linux/net/ipv4/esp4.c

1224 lines
28 KiB

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net: Use helpers to get/set UDP len tree-wide Since BIG TCP for UDP tunnels will start using len=0 in the UDP header as an indicator of a GSO packet bigger than 65535 bytes, this commit introduces the following getter and setters to use tree-wide, in order to explicitly mark places where len=0 may be expected, and handle them properly: 1. udp_set_len() sets uh->len to its real value if it's not bigger than 65535, and to 0 otherwise: to be used in GSO context with aggregated packets. 2. udp_set_len_short() is to be used when the length is known to fit 16 bits. It WARNs when the caller tries to assign a bigger value if CONFIG_DEBUG_NET=y. 3. udp_get_len_short() returns len in host byte order: to be used on the RX side to deal with non-aggregated packets, or to access the raw value of the len field. 4. udp_get_len() decodes uh->len set by udp_set_len(). It checks whether the packet is GSO to guard from malformed packets. At the moment udp_set_len() is not used, a following commit will start using it after enabling len>65535 for GSO. Raw uh->len (in network byte order) is still accessed in a few places for checksum calculation purposes, and to decode len=0 in udpv6_rcv for jumbograms. udp_rcv and udpv6_rcv will be addressed by the commit that starts using udp_set_len() to set UDP len=0 for BIG TCP packets in UDP tunnels. Signed-off-by: Alice Mikityanska <alice@isovalent.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Acked-by: Jason A. Donenfeld <Jason@zx2c4.com> Link: https://patch.msgid.link/20260710134242.216538-2-alice.kernel@fastmail.im Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-07-10 16:42:34 +03:00
esp: downgrade zerocopy managed frags before mutating skb frags On the out-of-place output path (esp->inplace == false) ESP rewrites the skb frag array: esp_output_head() appends a trailer frag and esp_output_tail() replaces the frags with a destination page, both referenced with get_page(). When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the payload frags are owned by the ubuf and must not be referenced or unreferenced individually, but ESP mutates the frag array without ever downgrading the skb. This breaks the managed-frag invariant two ways: - esp_ssg_unref() walks the source scatterlist and drops a page reference for every frag, including the ubuf-owned payload frags, pushing their refcount below the GUP pin bias while the pages are still pinned, i.e. a use-after-free of the zerocopy pages; - esp_output_tail() installs its destination page as frag 0 with get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so skb_release_data() takes the skip_unref branch and never drops that reference, leaking the x->xfrag page at packet rate. Fix this the way every other frag-mutating site does (__ip_append_data(), __ip6_append_data(), tcp_sendmsg_locked()) and call skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS, so the per-frag unref in esp_ssg_unref() and the frag release in skb_release_data() are both balanced and no mixed-ownership frag array is left behind. Fixes: 753f1ca4e1e5 ("net: introduce managed frags infrastructure") Signed-off-by: Maher Azzouzi <maherazz04@gmail.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-08-17 14:37:52 +01:00
esp: Skip TX bytes accounting when sending from a request socket On ESP output, sk_wmem_alloc is incremented for the added padding if a socket is associated to the skb. When replying with TCP SYNACKs over IPsec, the associated sk is a casted request socket, only. Increasing sk_wmem_alloc on a request socket results in a write at an arbitrary struct offset. In the best case, this produces the following WARNING: WARNING: CPU: 1 PID: 0 at lib/refcount.c:102 esp_output_head+0x2e4/0x308 [esp4] refcount_t: addition on 0; use-after-free. CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.0.0-rc3 #2 Hardware name: Marvell Armada 380/385 (Device Tree) [...] [<bf0ff354>] (esp_output_head [esp4]) from [<bf1006a4>] (esp_output+0xb8/0x180 [esp4]) [<bf1006a4>] (esp_output [esp4]) from [<c05dee64>] (xfrm_output_resume+0x558/0x664) [<c05dee64>] (xfrm_output_resume) from [<c05d07b0>] (xfrm4_output+0x44/0xc4) [<c05d07b0>] (xfrm4_output) from [<c05956bc>] (tcp_v4_send_synack+0xa8/0xe8) [<c05956bc>] (tcp_v4_send_synack) from [<c0586ad8>] (tcp_conn_request+0x7f4/0x948) [<c0586ad8>] (tcp_conn_request) from [<c058c404>] (tcp_rcv_state_process+0x2a0/0xe64) [<c058c404>] (tcp_rcv_state_process) from [<c05958ac>] (tcp_v4_do_rcv+0xf0/0x1f4) [<c05958ac>] (tcp_v4_do_rcv) from [<c0598a4c>] (tcp_v4_rcv+0xdb8/0xe20) [<c0598a4c>] (tcp_v4_rcv) from [<c056eb74>] (ip_protocol_deliver_rcu+0x2c/0x2dc) [<c056eb74>] (ip_protocol_deliver_rcu) from [<c056ee6c>] (ip_local_deliver_finish+0x48/0x54) [<c056ee6c>] (ip_local_deliver_finish) from [<c056eecc>] (ip_local_deliver+0x54/0xec) [<c056eecc>] (ip_local_deliver) from [<c056efac>] (ip_rcv+0x48/0xb8) [<c056efac>] (ip_rcv) from [<c0519c2c>] (__netif_receive_skb_one_core+0x50/0x6c) [...] The issue triggers only when not using TCP syncookies, as for syncookies no socket is associated. Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") Signed-off-by: Martin Willi <martin@strongswan.org> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2019-01-28 09:35:35 +01:00
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xfrm: esp: avoid in-place decrypt on shared skb frags MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP marks such skbs with SKBFL_SHARED_FRAG after skb_splice_from_iter(), so later paths that may modify packet data can first make a private copy. The IPv4/IPv6 datagram append paths did not set this flag when splicing pages into UDP skbs. That leaves an ESP-in-UDP packet made from shared pipe pages looking like an ordinary uncloned nonlinear skb. ESP input then takes the no-COW fast path for uncloned skbs without a frag_list and decrypts in place over data that is not owned privately by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG, matching TCP. Also make ESP input fall back to skb_cow_data() when the flag is present, so ESP does not decrypt externally backed frags in place. Private nonlinear skb frags still use the existing fast path. This intentionally does not change ESP output. In esp_output_head(), the path that appends the ESP trailer to existing skb tailroom without calling skb_cow_data() is not reachable for nonlinear skbs: skb_tailroom() returns zero when skb->data_len is nonzero, while ESP tailen is positive. Thus ESP output will either use the separate destination-frag path or fall back to skb_cow_data(). Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible") Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible") Fixes: 7da0dde68486 ("ip, udp: Support MSG_SPLICE_PAGES") Fixes: 6d8192bd69bb ("ip6, udp6: Support MSG_SPLICE_PAGES") Reported-by: Hyunwoo Kim <imv4bel@gmail.com> Reported-by: Kuan-Ting Chen <h3xrabbit@gmail.com> Tested-by: Hyunwoo Kim <imv4bel@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Kuan-Ting Chen <h3xrabbit@gmail.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-05-04 23:27:12 +08:00