kernel/linux.git/net/ipv6/addrconf.c, branch linux-6.9.y

ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr

2024-04-10T00:09:05+00:00

Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it still means hlist_for_each_entry_rcu can return an item that got removed from the list. The memory itself of such item is not freed thanks to RCU but nothing guarantees the actual content of the memory is sane. In particular, the reference count can be zero. This can happen if ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough timing, this can happen: 1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry. 2. Then, the whole ipv6_del_addr is executed for the given entry. The reference count drops to zero and kfree_rcu is scheduled. 3. ipv6_get_ifaddr continues and tries to increments the reference count (in6_ifa_hold). 4. The rcu is unlocked and the entry is freed. 5. The freed entry is returned. Prevent increasing of the reference count in such case. The name in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe. [ 41.506330] refcount_t: addition on 0; use-after-free. [ 41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130 [ 41.507413] Modules linked in: veth bridge stp llc [ 41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14 [ 41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) [ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130 [ 41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff [ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282 [ 41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000 [ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900 [ 41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff [ 41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000 [ 41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48 [ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000 [ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0 [ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 41.516799] Call Trace: [ 41.517037] [ 41.517249] ? __warn+0x7b/0x120 [ 41.517535] ? refcount_warn_saturate+0xa5/0x130 [ 41.517923] ? report_bug+0x164/0x190 [ 41.518240] ? handle_bug+0x3d/0x70 [ 41.518541] ? exc_invalid_op+0x17/0x70 [ 41.520972] ? asm_exc_invalid_op+0x1a/0x20 [ 41.521325] ? refcount_warn_saturate+0xa5/0x130 [ 41.521708] ipv6_get_ifaddr+0xda/0xe0 [ 41.522035] inet6_rtm_getaddr+0x342/0x3f0 [ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10 [ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0 [ 41.523102] ? netlink_unicast+0x30f/0x390 [ 41.523445] ? __pfx_rtnetlink_rcv_msg+0x10/0x10 [ 41.523832] netlink_rcv_skb+0x53/0x100 [ 41.524157] netlink_unicast+0x23b/0x390 [ 41.524484] netlink_sendmsg+0x1f2/0x440 [ 41.524826] __sys_sendto+0x1d8/0x1f0 [ 41.525145] __x64_sys_sendto+0x1f/0x30 [ 41.525467] do_syscall_64+0xa5/0x1b0 [ 41.525794] entry_SYSCALL_64_after_hwframe+0x72/0x7a [ 41.526213] RIP: 0033:0x7fbc4cfcea9a [ 41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89 [ 41.527942] RSP: 002b:00007ffcf54012a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 41.528593] RAX: ffffffffffffffda RBX: 00007ffcf5401368 RCX: 00007fbc4cfcea9a [ 41.529173] RDX: 000000000000002c RSI: 00007fbc4b9d9bd0 RDI: 0000000000000005 [ 41.529786] RBP: 00007fbc4bafb040 R08: 00007ffcf54013e0 R09: 000000000000000c [ 41.530375] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 41.530977] R13: ffffffffc4653600 R14: 0000000000000001 R15: 00007fbc4ca85d1b [ 41.531573] Fixes: 5c578aedcb21d ("IPv6: convert addrconf hash list to RCU") Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Signed-off-by: Jiri Benc Link: https://lore.kernel.org/r/8ab821e36073a4a406c50ec83c9e8dc586c539e4.1712585809.git.jbenc@redhat.com Signed-off-by: Jakub Kicinski

ipv6: Fix address dump when IPv6 is disabled on an interface

2024-03-23T01:03:40+00:00

Cited commit started returning an error when user space requests to dump the interface's IPv6 addresses and IPv6 is disabled on the interface. Restore the previous behavior and do not return an error. Before cited commit: # ip address show dev dummy1 2: dummy1: mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 1a:52:02:5a:c2:6e brd ff:ff:ff:ff:ff:ff inet6 fe80::1852:2ff:fe5a:c26e/64 scope link proto kernel_ll valid_lft forever preferred_lft forever # ip link set dev dummy1 mtu 1000 # ip address show dev dummy1 2: dummy1: mtu 1000 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 1a:52:02:5a:c2:6e brd ff:ff:ff:ff:ff:ff After cited commit: # ip address show dev dummy1 2: dummy1: mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 1e:9b:94:00:ac:e8 brd ff:ff:ff:ff:ff:ff inet6 fe80::1c9b:94ff:fe00:ace8/64 scope link proto kernel_ll valid_lft forever preferred_lft forever # ip link set dev dummy1 mtu 1000 # ip address show dev dummy1 RTNETLINK answers: No such device Dump terminated With this patch: # ip address show dev dummy1 2: dummy1: mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 42:35:fc:53:66:cf brd ff:ff:ff:ff:ff:ff inet6 fe80::4035:fcff:fe53:66cf/64 scope link proto kernel_ll valid_lft forever preferred_lft forever # ip link set dev dummy1 mtu 1000 # ip address show dev dummy1 2: dummy1: mtu 1000 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether 42:35:fc:53:66:cf brd ff:ff:ff:ff:ff:ff Fixes: 9cc4cc329d30 ("ipv6: use xa_array iterator to implement inet6_dump_addr()") Reported-by: Gal Pressman Closes: https://lore.kernel.org/netdev/7e261328-42eb-411d-b1b4-ad884eeaae4d@linux.dev/ Tested-by: Gal Pressman Signed-off-by: Ido Schimmel Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20240321173042.2151756-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski

ipv6: remove RTNL protection from inet6_dump_addr()

2024-03-08T11:15:36+00:00

We can now remove RTNL acquisition while running inet6_dump_addr(), inet6_dump_ifmcaddr() and inet6_dump_ifacaddr(). Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: use xa_array iterator to implement inet6_dump_addr()

2024-03-08T11:15:36+00:00

inet6_dump_addr() can use the new xa_array iterator for better scalability. Make it ready for RCU-only protection. RTNL use is removed in the following patch. Also properly return 0 at the end of a dump to avoid and extra recvmsg() to get NLMSG_DONE. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: make in6_dump_addrs() lockless

2024-03-08T11:15:35+00:00

in6_dump_addrs() is called with RCU protection. There is no need holding idev->lock to iterate through unicast addresses. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

ipv6: make inet6_fill_ifaddr() lockless

2024-03-08T11:15:35+00:00

Make inet6_fill_ifaddr() lockless, and add approriate annotations on ifa->tstamp, ifa->valid_lft, ifa->preferred_lft, ifa->ifa_proto and ifa->rt_priority. Also constify 2nd argument of inet6_fill_ifaddr(), inet6_fill_ifmcaddr() and inet6_fill_ifacaddr(). Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

netlink: let core handle error cases in dump operations

2024-03-08T04:48:22+00:00

After commit b5a899154aa9 ("netlink: handle EMSGSIZE errors in the core"), we can remove some code that was not 100 % correct anyway. Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Reviewed-by: Ido Schimmel Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20240306102426.245689-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: use xa_array iterator to implement inet6_netconf_dump_devconf()

2024-03-01T08:42:33+00:00

1) inet6_netconf_dump_devconf() can run under RCU protection instead of RTNL. 2) properly return 0 at the end of a dump, avoiding an an extra recvmsg() system call. 3) Do not use inet6_base_seq() anymore, for_each_netdev_dump() has nice properties. Restarting a GETDEVCONF dump if a device has been added/removed or if net->ipv6.dev_addr_genid has changed is moot. Signed-off-by: Eric Dumazet Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

ipv6/addrconf: annotate data-races around devconf fields (II)

2024-03-01T08:42:33+00:00

Final (?) round of this series. Annotate lockless reads on following devconf fields, because they be changed concurrently from /proc/net/ipv6/conf. - accept_dad - optimistic_dad - use_optimistic - use_oif_addrs_only - ra_honor_pio_life - keep_addr_on_down - ndisc_notify - ndisc_evict_nocarrier - suppress_frag_ndisc - addr_gen_mode - seg6_enabled - ioam6_enabled - ioam6_id - ioam6_id_wide - drop_unicast_in_l2_multicast - mldv[12]_unsolicited_report_interval - force_mld_version - force_tllao - accept_untracked_na - drop_unsolicited_na - accept_source_route Signed-off-by: Eric Dumazet Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

ipv6/addrconf: annotate data-races around devconf fields (I)

2024-03-01T08:42:32+00:00

Annotate lockless reads and writes on following devconf fields: - regen_min_advance - regen_max_retry - dad_transmits - use_tempaddr - max_addresses - max_desync_factor - temp_valid_lft - rtr_solicits - rtr_solicit_max_interval - rtr_solicit_interval - rtr_solicit_delay - enhanced_dad - accept_redirects Signed-off-by: Eric Dumazet Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller