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[35.236.206.96]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b7047aa6f8sm327843685a.25.2024.12.17.07.35.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2024 07:35:44 -0800 (PST) Date: Tue, 17 Dec 2024 10:35:44 -0500 From: Willem de Bruijn To: Kees Cook , "David S. Miller" Cc: Kees Cook , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, Simon Horman , David Ahern , Sebastian Andrzej Siewior , Lorenzo Bianconi , Joe Damato , Alexander Lobakin , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Message-ID: <67619a5029d2c_a046929426@willemb.c.googlers.com.notmuch> In-Reply-To: <20241217012445.work.979-kees@kernel.org> References: <20241217012445.work.979-kees@kernel.org> Subject: Re: [PATCH] net: core: dev.c confirmed to use classic sockaddr Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Kees Cook wrote: > As part of trying to clean up struct sock_addr, add comments about the > sockaddr arguments of dev_[gs]et_mac_address() being actual classic "max > 14 bytes in sa_data" sockaddr instances and not struct sockaddr_storage. What is this assertion based on? I see various non-Ethernet .ndo_set_mac_address implementations, which dev_set_mac_address calls. And dev_set_mac_addr_user is called from rtnetlink do_setlink. Which kmalloc's sa based on dev->addr_len. > > Signed-off-by: Kees Cook > --- > Cc: "David S. Miller" > Cc: Eric Dumazet > Cc: Jakub Kicinski > Cc: Paolo Abeni > Cc: netdev@vger.kernel.org > --- > net/core/dev.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/net/core/dev.c b/net/core/dev.c > index 45a8c3dd4a64..5abfd29a35bf 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -9183,7 +9183,8 @@ EXPORT_SYMBOL(dev_pre_changeaddr_notify); > /** > * dev_set_mac_address - Change Media Access Control Address > * @dev: device > - * @sa: new address > + * @sa: new address in a classic "struct sockaddr", which will never > + * have more than 14 bytes in @sa::sa_data > * @extack: netlink extended ack > * > * Change the hardware (MAC) address of the device > @@ -9217,6 +9218,7 @@ EXPORT_SYMBOL(dev_set_mac_address); > > DECLARE_RWSEM(dev_addr_sem); > > +/* "sa" is a classic sockaddr: it will only ever use 14 bytes from sa_data. */ > int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa, > struct netlink_ext_ack *extack) > { > @@ -9229,6 +9231,7 @@ int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa, > } > EXPORT_SYMBOL(dev_set_mac_address_user); > > +/* "sa" is a classic sockaddr: it will only ever use 14 bytes from sa_data. */ > int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name) > { > size_t size = sizeof(sa->sa_data_min); > -- > 2.34.1 >