user/sven/linux.git/arch/powerpc/include, branch v4.9.254

powerpc: Fix incorrect stw{, ux, u, x} instructions in __set_pte_at

2021-01-17T12:57:53Z

[ Upstream commit d85be8a49e733dcd23674aa6202870d54bf5600d ] The placeholder for instruction selection should use the second argument's operand, which is %1, not %0. This could generate incorrect assembly code if the memory addressing of operand %0 is a different form from that of operand %1. Also remove the %Un placeholder because having %Un placeholders for two operands which are based on the same local var (ptep) doesn't make much sense. By the way, it doesn't change the current behaviour because "<>" constraint is missing for the associated "=m". [chleroy: revised commit log iaw segher's comments and removed %U0] Fixes: 9bf2b5cdc5fe ("powerpc: Fixes for CONFIG_PTE_64BIT for SMP support") Cc: # v2.6.28+ Signed-off-by: Mathieu Desnoyers Signed-off-by: Christophe Leroy Acked-by: Segher Boessenkool Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/96354bd77977a6a933fe9020da57629007fdb920.1603358942.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin

powerpc/feature: Fix CPU_FTRS_ALWAYS by removing CPU_FTRS_GENERIC_32

2020-12-29T12:44:55Z

[ Upstream commit 78665179e569c7e1fe102fb6c21d0f5b6951f084 ] On 8xx, we get the following features: [ 0.000000] cpu_features = 0x0000000000000100 [ 0.000000] possible = 0x0000000000000120 [ 0.000000] always = 0x0000000000000000 This is not correct. As CONFIG_PPC_8xx is mutually exclusive with all other configurations, the three lines should be equal. The problem is due to CPU_FTRS_GENERIC_32 which is taken when CONFIG_BOOK3S_32 is NOT selected. This CPU_FTRS_GENERIC_32 is pointless because there is no generic configuration supporting all 32 bits but book3s/32. Remove this pointless generic features definition to unbreak the calculation of 'possible' features and 'always' features. Fixes: 76bc080ef5a3 ("[POWERPC] Make default cputable entries reflect selected CPU family") Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/76a85f30bf981d1aeaae00df99321235494da254.1604426550.git.christophe.leroy@csgroup.eu Signed-off-by: Sasha Levin

powerpc/uaccess-flush: fix missing includes in kup-radix.h

2020-11-24T12:03:05Z

Guenter reports a build failure on cell_defconfig and maple_defconfg: In file included from arch/powerpc/include/asm/kup.h:10:0, from arch/powerpc/include/asm/uaccess.h:12, from arch/powerpc/lib/checksum_wrappers.c:24: arch/powerpc/include/asm/book3s/64/kup-radix.h:5:1: error: data definition has no type or storage class [-Werror] DECLARE_STATIC_KEY_FALSE(uaccess_flush_key); ^~~~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/book3s/64/kup-radix.h:5:1: error: type defaults to ‘int’ in declaration of ‘DECLARE_STATIC_KEY_FALSE’ [-Werror=implicit-int] arch/powerpc/include/asm/book3s/64/kup-radix.h:5:1: error: parameter names (without types) in function declaration [-Werror] arch/powerpc/include/asm/book3s/64/kup-radix.h: In function ‘prevent_user_access’: arch/powerpc/include/asm/book3s/64/kup-radix.h:18:6: error: implicit declaration of function ‘static_branch_unlikely’ [-Werror=implicit-function-declaration] if (static_branch_unlikely(&uaccess_flush_key)) ^~~~~~~~~~~~~~~~~~~~~~ arch/powerpc/include/asm/book3s/64/kup-radix.h:18:30: error: ‘uaccess_flush_key’ undeclared (first use in this function); did you mean ‘do_uaccess_flush’? if (static_branch_unlikely(&uaccess_flush_key)) ^~~~~~~~~~~~~~~~~ do_uaccess_flush arch/powerpc/include/asm/book3s/64/kup-radix.h:18:30: note: each undeclared identifier is reported only once for each function it appears in cc1: all warnings being treated as errors This is because I failed to include linux/jump_label.h in kup-radix.h. Include it. Reported-by: Guenter Roeck Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/64s: flush L1D after user accesses

2020-11-22T08:58:14Z

commit 9a32a7e78bd0cd9a9b6332cbdc345ee5ffd0c5de upstream. IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache after user accesses. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/uaccess: Evaluate macro arguments once, before user access is allowed

2020-11-22T08:58:13Z

commit d02f6b7dab8228487268298ea1f21081c0b4b3eb upstream. get/put_user() can be called with nontrivial arguments. fs/proc/page.c has a good example: if (put_user(stable_page_flags(ppage), out)) { stable_page_flags() is quite a lot of code, including spin locks in the page allocator. Ensure these arguments are evaluated before user access is allowed. This improves security by reducing code with access to userspace, but it also fixes a PREEMPT bug with KUAP on powerpc/64s: stable_page_flags() is currently called with AMR set to allow writes, it ends up calling spin_unlock(), which can call preempt_schedule. But the task switch code can not be called with AMR set (it relies on interrupts saving the register), so this blows up. It's fine if the code inside allow_user_access() is preemptible, because a timer or IPI will save the AMR, but it's not okay to explicitly cause a reschedule. Fixes: de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200407041245.600651-1-npiggin@gmail.com Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc: Fix __clear_user() with KUAP enabled

2020-11-22T08:58:13Z

commit 61e3acd8c693a14fc69b824cb5b08d02cb90a6e7 upstream. The KUAP implementation adds calls in clear_user() to enable and disable access to userspace memory. However, it doesn't add these to __clear_user(), which is used in the ptrace regset code. As there's only one direct user of __clear_user() (the regset code), and the time taken to set the AMR for KUAP purposes is going to dominate the cost of a quick access_ok(), there's not much point having a separate path. Rename __clear_user() to __arch_clear_user(), and make __clear_user() just call clear_user(). Reported-by: syzbot+f25ecf4b2982d8c7a640@syzkaller-ppc64.appspotmail.com Reported-by: Daniel Axtens Suggested-by: Michael Ellerman Fixes: de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection") Signed-off-by: Andrew Donnellan [mpe: Use __arch_clear_user() for the asm version like arm64 & nds32] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191209132221.15328-1-ajd@linux.ibm.com Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc: Implement user_access_begin and friends

2020-11-22T08:58:13Z

commit 5cd623333e7cf4e3a334c70529268b65f2a6c2c7 upstream. Today, when a function like strncpy_from_user() is called, the userspace access protection is de-activated and re-activated for every word read. By implementing user_access_begin and friends, the protection is de-activated at the beginning of the copy and re-activated at the end. Implement user_access_begin(), user_access_end() and unsafe_get_user(), unsafe_put_user() and unsafe_copy_to_user() For the time being, we keep user_access_save() and user_access_restore() as nops. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/36d4fbf9e56a75994aca4ee2214c77b26a5a8d35.1579866752.git.christophe.leroy@c-s.fr Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc: Add a framework for user access tracking

2020-11-22T08:58:13Z

Backported from commit de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection"). Here we don't try to add the KUAP framework, we just want the helper functions because we want to put uaccess flush helpers in them. In terms of fixes, we don't need commit 1d8f739b07bd ("powerpc/kuap: Fix set direction in allow/prevent_user_access()") as we don't have real KUAP. Likewise as all our allows are noops and all our prevents are just flushes, we don't need commit 9dc086f1e9ef ("powerpc/futex: Fix incorrect user access blocking") The other 2 fixes we do need. The original description is: This patch implements a framework for Kernel Userspace Access Protection. Then subarches will have the possibility to provide their own implementation by providing setup_kuap() and allow/prevent_user_access(). Some platforms will need to know the area accessed and whether it is accessed from read, write or both. Therefore source, destination and size and handed over to the two functions. mpe: Rename to allow/prevent rather than unlock/lock, and add read/write wrappers. Drop the 32-bit code for now until we have an implementation for it. Add kuap to pt_regs for 64-bit as well as 32-bit. Don't split strings, use pr_crit_ratelimited(). Signed-off-by: Christophe Leroy Signed-off-by: Russell Currey Signed-off-by: Michael Ellerman Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/64s: flush L1D on kernel entry

2020-11-22T08:58:13Z

commit f79643787e0a0762d2409b7b8334e83f22d85695 upstream. IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache on kernel entry. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/64s: Define MASKABLE_RELON_EXCEPTION_PSERIES_OOL

2020-11-22T08:58:13Z

Commit da2bc4644c75 ("powerpc/64s: Add new exception vector macros") adds: +#define __TRAMP_REAL_VIRT_OOL_MASKABLE(name, realvec) \ + TRAMP_REAL_BEGIN(tramp_virt_##name); \ + MASKABLE_RELON_EXCEPTION_PSERIES_OOL(realvec, name##_common); \ However there's no reference there or anywhere else to MASKABLE_RELON_EXCEPTION_PSERIES_OOL and an attempt to use it unsurprisingly doesn't work. Add a definition provided by mpe. Fixes: da2bc4644c75 ("powerpc/64s: Add new exception vector macros") Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman