kernel/git/stable/linux.git/net/netlink, branch linux-6.7.y

netlink: Fix kernel-infoleak-after-free in __skb_datagram_iter

2024-03-06T14:53:49+00:00

[ Upstream commit 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd ] syzbot reported the following uninit-value access issue [1]: netlink_to_full_skb() creates a new `skb` and puts the `skb->data` passed as a 1st arg of netlink_to_full_skb() onto new `skb`. The data size is specified as `len` and passed to skb_put_data(). This `len` is based on `skb->end` that is not data offset but buffer offset. The `skb->end` contains data and tailroom. Since the tailroom is not initialized when the new `skb` created, KMSAN detects uninitialized memory area when copying the data. This patch resolved this issue by correct the len from `skb->end` to `skb->len`, which is the actual data offset. BUG: KMSAN: kernel-infoleak-after-free in instrument_copy_to_user include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak-after-free in copy_to_user_iter lib/iov_iter.c:24 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_ubuf include/linux/iov_iter.h:29 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance2 include/linux/iov_iter.h:245 [inline] BUG: KMSAN: kernel-infoleak-after-free in iterate_and_advance include/linux/iov_iter.h:271 [inline] BUG: KMSAN: kernel-infoleak-after-free in _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186 instrument_copy_to_user include/linux/instrumented.h:114 [inline] copy_to_user_iter lib/iov_iter.c:24 [inline] iterate_ubuf include/linux/iov_iter.h:29 [inline] iterate_and_advance2 include/linux/iov_iter.h:245 [inline] iterate_and_advance include/linux/iov_iter.h:271 [inline] _copy_to_iter+0x364/0x2520 lib/iov_iter.c:186 copy_to_iter include/linux/uio.h:197 [inline] simple_copy_to_iter+0x68/0xa0 net/core/datagram.c:532 __skb_datagram_iter+0x123/0xdc0 net/core/datagram.c:420 skb_copy_datagram_iter+0x5c/0x200 net/core/datagram.c:546 skb_copy_datagram_msg include/linux/skbuff.h:3960 [inline] packet_recvmsg+0xd9c/0x2000 net/packet/af_packet.c:3482 sock_recvmsg_nosec net/socket.c:1044 [inline] sock_recvmsg net/socket.c:1066 [inline] sock_read_iter+0x467/0x580 net/socket.c:1136 call_read_iter include/linux/fs.h:2014 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x8f6/0xe00 fs/read_write.c:470 ksys_read+0x20f/0x4c0 fs/read_write.c:613 __do_sys_read fs/read_write.c:623 [inline] __se_sys_read fs/read_write.c:621 [inline] __x64_sys_read+0x93/0xd0 fs/read_write.c:621 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was stored to memory at: skb_put_data include/linux/skbuff.h:2622 [inline] netlink_to_full_skb net/netlink/af_netlink.c:181 [inline] __netlink_deliver_tap_skb net/netlink/af_netlink.c:298 [inline] __netlink_deliver_tap+0x5be/0xc90 net/netlink/af_netlink.c:325 netlink_deliver_tap net/netlink/af_netlink.c:338 [inline] netlink_deliver_tap_kernel net/netlink/af_netlink.c:347 [inline] netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x10f1/0x1250 net/netlink/af_netlink.c:1368 netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638 __sys_sendmsg net/socket.c:2667 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: free_pages_prepare mm/page_alloc.c:1087 [inline] free_unref_page_prepare+0xb0/0xa40 mm/page_alloc.c:2347 free_unref_page_list+0xeb/0x1100 mm/page_alloc.c:2533 release_pages+0x23d3/0x2410 mm/swap.c:1042 free_pages_and_swap_cache+0xd9/0xf0 mm/swap_state.c:316 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline] tlb_flush_mmu_free mm/mmu_gather.c:293 [inline] tlb_flush_mmu+0x6f5/0x980 mm/mmu_gather.c:300 tlb_finish_mmu+0x101/0x260 mm/mmu_gather.c:392 exit_mmap+0x49e/0xd30 mm/mmap.c:3321 __mmput+0x13f/0x530 kernel/fork.c:1349 mmput+0x8a/0xa0 kernel/fork.c:1371 exit_mm+0x1b8/0x360 kernel/exit.c:567 do_exit+0xd57/0x4080 kernel/exit.c:858 do_group_exit+0x2fd/0x390 kernel/exit.c:1021 __do_sys_exit_group kernel/exit.c:1032 [inline] __se_sys_exit_group kernel/exit.c:1030 [inline] __x64_sys_exit_group+0x3c/0x50 kernel/exit.c:1030 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Bytes 3852-3903 of 3904 are uninitialized Memory access of size 3904 starts at ffff88812ea1e000 Data copied to user address 0000000020003280 CPU: 1 PID: 5043 Comm: syz-executor297 Not tainted 6.7.0-rc5-syzkaller-00047-g5bd7ef53ffe5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023 Fixes: 1853c9496460 ("netlink, mmap: transform mmap skb into full skb on taps") Reported-and-tested-by: syzbot+34ad5fab48f7bf510349@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=34ad5fab48f7bf510349 [1] Signed-off-by: Ryosuke Yasuoka Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240221074053.1794118-1-ryasuoka@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

netlink: fix potential sleeping issue in mqueue_flush_file

2024-02-01T00:21:07+00:00

[ Upstream commit 234ec0b6034b16869d45128b8cd2dc6ffe596f04 ] I analyze the potential sleeping issue of the following processes: Thread A Thread B ... netlink_create //ref = 1 do_mq_notify ... sock = netlink_getsockbyfilp ... //ref = 2 info->notify_sock = sock; ... ... netlink_sendmsg ... skb = netlink_alloc_large_skb //skb->head is vmalloced ... netlink_unicast ... sk = netlink_getsockbyportid //ref = 3 ... netlink_sendskb ... __netlink_sendskb ... skb_queue_tail //put skb to sk_receive_queue ... sock_put //ref = 2 ... ... ... netlink_release ... deferred_put_nlk_sk //ref = 1 mqueue_flush_file spin_lock remove_notification netlink_sendskb sock_put //ref = 0 sk_free ... __sk_destruct netlink_sock_destruct skb_queue_purge //get skb from sk_receive_queue ... __skb_queue_purge_reason kfree_skb_reason __kfree_skb ... skb_release_all skb_release_head_state netlink_skb_destructor vfree(skb->head) //sleeping while holding spinlock In netlink_sendmsg, if the memory pointed to by skb->head is allocated by vmalloc, and is put to sk_receive_queue queue, also the skb is not freed. When the mqueue executes flush, the sleeping bug will occur. Use vfree_atomic instead of vfree in netlink_skb_destructor to solve the issue. Fixes: c05cdb1b864f ("netlink: allow large data transfers from user-space") Signed-off-by: Zhengchao Shao Link: https://lore.kernel.org/r/20240122011807.2110357-1-shaozhengchao@huawei.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

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

2023-12-07T17:54:02+00:00

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

netlink: fill in missing MODULE_DESCRIPTION()

2023-11-03T11:42:48+00:00

W=1 builds now warn if a module is built without a MODULE_DESCRIPTION(). Fill it in for sock_diag. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

genetlink: don't merge dumpit split op for different cmds into single iter

2023-10-23T23:11:53+00:00

Currently, split ops of doit and dumpit are merged into a single iter item when they are subsequent. However, there is no guarantee that the dumpit op is for the same cmd as doit op. Fix this by checking if cmd is the same for both. This problem does not occur in existing families. Signed-off-by: Jiri Pirko Reviewed-by: Jacob Keller Link: https://lore.kernel.org/r/20231021112711.660606-2-jiri@resnulli.us Signed-off-by: Jakub Kicinski

netlink: add variable-length / auto integers

2023-10-20T10:43:35+00:00

We currently push everyone to use padding to align 64b values in netlink. Un-padded nla_put_u64() doesn't even exist any more. The story behind this possibly start with this thread: https://lore.kernel.org/netdev/20121204.130914.1457976839967676240.davem@davemloft.net/ where DaveM was concerned about the alignment of a structure containing 64b stats. If user space tries to access such struct directly: struct some_stats *stats = nla_data(attr); printf("A: %llu", stats->a); lack of alignment may become problematic for some architectures. These days we most often put every single member in a separate attribute, meaning that the code above would use a helper like nla_get_u64(), which can deal with alignment internally. Even for arches which don't have good unaligned access - access aligned to 4B should be pretty efficient. Kernel and well known libraries deal with unaligned input already. Padded 64b is quite space-inefficient (64b + pad means at worst 16B per attr vs 32b which takes 8B). It is also more typing: if (nla_put_u64_pad(rsp, NETDEV_A_SOMETHING_SOMETHING, value, NETDEV_A_SOMETHING_PAD)) Create a new attribute type which will use 32 bits at netlink level if value is small enough (probably most of the time?), and (4B-aligned) 64 bits otherwise. Kernel API is just: if (nla_put_uint(rsp, NETDEV_A_SOMETHING_SOMETHING, value)) Calling this new type "just" sint / uint with no specific size will hopefully also make people more comfortable with using it. Currently telling people "don't use u8, you may need the bits, and netlink will round up to 4B, anyway" is the #1 comment we give to newcomers. In terms of netlink layout it looks like this: 0 4 8 12 16 32b: [nlattr][ u32 ] 64b: [ pad ][nlattr][ u64 ] uint(32) [nlattr][ u32 ] uint(64) [nlattr][ u64 ] Signed-off-by: Jakub Kicinski Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller

netlink: Annotate struct netlink_policy_dump_state with __counted_by

2023-10-06T09:48:46+00:00

Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle[1], add __counted_by for struct netlink_policy_dump_state. Additionally update the size of the usage array length before accessing it. This requires remembering the old size for the memset() and later assignments. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Johannes Berg Cc: netdev@vger.kernel.org Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Signed-off-by: David S. Miller

netlink: annotate data-races around sk->sk_err

2023-10-05T00:32:54+00:00

syzbot caught another data-race in netlink when setting sk->sk_err. Annotate all of them for good measure. BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg write to 0xffff8881613bb220 of 4 bytes by task 28147 on cpu 0: netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994 sock_recvmsg_nosec net/socket.c:1027 [inline] sock_recvmsg net/socket.c:1049 [inline] __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229 __do_sys_recvfrom net/socket.c:2247 [inline] __se_sys_recvfrom net/socket.c:2243 [inline] __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd write to 0xffff8881613bb220 of 4 bytes by task 28146 on cpu 1: netlink_recvmsg+0x448/0x780 net/netlink/af_netlink.c:1994 sock_recvmsg_nosec net/socket.c:1027 [inline] sock_recvmsg net/socket.c:1049 [inline] __sys_recvfrom+0x1f4/0x2e0 net/socket.c:2229 __do_sys_recvfrom net/socket.c:2247 [inline] __se_sys_recvfrom net/socket.c:2243 [inline] __x64_sys_recvfrom+0x78/0x90 net/socket.c:2243 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x00000000 -> 0x00000016 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 28146 Comm: syz-executor.0 Not tainted 6.6.0-rc3-syzkaller-00055-g9ed22ae6be81 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20231003183455.3410550-1-edumazet@google.com Signed-off-by: Jakub Kicinski

genetlink: add a family pointer to struct genl_info

2023-08-15T22:01:03+00:00

Having family in struct genl_info is quite useful. It cuts down the number of arguments which need to be passed to helpers which already take struct genl_info. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-7-kuba@kernel.org Signed-off-by: Jakub Kicinski

genetlink: use attrs from struct genl_info

2023-08-15T22:00:45+00:00

Since dumps carry struct genl_info now, use the attrs pointer from genl_info and remove the one in struct genl_dumpit_info. Reviewed-by: Johannes Berg Reviewed-by: Miquel Raynal Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20230814214723.2924989-6-kuba@kernel.org Signed-off-by: Jakub Kicinski