kernel/git/next/linux-next.git/security/landlock, branch master

landlock: Harden sock_is_scoped() against file-less sockets

2026-07-10T10:59:15+00:00

sock_is_scoped() dereferences other->sk_socket->file->f_cred to read the peer's Landlock domain when evaluating LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET, without first checking that the peer has a backing socket and file. hook_unix_find() performs the same dereference for LANDLOCK_ACCESS_FS_RESOLVE_UNIX and does guard it. Guard it here too and treat a peer with no backing file, such as a kernel socket created by sock_create_kern(), as unscoped. This is defensive hardening, not a fix for a reachable bug. The unix_stream_connect() and unix_may_send() hooks run with the peer held under unix_state_lock() and only after the AF_UNIX core has excluded SOCK_DEAD, and no in-tree code binds a file-less AF_UNIX socket to an abstract address, so other->sk_socket->file is always valid at these call sites today. Cc: Günther Noack Link: https://patch.msgid.link/20260703152750.2022878-1-mic@digikod.net Signed-off-by: Mickaël Salaün

landlock: Update formatting

2026-07-10T10:59:10+00:00

Following commit 99df2a8eba34 ("clang-format: fix formatting of guard() and scoped_guard() statements"), update scoped_guard() formatting. Also, see the related fix [1]. Cc: Günther Noack Cc: Miguel Ojeda Link: https://lore.kernel.org/r/20260708105713.2073335-1-mic@digikod.net [1] Link: https://patch.msgid.link/20260708110635.2083515-1-mic@digikod.net Reviewed-by: Günther Noack Signed-off-by: Mickaël Salaün

landlock: Fix kernel-doc for the nested quiet layer flag

2026-07-10T10:59:09+00:00

kernel-doc emits "Excess struct member 'quiet' description in 'landlock_layer'" because "quiet" is a bitfield inside the named nested struct "flags", but its inline comment used the bare member name "@quiet:", which kernel-doc attributes to the enclosing landlock_layer. Use the canonical dotted notation "@flags.quiet:" so kernel-doc resolves the nested member, and include it in the generated documentation. Cc: Justin Suess Cc: Tingmao Wang Fixes: a260c0055665 ("landlock: Add a place for flags to layer rules") Link: https://patch.msgid.link/20260703141711.2016964-1-mic@digikod.net Signed-off-by: Mickaël Salaün

landlock: Fix TCP Fast Open connection bypass

2026-07-10T10:59:07+00:00

The documentation of the socket_connect() LSM hook states that it controls connecting a socket to a remote address. It has not been the case since the addition of TCP Fast Open (RFC 7413) support, which allows opening a TCP connection (thus, setting a socket's destination address) via the MSG_FASTOPEN flag passed to sendto()/sendmsg()/sendmmsg(). The problem then got duplicated into MPTCP. Landlock did not take it into account when its TCP support was added, leaving a bypass of TCP connect policy. Ideally a call to the LSM hook would be added in the fastopen code path, in order to fix this generically. But connect() hooks are designed to run with the socket locked, unlike sendmsg() hooks. Closes: https://github.com/landlock-lsm/linux/issues/41 Fixes: fff69fb03dde ("landlock: Support network rules with TCP bind and connect") Signed-off-by: Matthieu Buffet Link: https://patch.msgid.link/20260701214628.33319-1-matthieu@buffet.re Cc: stable@vger.kernel.org [mic: Wrap commit message] Signed-off-by: Mickaël Salaün

Merge tag 'landlock-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

2026-06-19T19:20:25+00:00

Pull landlock updates from Mickaël Salaün: "This adds new Landlock access rights to control UDP bind and connect/send operations, and a new "quiet" feature to mute specific specific audit logs (and other future observability events). A few commits also fix Landlock issues" * tag 'landlock-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: (24 commits) selftests/landlock: Add tests for invalid use of quiet flag selftests/landlock: Add tests for quiet flag with scope selftests/landlock: Add tests for quiet flag with net rules selftests/landlock: Add tests for quiet flag with fs rules selftests/landlock: Replace hard-coded 16 with a constant samples/landlock: Add quiet flag support to sandboxer landlock: Suppress logging when quiet flag is present landlock: Add API support and docs for the quiet flags landlock: Add a place for flags to layer rules landlock: Add documentation for UDP support samples/landlock: Add sandboxer UDP access control selftests/landlock: Add tests for UDP send selftests/landlock: Add tests for UDP bind/connect landlock: Add UDP send+connect access control landlock: Add UDP bind() access control landlock: Fix unmarked concurrent access to socket family selftests/landlock: Explicitly disable audit in teardowns selftests/landlock: Test SCOPE_SIGNAL on the SIGIO/fowner pgid path landlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path landlock: Demonstrate best-effort allowed_access filtering ...

landlock: Suppress logging when quiet flag is present

2026-06-14T18:17:19+00:00

The quietness behaviour is as documented in the previous patch. For optional accesses, since the existing deny_masks can only store 2x4bit of layer index, with no way to represent "no layer", we need to either expand it or have another field to correctly handle quieting of those. This commit uses the latter approach - we add another field to store which optional access (of the 2) are covered by quiet rules in their respective layers as stored in deny_masks. Assisted-by: GitHub-Copilot:claude-opus-4.8 copilot-review Signed-off-by: Tingmao Wang Link: https://patch.msgid.link/2510a357a94183683eefc49917dcb2240d67be96.1781228815.git.m@maowtm.org [mic: Cosmetic fixes] Signed-off-by: Mickaël Salaün

landlock: Add API support and docs for the quiet flags

2026-06-14T18:17:19+00:00

Adds the UAPI for the quiet flags feature (but not the implementation yet). Even though currently LANDLOCK_ADD_RULE_QUIET only affects audit logging, in the future this can also be used as part of a supervisor mechanism, where it will also suppress denial notifications on a per-object basis. Thus the name is deliberately generic, as opposed to e.g. LANDLOCK_ADD_RULE_LOG_QUIET. According to pahole, even after adding the struct access_masks quiet_masks in struct landlock_hierarchy, the u32 log_* bitfield still only has a size of 2 bytes, so there's minimal wasted space. Assisted-by: GitHub-Copilot:claude-opus-4.8 Signed-off-by: Tingmao Wang [mic: Update date, fix comment formatting] Link: https://patch.msgid.link/031184748a8e74c0bb02f1fa13d7a3f10918c627.1781228815.git.m@maowtm.org Signed-off-by: Mickaël Salaün

landlock: Add a place for flags to layer rules

2026-06-14T18:17:18+00:00

To avoid unnecessarily increasing the size of struct landlock_layer, we make the layer level a u8 and use the space to store the flags struct. struct layer_access_masks is renamed to struct layer_masks, and a new field is added to track whether a quiet flag rule is seen for each layer. Through use of bitfields, this does not increase the size of the struct. Cc: Justin Suess Assisted-by: GitHub-Copilot:claude-opus-4.8 copilot-review Signed-off-by: Tingmao Wang Co-developed-by: Justin Suess Signed-off-by: Justin Suess Tested-by: Justin Suess Link: https://patch.msgid.link/be3fec3927bc9faaacd4ce0e7f0d1ff5474e2210.1781228815.git.m@maowtm.org [mic: Fix comment formatting] Signed-off-by: Mickaël Salaün

landlock: Add UDP send+connect access control

2026-06-13T21:15:04+00:00

Add support for a second fine-grained UDP access right. LANDLOCK_ACCESS_NET_CONNECT_SEND_UDP controls the ability to set the remote port of a socket (via connect()) and to specify an explicit destination when sending a datagram, to override any remote peer set on a UDP socket (e.g. in sendto() or sendmsg()). It will be useful for applications that send datagrams, and for some servers too (those creating per-client sockets, which want to receive traffic only from a specific address). Similarly as for bind(), this access control is performed when configuring sockets, not in hot code paths. Add detection of when autobind is about to be required, and deny the operation if the process would not be allowed to call bind(0) explicitly. Autobind can only be performed in udp_lib_get_port() from code paths already controlled by LSM hooks: when connect()ing, sending a first datagram, and in some splice() EOF edge case which, afaiu, can only happen after a remote peer has been set. This invariant needs to be preserved to keep bind policies actually enforced. Signed-off-by: Matthieu Buffet Link: https://patch.msgid.link/20260611162107.49278-3-matthieu@buffet.re [mic: Add quick return for non-sandboxed tasks, fix sa_family dereferencing, fix comment formatting] Signed-off-by: Mickaël Salaün

landlock: Add UDP bind() access control

2026-06-13T21:15:04+00:00

Add support for a first fine-grained UDP access right. LANDLOCK_ACCESS_NET_BIND_UDP controls the ability to set the local port of a UDP socket (via bind()). It will be useful for servers (to start receiving datagrams), and for some clients that need to use a specific source port (e.g. mDNS requires to use port 5353) For obvious performance concerns, access control is only enforced when configuring sockets, not when using them for common send/recv operations. Bump ABI to allow userspace to detect and use this new right. Signed-off-by: Matthieu Buffet Link: https://patch.msgid.link/20260611162107.49278-2-matthieu@buffet.re [mic: Fix comment formatting] Signed-off-by: Mickaël Salaün