a/cpio/cpio.c +++ b/cpio/cpio.c @@ -171,6 +171,7 @@ main(int argc, char *argv[]) cpio->extract_flags |= ARCHIVE_EXTRACT_NO_OVERWRITE_NEWER; cpio->extract_flags |= ARCHIVE_EXTRACT_SECURE_SYMLINKS; cpio->extract_flags |= ARCHIVE_EXTRACT_SECURE_NODOTDOT; + cpio->extract_flags |= ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS; cpio->extract_flags |= ARCHIVE_EXTRACT_PERM; cpio->extract_flags |= ARCHIVE_EXTRACT_FFLAGS; cpio->extract_flags |= ARCHIVE_EXTRACT_ACL; @@ -256,6 +257,7 @@ main(int argc, char *argv[]) case OPTION_INSECURE: cpio->extract_flags &= ~ARCHIVE_EXTRACT_SECURE_SYMLINKS; cpio->extract_flags &= ~ARCHIVE_EXTRACT_SECURE_NODOTDOT; + cpio->extract_flags &= ~ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS; break; case 'L': /* GNU cpio */ cpio->option_follow_links = 1; diff --git a/libarchive/archive.h b/libarchive/archive.h index 1f0fc38..ef635ac 100644 --- a/libarchive/archive.h +++ b/libarchive/archive.h @@ -649,6 +649,8 @@ __LA_DECL int archive_read_set_passphrase_callback(struct archive *, /* Default: Do not use HFS+ compression if it was not compressed. */ /* This has no effect except on Mac OS v10.6 or later. */ #define ARCHIVE_EXTRACT_HFS_COMPRESSION_FORCED (0x8000) +/* Default: Do not reject entries with absolute paths */ +#define ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS (0x10000) __LA_DECL int archive_read_extract(struct archive *, struct archive_entry *, int flags); diff --git a/libarchive/archive_write_disk.3 b/libarchive/archive_write_disk.3 index fa925cc..a2e7afa 100644 --- a/libarchive/archive_write_disk.3 +++ b/libarchive/archive_write_disk.3 @@ -177,6 +177,9 @@ The default is to not refuse such paths. Note that paths ending in .Pa .. always cause an error, regardless of this flag. +.It Cm ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS +Refuse to extract an absolute path. +The default is to not refuse such paths. .It Cm ARCHIVE_EXTRACT_SPARSE Scan data for blocks of NUL bytes and try to recreate them with holes. This results in sparse files, independent of whether the archive format diff --git a/libarchive/archive_write_disk_posix.c b/libarchive/archive_write_disk_posix.c index ab3bdac..c1290eb 100644 --- a/libarchive/archive_write_disk_posix.c +++ b/libarchive/archive_write_disk_posix.c @@ -2509,8 +2509,9 @@ cleanup_pathname_win(struct archive_write_disk *a) /* * Canonicalize the pathname. In particular, this strips duplicate * '/' characters, '.' elements, and trailing '/'. It also raises an - * error for an empty path, a trailing '..' or (if _SECURE_NODOTDOT is - * set) any '..' in the path. + * error for an empty path, a trailing '..', (if _SECURE_NODOTDOT is + * set) any '..' in the path or (if ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS + * is set) if the path is absolute. */ static int cleanup_pathname(struct archive_write_disk *a) @@ -2529,8 +2530,15 @@ cleanup_pathname(struct archive_write_disk *a) cleanup_pathname_win(a); #endif /* Skip leading '/'. */ - if (*src == '/') + if (*src == '/') { + if (a->flags & ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS) { + archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC, + "Path is absolute"); + return (ARCHIVE_FAILED); + } + separator = *src++; + } /* Scan the pathname one element at a time. */ for (;;) { diff --git a/libarchive/test/test_write_disk_secure.c b/libarchive/test/test_write_disk_secure.c index 31c5bfd..2c94206 100644 --- a/libarchive/test/test_write_disk_secure.c +++ b/libarchive/test/test_write_disk_secure.c @@ -178,6 +178,29 @@ DEFINE_TEST(test_write_disk_secure) assert(S_ISDIR(st.st_mode)); archive_entry_free(ae); + /* + * Without security checks, we should be able to + * extract an absolute path. + */ + assert((ae = archive_entry_new()) != NULL); + archive_entry_copy_pathname(ae, "/tmp/libarchive_test-test_write_disk_secure-absolute_path.tmp"); + archive_entry_set_mode(ae, S_IFREG | 0777); + assert(0 == archive_write_header(a, ae)); + assert(0 == archive_write_finish_entry(a)); + assertFileExists("/tmp/libarchive_test-test_write_disk_secure-absolute_path.tmp"); + assert(0 == unlink("/tmp/libarchive_test-test_write_disk_secure-absolute_path.tmp")); + + /* But with security checks enabled, this should fail. */ + assert(archive_entry_clear(ae) != NULL); + archive_entry_copy_pathname(ae, "/tmp/libarchive_test-test_write_disk_secure-absolute_path.tmp"); + archive_entry_set_mode(ae, S_IFREG | 0777); + archive_write_disk_set_options(a, ARCHIVE_EXTRACT_SECURE_NOABSOLUTEPATHS); + failure("Extracting an absolute path should fail here."); + assertEqualInt(ARCHIVE_FAILED, archive_write_header(a, ae)); + archive_entry_free(ae); + assert(0 == archive_write_finish_entry(a)); + assertFileNotExists("/tmp/libarchive_test-test_write_disk_secure-absolute_path.tmp"); + assertEqualInt(ARCHIVE_OK, archive_write_free(a)); /* Test the entries on disk. */