[RFC,01/10] vmalloc: Add basic perm alloc implementation

Message ID	20201120202426.18009-2-rick.p.edgecombe@intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=cYCG=E2=kvack.org=owner-linux-mm@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6568022D0A IronPort-SDR: hxphsK5JeD9lSAc25IjUsMKF1MRsGXmttnumXbh/WX0pkZFPoWFYCrD4NY1gbZ9dWa0fRDJH/J 6E5yxYPog82Q== IronPort-SDR: dAe5oTws0poBfSLk4kjl9AcE0urnr2caDZLch0+CDP8DOUTygKloKA0cixjo5rjNeCqyOi9QHs 0bCDmiUZNaQg== From: Rick Edgecombe <rick.p.edgecombe@intel.com> To: akpm@linux-foundation.org, jeyu@kernel.org, bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, luto@kernel.org, dave.hansen@linux.intel.com, peterz@infradead.org, x86@kernel.org, rppt@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dan.j.williams@intel.com Cc: elena.reshetova@intel.com, ira.weiny@intel.com, Rick Edgecombe <rick.p.edgecombe@intel.com> Subject: [PATCH RFC 01/10] vmalloc: Add basic perm alloc implementation Date: Fri, 20 Nov 2020 12:24:17 -0800 Message-Id: <20201120202426.18009-2-rick.p.edgecombe@intel.com> In-Reply-To: <20201120202426.18009-1-rick.p.edgecombe@intel.com> References: <20201120202426.18009-1-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	New permission vmalloc interface \| expand [RFC,00/10] New permission vmalloc interface [RFC,01/10] vmalloc: Add basic perm alloc implementation [RFC,02/10] bpf: Use perm_alloc() for BPF JIT filters [RFC,03/10] module: Use perm_alloc() for modules [RFC,04/10] module: Support separate writable allocation [RFC,05/10] x86/modules: Use real perm_allocations [RFC,06/10] x86/alternatives: Handle perm_allocs for modules [RFC,07/10] x86/unwind: Unwind orc at module writable address [RFC,08/10] jump_label: Handle module writable address [RFC,09/10] ftrace: Use module writable address [RFC,10/10] vmalloc: Add perm_alloc x86 implementation

diff --git a/arch/Kconfig b/arch/Kconfig index 56b6ccc0e32d..0fa42f76548d 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -259,6 +259,9 @@ config ARCH_HAS_SET_MEMORY config ARCH_HAS_SET_DIRECT_MAP bool +config ARCH_HAS_PERM_ALLOC_IMPLEMENTATION + bool + # # Select if the architecture provides the arch_dma_set_uncached symbol to # either provide an uncached segement alias for a DMA allocation, or diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 938eaf9517e2..4a6b30014fff 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -248,4 +248,86 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) int register_vmap_purge_notifier(struct notifier_block *nb); int unregister_vmap_purge_notifier(struct notifier_block *nb); +#define PERM_R 1 +#define PERM_W 2 +#define PERM_X 4 +#define PERM_RWX (PERM_R | PERM_W | PERM_X) +#define PERM_RW (PERM_R | PERM_W) +#define PERM_RX (PERM_R | PERM_X) + +typedef u8 virtual_perm; + +struct perm_allocation { + struct page **pages; + virtual_perm cur_perm; + virtual_perm orig_perm; + struct vm_struct *area; + unsigned long offset; + unsigned long size; + void *writable; +}; + +/* + * Allocate a special permission kva region. The region may not be mapped + * until a call to perm_writable_finish(). A writable region will be mapped + * immediately at the address returned by perm_writable_addr(). The allocation + * will be made between the start and end virtual addresses. + */ +struct perm_allocation *perm_alloc(unsigned long vstart, unsigned long vend, unsigned long page_cnt, + virtual_perm perms); + +/* The writable address for data to be loaded into the allocation */ +unsigned long perm_writable_addr(struct perm_allocation *alloc, unsigned long addr); + +/* The writable address for data to be loaded into the allocation */ +bool perm_writable_finish(struct perm_allocation *alloc); + +/* Change the permission of an allocation that is already live */ +bool perm_change(struct perm_allocation *alloc, virtual_perm perms); + +/* Free an allocation */ +void perm_free(struct perm_allocation *alloc); + +/* Helper for memsetting an allocation. Should be called before perm_writable_finish() */ +void perm_memset(struct perm_allocation *alloc, char val); + +/* The final address of the allocation */ +static inline unsigned long perm_alloc_address(const struct perm_allocation *alloc) +{ + return (unsigned long)alloc->area->addr + alloc->offset; +} + +/* The size of the allocation */ +static inline unsigned long perm_alloc_size(const struct perm_allocation *alloc) +{ + return alloc->size; +} + +static inline unsigned long within_perm_alloc(const struct perm_allocation *alloc, + unsigned long addr) +{ + unsigned long base, size; + + if (!alloc) + return false; + + base = perm_alloc_address(alloc); + size = perm_alloc_size(alloc); + + return base <= addr && addr < base + size; +} + +static inline unsigned long perm_writable_base(struct perm_allocation *alloc) +{ + return perm_writable_addr(alloc, perm_alloc_address(alloc)); +} + +static inline bool perm_is_writable(struct perm_allocation *alloc) +{ + if (!alloc) + return false; + + return (alloc->cur_perm & PERM_W) || alloc->writable; +} + #endif /* _LINUX_VMALLOC_H */ diff --git a/mm/nommu.c b/mm/nommu.c index 0faf39b32cdb..6458bd23de3e 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1810,6 +1810,72 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, return 0; } +struct perm_allocation *perm_alloc(unsigned long vstart, unsigned long vend, unsigned long page_cnt, + virtual_perm perms) +{ + struct perm_allocation *alloc; + struct vm_struct *area; + unsigned long size = page_cnt << PAGE_SHIFT; + void *ptr; + + if (!size) + return NULL; + + alloc = kmalloc(sizeof(*alloc), GFP_KERNEL | __GFP_ZERO); + + if (!alloc) + return NULL; + + area = kmalloc(sizeof(*area), GFP_KERNEL | __GFP_ZERO); + + if (!area) + goto free_alloc; + + alloc->area = area; + + ptr = vmalloc(size); + + if (!ptr) + goto free_area; + + alloc->size = size; + alloc->cur_perm = PERM_RWX; + + return alloc; + +free_area: + kfree(area); +free_alloc: + kfree(alloc); + return NULL; +} + +unsigned long perm_writable_addr(struct perm_allocation *alloc, unsigned long addr) +{ + return addr; +} + +bool perm_writable_finish(struct perm_allocation *alloc) +{ + return true; +} + +bool perm_change(struct perm_allocation *alloc, virtual_perm perms) +{ + return true; +} + +void perm_free(struct perm_allocation *alloc) +{ + if (!alloc) + return; + + kfree(alloc->area); + kfree(alloc); +} + +void perm_memset(struct perm_allocation *alloc, char val) {} + /* * Initialise sysctl_user_reserve_kbytes. * diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 6ae491a8b210..3e8e54a75dfc 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -34,6 +34,7 @@ #include <linux/bitops.h> #include <linux/rbtree_augmented.h> #include <linux/overflow.h> +#include <linux/moduleloader.h> #include <linux/uaccess.h> #include <asm/tlbflush.h> @@ -3088,6 +3089,140 @@ void free_vm_area(struct vm_struct *area) } EXPORT_SYMBOL_GPL(free_vm_area); +#ifndef CONFIG_ARCH_HAS_PERM_ALLOC_IMPLEMENTATION + +#ifndef CONFIG_MODULES +/* If modules is not configured, provide stubs so perm_alloc() could use fallback logic. */ +void *module_alloc(unsigned long size) +{ + return NULL; +} + +void module_memfree(void *module_region) { } +#endif /* !CONFIG_MODULES */ + +struct perm_allocation *perm_alloc(unsigned long vstart, unsigned long vend, unsigned long page_cnt, + virtual_perm perms) +{ + struct perm_allocation *alloc; + unsigned long size = page_cnt << PAGE_SHIFT; + void *ptr; + + if (!size) + return NULL; + + alloc = kmalloc(sizeof(*alloc), GFP_KERNEL | __GFP_ZERO); + + if (!alloc) + return NULL; + + ptr = module_alloc(size); + + if (!ptr) { + kfree(alloc); + return NULL; + } + + /* + * In order to work with all arch's we call the arch's module_alloc() which is the only + * cross-arch place where information about where an executable allocation should go is + * located. If the caller passed in a different range they want for the allocation...we + * could try a vmalloc_node_range() at this point, but just return NULL for now. + */ + if ((unsigned long)ptr < vstart || (unsigned long)ptr >= vend) { + module_memfree(ptr); + kfree(alloc); + return NULL; + } + + alloc->area = find_vm_area(ptr); + alloc->size = size; + + if (IS_ENABLED(CONFIG_ARM) || IS_ENABLED(CONFIG_X86)) + alloc->cur_perm = PERM_RW; + else + alloc->cur_perm = PERM_RWX; + + alloc->orig_perm = perms; + + return alloc; +} + +unsigned long perm_writable_addr(struct perm_allocation *alloc, unsigned long addr) +{ + return addr; +} + +bool perm_writable_finish(struct perm_allocation *alloc) +{ + if (!alloc) + return false; + + return perm_change(alloc, alloc->orig_perm); +} + +bool perm_change(struct perm_allocation *alloc, virtual_perm perm) +{ + unsigned long start, npages; + virtual_perm unset, set; + + if (!alloc) + return false; + + npages = alloc->size >> PAGE_SHIFT; + + start = perm_alloc_address(alloc); + + set = ~alloc->cur_perm & perm; + unset = alloc->cur_perm & ~perm; + + if (set & PERM_W) + set_memory_rw(start, npages); + + if (unset & PERM_W) + set_memory_ro(start, npages); + + if (set & PERM_X) + set_memory_x(start, npages); + + if (unset & PERM_X) + set_memory_nx(start, npages); + + alloc->cur_perm = perm; + + return false; +} + +static inline bool perms_need_reset(struct perm_allocation *alloc) +{ + return (alloc->cur_perm & PERM_X) || (~alloc->cur_perm & PERM_W); +} + +void perm_free(struct perm_allocation *alloc) +{ + unsigned long addr; + + if (!alloc) + return; + + addr = perm_alloc_address(alloc); + + if (perms_need_reset(alloc)) + set_vm_flush_reset_perms((void *)addr); + + module_memfree((void *)addr); + + kfree(alloc); +} + +void perm_memset(struct perm_allocation *alloc, char val) +{ + if (!alloc) + return; + memset((void *)perm_writable_base(alloc), val, perm_alloc_size(alloc)); +} +#endif /* CONFIG_ARCH_HAS_PERM_ALLOC_IMPLEMENTATION */ + #ifdef CONFIG_SMP static struct vmap_area *node_to_va(struct rb_node *n) {

[RFC,01/10] vmalloc: Add basic perm alloc implementation

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