kernel/linux.git/security, branch v5.10.30

selinux: fix race between old and new sidtab

2021-04-14T06:41:57+00:00

commit 9ad6e9cb39c66366bf7b9aece114aca277981a1f upstream. Since commit 1b8b31a2e612 ("selinux: convert policy read-write lock to RCU"), there is a small window during policy load where the new policy pointer has already been installed, but some threads may still be holding the old policy pointer in their read-side RCU critical sections. This means that there may be conflicting attempts to add a new SID entry to both tables via sidtab_context_to_sid(). See also (and the rest of the thread): https://lore.kernel.org/selinux/CAFqZXNvfux46_f8gnvVvRYMKoes24nwm2n3sPbMjrB8vKTW00g@mail.gmail.com/ Fix this by installing the new policy pointer under the old sidtab's spinlock along with marking the old sidtab as "frozen". Then, if an attempt to add new entry to a "frozen" sidtab is detected, make sidtab_context_to_sid() return -ESTALE to indicate that a new policy has been installed and that the caller will have to abort the policy transaction and try again after re-taking the policy pointer (which is guaranteed to be a newer policy). This requires adding a retry-on-ESTALE logic to all callers of sidtab_context_to_sid(), but fortunately these are easy to determine and aren't that many. This seems to be the simplest solution for this problem, even if it looks somewhat ugly. Note that other places in the kernel (e.g. do_mknodat() in fs/namei.c) use similar stale-retry patterns, so I think it's reasonable. Cc: stable@vger.kernel.org Fixes: 1b8b31a2e612 ("selinux: convert policy read-write lock to RCU") Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

selinux: fix cond_list corruption when changing booleans

2021-04-14T06:41:57+00:00

commit d8f5f0ea5b86300390b026b6c6e7836b7150814a upstream. Currently, duplicate_policydb_cond_list() first copies the whole conditional avtab and then tries to link to the correct entries in cond_dup_av_list() using avtab_search(). However, since the conditional avtab may contain multiple entries with the same key, this approach often fails to find the right entry, potentially leading to wrong rules being activated/deactivated when booleans are changed. To fix this, instead start with an empty conditional avtab and add the individual entries one-by-one while building the new av_lists. This approach leads to the correct result, since each entry is present in the av_lists exactly once. The issue can be reproduced with Fedora policy as follows: # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True # setsebool ftpd_anon_write=off ftpd_connect_all_unreserved=off ftpd_connect_db=off ftpd_full_access=off On fixed kernels, the sesearch output is the same after the setsebool command: # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True allow ftpd_t public_content_rw_t:dir { add_name create link remove_name rename reparent rmdir setattr unlink watch watch_reads write }; [ ftpd_anon_write ]:True While on the broken kernels, it will be different: # sesearch -s ftpd_t -t public_content_rw_t -c dir -p create -A allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True allow ftpd_t non_security_file_type:dir { add_name create getattr ioctl link lock open read remove_name rename reparent rmdir search setattr unlink watch watch_reads write }; [ ftpd_full_access ]:True While there, also simplify the computation of nslots. This changes the nslots values for nrules 2 or 3 to just two slots instead of 4, which makes the sequence more consistent. Cc: stable@vger.kernel.org Fixes: c7c556f1e81b ("selinux: refactor changing booleans") Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

selinux: make nslot handling in avtab more robust

2021-04-14T06:41:57+00:00

commit 442dc00f82a9727dc0c48c44f792c168f593c6df upstream. 1. Make sure all fileds are initialized in avtab_init(). 2. Slightly refactor avtab_alloc() to use the above fact. 3. Use h->nslot == 0 as a sentinel in the access functions to prevent dereferencing h->htable when it's not allocated. Cc: stable@vger.kernel.org Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

integrity: double check iint_cache was initialized

2021-03-30T12:31:55+00:00

commit 92063f3ca73aab794bd5408d3361fd5b5ea33079 upstream. The kernel may be built with multiple LSMs, but only a subset may be enabled on the boot command line by specifying "lsm=". Not including "integrity" on the ordered LSM list may result in a NULL deref. As reported by Dmitry Vyukov: in qemu: qemu-system-x86_64 -enable-kvm -machine q35,nvdimm -cpu max,migratable=off -smp 4 -m 4G,slots=4,maxmem=16G -hda wheezy.img -kernel arch/x86/boot/bzImage -nographic -vga std -soundhw all -usb -usbdevice tablet -bt hci -bt device:keyboard -net user,host=10.0.2.10,hostfwd=tcp::10022-:22 -net nic,model=virtio-net-pci -object memory-backend-file,id=pmem1,share=off,mem-path=/dev/zero,size=64M -device nvdimm,id=nvdimm1,memdev=pmem1 -append "console=ttyS0 root=/dev/sda earlyprintk=serial rodata=n oops=panic panic_on_warn=1 panic=86400 lsm=smack numa=fake=2 nopcid dummy_hcd.num=8" -pidfile vm_pid -m 2G -cpu host But it crashes on NULL deref in integrity_inode_get during boot: Run /sbin/init as init process BUG: kernel NULL pointer dereference, address: 000000000000001c PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc2+ #97 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-44-g88ab0c15525c-prebuilt.qemu.org 04/01/2014 RIP: 0010:kmem_cache_alloc+0x2b/0x370 mm/slub.c:2920 Code: 57 41 56 41 55 41 54 41 89 f4 55 48 89 fd 53 48 83 ec 10 44 8b 3d d9 1f 90 0b 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 31 c0 <8b> 5f 1c 4cf RSP: 0000:ffffc9000032f9d8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888017fc4f00 RCX: 0000000000000000 RDX: ffff888040220000 RSI: 0000000000000c40 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffff888019263627 R10: ffffffff83937cd1 R11: 0000000000000000 R12: 0000000000000c40 R13: ffff888019263538 R14: 0000000000000000 R15: 0000000000ffffff FS: 0000000000000000(0000) GS:ffff88802d180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000001c CR3: 000000000b48e000 CR4: 0000000000750ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: integrity_inode_get+0x47/0x260 security/integrity/iint.c:105 process_measurement+0x33d/0x17e0 security/integrity/ima/ima_main.c:237 ima_bprm_check+0xde/0x210 security/integrity/ima/ima_main.c:474 security_bprm_check+0x7d/0xa0 security/security.c:845 search_binary_handler fs/exec.c:1708 [inline] exec_binprm fs/exec.c:1761 [inline] bprm_execve fs/exec.c:1830 [inline] bprm_execve+0x764/0x19a0 fs/exec.c:1792 kernel_execve+0x370/0x460 fs/exec.c:1973 try_to_run_init_process+0x14/0x4e init/main.c:1366 kernel_init+0x11d/0x1b8 init/main.c:1477 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Modules linked in: CR2: 000000000000001c ---[ end trace 22d601a500de7d79 ]--- Since LSMs and IMA may be configured at build time, but not enabled at run time, panic the system if "integrity" was not initialized before use. Reported-by: Dmitry Vyukov Fixes: 79f7865d844c ("LSM: Introduce "lsm=" for boottime LSM selection") Cc: stable@vger.kernel.org Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

selinux: fix variable scope issue in live sidtab conversion

2021-03-30T12:31:53+00:00

commit 6406887a12ee5dcdaffff1a8508d91113d545559 upstream. Commit 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") moved the selinux_policy_commit() call out of security_load_policy() into sel_write_load(), which caused a subtle yet rather serious bug. The problem is that security_load_policy() passes a reference to the convert_params local variable to sidtab_convert(), which stores it in the sidtab, where it may be accessed until the policy is swapped over and RCU synchronized. Before 02a52c5c8c3b, selinux_policy_commit() was called directly from security_load_policy(), so the convert_params pointer remained valid all the way until the old sidtab was destroyed, but now that's no longer the case and calls to sidtab_context_to_sid() on the old sidtab after security_load_policy() returns may cause invalid memory accesses. This can be easily triggered using the stress test from commit ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance"): ``` function rand_cat() { echo $(( $RANDOM % 1024 )) } function do_work() { while true; do echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \ >/sys/fs/selinux/context 2>/dev/null || true done } do_work >/dev/null & do_work >/dev/null & do_work >/dev/null & while load_policy; do echo -n .; sleep 0.1; done kill %1 kill %2 kill %3 ``` Fix this by allocating the temporary sidtab convert structures dynamically and passing them among the selinux_policy_{load,cancel,commit} functions. Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") Cc: stable@vger.kernel.org Tested-by: Tyler Hicks Reviewed-by: Tyler Hicks Signed-off-by: Ondrej Mosnacek [PM: merge fuzz in security.h and services.c] Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

selinux: don't log MAC_POLICY_LOAD record on failed policy load

2021-03-30T12:31:53+00:00

commit 519dad3bcd809dc1523bf80ab0310ddb3bf00ade upstream. If sel_make_policy_nodes() fails, we should jump to 'out', not 'out1', as the latter would incorrectly log an MAC_POLICY_LOAD audit record, even though the policy hasn't actually been reloaded. The 'out1' jump label now becomes unused and can be removed. Fixes: 02a52c5c8c3b ("selinux: move policy commit after updating selinuxfs") Cc: stable@vger.kernel.org Signed-off-by: Ondrej Mosnacek Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman

Revert 95ebabde382c ("capabilities: Don't allow writing ambiguous v3 file capabilities")

2021-03-17T16:06:27+00:00

commit 3b0c2d3eaa83da259d7726192cf55a137769012f upstream. It turns out that there are in fact userspace implementations that care and this recent change caused a regression. https://github.com/containers/buildah/issues/3071 As the motivation for the original change was future development, and the impact is existing real world code just revert this change and allow the ambiguity in v3 file caps. Cc: stable@vger.kernel.org Fixes: 95ebabde382c ("capabilities: Don't allow writing ambiguous v3 file capabilities") Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

tomoyo: recognize kernel threads correctly

2021-03-09T10:11:15+00:00

commit 9c83465f3245c2faa82ffeb7016f40f02bfaa0ad upstream. Commit db68ce10c4f0a27c ("new helper: uaccess_kernel()") replaced segment_eq(get_fs(), KERNEL_DS) with uaccess_kernel(). But the correct method for tomoyo to check whether current is a kernel thread in order to assume that kernel threads are privileged for socket operations was (current->flags & PF_KTHREAD). Now that uaccess_kernel() became 0 on x86, tomoyo has to fix this problem. Do like commit 942cb357ae7d9249 ("Smack: Handle io_uring kernel thread privileges") does. Signed-off-by: Tetsuo Handa Signed-off-by: Greg Kroah-Hartman

tomoyo: ignore data race while checking quota

2021-03-07T11:34:05+00:00

commit 5797e861e402fff2bedce4ec8b7c89f4248b6073 upstream. syzbot is reporting that tomoyo's quota check is racy [1]. But this check is tolerant of some degree of inaccuracy. Thus, teach KCSAN to ignore this data race. [1] https://syzkaller.appspot.com/bug?id=999533deec7ba6337f8aa25d8bd1a4d5f7e50476 Reported-by: syzbot Signed-off-by: Tetsuo Handa Signed-off-by: Greg Kroah-Hartman

smackfs: restrict bytes count in smackfs write functions

2021-03-07T11:34:05+00:00

commit 7ef4c19d245f3dc233fd4be5acea436edd1d83d8 upstream. syzbot found WARNINGs in several smackfs write operations where bytes count is passed to memdup_user_nul which exceeds GFP MAX_ORDER. Check count size if bigger than PAGE_SIZE. Per smackfs doc, smk_write_net4addr accepts any label or -CIPSO, smk_write_net6addr accepts any label or -DELETE. I couldn't find any general rule for other label lengths except SMK_LABELLEN, SMK_LONGLABEL, SMK_CIPSOMAX which are documented. Let's constrain, in general, smackfs label lengths for PAGE_SIZE. Although fuzzer crashes write to smackfs/netlabel on 0x400000 length. Here is a quick way to reproduce the WARNING: python -c "print('A' * 0x400000)" > /sys/fs/smackfs/netlabel Reported-by: syzbot+a71a442385a0b2815497@syzkaller.appspotmail.com Signed-off-by: Sabyrzhan Tasbolatov Signed-off-by: Casey Schaufler Signed-off-by: Greg Kroah-Hartman