From 676599b36a92f3c201c5682ee7a5caddd9f370a4 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Fri, 2 Oct 2015 11:34:13 +0200 Subject: Harden putpwent, putgrent, putspent, putspent against injection [BZ #18724] This prevents injection of ':' and '\n' into output functions which use the NSS files database syntax. Critical fields (user/group names and file system paths) are checked strictly. For backwards compatibility, the GECOS field is rewritten instead. The getent program is adjusted to use the put*ent functions in libc, instead of local copies. This changes the behavior of getent if user names start with '-' or '+'. --- gshadow/putsgent.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'gshadow/putsgent.c') diff --git a/gshadow/putsgent.c b/gshadow/putsgent.c index 0b2cad6eaa..c1cb921595 100644 --- a/gshadow/putsgent.c +++ b/gshadow/putsgent.c @@ -15,9 +15,11 @@ License along with the GNU C Library; if not, see . */ +#include #include #include #include +#include #define _S(x) x ? x : "" @@ -29,6 +31,15 @@ putsgent (const struct sgrp *g, FILE *stream) { int errors = 0; + if (g->sg_namp == NULL || !__nss_valid_field (g->sg_namp) + || !__nss_valid_field (g->sg_passwd) + || !__nss_valid_list_field (g->sg_adm) + || !__nss_valid_list_field (g->sg_mem)) + { + __set_errno (EINVAL); + return -1; + } + _IO_flockfile (stream); if (fprintf (stream, "%s:%s:", g->sg_namp, _S (g->sg_passwd)) < 0) -- cgit v1.2.3