git: 9ac25e9b5b31 - stable/14 - ipfilter: Add ipf_check_names_string()

The branch stable/14 has been updated by cy:

URL: https://cgit.FreeBSD.org/src/commit/?id=9ac25e9b5b31fb03f090e157166b05d2d501a8f0

commit 9ac25e9b5b31fb03f090e157166b05d2d501a8f0
Author:     Cy Schubert <cy@FreeBSD.org>
AuthorDate: 2025-11-18 19:23:06 +0000
Commit:     Cy Schubert <cy@FreeBSD.org>
CommitDate: 2026-01-05 20:00:53 +0000

    ipfilter: Add ipf_check_names_string()
    
    ipf_check_names_string will verify userland inputs in names strings
    (fr.fr_names, in.in_names) for correctness.
    
    Original concept of ipf_check_names_string() instead of macros by
    markj.
    
    Reviewed by:            markj
    MFC after:              1 week
    Differential revision:  https://reviews.freebsd.org/D53843
    
    (cherry picked from commit 525c535d5aa87f686dcfee620619827f7c6090db)
---
 sys/netpfil/ipfilter/netinet/fil.c    | 31 +++++++++++++++++++++++++++++++
 sys/netpfil/ipfilter/netinet/ip_fil.h |  1 +
 2 files changed, 32 insertions(+)

diff --git a/sys/netpfil/ipfilter/netinet/fil.c b/sys/netpfil/ipfilter/netinet/fil.c
index ce96558fe99a..e152fa23c83c 100644
--- a/sys/netpfil/ipfilter/netinet/fil.c
+++ b/sys/netpfil/ipfilter/netinet/fil.c
@@ -9955,3 +9955,34 @@ ipf_inet6_mask_del(int bits, i6addr_t *mask, ipf_v6_masktab_t *mtab)
 	ASSERT(mtab->imt6_max >= 0);
 }
 #endif
+
+/* ------------------------------------------------------------------------ */
+/* Function:    ipf_check_names_string                                      */
+/* Returns:     int       -  0 == success                                   */
+/*                        -  1 == negative offset                           */
+/*                        -  2 == offset exceds namelen                     */
+/*                        -  3 == string exceeds the names string           */
+/* Parameters:  names   - pointer to names string                           */
+/*              namelen - total length of names string                      */
+/*              offset  - offset into names string                          */
+/*                                                                          */
+/* Validate the names string (fr_names for ipfilter, in_names for ipnat).   */
+/* ------------------------------------------------------------------------ */
+int
+ipf_check_names_string(char *names, int namelen, int offset)
+{
+	const char *name;
+	size_t len;
+
+	if (offset == -1)
+		return (0);
+	if (offset < 0)
+		return (1);
+	if (offset > namelen)
+		return (2);
+	name = &names[offset];
+	len = strnlen(name, namelen - offset);
+	if (len == namelen - offset)
+		return (3);
+	return (0);
+}
diff --git a/sys/netpfil/ipfilter/netinet/ip_fil.h b/sys/netpfil/ipfilter/netinet/ip_fil.h
index 7343fd079564..92935689e0c4 100644
--- a/sys/netpfil/ipfilter/netinet/ip_fil.h
+++ b/sys/netpfil/ipfilter/netinet/ip_fil.h
@@ -1861,5 +1861,6 @@ extern	int	ipf_ht_node_del(host_track_t *, int, i6addr_t *);
 extern	void	ipf_rb_ht_flush(host_track_t *);
 extern	void	ipf_rb_ht_freenode(host_node_t *, void *);
 extern	void	ipf_rb_ht_init(host_track_t *);
+extern	int	ipf_check_names_string(char *, int, int);
 
 #endif	/* __IP_FIL_H__ */