From patchwork Mon Mar 3 19:45:12 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?G=C3=BCnther_Noack?= X-Patchwork-Id: 13999382 Received: from mail-ed1-f73.google.com (mail-ed1-f73.google.com [209.85.208.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B1CC1FFC60 for ; Mon, 3 Mar 2025 19:45:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741031142; cv=none; b=tZoPZHDk+hU/NxePi4WfhX0ws04e8K5BiwL10TvzhsM8mew2H44qcW7TOeOggdPYlLsloUG8kbw/XdsZ41Q2BA9uU8QKFLSjn1aLtb/Zuzu9V/zPn2xkxyLPl5LPwZb/HlnU7krfQ9MBead9MSIgV7Zrd5/M3DUEOEz6AEaSQW0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741031142; c=relaxed/simple; bh=LNhj+DGxktTxB8FdmUWwYvohBv0qL5MVFkUsGguvOds=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VuIpzLYpVN7QqE6Dx2QEW0uOzvbaWIDa0iUv4B55kbagy0Ty6yTCBeRSjLgEhWr4SbDDadOL3uObn1qcx1h4cJ/Mrd/fRAEwToI2nf7Ero9WtBhDxDjVr6fJCAEgTjcACzBBAF/cct3OLJqzvSd3sN+nEWI9df8LVKA32tF+wwY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--gnoack.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=DONYKt3U; arc=none smtp.client-ip=209.85.208.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--gnoack.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DONYKt3U" Received: by mail-ed1-f73.google.com with SMTP id 4fb4d7f45d1cf-5e4a0d66c69so6027844a12.0 for ; Mon, 03 Mar 2025 11:45:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1741031139; x=1741635939; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=duUSxcKBjL1V2Dc8BDWLklM2H+W6u03EYfGKcvUPxI4=; b=DONYKt3U6R2CRMWsPSjABt8osD+6FCB9C6Jb+HZ3fdeVJJ0TMrnjRyQxIf3g1jEROh GsQ0lGDmDFsxF5ToT4DJwS8hq42VbiRmcs7PTPKiT8BfTBsQVZWbOXxRUmz2K12UeO15 6HNTUfABRagFmfQtLVZgH7zFMJ4pEv3pHE/0YEisepco65gbpW9eGWW3yaI9oKM2VVeq PYSl2XaYngWDhvAomLbFJ3EfKh8RnFJQkW9LNF1XI3uY2t1h50YMMRilLcsSrR+iPW+A 1ZxSs9ZgZi1Hr9LdrTcsTib7v75PYicy8LGJAphayVsNDMyJ23ZV+S7ed+b/u1y9PXsl 07zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741031139; x=1741635939; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=duUSxcKBjL1V2Dc8BDWLklM2H+W6u03EYfGKcvUPxI4=; b=WMYUk53SVi00xMjDzlHLMLjyxMonkEjmtwRxa6LeBDdfbuC4JNcSCUUv3qYWV3BjFs /7mIpDLOtf84l7ro+mu81Unh4l/J1PUFae+HjIs1QMwJrLZppOnACSpBt21TnOiOriWw VYi97p4FZAF4zLDWOBMgZYREBODff9iL7zyrkEhtL1k0rKOYZXWIisBW6ElQd+KPJdu4 VrbzYqVRdo9sY+LOfN4zvdNxUp7ipb+o6BQDeF37YaFBRYuOtPUE0ne66WXo5aAiBggE EfpglKGpCUMhLEfyYSNo4NEeAxNApo8uZaFaDleGSiYb5DiQ45Y2Qzv4h4uBKD9vAonG oFKw== X-Forwarded-Encrypted: i=1; AJvYcCVm52K69fG72G9AeYAuyN1d1f1qK2cIrjwzRKh2eHEZ8i1Q5PlNv+yZdhMpcDNn6WQnmZaUfboG0hUjwRbmRrlbhVotCUo=@vger.kernel.org X-Gm-Message-State: AOJu0Yywt2OKLOHIfdjdwbpLpINkZqP2glTfvrIy4aH5Ttv+SkI4vm7/ jgJUM3T6hZ+SXAv8xULt77lBF73nGKEqYBrSgWnqcN3GHGKD4XcAuq1sUCoMQ5goN5LzMbrKENi 1hQ== X-Google-Smtp-Source: AGHT+IEI47ysZn1gwD3019R9A1nGc4J83o9X61Kejv4zfkJg/2a82TUZfTXuDTQol4MIym7PHZ9ctCgOhQ8= X-Received: from edqr23.prod.google.com ([2002:aa7:d597:0:b0:5e4:d0e4:7ac3]) (user=gnoack job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:42c4:b0:5e0:8920:c4c5 with SMTP id 4fb4d7f45d1cf-5e4d6ade0dfmr14498230a12.11.1741031138934; Mon, 03 Mar 2025 11:45:38 -0800 (PST) Date: Mon, 3 Mar 2025 20:45:12 +0100 In-Reply-To: <20250303194510.135506-2-gnoack@google.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250303194510.135506-2-gnoack@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250303194510.135506-4-gnoack@google.com> Subject: [PATCH v3 1/1] landlock: Clarify IPC scoping documentation From: " =?utf-8?q?G=C3=BCnther_Noack?= " To: " =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= " , Tahera Fahimi , Alejandro Colomar Cc: " =?utf-8?q?G=C3=BCnther_Noack?= " , Tanya Agarwal , linux-security-module@vger.kernel.org, Daniel Burgener * Clarify terminology * Stop mixing the unix(7) and signal(7) aspects in the explanation. Terminology: * The *IPC Scope* of a Landlock domain is that Landlock domain and its nested domains. * An *operation* (e.g., signaling, connecting to abstract UDS) is said to be *scoped within a domain* when the flag for that operation was set at ruleset creation time. This means that for the purpose of this operation, only processes within the domain's IPC scope are reachable. Signed-off-by: Günther Noack --- Documentation/userspace-api/landlock.rst | 45 ++++++++++++------------ 1 file changed, 22 insertions(+), 23 deletions(-) diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst index ad587f53fe41..4832b16deedb 100644 --- a/Documentation/userspace-api/landlock.rst +++ b/Documentation/userspace-api/landlock.rst @@ -317,33 +317,32 @@ IPC scoping ----------- Similar to the implicit `Ptrace restrictions`_, we may want to further restrict -interactions between sandboxes. Each Landlock domain can be explicitly scoped -for a set of actions by specifying it on a ruleset. For example, if a -sandboxed process should not be able to :manpage:`connect(2)` to a -non-sandboxed process through abstract :manpage:`unix(7)` sockets, we can -specify such a restriction with ``LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET``. -Moreover, if a sandboxed process should not be able to send a signal to a -non-sandboxed process, we can specify this restriction with -``LANDLOCK_SCOPE_SIGNAL``. +interactions between sandboxes. Therefore, at ruleset creation time, each +Landlock domain can restrict the scope for certain operations, so that these +operations can only reach out to processes within the same Landlock domain or in +a nested Landlock domain (the "scope"). -A sandboxed process can connect to a non-sandboxed process when its domain is -not scoped. If a process's domain is scoped, it can only connect to sockets -created by processes in the same scope. -Moreover, if a process is scoped to send signal to a non-scoped process, it can -only send signals to processes in the same scope. +The operations which can be scoped are: -A connected datagram socket behaves like a stream socket when its domain is -scoped, meaning if the domain is scoped after the socket is connected, it can -still :manpage:`send(2)` data just like a stream socket. However, in the same -scenario, a non-connected datagram socket cannot send data (with -:manpage:`sendto(2)`) outside its scope. +``LANDLOCK_SCOPE_SIGNAL`` + This limits the sending of signals to target processes which run within the + same or a nested Landlock domain. -A process with a scoped domain can inherit a socket created by a non-scoped -process. The process cannot connect to this socket since it has a scoped -domain. +``LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET`` + This limits the set of abstract :manpage:`unix(7)` sockets to which we can + :manpage:`connect(2)` to socket addresses which were created by a process in + the same or a nested Landlock domain. -IPC scoping does not support exceptions, so if a domain is scoped, no rules can -be added to allow access to resources or processes outside of the scope. + A :manpage:`sendto(2)` on a non-connected datagram socket is treated as if + it were doing an implicit :manpage:`connect(2)` and will be blocked if the + remote end does not stem from the same or a nested Landlock domain. + + A :manpage:`sendto(2)` on a socket which was previously connected will not + be restricted. This works for both datagram and stream sockets. + +IPC scoping does not support exceptions via :manpage:`landlock_add_rule(2)`. +If an operation is scoped within a domain, no rules can be added to allow access +to resources or processes outside of the scope. 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Mon, 03 Mar 2025 11:51:27 -0800 (PST) Date: Mon, 3 Mar 2025 20:50:31 +0100 In-Reply-To: <20250303194510.135506-2-gnoack@google.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250303194510.135506-2-gnoack@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250303195056.136777-4-gnoack@google.com> Subject: [PATCH man v3 2/2] landlock.7: Add IPC scoping documentation in line with kernel side From: " =?utf-8?q?G=C3=BCnther_Noack?= " To: Alejandro Colomar , " =?utf-8?q?Micka=C3=ABl_Sala=C3=BC?= =?utf-8?q?n?= " , Tahera Fahimi Cc: " =?utf-8?q?G=C3=BCnther_Noack?= " , Tanya Agarwal , linux-security-module@vger.kernel.org, linux-man@vger.kernel.org, Daniel Burgener * Move over documentation for ABI version 6 (IPC scoping features) * Clarify terminology * Stop mixing the unix(7) and signal(7) aspects in the explanation. With this ABI version, Landlock can restrict outgoing interactions with higher-privileged Landlock domains through Abstract Unix Domain sockets and signals. Terminology: * The *IPC Scope* of a Landlock domain is that Landlock domain and its nested domains. * An *operation* (e.g., signaling, connecting to abstract UDS) is said to be *scoped within a domain* when the flag for that operation was set at ruleset creation time. This means that for the purpose of this operation, only processes within the domain's IPC scope are reachable. Link: https://lore.kernel.org/all/20250303194510.135506-4-gnoack@google.com/ Signed-off-by: Günther Noack --- man/man7/landlock.7 | 65 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 64 insertions(+), 1 deletion(-) diff --git a/man/man7/landlock.7 b/man/man7/landlock.7 index 7b7a797ad..aa383860c 100644 --- a/man/man7/landlock.7 +++ b/man/man7/landlock.7 @@ -246,7 +246,8 @@ This access right is available since the fifth version of the Landlock ABI. .SS Network flags These flags enable to restrict a sandboxed process to a set of network actions. -This is supported since the Landlock ABI version 4. +.P +This is supported since Landlock ABI version 4. .P The following access rights apply to TCP port numbers: .TP @@ -256,6 +257,24 @@ Bind a TCP socket to a local port. .B LANDLOCK_ACCESS_NET_CONNECT_TCP Connect an active TCP socket to a remote port. .\" +.SS Scope flags +These flags enable isolating a sandboxed process from a set of IPC actions. +Setting a flag for a ruleset will isolate the Landlock domain +to forbid connections to resources outside the domain. +.P +This is supported since Landlock ABI version 6. +.P +The following scopes exist: +.TP +.B LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET +Restrict a sandboxed process from connecting to an abstract UNIX socket +created by a process outside the related Landlock domain +(e.g., a parent domain or a non-sandboxed process). +.TP +.B LANDLOCK_SCOPE_SIGNAL +Restrict a sandboxed process from sending a signal +to another process outside the domain. +.\" .SS Layers of file path access rights Each time a thread enforces a ruleset on itself, it updates its Landlock domain with a new layer of policy. @@ -332,6 +351,47 @@ and related syscalls on a target process, a sandboxed process should have a subset of the target process rules, which means the tracee must be in a sub-domain of the tracer. .\" +.SS IPC scoping +Similar to the implicit +.BR "Ptrace restrictions" , +we may want to further restrict interactions between sandboxes. +Therefore, at ruleset creation time, +each Landlock domain can restrict the scope for certain operations, +so that these operations can only reach out to processes +within the same Landlock domain or in a nested Landlock domain (the "scope"). +.P +The operations which can be scoped are: +.TP +.B LANDLOCK_SCOPE_SIGNAL +This limits the sending of signals to target processes +which run within the same or a nested Landlock domain. +.TP +.B LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET +This limits the set of abstract +.BR unix (7) +sockets to which we can +.BR connect (2) +to socket addresses which were created +by a process in the same or a nested Landlock domain. +.IP +A +.BR sendto (2) +on a non-connected datagram socket is treated as if it were doing an implicit +.BR connect (2) +and will be blocked if the remote end does not stem +from the same or a nested Landlock domain. +.IP +A +.BR sendto (2) +on a socket which was previously connected will not be restricted. +This works for both datagram and stream sockets. +.P +IPC scoping does not support exceptions via +.BR landlock_add_rule (2). +If an operation is scoped within a domain, +no rules can be added to allow access to +resources or processes outside of the scope. +.\" .SS Truncating files The operations covered by .B LANDLOCK_ACCESS_FS_WRITE_FILE @@ -411,6 +471,9 @@ _ _ _ \^ \^ LANDLOCK_ACCESS_NET_CONNECT_TCP _ _ _ 5 6.10 LANDLOCK_ACCESS_FS_IOCTL_DEV +_ _ _ +6 6.12 LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET +\^ \^ LANDLOCK_SCOPE_SIGNAL .TE .P Users should use the Landlock ABI version rather than the kernel version