| Age | Commit message (Collapse) | Author |
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`selinux_add_opt()` stopped taking ownership of the passed context since
commit 70f4169ab421 ("selinux: parse contexts for mount options early").
unreferenced object 0xffff888114dfd140 (size 64):
comm "mount", pid 15182, jiffies 4295687028 (age 796.340s)
hex dump (first 32 bytes):
73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f system_u:object_
72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65 r:test_filesyste
backtrace:
[<ffffffffa07dbef4>] kmemdup_nul+0x24/0x80
[<ffffffffa0d34253>] selinux_sb_eat_lsm_opts+0x293/0x560
[<ffffffffa0d13f08>] security_sb_eat_lsm_opts+0x58/0x80
[<ffffffffa0af1eb2>] generic_parse_monolithic+0x82/0x180
[<ffffffffa0a9c1a5>] do_new_mount+0x1f5/0x550
[<ffffffffa0a9eccb>] path_mount+0x2ab/0x1570
[<ffffffffa0aa019e>] __x64_sys_mount+0x20e/0x280
[<ffffffffa1f47124>] do_syscall_64+0x34/0x80
[<ffffffffa200007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
unreferenced object 0xffff888108e71640 (size 64):
comm "fsmount", pid 7607, jiffies 4295044974 (age 1601.016s)
hex dump (first 32 bytes):
73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f system_u:object_
72 3a 74 65 73 74 5f 66 69 6c 65 73 79 73 74 65 r:test_filesyste
backtrace:
[<ffffffff861dc2b1>] memdup_user+0x21/0x90
[<ffffffff861dc367>] strndup_user+0x47/0xa0
[<ffffffff864f6965>] __do_sys_fsconfig+0x485/0x9f0
[<ffffffff87940124>] do_syscall_64+0x34/0x80
[<ffffffff87a0007e>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
Cc: stable@vger.kernel.org
Fixes: 70f4169ab421 ("selinux: parse contexts for mount options early")
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Log the anonymous inode class name in the security hook
inode_init_security_anon. This name is the key for name based type
transitions on the anon_inode security class on creation. Example:
type=AVC msg=audit(02/16/22 22:02:50.585:216) : avc: granted \
{ create } for pid=2136 comm=mariadbd anonclass=[io_uring] \
scontext=system_u:system_r:mysqld_t:s0 \
tcontext=system_u:system_r:mysqld_iouring_t:s0 tclass=anon_inode
Add a new LSM audit data type holding the inode and the class name.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: adjusted 'anonclass' to be a trusted string, cgzones approved]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The checkreqprot functionality was disabled by default back in
Linux v4.4 (2015) with commit 2a35d196c160e3 ("selinux: change
CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE default") and it was
officially marked as deprecated in Linux v5.7. It was always a
bit of a hack to workaround very old userspace and to the best of
our knowledge, the checkreqprot functionality has been disabled by
Linux distributions for quite some time.
This patch moves the deprecation messages from KERN_WARNING to
KERN_ERR and adds a five second sleep to anyone using it to help
draw their attention to the deprecation and provide a URL which
helps explain things in more detail.
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Get rid of redundant assignments which end up in values not being
read either because they are overwritten or the function ends.
Reported by clang-tidy [deadcode.DeadStores]
Signed-off-by: Michal Orzel <michalorzel.eng@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull ptrace cleanups from Eric Biederman:
"This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was around
task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where anything left in tracehook.h was
some weird strange thing that was difficult to understand"
* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Remove duplicated include in ptrace.c
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
ptrace: Return the signal to continue with from ptrace_stop
ptrace: Move setting/clearing ptrace_message into ptrace_stop
tracehook: Remove tracehook.h
resume_user_mode: Move to resume_user_mode.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Introduce task_work_pending
task_work: Remove unnecessary include from posix_timers.h
ptrace: Remove tracehook_signal_handler
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Move ptrace_report_syscall into ptrace.h
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Now that all of the definitions have moved out of tracehook.h into
ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in
tracehook.h so remove it.
Update the few files that were depending upon tracehook.h to bring in
definitions to use the headers they need directly.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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These ioctls are equivalent to fcntl(fd, F_SETFD, flags), which SELinux
always allows too. Furthermore, a failed FIOCLEX could result in a file
descriptor being leaked to a process that should not have access to it.
As this patch removes access controls, a policy capability needs to be
enabled in policy to always allow these ioctls.
Based-on-patch-by: Demi Marie Obenour <demiobenour@gmail.com>
Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Those return statements at the end of a void function are redundant.
Reported by clang-tidy [readability-redundant-control-flow]
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Do this by extracting the peer labeling per-association logic from
selinux_sctp_assoc_request() into a new helper
selinux_sctp_process_new_assoc() and use this helper in both
selinux_sctp_assoc_request() and selinux_sctp_assoc_established(). This
ensures that the peer labeling behavior as documented in
Documentation/security/SCTP.rst is applied both on the client and server
side:
"""
An SCTP socket will only have one peer label assigned to it. This will be
assigned during the establishment of the first association. Any further
associations on this socket will have their packet peer label compared to
the sockets peer label, and only if they are different will the
``association`` permission be validated. This is validated by checking the
socket peer sid against the received packets peer sid to determine whether
the association should be allowed or denied.
"""
At the same time, it also ensures that the peer label of the association
is set to the correct value, such that if it is peeled off into a new
socket, the socket's peer label will then be set to the association's
peer label, same as it already works on the server side.
While selinux_inet_conn_established() (which we are replacing by
selinux_sctp_assoc_established() for SCTP) only deals with assigning a
peer label to the connection (socket), in case of SCTP we need to also
copy the (local) socket label to the association, so that
selinux_sctp_sk_clone() can then pick it up for the new socket in case
of SCTP peeloff.
Careful readers will notice that the selinux_sctp_process_new_assoc()
helper also includes the "IPv4 packet received over an IPv6 socket"
check, even though it hadn't been in selinux_sctp_assoc_request()
before. While such check is not necessary in
selinux_inet_conn_request() (because struct request_sock's family field
is already set according to the skb's family), here it is needed, as we
don't have request_sock and we take the initial family from the socket.
In selinux_sctp_assoc_established() it is similarly needed as well (and
also selinux_inet_conn_established() already has it).
Fixes: 72e89f50084c ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Based-on-patch-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Commit b8b87fd954b4 ("selinux: Fix selinux_sb_mnt_opts_compat()")
started to parse mount options into SIDs in selinux_add_opt() if policy
has already been loaded. Since it's extremely unlikely that anyone would
depend on the ability to set SELinux contexts on fs_context before
loading the policy and then mounting that context after simplify the
logic by always parsing the options early.
Note that the multi-step mounting is only possible with the new
fscontext mount API and wasn't possible before its introduction.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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When running the SELinux code through sparse, there are a handful of
warnings. This patch resolves some of these warnings caused by
"__rcu" mismatches.
% make W=1 C=1 security/selinux/
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Avoid unnecessary parsing of sids that have already been parsed via
selinux_sb_eat_lsm_opts().
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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selinux_sb_mnt_opts_compat() is called under the sb_lock spinlock and
shouldn't be performing any memory allocations. Fix this by parsing the
sids at the same time we're chopping up the security mount options
string and then using the pre-parsed sids when doing the comparison.
Fixes: cc274ae7763d ("selinux: fix sleeping function called from invalid context")
Fixes: 69c4a42d72eb ("lsm,selinux: add new hook to compare new mount to an existing mount")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The usual LSM hook "bail on fail" scheme doesn't work for cases where
a security module may return an error code indicating that it does not
recognize an input. In this particular case Smack sees a mount option
that it recognizes, and returns 0. A call to a BPF hook follows, which
returns -ENOPARAM, which confuses the caller because Smack has processed
its data.
The SELinux hook incorrectly returns 1 on success. There was a time
when this was correct, however the current expectation is that it
return 0 on success. This is repaired.
Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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In the process of removing an explicit type cast to preserve a cred
const qualifier in cred_init_security() we ran into a problem where
the task_struct::real_cred field is defined with the "__rcu"
attribute but the selinux_cred() function parameter is not, leading
to a sparse warning:
security/selinux/hooks.c:216:36: sparse: sparse:
incorrect type in argument 1 (different address spaces)
@@ expected struct cred const *cred
@@ got struct cred const [noderef] __rcu *real_cred
As we don't want to add the "__rcu" attribute to the selinux_cred()
parameter, we're going to add an explicit cast back to
cred_init_security().
Fixes: b084e189b01a ("selinux: simplify cred_init_security")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The parameter of selinux_cred() is declared const, so an explicit cast
dropping the const qualifier is not necessary. Without the cast the
local variable cred serves no purpose.
Reported by clang [-Wcast-qual]
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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LSM blob has been involved for superblock's security struct. So fix the
remaining direct access to sb->s_security by using the LSM blob
mechanism.
Fixes: 08abe46b2cfc ("selinux: fall back to SECURITY_FS_USE_GENFS if no xattr support")
Fixes: 69c4a42d72eb ("lsm,selinux: add new hook to compare new mount to an existing mount")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
"Nothing too significant, but five SELinux patches for v5.17 that do
the following:
- Harden the code through additional use of the struct_size() macro
- Plug some memory leaks
- Clean up the code via removal of the security_add_mnt_opt() LSM
hook and minor tweaks to selinux_add_opt()
- Rename security_task_getsecid_subj() to better reflect its actual
behavior/use - now called security_current_getsecid_subj()"
* tag 'selinux-pr-20220110' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: minor tweaks to selinux_add_opt()
selinux: fix potential memleak in selinux_add_opt()
security,selinux: remove security_add_mnt_opt()
selinux: Use struct_size() helper in kmalloc()
lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()
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Clang static analysis reports this warning
hooks.c:5765:6: warning: 4th function call argument is an uninitialized
value
if (selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
selinux_parse_skb() can return ok without setting proto. The later call
to selinux_xfrm_postroute_last() does an early check of proto and can
return ok if the garbage proto value matches. So initialize proto.
Cc: stable@vger.kernel.org
Fixes: eef9b41622f2 ("selinux: cleanup selinux_xfrm_sock_rcv_skb() and selinux_xfrm_postroute_last()")
Signed-off-by: Tom Rix <trix@redhat.com>
[PM: typo/spelling and checkpatch.pl description fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Two minor edits to selinux_add_opt(): use "sizeof(*ptr)" instead of
"sizeof(type)" in the kzalloc() call, and rename the "Einval" jump
target to "err" for the sake of consistency.
Signed-off-by: Paul Moore <paul@paul-moore.com>
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This patch try to fix potential memleak in error branch.
Fixes: ba6418623385 ("selinux: new helper - selinux_add_opt()")
Signed-off-by: Bernard Zhao <bernard@vivo.com>
[PM: tweak the subject line, add Fixes tag]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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selinux_sb_mnt_opts_compat() is called via sget_fc() under the sb_lock
spinlock, so it can't use GFP_KERNEL allocations:
[ 868.565200] BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:230
[ 868.568246] in_atomic(): 1, irqs_disabled(): 0,
non_block: 0, pid: 4914, name: mount.nfs
[ 868.569626] preempt_count: 1, expected: 0
[ 868.570215] RCU nest depth: 0, expected: 0
[ 868.570809] Preemption disabled at:
[ 868.570810] [<0000000000000000>] 0x0
[ 868.571848] CPU: 1 PID: 4914 Comm: mount.nfs Kdump: loaded
Tainted: G W 5.16.0-rc5.2585cf9dfa #1
[ 868.573273] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS 1.14.0-4.fc34 04/01/2014
[ 868.574478] Call Trace:
[ 868.574844] <TASK>
[ 868.575156] dump_stack_lvl+0x34/0x44
[ 868.575692] __might_resched.cold+0xd6/0x10f
[ 868.576308] slab_pre_alloc_hook.constprop.0+0x89/0xf0
[ 868.577046] __kmalloc_track_caller+0x72/0x420
[ 868.577684] ? security_context_to_sid_core+0x48/0x2b0
[ 868.578569] kmemdup_nul+0x22/0x50
[ 868.579108] security_context_to_sid_core+0x48/0x2b0
[ 868.579854] ? _nfs4_proc_pathconf+0xff/0x110 [nfsv4]
[ 868.580742] ? nfs_reconfigure+0x80/0x80 [nfs]
[ 868.581355] security_context_str_to_sid+0x36/0x40
[ 868.581960] selinux_sb_mnt_opts_compat+0xb5/0x1e0
[ 868.582550] ? nfs_reconfigure+0x80/0x80 [nfs]
[ 868.583098] security_sb_mnt_opts_compat+0x2a/0x40
[ 868.583676] nfs_compare_super+0x113/0x220 [nfs]
[ 868.584249] ? nfs_try_mount_request+0x210/0x210 [nfs]
[ 868.584879] sget_fc+0xb5/0x2f0
[ 868.585267] nfs_get_tree_common+0x91/0x4a0 [nfs]
[ 868.585834] vfs_get_tree+0x25/0xb0
[ 868.586241] fc_mount+0xe/0x30
[ 868.586605] do_nfs4_mount+0x130/0x380 [nfsv4]
[ 868.587160] nfs4_try_get_tree+0x47/0xb0 [nfsv4]
[ 868.587724] vfs_get_tree+0x25/0xb0
[ 868.588193] do_new_mount+0x176/0x310
[ 868.588782] __x64_sys_mount+0x103/0x140
[ 868.589388] do_syscall_64+0x3b/0x90
[ 868.589935] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 868.590699] RIP: 0033:0x7f2b371c6c4e
[ 868.591239] Code: 48 8b 0d dd 71 0e 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00
00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d aa 71
0e 00 f7 d8 64 89 01 48
[ 868.593810] RSP: 002b:00007ffc83775d88 EFLAGS: 00000246
ORIG_RAX: 00000000000000a5
[ 868.594691] RAX: ffffffffffffffda RBX: 00007ffc83775f10 RCX: 00007f2b371c6c4e
[ 868.595504] RDX: 0000555d517247a0 RSI: 0000555d51724700 RDI: 0000555d51724540
[ 868.596317] RBP: 00007ffc83775f10 R08: 0000555d51726890 R09: 0000555d51726890
[ 868.597162] R10: 0000000000000000 R11: 0000000000000246 R12: 0000555d51726890
[ 868.598005] R13: 0000000000000003 R14: 0000555d517246e0 R15: 0000555d511ac925
[ 868.598826] </TASK>
Cc: stable@vger.kernel.org
Fixes: 69c4a42d72eb ("lsm,selinux: add new hook to compare new mount to an existing mount")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
[PM: cleanup/line-wrap the backtrace]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Its last user has been removed in commit f2aedb713c28 ("NFS: Add
fs_context support.").
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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The security_task_getsecid_subj() LSM hook invites misuse by allowing
callers to specify a task even though the hook is only safe when the
current task is referenced. Fix this by removing the task_struct
argument to the hook, requiring LSM implementations to use the
current task. While we are changing the hook declaration we also
rename the function to security_current_getsecid_subj() in an effort
to reinforce that the hook captures the subjective credentials of the
current task and not an arbitrary task on the system.
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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This patch reverts two prior patches, e7310c94024c
("security: implement sctp_assoc_established hook in selinux") and
7c2ef0240e6a ("security: add sctp_assoc_established hook"), which
create the security_sctp_assoc_established() LSM hook and provide a
SELinux implementation. Unfortunately these two patches were merged
without proper review (the Reviewed-by and Tested-by tags from
Richard Haines were for previous revisions of these patches that
were significantly different) and there are outstanding objections
from the SELinux maintainers regarding these patches.
Work is currently ongoing to correct the problems identified in the
reverted patches, as well as others that have come up during review,
but it is unclear at this point in time when that work will be ready
for inclusion in the mainline kernel. In the interest of not keeping
objectionable code in the kernel for multiple weeks, and potentially
a kernel release, we are reverting the two problematic patches.
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Different from selinux_inet_conn_established(), it also gives the
secid to asoc->peer_secid in selinux_sctp_assoc_established(),
as one UDP-type socket may have more than one asocs.
Note that peer_secid in asoc will save the peer secid for this
asoc connection, and peer_sid in sksec will just keep the peer
secid for the latest connection. So the right use should be do
peeloff for UDP-type socket if there will be multiple asocs in
one socket, so that the peeloff socket has the right label for
its asoc.
v1->v2:
- call selinux_inet_conn_established() to reduce some code
duplication in selinux_sctp_assoc_established(), as Ondrej
suggested.
- when doing peeloff, it calls sock_create() where it actually
gets secid for socket from socket_sockcreate_sid(). So reuse
SECSID_WILD to ensure the peeloff socket keeps using that
secid after calling selinux_sctp_sk_clone() for client side.
Fixes: 72e89f50084c ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Reviewed-by: Richard Haines <richard_c_haines@btinternet.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch is to move secid and peer_secid from endpoint to association,
and pass asoc to sctp_assoc_request and sctp_sk_clone instead of ep. As
ep is the local endpoint and asoc represents a connection, and in SCTP
one sk/ep could have multiple asoc/connection, saving secid/peer_secid
for new asoc will overwrite the old asoc's.
Note that since asoc can be passed as NULL, security_sctp_assoc_request()
is moved to the place right after the new_asoc is created in
sctp_sf_do_5_1B_init() and sctp_sf_do_unexpected_init().
v1->v2:
- fix the description of selinux_netlbl_skbuff_setsid(), as Jakub noticed.
- fix the annotation in selinux_sctp_assoc_request(), as Richard Noticed.
Fixes: 72e89f50084c ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Reviewed-by: Richard Haines <richard_c_haines@btinternet.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
- Add LSM/SELinux/Smack controls and auditing for io-uring.
As usual, the individual commit descriptions have more detail, but we
were basically missing two things which we're adding here:
+ establishment of a proper audit context so that auditing of
io-uring ops works similarly to how it does for syscalls (with
some io-uring additions because io-uring ops are *not* syscalls)
+ additional LSM hooks to enable access control points for some of
the more unusual io-uring features, e.g. credential overrides.
The additional audit callouts and LSM hooks were done in conjunction
with the io-uring folks, based on conversations and RFC patches
earlier in the year.
- Fixup the binder credential handling so that the proper credentials
are used in the LSM hooks; the commit description and the code
comment which is removed in these patches are helpful to understand
the background and why this is the proper fix.
- Enable SELinux genfscon policy support for securityfs, allowing
improved SELinux filesystem labeling for other subsystems which make
use of securityfs, e.g. IMA.
* tag 'selinux-pr-20211101' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
security: Return xattr name from security_dentry_init_security()
selinux: fix a sock regression in selinux_ip_postroute_compat()
binder: use cred instead of task for getsecid
binder: use cred instead of task for selinux checks
binder: use euid from cred instead of using task
LSM: Avoid warnings about potentially unused hook variables
selinux: fix all of the W=1 build warnings
selinux: make better use of the nf_hook_state passed to the NF hooks
selinux: fix race condition when computing ocontext SIDs
selinux: remove unneeded ipv6 hook wrappers
selinux: remove the SELinux lockdown implementation
selinux: enable genfscon labeling for securityfs
Smack: Brutalist io_uring support
selinux: add support for the io_uring access controls
lsm,io_uring: add LSM hooks to io_uring
io_uring: convert io_uring to the secure anon inode interface
fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure()
audit: add filtering for io_uring records
audit,io_uring,io-wq: add some basic audit support to io_uring
audit: prepare audit_context for use in calling contexts beyond syscalls
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Right now security_dentry_init_security() only supports single security
label and is used by SELinux only. There are two users of this hook,
namely ceph and nfs.
NFS does not care about xattr name. Ceph hardcodes the xattr name to
security.selinux (XATTR_NAME_SELINUX).
I am making changes to fuse/virtiofs to send security label to virtiofsd
and I need to send xattr name as well. I also hardcoded the name of
xattr to security.selinux.
Stephen Smalley suggested that it probably is a good idea to modify
security_dentry_init_security() to also return name of xattr so that
we can avoid this hardcoding in the callers.
This patch adds a new parameter "const char **xattr_name" to
security_dentry_init_security() and LSM puts the name of xattr
too if caller asked for it (xattr_name != NULL).
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
[PM: fixed typos in the commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Unfortunately we can't rely on nf_hook_state->sk being the proper
originating socket so revert to using skb_to_full_sk(skb).
Fixes: 1d1e1ded1356 ("selinux: make better use of the nf_hook_state passed to the NF hooks")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Since binder was integrated with selinux, it has passed
'struct task_struct' associated with the binder_proc
to represent the source and target of transactions.
The conversion of task to SID was then done in the hook
implementations. It turns out that there are race conditions
which can result in an incorrect security context being used.
Fix by using the 'struct cred' saved during binder_open and pass
it to the selinux subsystem.
Cc: stable@vger.kernel.org # 5.14 (need backport for earlier stables)
Fixes: 79af73079d75 ("Add security hooks to binder and implement the hooks for SELinux.")
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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This patch builds on a previous SELinux/netfilter patch by Florian
Westphal and makes better use of the nf_hook_state variable passed
into the SELinux/netfilter hooks as well as a number of other small
cleanups in the related code.
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Netfilter places the protocol number the hook function is getting called
from in state->pf, so we can use that instead of an extra wrapper.
While at it, remove one-line wrappers too and make
selinux_ip_{out,forward,postroute} useable as hook function.
Signed-off-by: Florian Westphal <fw@strlen.de>
Message-Id: <20211011202229.28289-1-fw@strlen.de>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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NOTE: This patch intentionally omits any "Fixes:" metadata or stable
tagging since it removes a SELinux access control check; while
removing the control point is the right thing to do moving forward,
removing it in stable kernels could be seen as a regression.
The original SELinux lockdown implementation in 59438b46471a
("security,lockdown,selinux: implement SELinux lockdown") used the
current task's credentials as both the subject and object in the
SELinux lockdown hook, selinux_lockdown(). Unfortunately that
proved to be incorrect in a number of cases as the core kernel was
calling the LSM lockdown hook in places where the credentials from
the "current" task_struct were not the correct credentials to use
in the SELinux access check.
Attempts were made to resolve this by adding a credential pointer
to the LSM lockdown hook as well as suggesting that the single hook
be split into two: one for user tasks, one for kernel tasks; however
neither approach was deemed acceptable by Linus. Faced with the
prospect of either changing the subj/obj in the access check to a
constant context (likely the kernel's label) or removing the SELinux
lockdown check entirely, the SELinux community decided that removing
the lockdown check was preferable.
The supporting changes to the general LSM layer are left intact, this
patch only removes the SELinux implementation.
Acked-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Add support for genfscon per-file labeling of securityfs files.
This allows for separate labels and thereby access control for
different files. For example a genfscon statement
genfscon securityfs /integrity/ima/policy \
system_u:object_r:ima_policy_t:s0
will set a private label to the IMA policy file and thus allow to
control the ability to set the IMA policy. Setting labels directly
with setxattr(2), e.g. by chcon(1) or setfiles(8), is still not
supported.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
[PM: line width fixes in the commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Jann Horn reported a problem with commit eb1231f73c4d ("selinux:
clarify task subjective and objective credentials") where some LSM
hooks were attempting to access the subjective credentials of a task
other than the current task. Generally speaking, it is not safe to
access another task's subjective credentials and doing so can cause
a number of problems.
Further, while looking into the problem, I realized that Smack was
suffering from a similar problem brought about by a similar commit
1fb057dcde11 ("smack: differentiate between subjective and objective
task credentials").
This patch addresses this problem by restoring the use of the task's
objective credentials in those cases where the task is other than the
current executing task. Not only does this resolve the problem
reported by Jann, it is arguably the correct thing to do in these
cases.
Cc: stable@vger.kernel.org
Fixes: eb1231f73c4d ("selinux: clarify task subjective and objective credentials")
Fixes: 1fb057dcde11 ("smack: differentiate between subjective and objective task credentials")
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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This patch implements two new io_uring access controls, specifically
support for controlling the io_uring "personalities" and
IORING_SETUP_SQPOLL. Controlling the sharing of io_urings themselves
is handled via the normal file/inode labeling and sharing mechanisms.
The io_uring { override_creds } permission restricts which domains
the subject domain can use to override it's own credentials.
Granting a domain the io_uring { override_creds } permission allows
it to impersonate another domain in io_uring operations.
The io_uring { sqpoll } permission restricts which domains can create
asynchronous io_uring polling threads. This is important from a
security perspective as operations queued by this asynchronous thread
inherit the credentials of the thread creator by default; if an
io_uring is shared across process/domain boundaries this could result
in one domain impersonating another. Controlling the creation of
sqpoll threads, and the sharing of io_urings across processes, allow
policy authors to restrict the ability of one domain to impersonate
another via io_uring.
As a quick summary, this patch adds a new object class with two
permissions:
io_uring { override_creds sqpoll }
These permissions can be seen in the two simple policy statements
below:
allow domA_t domB_t : io_uring { override_creds };
allow domA_t self : io_uring { sqpoll };
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- Enable memcg accounting for various networking objects.
BPF:
- Introduce bpf timers.
- Add perf link and opaque bpf_cookie which the program can read out
again, to be used in libbpf-based USDT library.
- Add bpf_task_pt_regs() helper to access user space pt_regs in
kprobes, to help user space stack unwinding.
- Add support for UNIX sockets for BPF sockmap.
- Extend BPF iterator support for UNIX domain sockets.
- Allow BPF TCP congestion control progs and bpf iterators to call
bpf_setsockopt(), e.g. to switch to another congestion control
algorithm.
Protocols:
- Support IOAM Pre-allocated Trace with IPv6.
- Support Management Component Transport Protocol.
- bridge: multicast: add vlan support.
- netfilter: add hooks for the SRv6 lightweight tunnel driver.
- tcp:
- enable mid-stream window clamping (by user space or BPF)
- allow data-less, empty-cookie SYN with TFO_SERVER_COOKIE_NOT_REQD
- more accurate DSACK processing for RACK-TLP
- mptcp:
- add full mesh path manager option
- add partial support for MP_FAIL
- improve use of backup subflows
- optimize option processing
- af_unix: add OOB notification support.
- ipv6: add IFLA_INET6_RA_MTU to expose MTU value advertised by the
router.
- mac80211: Target Wake Time support in AP mode.
- can: j1939: extend UAPI to notify about RX status.
Driver APIs:
- Add page frag support in page pool API.
- Many improvements to the DSA (distributed switch) APIs.
- ethtool: extend IRQ coalesce uAPI with timer reset modes.
- devlink: control which auxiliary devices are created.
- Support CAN PHYs via the generic PHY subsystem.
- Proper cross-chip support for tag_8021q.
- Allow TX forwarding for the software bridge data path to be
offloaded to capable devices.
Drivers:
- veth: more flexible channels number configuration.
- openvswitch: introduce per-cpu upcall dispatch.
- Add internet mix (IMIX) mode to pktgen.
- Transparently handle XDP operations in the bonding driver.
- Add LiteETH network driver.
- Renesas (ravb):
- support Gigabit Ethernet IP
- NXP Ethernet switch (sja1105):
- fast aging support
- support for "H" switch topologies
- traffic termination for ports under VLAN-aware bridge
- Intel 1G Ethernet
- support getcrosststamp() with PCIe PTM (Precision Time
Measurement) for better time sync
- support Credit-Based Shaper (CBS) offload, enabling HW traffic
prioritization and bandwidth reservation
- Broadcom Ethernet (bnxt)
- support pulse-per-second output
- support larger Rx rings
- Mellanox Ethernet (mlx5)
- support ethtool RSS contexts and MQPRIO channel mode
- support LAG offload with bridging
- support devlink rate limit API
- support packet sampling on tunnels
- Huawei Ethernet (hns3):
- basic devlink support
- add extended IRQ coalescing support
- report extended link state
- Netronome Ethernet (nfp):
- add conntrack offload support
- Broadcom WiFi (brcmfmac):
- add WPA3 Personal with FT to supported cipher suites
- support 43752 SDIO device
- Intel WiFi (iwlwifi):
- support scanning hidden 6GHz networks
- support for a new hardware family (Bz)
- Xen pv driver:
- harden netfront against malicious backends
- Qualcomm mobile
- ipa: refactor power management and enable automatic suspend
- mhi: move MBIM to WWAN subsystem interfaces
Refactor:
- Ambient BPF run context and cgroup storage cleanup.
- Compat rework for ndo_ioctl.
Old code removal:
- prism54 remove the obsoleted driver, deprecated by the p54 driver.
- wan: remove sbni/granch driver"
* tag 'net-next-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1715 commits)
net: Add depends on OF_NET for LiteX's LiteETH
ipv6: seg6: remove duplicated include
net: hns3: remove unnecessary spaces
net: hns3: add some required spaces
net: hns3: clean up a type mismatch warning
net: hns3: refine function hns3_set_default_feature()
ipv6: remove duplicated 'net/lwtunnel.h' include
net: w5100: check return value after calling platform_get_resource()
net/mlxbf_gige: Make use of devm_platform_ioremap_resourcexxx()
net: mdio: mscc-miim: Make use of the helper function devm_platform_ioremap_resource()
net: mdio-ipq4019: Make use of devm_platform_ioremap_resource()
fou: remove sparse errors
ipv4: fix endianness issue in inet_rtm_getroute_build_skb()
octeontx2-af: Set proper errorcode for IPv4 checksum errors
octeontx2-af: Fix static code analyzer reported issues
octeontx2-af: Fix mailbox errors in nix_rss_flowkey_cfg
octeontx2-af: Fix loop in free and unmap counter
af_unix: fix potential NULL deref in unix_dgram_connect()
dpaa2-eth: Replace strlcpy with strscpy
octeontx2-af: Use NDC TX for transmit packet data
...
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Add basic Kconfig, an initial (empty) af_mctp source object, and
{AF,PF}_MCTP definitions, and the required definitions for a new
protocol type.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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audit_log_start() may return NULL in below cases:
- when audit is not initialized.
- when audit backlog limit exceeds.
After the call to audit_log_start() is made and then possible NULL audit
buffer argument is passed to audit_log_*() functions,
audit_log_*() functions return immediately in case of a NULL audit buffer
argument.
But it is optimal to return early when audit_log_start() returns NULL,
because it is not necessary for audit_log_*() functions to be called with
NULL audit buffer argument.
So add exception handling for possible NULL audit buffers where
return value can be handled from callers.
Signed-off-by: Austin Kim <austin.kim@lge.com>
[PM: tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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|
... along with avc_has_perm_flags() itself, since now it's identical
to avc_has_perm() (as pointed out by Paul Moore)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[PM: add "selinux:" prefix to subj and tweak for length]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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dump_common_audit_data() is safe to use under rcu_read_lock() now;
no need for AVC_NONBLOCKING and games around it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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While trying to address a Coverity warning that the dev_name string
might end up unterminated when strcpy'ing it in
selinux_ib_endport_manage_subnet(), I realized that it is possible (and
simpler) to just pass the dev_name pointer directly, rather than copying
the string to a buffer.
The ibendport variable goes out of scope at the end of the function
anyway, so the lifetime of the dev_name pointer will never be shorter
than that of ibendport, thus we can safely just pass the dev_name
pointer and be done with it.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull Landlock LSM from James Morris:
"Add Landlock, a new LSM from Mickaël Salaün.
Briefly, Landlock provides for unprivileged application sandboxing.
From Mickaël's cover letter:
"The goal of Landlock is to enable to restrict ambient rights (e.g.
global filesystem access) for a set of processes. Because Landlock
is a stackable LSM [1], it makes possible to create safe security
sandboxes as new security layers in addition to the existing
system-wide access-controls. This kind of sandbox is expected to
help mitigate the security impact of bugs or unexpected/malicious
behaviors in user-space applications. Landlock empowers any
process, including unprivileged ones, to securely restrict
themselves.
Landlock is inspired by seccomp-bpf but instead of filtering
syscalls and their raw arguments, a Landlock rule can restrict the
use of kernel objects like file hierarchies, according to the
kernel semantic. Landlock also takes inspiration from other OS
sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
Pledge/Unveil.
In this current form, Landlock misses some access-control features.
This enables to minimize this patch series and ease review. This
series still addresses multiple use cases, especially with the
combined use of seccomp-bpf: applications with built-in sandboxing,
init systems, security sandbox tools and security-oriented APIs [2]"
The cover letter and v34 posting is here:
https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/
See also:
https://landlock.io/
This code has had extensive design discussion and review over several
years"
Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]
* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
landlock: Enable user space to infer supported features
landlock: Add user and kernel documentation
samples/landlock: Add a sandbox manager example
selftests/landlock: Add user space tests
landlock: Add syscall implementations
arch: Wire up Landlock syscalls
fs,security: Add sb_delete hook
landlock: Support filesystem access-control
LSM: Infrastructure management of the superblock
landlock: Add ptrace restrictions
landlock: Set up the security framework and manage credentials
landlock: Add ruleset and domain management
landlock: Add object management
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Move management of the superblock->sb_security blob out of the
individual security modules and into the security infrastructure.
Instead of allocating the blobs from within the modules, the modules
tell the infrastructure how much space is required, and the space is
allocated there.
Cc: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-6-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
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SELinux has a function, task_sid(), which returns the task's
objective credentials, but unfortunately is used in a few places
where the subjective task credentials should be used. Most notably
in the new security_task_getsecid_subj() LSM hook.
This patch fixes this and attempts to make things more obvious by
introducing a new function, task_sid_subj(), and renaming the
existing task_sid() function to task_sid_obj().
This patch also adds an interesting function in task_sid_binder().
The task_sid_binder() function has a comment which hopefully
describes it's reason for being, but it basically boils down to the
simple fact that we can't safely access another task's subjective
credentials so in the case of binder we need to stick with the
objective credentials regardless.
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Of the three LSMs that implement the security_task_getsecid() LSM
hook, all three LSMs provide the task's objective security
credentials. This turns out to be unfortunate as most of the hook's
callers seem to expect the task's subjective credentials, although
a small handful of callers do correctly expect the objective
credentials.
This patch is the first step towards fixing the problem: it splits
the existing security_task_getsecid() hook into two variants, one
for the subjective creds, one for the objective creds.
void security_task_getsecid_subj(struct task_struct *p,
u32 *secid);
void security_task_getsecid_obj(struct task_struct *p,
u32 *secid);
While this patch does fix all of the callers to use the correct
variant, in order to keep this patch focused on the callers and to
ease review, the LSMs continue to use the same implementation for
both hooks. The net effect is that this patch should not change
the behavior of the kernel in any way, it will be up to the latter
LSM specific patches in this series to change the hook
implementations and return the correct credentials.
Acked-by: Mimi Zohar <zohar@linux.ibm.com> (IMA)
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Add a new hook that takes an existing super block and a new mount
with new options and determines if new options confict with an
existing mount or not.
A filesystem can use this new hook to determine if it can share
the an existing superblock with a new superblock for the new mount.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
[PM: tweak the subject line, fix tab/space problems]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Now overlayfs allow unpriviliged mounts. That is root inside a non-init
user namespace can mount overlayfs. This is being added in 5.11 kernel.
Giuseppe tried to mount overlayfs with option "context" and it failed
with error -EACCESS.
$ su test
$ unshare -rm
$ mkdir -p lower upper work merged
$ mount -t overlay -o lowerdir=lower,workdir=work,upperdir=upper,userxattr,context='system_u:object_r:container_file_t:s0' none merged
This fails with -EACCESS. It works if option "-o context" is not specified.
Little debugging showed that selinux_set_mnt_opts() returns -EACCESS.
So this patch adds "overlay" to the list, where it is fine to specific
context from non init_user_ns.
Reported-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
[PM: trimmed the changelog from the description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
https://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
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