| Message ID | 20210807132703.26303-1-pali@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2459dcb96bcba94c08d6861f8a050185ff301672 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | ppp: Fix generating ifname when empty IFLA_IFNAME is specified | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 6 of 6 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: line length of 97 exceeds 80 columns |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Sat, 7 Aug 2021 15:27:03 +0200 you wrote: > IFLA_IFNAME is nul-term string which means that IFLA_IFNAME buffer can be > larger than length of string which contains. > > Function __rtnl_newlink() generates new own ifname if either IFLA_IFNAME > was not specified at all or userspace passed empty nul-term string. > > It is expected that if userspace does not specify ifname for new ppp netdev > then kernel generates one in format "ppp<id>" where id matches to the ppp > unit id which can be later obtained by PPPIOCGUNIT ioctl. > > [...] Here is the summary with links: - ppp: Fix generating ifname when empty IFLA_IFNAME is specified https://git.kernel.org/netdev/net/c/2459dcb96bcb You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index d445ecb1d0c7..1c6ba5a5e081 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -1306,7 +1306,7 @@ static int ppp_nl_newlink(struct net *src_net, struct net_device *dev, * the PPP unit identifer as suffix (i.e. ppp<unit_id>). This allows * userspace to infer the device name using to the PPPIOCGUNIT ioctl. */ - if (!tb[IFLA_IFNAME]) + if (!tb[IFLA_IFNAME] || !nla_len(tb[IFLA_IFNAME]) || !*(char *)nla_data(tb[IFLA_IFNAME])) conf.ifname_is_set = false; err = ppp_dev_configure(src_net, dev, &conf);
IFLA_IFNAME is nul-term string which means that IFLA_IFNAME buffer can be larger than length of string which contains. Function __rtnl_newlink() generates new own ifname if either IFLA_IFNAME was not specified at all or userspace passed empty nul-term string. It is expected that if userspace does not specify ifname for new ppp netdev then kernel generates one in format "ppp<id>" where id matches to the ppp unit id which can be later obtained by PPPIOCGUNIT ioctl. And it works in this way if IFLA_IFNAME is not specified at all. But it does not work when IFLA_IFNAME is specified with empty string. So fix this logic also for empty IFLA_IFNAME in ppp_nl_newlink() function and correctly generates ifname based on ppp unit identifier if userspace did not provided preferred ifname. Without this patch when IFLA_IFNAME was specified with empty string then kernel created a new ppp interface in format "ppp<id>" but id did not match ppp unit id returned by PPPIOCGUNIT ioctl. In this case id was some number generated by __rtnl_newlink() function. Signed-off-by: Pali Rohár <pali@kernel.org> Fixes: bb8082f69138 ("ppp: build ifname using unit identifier for rtnl based devices") --- drivers/net/ppp/ppp_generic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)