kernel/linux.git/include/net/genetlink.h, branch v4.19.302

drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group

2023-12-13T16:42:20+00:00

commit e03781879a0d524ce3126678d50a80484a513c4b upstream. The "NET_DM" generic netlink family notifies drop locations over the "events" multicast group. This is problematic since by default generic netlink allows non-root users to listen to these notifications. Fix by adding a new field to the generic netlink multicast group structure that when set prevents non-root users or root without the 'CAP_SYS_ADMIN' capability (in the user namespace owning the network namespace) from joining the group. Set this field for the "events" group. Use 'CAP_SYS_ADMIN' rather than 'CAP_NET_ADMIN' because of the nature of the information that is shared over this group. Note that the capability check in this case will always be performed against the initial user namespace since the family is not netns aware and only operates in the initial network namespace. A new field is added to the structure rather than using the "flags" field because the existing field uses uAPI flags and it is inappropriate to add a new uAPI flag for an internal kernel check. In net-next we can rework the "flags" field to use internal flags and fold the new field into it. But for now, in order to reduce the amount of changes, add a new field. Since the information can only be consumed by root, mark the control plane operations that start and stop the tracing as root-only using the 'GENL_ADMIN_PERM' flag. Tested using [1]. Before: # capsh -- -c ./dm_repo # capsh --drop=cap_sys_admin -- -c ./dm_repo After: # capsh -- -c ./dm_repo # capsh --drop=cap_sys_admin -- -c ./dm_repo Failed to join "events" multicast group [1] $ cat dm.c #include #include #include #include int main(int argc, char **argv) { struct nl_sock *sk; int grp, err; sk = nl_socket_alloc(); if (!sk) { fprintf(stderr, "Failed to allocate socket\n"); return -1; } err = genl_connect(sk); if (err) { fprintf(stderr, "Failed to connect socket\n"); return err; } grp = genl_ctrl_resolve_grp(sk, "NET_DM", "events"); if (grp < 0) { fprintf(stderr, "Failed to resolve \"events\" multicast group\n"); return grp; } err = nl_socket_add_memberships(sk, grp, NFNLGRP_NONE); if (err) { fprintf(stderr, "Failed to join \"events\" multicast group\n"); return err; } return 0; } $ gcc -I/usr/include/libnl3 -lnl-3 -lnl-genl-3 -o dm_repo dm.c Fixes: 9a8afc8d3962 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol") Reported-by: "The UK's National Cyber Security Centre (NCSC)" Signed-off-by: Ido Schimmel Reviewed-by: Jacob Keller Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231206213102.1824398-3-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

genetlink: add CAP_NET_ADMIN test for multicast bind

2023-12-13T16:42:20+00:00

This is a partial backport of upstream commit 4d54cc32112d ("mptcp: avoid lock_fast usage in accept path"). It is only a partial backport because the patch in the link below was erroneously squash-merged into upstream commit 4d54cc32112d ("mptcp: avoid lock_fast usage in accept path"). Below is the original patch description from Florian Westphal: " genetlink sets NL_CFG_F_NONROOT_RECV for its netlink socket so anyone can subscribe to multicast messages. rtnetlink doesn't allow this unconditionally, rtnetlink_bind() restricts bind requests to CAP_NET_ADMIN for a few groups. This allows to set GENL_UNS_ADMIN_PERM flag on genl mcast groups to mandate CAP_NET_ADMIN. This will be used by the upcoming mptcp netlink event facility which exposes the token (mptcp connection identifier) to userspace. " Link: https://lore.kernel.org/mptcp/20210213000001.379332-8-mathew.j.martineau@linux.intel.com/ Signed-off-by: Ido Schimmel Signed-off-by: Greg Kroah-Hartman

genetlink: remove genl_bind

2020-07-22T07:31:58+00:00

[ Upstream commit 1e82a62fec613844da9e558f3493540a5b7a7b67 ] A potential deadlock can occur during registering or unregistering a new generic netlink family between the main nl_table_lock and the cb_lock where each thread wants the lock held by the other, as demonstrated below. 1) Thread 1 is performing a netlink_bind() operation on a socket. As part of this call, it will call netlink_lock_table(), incrementing the nl_table_users count to 1. 2) Thread 2 is registering (or unregistering) a genl_family via the genl_(un)register_family() API. The cb_lock semaphore will be taken for writing. 3) Thread 1 will call genl_bind() as part of the bind operation to handle subscribing to GENL multicast groups at the request of the user. It will attempt to take the cb_lock semaphore for reading, but it will fail and be scheduled away, waiting for Thread 2 to finish the write. 4) Thread 2 will call netlink_table_grab() during the (un)registration call. However, as Thread 1 has incremented nl_table_users, it will not be able to proceed, and both threads will be stuck waiting for the other. genl_bind() is a noop, unless a genl_family implements the mcast_bind() function to handle setting up family-specific multicast operations. Since no one in-tree uses this functionality as Cong pointed out, simply removing the genl_bind() function will remove the possibility for deadlock, as there is no attempt by Thread 1 above to take the cb_lock semaphore. Fixes: c380d9a7afff ("genetlink: pass multicast bind/unbind to families") Suggested-by: Cong Wang Acked-by: Johannes Berg Reported-by: kernel test robot Signed-off-by: Sean Tranchetti Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

genetlink: fix genlmsg_nlhdr()

2017-11-16T01:49:00+00:00

According to the description, first argument of genlmsg_nlhdr() points to what genlmsg_put() returns, i.e. beginning of user header. Therefore we should only subtract size of genetlink header and netlink message header, not user header. This also means we don't need to pass the pointer to genetlink family and the same is true for genl_dump_check_consistent() which is the only caller of genlmsg_nlhdr(). (Note that at the moment, these functions are only used for families which do not have user header so that they are not affected.) Fixes: 670dc2833d14 ("netlink: advertise incomplete dumps") Signed-off-by: Michal Kubecek Reviewed-by: Johannes Berg Signed-off-by: David S. Miller

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55+00:00

Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart Reviewed-by: Philippe Ombredanne Reviewed-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

genetlink: remove ops_list from genetlink header.

2017-06-05T14:54:55+00:00

commit d91824c08fbc ("genetlink: register family ops as array") removed the ops_list member from both genl_family and genl_ops; while the documentation of genl_family was updated accordingly by this patch, ops_list remained in the documentation of the genl_ops object. This patch fixes it by removing ops_list from genl_ops documentation. Signed-off-by: Rami Rosen Signed-off-by: David S. Miller

netlink: pass extended ACK struct to parsing functions

2017-04-13T17:58:22+00:00

Pass the new extended ACK reporting struct to all of the generic netlink parsing functions. For now, pass NULL in almost all callers (except for some in the core.) Signed-off-by: Johannes Berg Signed-off-by: David S. Miller

genetlink: pass extended ACK report down

2017-04-13T17:58:21+00:00

Pass the extended ACK reporting struct down from generic netlink to the families, using the existing struct genl_info for simplicity. Also add support to set the extended ACK information from generic netlink users. Signed-off-by: Johannes Berg Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

genetlink: Make family a signed integer.

2016-11-13T17:14:59+00:00

The idr_alloc(), idr_remove(), et al. routines all expect IDs to be signed integers. Therefore make the genl_family member 'id' signed too. Signed-off-by: David S. Miller

genetlink: use idr to track families

2016-10-27T20:16:09+00:00

Since generic netlink family IDs are small integers, allocated densely, IDR is an ideal match for lookups. Replace the existing hand-written hash-table with IDR for allocation and lookup. This lets the families only be written to once, during register, since the list_head can be removed and removal of a family won't cause any writes. It also slightly reduces the code size (by about 1.3k on x86-64). Signed-off-by: Johannes Berg Signed-off-by: David S. Miller