kernel/linux.git, branch v4.19.204

Linux 4.19.204

2021-08-15T11:05:05+00:00

Link: https://lore.kernel.org/r/20210813150520.072304554@linuxfoundation.org Tested-by: Shuah Khan Tested-by: Sudip Mukherjee Tested-by: Linux Kernel Functional Testing Tested-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

net: xilinx_emaclite: Do not print real IOMEM pointer

2021-08-15T11:05:05+00:00

commit d0d62baa7f505bd4c59cd169692ff07ec49dde37 upstream. Printing kernel pointers is discouraged because they might leak kernel memory layout. This fixes smatch warning: drivers/net/ethernet/xilinx/xilinx_emaclite.c:1191 xemaclite_of_probe() warn: argument 4 to %08lX specifier is cast from pointer Signed-off-by: YueHaibing Signed-off-by: David S. Miller Signed-off-by: Pavel Machek (CIP) Signed-off-by: Greg Kroah-Hartman

ovl: prevent private clone if bind mount is not allowed

2021-08-15T11:05:05+00:00

commit 427215d85e8d1476da1a86b8d67aceb485eb3631 upstream. Add the following checks from __do_loopback() to clone_private_mount() as well: - verify that the mount is in the current namespace - verify that there are no locked children Reported-by: Alois Wohlschlager Fixes: c771d683a62e ("vfs: introduce clone_private_mount()") Cc: # v3.18 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ppp: Fix generating ppp unit id when ifname is not specified

2021-08-15T11:05:05+00:00

commit 3125f26c514826077f2a4490b75e9b1c7a644c42 upstream. When registering new ppp interface via PPPIOCNEWUNIT ioctl then kernel has to choose interface name as this ioctl API does not support specifying it. Kernel in this case register new interface with name "ppp" where is the ppp unit id, which can be obtained via PPPIOCGUNIT ioctl. This applies also in the case when registering new ppp interface via rtnl without supplying IFLA_IFNAME. PPPIOCNEWUNIT ioctl allows to specify own ppp unit id which will kernel assign to ppp interface, in case this ppp id is not already used by other ppp interface. In case user does not specify ppp unit id then kernel choose the first free ppp unit id. This applies also for case when creating ppp interface via rtnl method as it does not provide a way for specifying own ppp unit id. If some network interface (does not have to be ppp) has name "ppp" with this first free ppp id then PPPIOCNEWUNIT ioctl or rtnl call fails. And registering new ppp interface is not possible anymore, until interface which holds conflicting name is renamed. Or when using rtnl method with custom interface name in IFLA_IFNAME. As list of allocated / used ppp unit ids is not possible to retrieve from kernel to userspace, userspace has no idea what happens nor which interface is doing this conflict. So change the algorithm how ppp unit id is generated. And choose the first number which is not neither used as ppp unit id nor in some network interface with pattern "ppp". This issue can be simply reproduced by following pppd call when there is no ppp interface registered and also no interface with name pattern "ppp": pppd ifname ppp1 +ipv6 noip noauth nolock local nodetach pty "pppd +ipv6 noip noauth nolock local nodetach notty" Or by creating the one ppp interface (which gets assigned ppp unit id 0), renaming it to "ppp1" and then trying to create a new ppp interface (which will always fails as next free ppp unit id is 1, but network interface with name "ppp1" exists). This patch fixes above described issue by generating new and new ppp unit id until some non-conflicting id with network interfaces is generated. Signed-off-by: Pali Rohár Cc: stable@vger.kernel.org Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

USB:ehci:fix Kunpeng920 ehci hardware problem

2021-08-15T11:05:04+00:00

commit 26b75952ca0b8b4b3050adb9582c8e2f44d49687 upstream. Kunpeng920's EHCI controller does not have SBRN register. Reading the SBRN register when the controller driver is initialized will get 0. When rebooting the EHCI driver, ehci_shutdown() will be called. if the sbrn flag is 0, ehci_shutdown() will return directly. The sbrn flag being 0 will cause the EHCI interrupt signal to not be turned off after reboot. this interrupt that is not closed will cause an exception to the device sharing the interrupt. Therefore, the EHCI controller of Kunpeng920 needs to skip the read operation of the SBRN register. Acked-by: Alan Stern Signed-off-by: Longfang Liu Link: https://lore.kernel.org/r/1617958081-17999-1-git-send-email-liulongfang@huawei.com Signed-off-by: Greg Kroah-Hartman

KVM: X86: MMU: Use the correct inherited permissions to get shadow page

2021-08-15T11:05:04+00:00

commit b1bd5cba3306691c771d558e94baa73e8b0b96b7 upstream. When computing the access permissions of a shadow page, use the effective permissions of the walk up to that point, i.e. the logic AND of its parents' permissions. Two guest PxE entries that point at the same table gfn need to be shadowed with different shadow pages if their parents' permissions are different. KVM currently uses the effective permissions of the last non-leaf entry for all non-leaf entries. Because all non-leaf SPTEs have full ("uwx") permissions, and the effective permissions are recorded only in role.access and merged into the leaves, this can lead to incorrect reuse of a shadow page and eventually to a missing guest protection page fault. For example, here is a shared pagetable: pgd[] pud[] pmd[] virtual address pointers /->pmd1(u--)->pte1(uw-)->page1 <- ptr1 (u--) /->pud1(uw-)--->pmd2(uw-)->pte2(uw-)->page2 <- ptr2 (uw-) pgd-| (shared pmd[] as above) \->pud2(u--)--->pmd1(u--)->pte1(uw-)->page1 <- ptr3 (u--) \->pmd2(uw-)->pte2(uw-)->page2 <- ptr4 (u--) pud1 and pud2 point to the same pmd table, so: - ptr1 and ptr3 points to the same page. - ptr2 and ptr4 points to the same page. (pud1 and pud2 here are pud entries, while pmd1 and pmd2 here are pmd entries) - First, the guest reads from ptr1 first and KVM prepares a shadow page table with role.access=u--, from ptr1's pud1 and ptr1's pmd1. "u--" comes from the effective permissions of pgd, pud1 and pmd1, which are stored in pt->access. "u--" is used also to get the pagetable for pud1, instead of "uw-". - Then the guest writes to ptr2 and KVM reuses pud1 which is present. The hypervisor set up a shadow page for ptr2 with pt->access is "uw-" even though the pud1 pmd (because of the incorrect argument to kvm_mmu_get_page in the previous step) has role.access="u--". - Then the guest reads from ptr3. The hypervisor reuses pud1's shadow pmd for pud2, because both use "u--" for their permissions. Thus, the shadow pmd already includes entries for both pmd1 and pmd2. - At last, the guest writes to ptr4. This causes no vmexit or pagefault, because pud1's shadow page structures included an "uw-" page even though its role.access was "u--". Any kind of shared pagetable might have the similar problem when in virtual machine without TDP enabled if the permissions are different from different ancestors. In order to fix the problem, we change pt->access to be an array, and any access in it will not include permissions ANDed from child ptes. The test code is: https://lore.kernel.org/kvm/20210603050537.19605-1-jiangshanlai@gmail.com/ Remember to test it with TDP disabled. The problem had existed long before the commit 41074d07c78b ("KVM: MMU: Fix inherited permissions for emulated guest pte updates"), and it is hard to find which is the culprit. So there is no fixes tag here. Signed-off-by: Lai Jiangshan Message-Id: <20210603052455.21023-1-jiangshanlai@gmail.com> Cc: stable@vger.kernel.org Fixes: cea0f0e7ea54 ("[PATCH] KVM: MMU: Shadow page table caching") Signed-off-by: Paolo Bonzini [OP: - apply arch/x86/kvm/mmu/* changes to arch/x86/kvm - apply documentation changes to Documentation/virtual/kvm/mmu.txt - adjusted context in arch/x86/kvm/paging_tmpl.h] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf, selftests: Adjust few selftest outcomes wrt unreachable code

2021-08-15T11:05:04+00:00

commit 973377ffe8148180b2651825b92ae91988141b05 upstream. In almost all cases from test_verifier that have been changed in here, we've had an unreachable path with a load from a register which has an invalid address on purpose. This was basically to make sure that we never walk this path and to have the verifier complain if it would otherwise. Change it to match on the right error for unprivileged given we now test these paths under speculative execution. There's one case where we match on exact # of insns_processed. Due to the extra path, this will of course mismatch on unprivileged. Thus, restrict the test->insn_processed check to privileged-only. In one other case, we result in a 'pointer comparison prohibited' error. This is similarly due to verifying an 'invalid' branch where we end up with a value pointer on one side of the comparison. Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Acked-by: Alexei Starovoitov [OP: ignore changes to tests that do not exist in 4.19] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf: Fix leakage under speculation on mispredicted branches

2021-08-15T11:05:04+00:00

commit 9183671af6dbf60a1219371d4ed73e23f43b49db upstream. The verifier only enumerates valid control-flow paths and skips paths that are unreachable in the non-speculative domain. And so it can miss issues under speculative execution on mispredicted branches. For example, a type confusion has been demonstrated with the following crafted program: // r0 = pointer to a map array entry // r6 = pointer to readable stack slot // r9 = scalar controlled by attacker 1: r0 = *(u64 *)(r0) // cache miss 2: if r0 != 0x0 goto line 4 3: r6 = r9 4: if r0 != 0x1 goto line 6 5: r9 = *(u8 *)(r6) 6: // leak r9 Since line 3 runs iff r0 == 0 and line 5 runs iff r0 == 1, the verifier concludes that the pointer dereference on line 5 is safe. But: if the attacker trains both the branches to fall-through, such that the following is speculatively executed ... r6 = r9 r9 = *(u8 *)(r6) // leak r9 ... then the program will dereference an attacker-controlled value and could leak its content under speculative execution via side-channel. This requires to mistrain the branch predictor, which can be rather tricky, because the branches are mutually exclusive. However such training can be done at congruent addresses in user space using different branches that are not mutually exclusive. That is, by training branches in user space ... A: if r0 != 0x0 goto line C B: ... C: if r0 != 0x0 goto line D D: ... ... such that addresses A and C collide to the same CPU branch prediction entries in the PHT (pattern history table) as those of the BPF program's lines 2 and 4, respectively. A non-privileged attacker could simply brute force such collisions in the PHT until observing the attack succeeding. Alternative methods to mistrain the branch predictor are also possible that avoid brute forcing the collisions in the PHT. A reliable attack has been demonstrated, for example, using the following crafted program: // r0 = pointer to a [control] map array entry // r7 = *(u64 *)(r0 + 0), training/attack phase // r8 = *(u64 *)(r0 + 8), oob address // [...] // r0 = pointer to a [data] map array entry 1: if r7 == 0x3 goto line 3 2: r8 = r0 // crafted sequence of conditional jumps to separate the conditional // branch in line 193 from the current execution flow 3: if r0 != 0x0 goto line 5 4: if r0 == 0x0 goto exit 5: if r0 != 0x0 goto line 7 6: if r0 == 0x0 goto exit [...] 187: if r0 != 0x0 goto line 189 188: if r0 == 0x0 goto exit // load any slowly-loaded value (due to cache miss in phase 3) ... 189: r3 = *(u64 *)(r0 + 0x1200) // ... and turn it into known zero for verifier, while preserving slowly- // loaded dependency when executing: 190: r3 &= 1 191: r3 &= 2 // speculatively bypassed phase dependency 192: r7 += r3 193: if r7 == 0x3 goto exit 194: r4 = *(u8 *)(r8 + 0) // leak r4 As can be seen, in training phase (phase != 0x3), the condition in line 1 turns into false and therefore r8 with the oob address is overridden with the valid map value address, which in line 194 we can read out without issues. However, in attack phase, line 2 is skipped, and due to the cache miss in line 189 where the map value is (zeroed and later) added to the phase register, the condition in line 193 takes the fall-through path due to prior branch predictor training, where under speculation, it'll load the byte at oob address r8 (unknown scalar type at that point) which could then be leaked via side-channel. One way to mitigate these is to 'branch off' an unreachable path, meaning, the current verification path keeps following the is_branch_taken() path and we push the other branch to the verification stack. Given this is unreachable from the non-speculative domain, this branch's vstate is explicitly marked as speculative. This is needed for two reasons: i) if this path is solely seen from speculative execution, then we later on still want the dead code elimination to kick in in order to sanitize these instructions with jmp-1s, and ii) to ensure that paths walked in the non-speculative domain are not pruned from earlier walks of paths walked in the speculative domain. Additionally, for robustness, we mark the registers which have been part of the conditional as unknown in the speculative path given there should be no assumptions made on their content. The fix in here mitigates type confusion attacks described earlier due to i) all code paths in the BPF program being explored and ii) existing verifier logic already ensuring that given memory access instruction references one specific data structure. An alternative to this fix that has also been looked at in this scope was to mark aux->alu_state at the jump instruction with a BPF_JMP_TAKEN state as well as direction encoding (always-goto, always-fallthrough, unknown), such that mixing of different always-* directions themselves as well as mixing of always-* with unknown directions would cause a program rejection by the verifier, e.g. programs with constructs like 'if ([...]) { x = 0; } else { x = 1; }' with subsequent 'if (x == 1) { [...] }'. For unprivileged, this would result in only single direction always-* taken paths, and unknown taken paths being allowed, such that the former could be patched from a conditional jump to an unconditional jump (ja). Compared to this approach here, it would have two downsides: i) valid programs that otherwise are not performing any pointer arithmetic, etc, would potentially be rejected/broken, and ii) we are required to turn off path pruning for unprivileged, where both can be avoided in this work through pushing the invalid branch to the verification stack. The issue was originally discovered by Adam and Ofek, and later independently discovered and reported as a result of Benedict and Piotr's research work. Fixes: b2157399cc98 ("bpf: prevent out-of-bounds speculation") Reported-by: Adam Morrison Reported-by: Ofek Kirzner Reported-by: Benedict Schlueter Reported-by: Piotr Krysiuk Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Reviewed-by: Benedict Schlueter Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov [OP: use allow_ptr_leaks instead of bypass_spec_v1] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf: Do not mark insn as seen under speculative path verification

2021-08-15T11:05:04+00:00

commit fe9a5ca7e370e613a9a75a13008a3845ea759d6e upstream. ... in such circumstances, we do not want to mark the instruction as seen given the goal is still to jmp-1 rewrite/sanitize dead code, if it is not reachable from the non-speculative path verification. We do however want to verify it for safety regardless. With the patch as-is all the insns that have been marked as seen before the patch will also be marked as seen after the patch (just with a potentially different non-zero count). An upcoming patch will also verify paths that are unreachable in the non-speculative domain, hence this extension is needed. Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Reviewed-by: Benedict Schlueter Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov [OP: - env->pass_cnt is not used in 4.19, so adjust sanitize_mark_insn_seen() to assign "true" instead - drop sanitize_insn_aux_data() comment changes, as the function is not present in 4.19] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman

bpf: Inherit expanded/patched seen count from old aux data

2021-08-15T11:05:04+00:00

commit d203b0fd863a2261e5d00b97f3d060c4c2a6db71 upstream. Instead of relying on current env->pass_cnt, use the seen count from the old aux data in adjust_insn_aux_data(), and expand it to the new range of patched instructions. This change is valid given we always expand 1:n with n>=1, so what applies to the old/original instruction needs to apply for the replacement as well. Not relying on env->pass_cnt is a prerequisite for a later change where we want to avoid marking an instruction seen when verified under speculative execution path. Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Reviewed-by: Benedict Schlueter Reviewed-by: Piotr Krysiuk Acked-by: Alexei Starovoitov [OP: - declare old_data as bool instead of u32 (struct bpf_insn_aux_data.seen is bool in 5.4) - adjusted context for 4.19] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman