[PATCH] fix 16018 masking of potentially malicious tar/cpio content - RESEND

[Ian Norton]

Prevent unprintable bytes including terminal escapes being printed when
listing tar file contents in a terminal as this can be used to hide
malicious archive content from users prior to unpacking a file.

Fixes #16018

Also added bb_safe_dump_str() to include/libbb.h


---
archival/libarchive/header_list.c         |  3 ++-
archival/libarchive/header_verbose_list.c | 14 +++++++-------
include/libbb.h                           |  8 ++++++++
3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/archival/libarchive/header_list.c b/archival/libarchive/header_list.c
index 0621aa406..9ee69aae2 100644
--- a/archival/libarchive/header_list.c
+++ b/archival/libarchive/header_list.c
@@ -8,5 +8,6 @@
void FAST_FUNC header_list(const file_header_t *file_header)
{
//TODO: cpio -vp DIR should output "DIR/NAME", not just "NAME" */
-       puts(file_header->name);
+       bb_safe_dump_str(stdout, file_header->name);
+       bb_putchar('\n');
}
diff --git a/archival/libarchive/header_verbose_list.c b/archival/libarchive/header_verbose_list.c
index a575a08a0..956589a1b 100644
--- a/archival/libarchive/header_verbose_list.c
+++ b/archival/libarchive/header_verbose_list.c
@@ -29,7 +29,7 @@ void FAST_FUNC header_verbose_list(const file_header_t *file_header)
                /*sprintf(gid, "%u", (unsigned)file_header->gid);*/
                group = utoa(file_header->gid);
        }
-       printf("%s %s/%s %9"OFF_FMT"u %4u-%02u-%02u %02u:%02u:%02u %s",
+       printf("%s %s/%s %9"OFF_FMT"u %4u-%02u-%02u %02u:%02u:%02u ",
                bb_mode_string(modestr, file_header->mode),
                user,
                group,
@@ -39,14 +39,13 @@ void FAST_FUNC header_verbose_list(const file_header_t *file_header)
                ptm->tm_mday,
                ptm->tm_hour,
                ptm->tm_min,
-               ptm->tm_sec,
-               file_header->name);
+               ptm->tm_sec);

#else /* !FEATURE_TAR_UNAME_GNAME */

        localtime_r(&file_header->mtime, ptm);

-       printf("%s %u/%u %9"OFF_FMT"u %4u-%02u-%02u %02u:%02u:%02u %s",
+       printf("%s %u/%u %9"OFF_FMT"u %4u-%02u-%02u %02u:%02u:%02u ",
                bb_mode_string(modestr, file_header->mode),
                (unsigned)file_header->uid,
                (unsigned)file_header->gid,
@@ -56,14 +55,15 @@ void FAST_FUNC header_verbose_list(const file_header_t *file_header)
                ptm->tm_mday,
                ptm->tm_hour,
                ptm->tm_min,
-               ptm->tm_sec,
-               file_header->name);
+               ptm->tm_sec);

#endif /* FEATURE_TAR_UNAME_GNAME */

+       bb_safe_dump_str(stdout, file_header->name);
        /* NB: GNU tar shows "->" for symlinks and "link to" for hardlinks */
        if (file_header->link_target) {
-               printf(" -> %s", file_header->link_target);
+               printf(" -> ");
+               bb_safe_dump_str(stdout, file_header->link_target);
        }
        bb_putchar('\n');
}
diff --git a/include/libbb.h b/include/libbb.h
index 01cdb1bdc..3222fac8b 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -2524,6 +2524,14 @@ static ALWAYS_INLINE unsigned char bb_ascii_tolower(unsigned char a)
#define isgraph_asciionly(a) ((unsigned)((a) - 0x21) <= 0x7e - 0x21)
#define isprint_asciionly(a) ((unsigned)((a) - 0x20) <= 0x7e - 0x20)

+/* Print msg to a file-descriptor, replacing any unprintable and terminal escape bytes with '?' if fd is a TTY */
+static ALWAYS_INLINE void bb_safe_dump_str(FILE* fd, const char* msg) {
+       int fdno = fileno(fd);
+       if (isatty(fdno)) {
+    msg = printable_string(msg);
+       }
+       fprintf(fd, "%s", msg);
+}

/* Simple unit-testing framework */

--
2.20.1


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