kernel/linux.git/drivers/net/ppp/ppp_generic.c, branch v7.0.10

pppoe: drop PFC frames

2026-05-23T11:09:20+00:00

[ Upstream commit cc1ff87bce1ccd38410ab10960f576dcd17db679 ] RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the current PPPoE driver assumes an uncompressed (2-byte) protocol field. However, the generic PPP layer function ppp_input() is not aware of the negotiation result, and still accepts PFC frames. If a peer with a broken implementation or an attacker sends a frame with a compressed (1-byte) protocol field, the subsequent PPP payload is shifted by one byte. This causes the network header to be 4-byte misaligned, which may trigger unaligned access exceptions on some architectures. To reduce the attack surface, drop PPPoE PFC frames. Introduce ppp_skb_is_compressed_proto() helper function to be used in both ppp_generic.c and pppoe.c to avoid open-coding. Fixes: 7fb1b8ca8fa1 ("ppp: Move PFC decompression to PPP generic layer") Signed-off-by: Qingfang Deng Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260415022456.141758-2-qingfang.deng@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ppp: require CAP_NET_ADMIN in target netns for unattached ioctls

2026-05-23T11:08:39+00:00

[ Upstream commit 2bb6379416fd19f44c3423a00bfd8626259f6067 ] /dev/ppp open is currently authorized against file->f_cred->user_ns, while unattached administrative ioctls operate on current->nsproxy->net_ns. As a result, a local unprivileged user can create a new user namespace with CLONE_NEWUSER, gain CAP_NET_ADMIN only in that new user namespace, and still issue PPPIOCNEWUNIT, PPPIOCATTACH, or PPPIOCATTCHAN against an inherited network namespace. Require CAP_NET_ADMIN in the user namespace that owns the target network namespace before handling unattached PPP administrative ioctls. This preserves normal pppd operation in the network namespace it is actually privileged in, while rejecting the userns-only inherited-netns case. Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2") Signed-off-by: Taegu Ha Link: https://patch.msgid.link/20260409071117.4354-1-hataegu0826@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

ppp: enable TX scatter-gather

2026-02-05T09:06:27+00:00

PPP channels using chan->direct_xmit prepend the PPP header to a skb and call dev_queue_xmit() directly. In this mode the skb does not need to be linear, but the PPP netdevice currently does not advertise scatter-gather features, causing unnecessary linearization and preventing GSO. Enable NETIF_F_SG and NETIF_F_FRAGLIST on PPP devices. In case a linear buffer is required (PPP compression, multilink, and channels without direct_xmit), call skb_linearize() explicitly. Signed-off-by: Qingfang Deng Link: https://patch.msgid.link/20260129012902.941-1-dqfext@gmail.com Signed-off-by: Paolo Abeni

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-09-04T20:33:00+00:00

Cross-merge networking fixes after downstream PR (net-6.17-rc5). No conflicts. Adjacent changes: include/net/sock.h c51613fa276f ("net: add sk->sk_drop_counters") 5d6b58c932ec ("net: lockless sock_i_ino()") Signed-off-by: Jakub Kicinski

ppp: fix memory leak in pad_compress_skb

2025-09-04T14:25:48+00:00

If alloc_skb() fails in pad_compress_skb(), it returns NULL without releasing the old skb. The caller does: skb = pad_compress_skb(ppp, skb); if (!skb) goto drop; drop: kfree_skb(skb); When pad_compress_skb() returns NULL, the reference to the old skb is lost and kfree_skb(skb) ends up doing nothing, leading to a memory leak. Align pad_compress_skb() semantics with realloc(): only free the old skb if allocation and compression succeed. At the call site, use the new_skb variable so the original skb is not lost when pad_compress_skb() fails. Fixes: b3f9b92a6ec1 ("[PPP]: add PPP MPPE encryption module") Signed-off-by: Qingfang Deng Reviewed-by: Eric Dumazet Reviewed-by: Yue Haibing Link: https://patch.msgid.link/20250903100726.269839-1-dqfext@gmail.com Signed-off-by: Jakub Kicinski

ppp: remove rwlock usage

2025-08-25T23:45:09+00:00

In struct channel, the upl lock is implemented using rwlock_t, protecting access to pch->ppp and pch->bridge. As previously discussed on the list, using rwlock in the network fast path is not recommended. This patch replaces the rwlock with a spinlock for writers, and uses RCU for readers. - pch->ppp and pch->bridge are now declared as __rcu pointers. - Readers use rcu_dereference_bh() under rcu_read_lock_bh(). - Writers use spin_lock() to update. Signed-off-by: Qingfang Deng Link: https://patch.msgid.link/20250822012548.6232-1-dqfext@gmail.com Signed-off-by: Jakub Kicinski

ppp: fix race conditions in ppp_fill_forward_path

2025-08-19T09:25:32+00:00

ppp_fill_forward_path() has two race conditions: 1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic. 2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels. Fix these by using a lockless RCU approach: - Use list_first_or_null_rcu() to safely test and access the first list entry. - Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal. - Check for a NULL pch->chan before dereferencing it. Fixes: f6efc675c9dd ("net: ppp: resolve forwarding path for bridge pppoe devices") Signed-off-by: Qingfang Deng Link: https://patch.msgid.link/20250814012559.3705-2-dqfext@gmail.com Signed-off-by: Paolo Abeni

ppp: Replace per-CPU recursion counter with lock-owner field

2025-07-17T13:36:18+00:00

The per-CPU variable ppp::xmit_recursion is protecting against recursion due to wrong configuration of the ppp unit. The per-CPU variable relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. The ppp::xmit_recursion is used as a per-CPU boolean. The counter is checked early in the send routing and the transmit path is only entered if the counter is zero. Then the counter is incremented to avoid recursion. It used to detect recursion on channel::downl and ppp::wlock. Create a struct ppp_xmit_recursion and move the counter into it. Add local_lock_t to the struct and use local_lock_nested_bh() for locking. Due to possible nesting, the lock cannot be acquired unconditionally but it requires an owner field to identify recursion before attempting to acquire the lock. The counter is incremented and checked only after the lock is acquired. Since it functions as a boolean rather than a count, and its role is now superseded by the owner field, it can be safely removed. Signed-off-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20250715150806.700536-2-bigeasy@linutronix.de Reviewed-by: Guillaume Nault Signed-off-by: Paolo Abeni