linux.git/fs/smb/client, branch v6.12

smb: client: Fix use-after-free of network namespace.

2024-11-04T01:28:31+00:00

Recently, we got a customer report that CIFS triggers oops while
reconnecting to a server.  [0]

The workload runs on Kubernetes, and some pods mount CIFS servers
in non-root network namespaces.  The problem rarely happened, but
it was always while the pod was dying.

The root cause is wrong reference counting for network namespace.

CIFS uses kernel sockets, which do not hold refcnt of the netns that
the socket belongs to.  That means CIFS must ensure the socket is
always freed before its netns; otherwise, use-after-free happens.

The repro steps are roughly:

  1. mount CIFS in a non-root netns
  2. drop packets from the netns
  3. destroy the netns
  4. unmount CIFS

We can reproduce the issue quickly with the script [1] below and see
the splat [2] if CONFIG_NET_NS_REFCNT_TRACKER is enabled.

When the socket is TCP, it is hard to guarantee the netns lifetime
without holding refcnt due to async timers.

Let's hold netns refcnt for each socket as done for SMC in commit
9744d2bf1976 ("smc: Fix use-after-free in tcp_write_timer_handler().").

Note that we need to move put_net() from cifs_put_tcp_session() to
clean_demultiplex_info(); otherwise, __sock_create() still could touch a
freed netns while cifsd tries to reconnect from cifs_demultiplex_thread().

Also, maybe_get_net() cannot be put just before __sock_create() because
the code is not under RCU and there is a small chance that the same
address happened to be reallocated to another netns.

[0]:
CIFS: VFS: \\XXXXXXXXXXX has not responded in 15 seconds. Reconnecting...
CIFS: Serverclose failed 4 times, giving up
Unable to handle kernel paging request at virtual address 14de99e461f84a07
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004
  CM = 0, WnR = 0
[14de99e461f84a07] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] SMP
Modules linked in: cls_bpf sch_ingress nls_utf8 cifs cifs_arc4 cifs_md4 dns_resolver tcp_diag inet_diag veth xt_state xt_connmark nf_conntrack_netlink xt_nat xt_statistic xt_MASQUERADE xt_mark xt_addrtype ipt_REJECT nf_reject_ipv4 nft_chain_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xt_comment nft_compat nf_tables nfnetlink overlay nls_ascii nls_cp437 sunrpc vfat fat aes_ce_blk aes_ce_cipher ghash_ce sm4_ce_cipher sm4 sm3_ce sm3 sha3_ce sha512_ce sha512_arm64 sha1_ce ena button sch_fq_codel loop fuse configfs dmi_sysfs sha2_ce sha256_arm64 dm_mirror dm_region_hash dm_log dm_mod dax efivarfs
CPU: 5 PID: 2690970 Comm: cifsd Not tainted 6.1.103-109.184.amzn2023.aarch64 #1
Hardware name: Amazon EC2 r7g.4xlarge/, BIOS 1.0 11/1/2018
pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : fib_rules_lookup+0x44/0x238
lr : __fib_lookup+0x64/0xbc
sp : ffff8000265db790
x29: ffff8000265db790 x28: 0000000000000000 x27: 000000000000bd01
x26: 0000000000000000 x25: ffff000b4baf8000 x24: ffff00047b5e4580
x23: ffff8000265db7e0 x22: 0000000000000000 x21: ffff00047b5e4500
x20: ffff0010e3f694f8 x19: 14de99e461f849f7 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000000 x12: 3f92800abd010002
x11: 0000000000000001 x10: ffff0010e3f69420 x9 : ffff800008a6f294
x8 : 0000000000000000 x7 : 0000000000000006 x6 : 0000000000000000
x5 : 0000000000000001 x4 : ffff001924354280 x3 : ffff8000265db7e0
x2 : 0000000000000000 x1 : ffff0010e3f694f8 x0 : ffff00047b5e4500
Call trace:
 fib_rules_lookup+0x44/0x238
 __fib_lookup+0x64/0xbc
 ip_route_output_key_hash_rcu+0x2c4/0x398
 ip_route_output_key_hash+0x60/0x8c
 tcp_v4_connect+0x290/0x488
 __inet_stream_connect+0x108/0x3d0
 inet_stream_connect+0x50/0x78
 kernel_connect+0x6c/0xac
 generic_ip_connect+0x10c/0x6c8 [cifs]
 __reconnect_target_unlocked+0xa0/0x214 [cifs]
 reconnect_dfs_server+0x144/0x460 [cifs]
 cifs_reconnect+0x88/0x148 [cifs]
 cifs_readv_from_socket+0x230/0x430 [cifs]
 cifs_read_from_socket+0x74/0xa8 [cifs]
 cifs_demultiplex_thread+0xf8/0x704 [cifs]
 kthread+0xd0/0xd4
Code: aa0003f8 f8480f13 eb18027f 540006c0 (b9401264)

[1]:
CIFS_CRED="/root/cred.cifs"
CIFS_USER="Administrator"
CIFS_PASS="Password"
CIFS_IP="X.X.X.X"
CIFS_PATH="//${CIFS_IP}/Users/Administrator/Desktop/CIFS_TEST"
CIFS_MNT="/mnt/smb"
DEV="enp0s3"

cat < ${CIFS_CRED}
username=${CIFS_USER}
password=${CIFS_PASS}
domain=EXAMPLE.COM
EOF

unshare -n bash -c "
mkdir -p ${CIFS_MNT}
ip netns attach root 1
ip link add eth0 type veth peer veth0 netns root
ip link set eth0 up
ip -n root link set veth0 up
ip addr add 192.168.0.2/24 dev eth0
ip -n root addr add 192.168.0.1/24 dev veth0
ip route add default via 192.168.0.1 dev eth0
ip netns exec root sysctl net.ipv4.ip_forward=1
ip netns exec root iptables -t nat -A POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE
mount -t cifs ${CIFS_PATH} ${CIFS_MNT} -o vers=3.0,sec=ntlmssp,credentials=${CIFS_CRED},rsize=65536,wsize=65536,cache=none,echo_interval=1
touch ${CIFS_MNT}/a.txt
ip netns exec root iptables -t nat -D POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE
"

umount ${CIFS_MNT}

[2]:
ref_tracker: net notrefcnt@000000004bbc008d has 1/1 users at
     sk_alloc (./include/net/net_namespace.h:339 net/core/sock.c:2227)
     inet_create (net/ipv4/af_inet.c:326 net/ipv4/af_inet.c:252)
     __sock_create (net/socket.c:1576)
     generic_ip_connect (fs/smb/client/connect.c:3075)
     cifs_get_tcp_session.part.0 (fs/smb/client/connect.c:3160 fs/smb/client/connect.c:1798)
     cifs_mount_get_session (fs/smb/client/trace.h:959 fs/smb/client/connect.c:3366)
     dfs_mount_share (fs/smb/client/dfs.c:63 fs/smb/client/dfs.c:285)
     cifs_mount (fs/smb/client/connect.c:3622)
     cifs_smb3_do_mount (fs/smb/client/cifsfs.c:949)
     smb3_get_tree (fs/smb/client/fs_context.c:784 fs/smb/client/fs_context.c:802 fs/smb/client/fs_context.c:794)
     vfs_get_tree (fs/super.c:1800)
     path_mount (fs/namespace.c:3508 fs/namespace.c:3834)
     __x64_sys_mount (fs/namespace.c:3848 fs/namespace.c:4057 fs/namespace.c:4034 fs/namespace.c:4034)
     do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
     entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Fixes: 26abe14379f8 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.")
Signed-off-by: Kuniyuki Iwashima 
Acked-by: Tom Talpey 
Signed-off-by: Steve French

cifs: fix warning when destroy 'cifs_io_request_pool'

2024-10-23T12:42:44+00:00

There's a issue as follows:
WARNING: CPU: 1 PID: 27826 at mm/slub.c:4698 free_large_kmalloc+0xac/0xe0
RIP: 0010:free_large_kmalloc+0xac/0xe0
Call Trace:
 
 ? __warn+0xea/0x330
 mempool_destroy+0x13f/0x1d0
 init_cifs+0xa50/0xff0 [cifs]
 do_one_initcall+0xdc/0x550
 do_init_module+0x22d/0x6b0
 load_module+0x4e96/0x5ff0
 init_module_from_file+0xcd/0x130
 idempotent_init_module+0x330/0x620
 __x64_sys_finit_module+0xb3/0x110
 do_syscall_64+0xc1/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Obviously, 'cifs_io_request_pool' is not created by mempool_create().
So just use mempool_exit() to revert 'cifs_io_request_pool'.

Fixes: edea94a69730 ("cifs: Add mempools for cifs_io_request and cifs_io_subrequest structs")
Signed-off-by: Ye Bin 
Acked-by: David Howells

smb: client: Handle kstrdup failures for passwords

2024-10-23T12:42:22+00:00

In smb3_reconfigure(), after duplicating ctx->password and
ctx->password2 with kstrdup(), we need to check for allocation
failures.

If ses->password allocation fails, return -ENOMEM.
If ses->password2 allocation fails, free ses->password, set it
to NULL, and return -ENOMEM.

Fixes: c1eb537bf456 ("cifs: allow changing password during remount")
Reviewed-by: David Howells 
Signed-off-by: Henrique Carvalho 
Signed-off-by: Steve French

cifs: Remove unused functions

2024-10-16T05:30:52+00:00

cifs_ses_find_chan() has been unused since commit
f486ef8e2003 ("cifs: use the chans_need_reconnect bitmap for reconnect status")

cifs_read_page_from_socket() has been unused since commit
d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")

cifs_chan_in_reconnect() has been unused since commit
bc962159e8e3 ("cifs: avoid race conditions with parallel reconnects")

Remove them.

Signed-off-by: Dr. David Alan Gilbert 
Signed-off-by: Steve French

smb/client: Fix logically dead code

2024-10-16T05:30:52+00:00

The if condition in collect_sample: can never be satisfied
because of a logical contradiction. The indicated dead code
may have performed some action; that action will never occur.

Fixes: 94ae8c3fee94 ("smb: client: compress: LZ77 code improvements cleanup")
Signed-off-by: Advait Dhamorikar 
Signed-off-by: Steve French

smb: client: fix OOBs when building SMB2_IOCTL request

2024-10-16T05:30:52+00:00

When using encryption, either enforced by the server or when using
'seal' mount option, the client will squash all compound request buffers
down for encryption into a single iov in smb2_set_next_command().

SMB2_ioctl_init() allocates a small buffer (448 bytes) to hold the
SMB2_IOCTL request in the first iov, and if the user passes an input
buffer that is greater than 328 bytes, smb2_set_next_command() will
end up writing off the end of @rqst->iov[0].iov_base as shown below:

  mount.cifs //srv/share /mnt -o ...,seal
  ln -s $(perl -e "print('a')for 1..1024") /mnt/link

  BUG: KASAN: slab-out-of-bounds in
  smb2_set_next_command.cold+0x1d6/0x24c [cifs]
  Write of size 4116 at addr ffff8881148fcab8 by task ln/859

  CPU: 1 UID: 0 PID: 859 Comm: ln Not tainted 6.12.0-rc3 #1
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
  1.16.3-2.fc40 04/01/2014
  Call Trace:
   
   dump_stack_lvl+0x5d/0x80
   ? smb2_set_next_command.cold+0x1d6/0x24c [cifs]
   print_report+0x156/0x4d9
   ? smb2_set_next_command.cold+0x1d6/0x24c [cifs]
   ? __virt_addr_valid+0x145/0x310
   ? __phys_addr+0x46/0x90
   ? smb2_set_next_command.cold+0x1d6/0x24c [cifs]
   kasan_report+0xda/0x110
   ? smb2_set_next_command.cold+0x1d6/0x24c [cifs]
   kasan_check_range+0x10f/0x1f0
   __asan_memcpy+0x3c/0x60
   smb2_set_next_command.cold+0x1d6/0x24c [cifs]
   smb2_compound_op+0x238c/0x3840 [cifs]
   ? kasan_save_track+0x14/0x30
   ? kasan_save_free_info+0x3b/0x70
   ? vfs_symlink+0x1a1/0x2c0
   ? do_symlinkat+0x108/0x1c0
   ? __pfx_smb2_compound_op+0x10/0x10 [cifs]
   ? kmem_cache_free+0x118/0x3e0
   ? cifs_get_writable_path+0xeb/0x1a0 [cifs]
   smb2_get_reparse_inode+0x423/0x540 [cifs]
   ? __pfx_smb2_get_reparse_inode+0x10/0x10 [cifs]
   ? rcu_is_watching+0x20/0x50
   ? __kmalloc_noprof+0x37c/0x480
   ? smb2_create_reparse_symlink+0x257/0x490 [cifs]
   ? smb2_create_reparse_symlink+0x38f/0x490 [cifs]
   smb2_create_reparse_symlink+0x38f/0x490 [cifs]
   ? __pfx_smb2_create_reparse_symlink+0x10/0x10 [cifs]
   ? find_held_lock+0x8a/0xa0
   ? hlock_class+0x32/0xb0
   ? __build_path_from_dentry_optional_prefix+0x19d/0x2e0 [cifs]
   cifs_symlink+0x24f/0x960 [cifs]
   ? __pfx_make_vfsuid+0x10/0x10
   ? __pfx_cifs_symlink+0x10/0x10 [cifs]
   ? make_vfsgid+0x6b/0xc0
   ? generic_permission+0x96/0x2d0
   vfs_symlink+0x1a1/0x2c0
   do_symlinkat+0x108/0x1c0
   ? __pfx_do_symlinkat+0x10/0x10
   ? strncpy_from_user+0xaa/0x160
   __x64_sys_symlinkat+0xb9/0xf0
   do_syscall_64+0xbb/0x1d0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x7f08d75c13bb

Reported-by: David Howells 
Fixes: e77fe73c7e38 ("cifs: we can not use small padding iovs together with encryption")
Signed-off-by: Paulo Alcantara (Red Hat) 
Signed-off-by: Steve French

smb: client: fix possible double free in smb2_set_ea()

2024-10-16T05:25:54+00:00

Clang static checker(scan-build) warning：
fs/smb/client/smb2ops.c:1304:2: Attempt to free released memory.
 1304 |         kfree(ea);
      |         ^~~~~~~~~

There is a double free in such case:
'ea is initialized to NULL' -> 'first successful memory allocation for
ea' -> 'something failed, goto sea_exit' -> 'first memory release for ea'
-> 'goto replay_again' -> 'second goto sea_exit before allocate memory
for ea' -> 'second memory release for ea resulted in double free'.

Re-initialie 'ea' to NULL near to the replay_again label, it can fix this
double free problem.

Fixes: 4f1fffa23769 ("cifs: commands that are retried should have replay flag set")
Reviewed-by: Dan Carpenter 
Signed-off-by: Su Hui 
Signed-off-by: Steve French

cifs: Fix creating native symlinks pointing to current or parent directory

2024-10-07T03:57:12+00:00

Calling 'ln -s . symlink' or 'ln -s .. symlink' creates symlink pointing to
some object name which ends with U+F029 unicode codepoint. This is because
trailing dot in the object name is replaced by non-ASCII unicode codepoint.

So Linux SMB client currently is not able to create native symlink pointing
to current or parent directory on Windows SMB server which can be read by
either on local Windows server or by any other SMB client which does not
implement compatible-reverse character replacement.

Fix this problem in cifsConvertToUTF16() function which is doing that
character replacement. Function comment already says that it does not need
to handle special cases '.' and '..', but after introduction of native
symlinks in reparse point form, this handling is needed.

Note that this change depends on the previous change
"cifs: Improve creating native symlinks pointing to directory".

Signed-off-by: Pali Rohár 
Signed-off-by: Steve French

cifs: Improve creating native symlinks pointing to directory

2024-10-07T03:57:12+00:00

SMB protocol for native symlinks distinguish between symlink to directory
and symlink to file. These two symlink types cannot be exchanged, which
means that symlink of file type pointing to directory cannot be resolved at
all (and vice-versa).

Windows follows this rule for local filesystems (NTFS) and also for SMB.

Linux SMB client currenly creates all native symlinks of file type. Which
means that Windows (and some other SMB clients) cannot resolve symlinks
pointing to directory created by Linux SMB client.

As Linux system does not distinguish between directory and file symlinks,
its API does not provide enough information for Linux SMB client during
creating of native symlinks.

Add some heuristic into the Linux SMB client for choosing the correct
symlink type during symlink creation. Check if the symlink target location
ends with slash, or last path component is dot or dot-dot, and check if the
target location on SMB share exists and is a directory. If at least one
condition is truth then create a new SMB symlink of directory type.
Otherwise create it as file type symlink.

This change improves interoperability with Windows systems. Windows systems
would be able to resolve more SMB symlinks created by Linux SMB client
which points to existing directory.

Signed-off-by: Pali Rohár 
Signed-off-by: Steve French

Merge tag 'v6.12-rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

2024-10-04T16:56:05+00:00

Pull smb client fixes from Steve French:

 - statfs fix (e.g. when limited access to root directory of share)

 - special file handling fixes: fix packet validation to avoid buffer
   overflow for reparse points, fixes for symlink path parsing (one for
   reparse points, and one for SFU use case), and fix for cleanup after
   failed SET_REPARSE operation.

 - fix for SMB2.1 signing bug introduced by recent patch to NFS symlink
   path, and NFS reparse point validation

 - comment cleanup

* tag 'v6.12-rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: Do not convert delimiter when parsing NFS-style symlinks
  cifs: Validate content of NFS reparse point buffer
  cifs: Fix buffer overflow when parsing NFS reparse points
  smb: client: Correct typos in multiple comments across various files
  smb: client: use actual path when queryfs
  cifs: Remove intermediate object of failed create reparse call
  Revert "smb: client: make SHA-512 TFM ephemeral"
  smb: Update comments about some reparse point tags
  cifs: Check for UTF-16 null codepoint in SFU symlink target location