[PATCH AUTOSEL 5.12 40/49] net: ipconfig: Don't override command-line hostnames or domains

Sasha Levin
2021-06-07T16:15:15Z

From: Josh Triplett <josh@joshtriplett.org>

[ Upstream commit b508d5fb69c2211a1b860fc058aafbefc3b3c3cd ]

If the user specifies a hostname or domain name as part of the ip=
command-line option, preserve it and don't overwrite it with one
supplied by DHCP/BOOTP.

For instance, ip=::::myhostname::dhcp will use "myhostname" rather than
ignoring and overwriting it.

Fix the comment on ic_bootp_string that suggests it only copies a string
"if not already set"; it doesn't have any such logic.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/ipconfig.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index bc2f6ca97152..816d8aad5a68 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -886,7 +886,7 @@ static void __init ic_bootp_send_if(struct ic_device *d, unsigned long jiffies_d

/*
- * Copy BOOTP-supplied string if not already set.
+ * Copy BOOTP-supplied string
*/
static int __init ic_bootp_string(char *dest, char *src, int len, int max)
{
@@ -935,12 +935,15 @@ static void __init ic_do_bootp_ext(u8 *ext)
}
break;
case 12: /* Host name */
- ic_bootp_string(utsname()->nodename, ext+1, *ext,
- __NEW_UTS_LEN);
- ic_host_name_set = 1;
+ if (!ic_host_name_set) {
+ ic_bootp_string(utsname()->nodename, ext+1, *ext,
+ __NEW_UTS_LEN);
+ ic_host_name_set = 1;
+ }
break;
case 15: /* Domain name (DNS) */
- ic_bootp_string(ic_domain, ext+1, *ext, sizeof(ic_domain));
+ if (!ic_domain[0])
+ ic_bootp_string(ic_domain, ext+1, *ext, sizeof(ic_domain));
break;
case 17: /* Root path */
if (!root_server_path[0])
--
2.30.2