diff options
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index ed8e9deae284..b0e47fe1eb4b 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -72,6 +72,7 @@ #include <linux/io_uring.h> #include <linux/audit.h> #include <linux/security.h> +#include <asm/shmparam.h> #define CREATE_TRACE_POINTS #include <trace/events/io_uring.h> @@ -3110,6 +3111,49 @@ static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma) return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot); } +static unsigned long io_uring_mmu_get_unmapped_area(struct file *filp, + unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + void *ptr; + + /* + * Do not allow to map to user-provided address to avoid breaking the + * aliasing rules. Userspace is not able to guess the offset address of + * kernel kmalloc()ed memory area. + */ + if (addr) + return -EINVAL; + + ptr = io_uring_validate_mmap_request(filp, pgoff, len); + if (IS_ERR(ptr)) + return -ENOMEM; + + /* + * Some architectures have strong cache aliasing requirements. + * For such architectures we need a coherent mapping which aliases + * kernel memory *and* userspace memory. To achieve that: + * - use a NULL file pointer to reference physical memory, and + * - use the kernel virtual address of the shared io_uring context + * (instead of the userspace-provided address, which has to be 0UL + * anyway). + * - use the same pgoff which the get_unmapped_area() uses to + * calculate the page colouring. + * For architectures without such aliasing requirements, the + * architecture will return any suitable mapping because addr is 0. + */ + filp = NULL; + flags |= MAP_SHARED; + pgoff = 0; /* has been translated to ptr above */ +#ifdef SHM_COLOUR + addr = (uintptr_t) ptr; + pgoff = addr >> PAGE_SHIFT; +#else + addr = 0UL; +#endif + return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); +} + #else /* !CONFIG_MMU */ static int io_uring_mmap(struct file *file, struct vm_area_struct *vma) @@ -3324,6 +3368,8 @@ static const struct file_operations io_uring_fops = { #ifndef CONFIG_MMU .get_unmapped_area = io_uring_nommu_get_unmapped_area, .mmap_capabilities = io_uring_nommu_mmap_capabilities, +#else + .get_unmapped_area = io_uring_mmu_get_unmapped_area, #endif .poll = io_uring_poll, #ifdef CONFIG_PROC_FS |