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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306// SPDX-License-Identifier: GPL-2.0-or-later/* * linux/mm/process_vm_access.c * * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp. */
#include <linux/compat.h>#include <linux/mm.h>#include <linux/uio.h>#include <linux/sched.h>#include <linux/sched/mm.h>#include <linux/highmem.h>#include <linux/ptrace.h>#include <linux/slab.h>#include <linux/syscalls.h>
/** * process_vm_rw_pages - read/write pages from task specified * @pages: array of pointers to pages we want to copy * @offset: offset in page to start copying from/to * @len: number of bytes to copy * @iter: where to copy to/from locally * @vm_write: 0 means copy from, 1 means copy to * Returns 0 on success, error code otherwise */static int process_vm_rw_pages(struct page **pages, unsigned offset, size_t len, struct iov_iter *iter, int vm_write){ /* Do the copy for each page */ while (len && iov_iter_count(iter)) { struct page *page = *pages++; size_t copy = PAGE_SIZE - offset; size_t copied;
if (copy > len) copy = len;
if (vm_write) copied = copy_page_from_iter(page, offset, copy, iter); else copied = copy_page_to_iter(page, offset, copy, iter);
len -= copied; if (copied < copy && iov_iter_count(iter)) return -EFAULT; offset = 0; } return 0;}
/* Maximum number of pages kmalloc'd to hold struct page's during copy */#define PVM_MAX_KMALLOC_PAGES 2
/* Maximum number of pages that can be stored at a time */#define PVM_MAX_USER_PAGES (PVM_MAX_KMALLOC_PAGES * PAGE_SIZE / sizeof(struct page *))
/** * process_vm_rw_single_vec - read/write pages from task specified * @addr: start memory address of target process * @len: size of area to copy to/from * @iter: where to copy to/from locally * @process_pages: struct pages area that can store at least * nr_pages_to_copy struct page pointers * @mm: mm for task * @task: task to read/write from * @vm_write: 0 means copy from, 1 means copy to * Returns 0 on success or on failure error code */static int process_vm_rw_single_vec(unsigned long addr, unsigned long len, struct iov_iter *iter, struct page **process_pages, struct mm_struct *mm, struct task_struct *task, int vm_write){ unsigned long pa = addr & PAGE_MASK; unsigned long start_offset = addr - pa; unsigned long nr_pages; ssize_t rc = 0; unsigned int flags = 0;
/* Work out address and page range required */ if (len == 0) return 0; nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
if (vm_write) flags |= FOLL_WRITE;
while (!rc && nr_pages && iov_iter_count(iter)) { int pinned_pages = min_t(unsigned long, nr_pages, PVM_MAX_USER_PAGES); int locked = 1; size_t bytes;
/* * Get the pages we're interested in. We must * access remotely because task/mm might not * current/current->mm */ mmap_read_lock(mm); pinned_pages = pin_user_pages_remote(mm, pa, pinned_pages, flags, process_pages, &locked); if (locked) mmap_read_unlock(mm); if (pinned_pages <= 0) return -EFAULT;
bytes = pinned_pages * PAGE_SIZE - start_offset; if (bytes > len) bytes = len;
rc = process_vm_rw_pages(process_pages, start_offset, bytes, iter, vm_write); len -= bytes; start_offset = 0; nr_pages -= pinned_pages; pa += pinned_pages * PAGE_SIZE;
/* If vm_write is set, the pages need to be made dirty: */ unpin_user_pages_dirty_lock(process_pages, pinned_pages, vm_write); }
return rc;}
/* Maximum number of entries for process pages array which lives on stack */#define PVM_MAX_PP_ARRAY_COUNT 16
/** * process_vm_rw_core - core of reading/writing pages from task specified * @pid: PID of process to read/write from/to * @iter: where to copy to/from locally * @rvec: iovec array specifying where to copy to/from in the other process * @riovcnt: size of rvec array * @flags: currently unused * @vm_write: 0 if reading from other process, 1 if writing to other process * * Returns the number of bytes read/written or error code. May * return less bytes than expected if an error occurs during the copying * process. */static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, const struct iovec *rvec, unsigned long riovcnt, unsigned long flags, int vm_write){ struct task_struct *task; struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; struct page **process_pages = pp_stack; struct mm_struct *mm; unsigned long i; ssize_t rc = 0; unsigned long nr_pages = 0; unsigned long nr_pages_iov; ssize_t iov_len; size_t total_len = iov_iter_count(iter);
/* * Work out how many pages of struct pages we're going to need * when eventually calling get_user_pages */ for (i = 0; i < riovcnt; i++) { iov_len = rvec[i].iov_len; if (iov_len > 0) { nr_pages_iov = ((unsigned long)rvec[i].iov_base + iov_len - 1) / PAGE_SIZE - (unsigned long)rvec[i].iov_base / PAGE_SIZE + 1; nr_pages = max(nr_pages, nr_pages_iov); } }
if (nr_pages == 0) return 0;
if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { /* For reliability don't try to kmalloc more than 2 pages worth */ process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES * PAGE_SIZE, sizeof(struct page *)*nr_pages), GFP_KERNEL);
if (!process_pages) return -ENOMEM; }
/* Get process information */ task = find_get_task_by_vpid(pid); if (!task) { rc = -ESRCH; goto free_proc_pages; }
mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS); if (IS_ERR(mm)) { rc = PTR_ERR(mm); /* * Explicitly map EACCES to EPERM as EPERM is a more * appropriate error code for process_vw_readv/writev */ if (rc == -EACCES) rc = -EPERM; goto put_task_struct; }
for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++) rc = process_vm_rw_single_vec( (unsigned long)rvec[i].iov_base, rvec[i].iov_len, iter, process_pages, mm, task, vm_write);
/* copied = space before - space after */ total_len -= iov_iter_count(iter);
/* If we have managed to copy any data at all then we return the number of bytes copied. Otherwise we return the error code */ if (total_len) rc = total_len;
mmput(mm);
put_task_struct: put_task_struct(task);
free_proc_pages: if (process_pages != pp_stack) kfree(process_pages); return rc;}
/** * process_vm_rw - check iovecs before calling core routine * @pid: PID of process to read/write from/to * @lvec: iovec array specifying where to copy to/from locally * @liovcnt: size of lvec array * @rvec: iovec array specifying where to copy to/from in the other process * @riovcnt: size of rvec array * @flags: currently unused * @vm_write: 0 if reading from other process, 1 if writing to other process * * Returns the number of bytes read/written or error code. May * return less bytes than expected if an error occurs during the copying * process. */static ssize_t process_vm_rw(pid_t pid, const struct iovec __user *lvec, unsigned long liovcnt, const struct iovec __user *rvec, unsigned long riovcnt, unsigned long flags, int vm_write){ struct iovec iovstack_l[UIO_FASTIOV]; struct iovec iovstack_r[UIO_FASTIOV]; struct iovec *iov_l = iovstack_l; struct iovec *iov_r; struct iov_iter iter; ssize_t rc; int dir = vm_write ? ITER_SOURCE : ITER_DEST;
if (flags != 0) return -EINVAL;
/* Check iovecs */ rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); if (rc < 0) return rc; if (!iov_iter_count(&iter)) goto free_iov_l; iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r, in_compat_syscall()); if (IS_ERR(iov_r)) { rc = PTR_ERR(iov_r); goto free_iov_l; } rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); if (iov_r != iovstack_r) kfree(iov_r);free_iov_l: kfree(iov_l); return rc;}
SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, unsigned long, liovcnt, const struct iovec __user *, rvec, unsigned long, riovcnt, unsigned long, flags){ return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);}
SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, const struct iovec __user *, lvec, unsigned long, liovcnt, const struct iovec __user *, rvec, unsigned long, riovcnt, unsigned long, flags){ return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);}