wireguard-linux/arch/powerpc/include/asm/uaccess.h, branch jd/unified-crypt-queue

powerpc: Implement user_access_save() and user_access_restore()

2020-01-28T12:14:44Z

Implement user_access_save() and user_access_restore() On 8xx and radix: - On save, get the value of the associated special register then prevent user access. - On restore, set back the saved value to the associated special register. On book3s/32: - On save, get the value stored in current->thread.kuap and prevent user access. - On restore, regenerate address range from the stored value and reopen read/write access for that range. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/54f2f74938006b33c55a416674807b42ef222068.1579866752.git.christophe.leroy@c-s.fr

powerpc: Implement user_access_begin and friends

2020-01-28T12:14:44Z

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

powerpc/kuap: Fix set direction in allow/prevent_user_access()

2020-01-28T12:13:44Z

__builtin_constant_p() always return 0 for pointers, so on RADIX we always end up opening both direction (by writing 0 in SPR29): 0000000000000170 <._copy_to_user>: ... 1b0: 4c 00 01 2c isync 1b4: 39 20 00 00 li r9,0 1b8: 7d 3d 03 a6 mtspr 29,r9 1bc: 4c 00 01 2c isync 1c0: 48 00 00 01 bl 1c0 <._copy_to_user+0x50> 1c0: R_PPC64_REL24 .__copy_tofrom_user ... 0000000000000220 <._copy_from_user>: ... 2ac: 4c 00 01 2c isync 2b0: 39 20 00 00 li r9,0 2b4: 7d 3d 03 a6 mtspr 29,r9 2b8: 4c 00 01 2c isync 2bc: 7f c5 f3 78 mr r5,r30 2c0: 7f 83 e3 78 mr r3,r28 2c4: 48 00 00 01 bl 2c4 <._copy_from_user+0xa4> 2c4: R_PPC64_REL24 .__copy_tofrom_user ... Use an explicit parameter for direction selection, so that GCC is able to see it is a constant: 00000000000001b0 <._copy_to_user>: ... 1f0: 4c 00 01 2c isync 1f4: 3d 20 40 00 lis r9,16384 1f8: 79 29 07 c6 rldicr r9,r9,32,31 1fc: 7d 3d 03 a6 mtspr 29,r9 200: 4c 00 01 2c isync 204: 48 00 00 01 bl 204 <._copy_to_user+0x54> 204: R_PPC64_REL24 .__copy_tofrom_user ... 0000000000000260 <._copy_from_user>: ... 2ec: 4c 00 01 2c isync 2f0: 39 20 ff ff li r9,-1 2f4: 79 29 00 04 rldicr r9,r9,0,0 2f8: 7d 3d 03 a6 mtspr 29,r9 2fc: 4c 00 01 2c isync 300: 7f c5 f3 78 mr r5,r30 304: 7f 83 e3 78 mr r3,r28 308: 48 00 00 01 bl 308 <._copy_from_user+0xa8> 308: R_PPC64_REL24 .__copy_tofrom_user ... Signed-off-by: Christophe Leroy [mpe: Spell out the directions, s/KUAP_R/KUAP_READ/ etc.] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/f4e88ec4941d5facb35ce75026b0112f980086c3.1579866752.git.christophe.leroy@c-s.fr

powerpc: Fix __clear_user() with KUAP enabled

2019-12-16T12:19:44Z

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

powerpc: add machine check safe copy_to_user

2019-08-21T12:23:49Z

Use memcpy_mcsafe() implementation to define copy_to_user_mcsafe() Signed-off-by: Santosh Sivaraj Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190820081352.8641-8-santosh@fossix.org

powerpc: Add barrier_nospec to raw_copy_in_user()

2019-07-03T05:19:36Z

Commit ddf35cf3764b ("powerpc: Use barrier_nospec in copy_from_user()") Added barrier_nospec before loading from user-controlled pointers. The intention was to order the load from the potentially user-controlled pointer vs a previous branch based on an access_ok() check or similar. In order to achieve the same result, add a barrier_nospec to the raw_copy_in_user() function before loading from such a user-controlled pointer. Fixes: ddf35cf3764b ("powerpc: Use barrier_nospec in copy_from_user()") Signed-off-by: Suraj Jitindar Singh Signed-off-by: Michael Ellerman

powerpc: Add a framework for Kernel Userspace Access Protection

2019-04-21T13:05:57Z

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

get rid of legacy 'get_ds()' function

2019-03-04T18:50:14Z

Every in-kernel use of this function defined it to KERNEL_DS (either as an actual define, or as an inline function). It's an entirely historical artifact, and long long long ago used to actually read the segment selector valueof '%ds' on x86. Which in the kernel is always KERNEL_DS. Inspired by a patch from Jann Horn that just did this for a very small subset of users (the ones in fs/), along with Al who suggested a script. I then just took it to the logical extreme and removed all the remaining gunk. Roughly scripted with git grep -l '(get_ds())' -- :^tools/ | xargs sed -i 's/(get_ds())/(KERNEL_DS)/' git grep -lw 'get_ds' -- :^tools/ | xargs sed -i '/^#define get_ds()/d' plus manual fixups to remove a few unusual usage patterns, the couple of inline function cases and to fix up a comment that had become stale. The 'get_ds()' function remains in an x86 kvm selftest, since in user space it actually does something relevant. Inspired-by: Jann Horn Inspired-by: Al Viro Signed-off-by: Linus Torvalds

Fix access_ok() fallout for sparc32 and powerpc

2019-01-04T17:58:25Z

These two architectures actually had an intentional use of the 'type' argument to access_ok() just to avoid warnings. I had actually noticed the powerpc one, but forgot to then fix it up. And I missed the sparc32 case entirely. This is hopefully all of it. Reported-by: Mathieu Malaterre Reported-by: Guenter Roeck Fixes: 96d4f267e40f ("Remove 'type' argument from access_ok() function") Signed-off-by: Linus Torvalds

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57Z

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds