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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2020-01-24 11:54:43 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-01-28 23:14:40 +1100 |
| commit | bedb4dbe443c11ff551b4ae4e48c8676fdc96467 (patch) | |
| tree | f82b693795ae0089a230efac3f02c01a8ede42f1 /arch/powerpc/include/asm/book3s | |
| parent | 88f8c080d47f307871840a0a825ef556673eb592 (diff) | |
| download | linux-bedb4dbe443c11ff551b4ae4e48c8676fdc96467.tar.bz2 | |
powerpc/32s: Prepare prevent_user_access() for user_access_end()
In preparation of implementing user_access_begin and friends
on powerpc, the book3s/32 version of prevent_user_access() need
to be prepared for user_access_end().
user_access_end() doesn't provide the address and size which
were passed to user_access_begin(), required by prevent_user_access()
to know which segment to modify.
The list of segments which where unprotected by allow_user_access()
are available in current->kuap. But we don't want prevent_user_access()
to read this all the time, especially everytime it is 0 (for instance
because the access was not a write access).
Implement a special direction named KUAP_CURRENT. In this case only,
the addr and end are retrieved from current->kuap.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/55bcc1f25d8200892a31f67a0b024ff3b816c3cc.1579866752.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/include/asm/book3s')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/32/kup.h | 23 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/kup-radix.h | 4 |
2 files changed, 21 insertions, 6 deletions
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index de29fb752cca..17e069291c72 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -108,6 +108,8 @@ static __always_inline void allow_user_access(void __user *to, const void __user u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); + BUILD_BUG_ON(dir == KUAP_CURRENT); + if (!(dir & KUAP_WRITE)) return; @@ -117,6 +119,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user return; end = min(addr + size, TASK_SIZE); + current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf); kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */ } @@ -127,15 +130,25 @@ static __always_inline void prevent_user_access(void __user *to, const void __us u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); - if (!(dir & KUAP_WRITE)) - return; - addr = (__force u32)to; + if (dir == KUAP_CURRENT) { + u32 kuap = current->thread.kuap; - if (unlikely(addr >= TASK_SIZE || !size)) + if (unlikely(!kuap)) + return; + + addr = kuap & 0xf0000000; + end = kuap << 28; + } else if (dir & KUAP_WRITE) { + addr = (__force u32)to; + end = min(addr + size, TASK_SIZE); + + if (unlikely(addr >= TASK_SIZE || !size)) + return; + } else { return; + } - end = min(addr + size, TASK_SIZE); current->thread.kuap = 0; kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index c8d1076e0ebb..a0263e94df33 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -86,8 +86,10 @@ static __always_inline void allow_user_access(void __user *to, const void __user set_kuap(AMR_KUAP_BLOCK_WRITE); else if (dir == KUAP_WRITE) set_kuap(AMR_KUAP_BLOCK_READ); - else + else if (dir == KUAP_READ_WRITE) set_kuap(0); + else + BUILD_BUG(); } static inline void prevent_user_access(void __user *to, const void __user *from, |