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author | Michael Ellerman <mpe@ellerman.id.au> | 2020-02-01 21:47:17 +1100 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-02-01 21:47:17 +1100 |
commit | 4c25df5640ae6e4491ee2c50d3f70c1559ef037d (patch) | |
tree | 9d68b0361918926d7d7b6d78090dcfb942ec4e72 /arch/powerpc | |
parent | 34b5a946a9543ce38d8ad1aacc4362533a813db7 (diff) | |
parent | 3d7dfd632f9b60cfce069b4da517e6b1a1c3f613 (diff) | |
download | linux-stable-4c25df5640ae6e4491ee2c50d3f70c1559ef037d.tar.gz linux-stable-4c25df5640ae6e4491ee2c50d3f70c1559ef037d.tar.bz2 linux-stable-4c25df5640ae6e4491ee2c50d3f70c1559ef037d.zip |
Merge branch 'topic/user-access-begin' into next
Merge the user_access_begin() series from Christophe. This is based on
a commit from Linus that went into v5.5-rc7.
Diffstat (limited to 'arch/powerpc')
-rw-r--r-- | arch/powerpc/include/asm/book3s/32/kup.h | 68 | ||||
-rw-r--r-- | arch/powerpc/include/asm/book3s/64/kup-radix.h | 40 | ||||
-rw-r--r-- | arch/powerpc/include/asm/kup.h | 49 | ||||
-rw-r--r-- | arch/powerpc/include/asm/nohash/32/kup-8xx.h | 21 | ||||
-rw-r--r-- | arch/powerpc/include/asm/uaccess.h | 88 | ||||
-rw-r--r-- | arch/powerpc/mm/fault.c | 2 |
6 files changed, 219 insertions, 49 deletions
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index f9dc597b0b86..3c0ba22dc360 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -102,41 +102,91 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end) isync(); /* Context sync required after mtsrin() */ } -static inline void allow_user_access(void __user *to, const void __user *from, u32 size) +static __always_inline void allow_user_access(void __user *to, const void __user *from, + u32 size, unsigned long dir) { u32 addr, end; - if (__builtin_constant_p(to) && to == NULL) + BUILD_BUG_ON(!__builtin_constant_p(dir)); + BUILD_BUG_ON(dir == KUAP_CURRENT); + + if (!(dir & KUAP_WRITE)) return; addr = (__force u32)to; - if (!addr || addr >= TASK_SIZE || !size) + if (unlikely(addr >= TASK_SIZE || !size)) 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 */ } -static inline void prevent_user_access(void __user *to, const void __user *from, u32 size) +static __always_inline void prevent_user_access(void __user *to, const void __user *from, + u32 size, unsigned long dir) { - u32 addr = (__force u32)to; - u32 end = min(addr + size, TASK_SIZE); + u32 addr, end; + + BUILD_BUG_ON(!__builtin_constant_p(dir)); + + if (dir == KUAP_CURRENT) { + u32 kuap = current->thread.kuap; - if (!addr || 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; + } current->thread.kuap = 0; kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline unsigned long prevent_user_access_return(void) +{ + unsigned long flags = current->thread.kuap; + unsigned long addr = flags & 0xf0000000; + unsigned long end = flags << 28; + void __user *to = (__force void __user *)addr; + + if (flags) + prevent_user_access(to, to, end - addr, KUAP_READ_WRITE); + + return flags; +} + +static inline void restore_user_access(unsigned long flags) { + unsigned long addr = flags & 0xf0000000; + unsigned long end = flags << 28; + void __user *to = (__force void __user *)addr; + + if (flags) + allow_user_access(to, to, end - addr, KUAP_READ_WRITE); +} + +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +{ + unsigned long begin = regs->kuap & 0xf0000000; + unsigned long end = regs->kuap << 28; + if (!is_write) return false; - return WARN(!regs->kuap, "Bug: write fault blocked by segment registers !"); + return WARN(address < begin || address >= end, + "Bug: write fault blocked by segment registers !"); } #endif /* CONFIG_PPC_KUAP */ diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index f254de956d6a..90dd3a3fc8c7 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -63,6 +63,14 @@ * because that would require an expensive read/modify write of the AMR. */ +static inline unsigned long get_kuap(void) +{ + if (!early_mmu_has_feature(MMU_FTR_RADIX_KUAP)) + return 0; + + return mfspr(SPRN_AMR); +} + static inline void set_kuap(unsigned long value) { if (!early_mmu_has_feature(MMU_FTR_RADIX_KUAP)) @@ -77,25 +85,43 @@ static inline void set_kuap(unsigned long value) isync(); } -static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) +static __always_inline void allow_user_access(void __user *to, const void __user *from, + unsigned long size, unsigned long dir) { // This is written so we can resolve to a single case at build time - if (__builtin_constant_p(to) && to == NULL) + BUILD_BUG_ON(!__builtin_constant_p(dir)); + if (dir == KUAP_READ) set_kuap(AMR_KUAP_BLOCK_WRITE); - else if (__builtin_constant_p(from) && from == NULL) + 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, - unsigned long size) + unsigned long size, unsigned long dir) +{ + set_kuap(AMR_KUAP_BLOCKED); +} + +static inline unsigned long prevent_user_access_return(void) { + unsigned long flags = get_kuap(); + set_kuap(AMR_KUAP_BLOCKED); + + return flags; +} + +static inline void restore_user_access(unsigned long flags) +{ + set_kuap(flags); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) && (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index 5b5e39643a27..92bcd1a26d73 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -2,6 +2,16 @@ #ifndef _ASM_POWERPC_KUP_H_ #define _ASM_POWERPC_KUP_H_ +#define KUAP_READ 1 +#define KUAP_WRITE 2 +#define KUAP_READ_WRITE (KUAP_READ | KUAP_WRITE) +/* + * For prevent_user_access() only. + * Use the current saved situation instead of the to/from/size params. + * Used on book3s/32 + */ +#define KUAP_CURRENT 4 + #ifdef CONFIG_PPC64 #include <asm/book3s/64/kup-radix.h> #endif @@ -42,32 +52,55 @@ void setup_kuap(bool disabled); #else static inline void setup_kuap(bool disabled) { } static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) { } + unsigned long size, unsigned long dir) { } static inline void prevent_user_access(void __user *to, const void __user *from, - unsigned long size) { } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) { return false; } + unsigned long size, unsigned long dir) { } +static inline unsigned long prevent_user_access_return(void) { return 0UL; } +static inline void restore_user_access(unsigned long flags) { } +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +{ + return false; +} #endif /* CONFIG_PPC_KUAP */ static inline void allow_read_from_user(const void __user *from, unsigned long size) { - allow_user_access(NULL, from, size); + allow_user_access(NULL, from, size, KUAP_READ); } static inline void allow_write_to_user(void __user *to, unsigned long size) { - allow_user_access(to, NULL, size); + allow_user_access(to, NULL, size, KUAP_WRITE); +} + +static inline void allow_read_write_user(void __user *to, const void __user *from, + unsigned long size) +{ + allow_user_access(to, from, size, KUAP_READ_WRITE); } static inline void prevent_read_from_user(const void __user *from, unsigned long size) { - prevent_user_access(NULL, from, size); + prevent_user_access(NULL, from, size, KUAP_READ); } static inline void prevent_write_to_user(void __user *to, unsigned long size) { - prevent_user_access(to, NULL, size); + prevent_user_access(to, NULL, size, KUAP_WRITE); +} + +static inline void prevent_read_write_user(void __user *to, const void __user *from, + unsigned long size) +{ + prevent_user_access(to, from, size, KUAP_READ_WRITE); +} + +static inline void prevent_current_access_user(void) +{ + prevent_user_access(NULL, NULL, ~0UL, KUAP_CURRENT); } #endif /* !__ASSEMBLY__ */ -#endif /* _ASM_POWERPC_KUP_H_ */ +#endif /* _ASM_POWERPC_KUAP_H_ */ diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index 1006a427e99c..85ed2390fb99 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -35,18 +35,33 @@ #include <asm/reg.h> static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) + unsigned long size, unsigned long dir) { mtspr(SPRN_MD_AP, MD_APG_INIT); } static inline void prevent_user_access(void __user *to, const void __user *from, - unsigned long size) + unsigned long size, unsigned long dir) { mtspr(SPRN_MD_AP, MD_APG_KUAP); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline unsigned long prevent_user_access_return(void) +{ + unsigned long flags = mfspr(SPRN_MD_AP); + + mtspr(SPRN_MD_AP, MD_APG_KUAP); + + return flags; +} + +static inline void restore_user_access(unsigned long flags) +{ + mtspr(SPRN_MD_AP, flags); +} + +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xf0000000), "Bug: fault blocked by AP register !"); diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index c92fe7fe9692..2f500debae21 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -91,9 +91,14 @@ static inline int __access_ok(unsigned long addr, unsigned long size, __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) #define __get_user(x, ptr) \ - __get_user_nocheck((x), (ptr), sizeof(*(ptr))) + __get_user_nocheck((x), (ptr), sizeof(*(ptr)), true) #define __put_user(x, ptr) \ - __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) + __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), true) + +#define __get_user_allowed(x, ptr) \ + __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false) +#define __put_user_allowed(x, ptr) \ + __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), false) #define __get_user_inatomic(x, ptr) \ __get_user_nosleep((x), (ptr), sizeof(*(ptr))) @@ -138,10 +143,9 @@ extern long __put_user_bad(void); : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err)) #endif /* __powerpc64__ */ -#define __put_user_size(x, ptr, size, retval) \ +#define __put_user_size_allowed(x, ptr, size, retval) \ do { \ retval = 0; \ - allow_write_to_user(ptr, size); \ switch (size) { \ case 1: __put_user_asm(x, ptr, retval, "stb"); break; \ case 2: __put_user_asm(x, ptr, retval, "sth"); break; \ @@ -149,17 +153,26 @@ do { \ case 8: __put_user_asm2(x, ptr, retval); break; \ default: __put_user_bad(); \ } \ +} while (0) + +#define __put_user_size(x, ptr, size, retval) \ +do { \ + allow_write_to_user(ptr, size); \ + __put_user_size_allowed(x, ptr, size, retval); \ prevent_write_to_user(ptr, size); \ } while (0) -#define __put_user_nocheck(x, ptr, size) \ +#define __put_user_nocheck(x, ptr, size, do_allow) \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ if (!is_kernel_addr((unsigned long)__pu_addr)) \ might_fault(); \ __chk_user_ptr(ptr); \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + if (do_allow) \ + __put_user_size((x), __pu_addr, (size), __pu_err); \ + else \ + __put_user_size_allowed((x), __pu_addr, (size), __pu_err); \ __pu_err; \ }) @@ -236,13 +249,12 @@ extern long __get_user_bad(void); : "b" (addr), "i" (-EFAULT), "0" (err)) #endif /* __powerpc64__ */ -#define __get_user_size(x, ptr, size, retval) \ +#define __get_user_size_allowed(x, ptr, size, retval) \ do { \ retval = 0; \ __chk_user_ptr(ptr); \ if (size > sizeof(x)) \ (x) = __get_user_bad(); \ - allow_read_from_user(ptr, size); \ switch (size) { \ case 1: __get_user_asm(x, ptr, retval, "lbz"); break; \ case 2: __get_user_asm(x, ptr, retval, "lhz"); break; \ @@ -250,6 +262,12 @@ do { \ case 8: __get_user_asm2(x, ptr, retval); break; \ default: (x) = __get_user_bad(); \ } \ +} while (0) + +#define __get_user_size(x, ptr, size, retval) \ +do { \ + allow_read_from_user(ptr, size); \ + __get_user_size_allowed(x, ptr, size, retval); \ prevent_read_from_user(ptr, size); \ } while (0) @@ -260,7 +278,7 @@ do { \ #define __long_type(x) \ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) -#define __get_user_nocheck(x, ptr, size) \ +#define __get_user_nocheck(x, ptr, size, do_allow) \ ({ \ long __gu_err; \ __long_type(*(ptr)) __gu_val; \ @@ -269,7 +287,10 @@ do { \ if (!is_kernel_addr((unsigned long)__gu_addr)) \ might_fault(); \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + if (do_allow) \ + __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + else \ + __get_user_size_allowed(__gu_val, __gu_addr, (size), __gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ __gu_err; \ }) @@ -313,9 +334,9 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n) unsigned long ret; barrier_nospec(); - allow_user_access(to, from, n); + allow_read_write_user(to, from, n); ret = __copy_tofrom_user(to, from, n); - prevent_user_access(to, from, n); + prevent_read_write_user(to, from, n); return ret; } #endif /* __powerpc64__ */ @@ -356,33 +377,40 @@ static inline unsigned long raw_copy_from_user(void *to, return ret; } -static inline unsigned long raw_copy_to_user(void __user *to, - const void *from, unsigned long n) +static inline unsigned long +raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n) { - unsigned long ret; if (__builtin_constant_p(n) && (n <= 8)) { - ret = 1; + unsigned long ret = 1; switch (n) { case 1: - __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret); + __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret); break; case 2: - __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret); + __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret); break; case 4: - __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret); + __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret); break; case 8: - __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret); + __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret); break; } if (ret == 0) return 0; } + return __copy_tofrom_user(to, (__force const void __user *)from, n); +} + +static inline unsigned long +raw_copy_to_user(void __user *to, const void *from, unsigned long n) +{ + unsigned long ret; + allow_write_to_user(to, n); - ret = __copy_tofrom_user(to, (__force const void __user *)from, n); + ret = raw_copy_to_user_allowed(to, from, n); prevent_write_to_user(to, n); return ret; } @@ -428,4 +456,22 @@ extern long __copy_from_user_flushcache(void *dst, const void __user *src, extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len); +static __must_check inline bool user_access_begin(const void __user *ptr, size_t len) +{ + if (unlikely(!access_ok(ptr, len))) + return false; + allow_read_write_user((void __user *)ptr, ptr, len); + return true; +} +#define user_access_begin user_access_begin +#define user_access_end prevent_current_access_user +#define user_access_save prevent_user_access_return +#define user_access_restore restore_user_access + +#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) +#define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) +#define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e) +#define unsafe_copy_to_user(d, s, l, e) \ + unsafe_op_wrap(raw_copy_to_user_allowed(d, s, l), e) + #endif /* _ARCH_POWERPC_UACCESS_H */ diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 7534ee5bf9b2..8db0507619e2 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -233,7 +233,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, // Read/write fault in a valid region (the exception table search passed // above), but blocked by KUAP is bad, it can never succeed. - if (bad_kuap_fault(regs, is_write)) + if (bad_kuap_fault(regs, address, is_write)) return true; // What's left? Kernel fault on user in well defined regions (extable |