| Message ID | 20241117045512.111515-1-chensong_2000@189.cn (mailing list archive) |
|---|---|
| State | Rejected |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net/core/dev_ioctl: avoid invoking modprobe with empty ifr_name | expand |
On 11/17/24 05:55, Song Chen wrote: > dev_ioctl handles requests from user space if a process calls > ioctl(sockfd, SIOCGIFINDEX, &ifr). However, if this user space > process doesn't have interface name well specified, dev_ioctl > doesn't give it an essential check, as a result, dev_load will > invoke modprobe with a nonsense module name if the user happens > to be sys admin or root, see following code in dev_load: > > no_module = !dev; > if (no_module && capable(CAP_NET_ADMIN)) > no_module = request_module("netdev-%s", name); > if (no_module && capable(CAP_SYS_MODULE)) > request_module("%s", name); > > This patch checks if ifr_name is empty at the beginning, reduces > the overhead of calling modprobe. AFAICS technically this optimize a slow path (bad input from the user-space) at the expense of the more usual path (additional unneeded conditional) and still AFAICS, there are no functional issues addressed here. Note that even the latter more usual path is not a fast path, still the optimization is not worthy. /P
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c index 473c437b6b53..1371269f17d5 100644 --- a/net/core/dev_ioctl.c +++ b/net/core/dev_ioctl.c @@ -676,6 +676,9 @@ int dev_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr, if (cmd == SIOCGIFNAME) return dev_ifname(net, ifr); + if (ifr->ifr_name[0] == '\0') + return -EINVAL; + ifr->ifr_name[IFNAMSIZ-1] = 0; colon = strchr(ifr->ifr_name, ':');
dev_ioctl handles requests from user space if a process calls ioctl(sockfd, SIOCGIFINDEX, &ifr). However, if this user space process doesn't have interface name well specified, dev_ioctl doesn't give it an essential check, as a result, dev_load will invoke modprobe with a nonsense module name if the user happens to be sys admin or root, see following code in dev_load: no_module = !dev; if (no_module && capable(CAP_NET_ADMIN)) no_module = request_module("netdev-%s", name); if (no_module && capable(CAP_SYS_MODULE)) request_module("%s", name); This patch checks if ifr_name is empty at the beginning, reduces the overhead of calling modprobe. Signed-off-by: Song Chen <chensong_2000@189.cn> --- net/core/dev_ioctl.c | 3 +++ 1 file changed, 3 insertions(+)