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[68.48.65.54]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-517af149fa5sm46086911cf.3.2026.06.08.05.22.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 05:22:11 -0700 (PDT) From: Michael Bommarito To: Jon Maloy , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Ying Xue , netdev@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: [PATCH net v3 1/3] tipc: require net admin for TIPCv2 netlink mutators Date: Mon, 8 Jun 2026 08:22:04 -0400 Message-ID: <20260608122206.458290-2-michael.bommarito@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260608122206.458290-1-michael.bommarito@gmail.com> References: <20260608122206.458290-1-michael.bommarito@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit TIPCv2 registers mutating generic-netlink operations without admin permission flags. Generic netlink only checks CAP_NET_ADMIN when an operation sets GENL_ADMIN_PERM or GENL_UNS_ADMIN_PERM, so a local unprivileged process can currently change TIPC state through commands such as TIPC_NL_NET_SET, TIPC_NL_KEY_SET, TIPC_NL_KEY_FLUSH, and bearer enable/disable. The legacy TIPC netlink API already checks netlink_net_capable(..., CAP_NET_ADMIN) for administrative commands. Give the TIPCv2 mutators the equivalent generic-netlink gate. Use GENL_UNS_ADMIN_PERM for network-namespace scoped operations and GENL_ADMIN_PERM for TIPC_NL_MEDIA_SET, which updates the shared media defaults rather than state owned only by the target network namespace. A QEMU/KASAN repro run as uid/gid 65534 with zero effective capabilities previously succeeded in changing the network id and node identity, setting and flushing key material, and enabling/disabling a UDP bearer. With this patch applied the same operations fail with -EPERM. Fixes: 0655f6a8635b ("tipc: add bearer disable/enable to new netlink api") Link: https://lore.kernel.org/all/20260604163102.2658553-1-dominik.czarnota@trailofbits.com/ Assisted-by: Codex:gpt-5-5-xhigh Signed-off-by: Michael Bommarito --- v2: - Use GENL_ADMIN_PERM for TIPC_NL_MEDIA_SET because it updates global media defaults, while keeping GENL_UNS_ADMIN_PERM for netns-scoped mutators. net/tipc/netlink.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/tipc/netlink.c b/net/tipc/netlink.c index 1a9a5bdaccf4f..5bbe134284acc 100644 --- a/net/tipc/netlink.c +++ b/net/tipc/netlink.c @@ -152,11 +152,13 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_BEARER_DISABLE, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_bearer_disable, }, { .cmd = TIPC_NL_BEARER_ENABLE, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_bearer_enable, }, { @@ -168,11 +170,13 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_BEARER_ADD, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_bearer_add, }, { .cmd = TIPC_NL_BEARER_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_bearer_set, }, { @@ -197,11 +201,13 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_LINK_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_node_set_link, }, { .cmd = TIPC_NL_LINK_RESET_STATS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_node_reset_link_stats, }, { @@ -213,6 +219,7 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_MEDIA_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_ADMIN_PERM, .doit = tipc_nl_media_set, }, { @@ -228,6 +235,7 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_NET_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_net_set, }, { @@ -238,6 +246,7 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_MON_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_node_set_monitor, }, { @@ -255,6 +264,7 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_PEER_REMOVE, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_peer_rm, }, #ifdef CONFIG_TIPC_MEDIA_UDP @@ -269,11 +279,13 @@ static const struct genl_ops tipc_genl_v2_ops[] = { { .cmd = TIPC_NL_KEY_SET, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_node_set_key, }, { .cmd = TIPC_NL_KEY_FLUSH, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, + .flags = GENL_UNS_ADMIN_PERM, .doit = tipc_nl_node_flush_key, }, #endif -- 2.53.0