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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/mm.h>#include <linux/miscdevice.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <linux/mman.h>#include <linux/random.h>#include <linux/init.h>#include <linux/tty.h>#include <linux/capability.h>#include <linux/ptrace.h>#include <linux/device.h>#include <linux/highmem.h>#include <linux/backing-dev.h>#include <linux/shmem_fs.h>#include <linux/splice.h>#include <linux/pfn.h>#include <linux/export.h>#include <linux/io.h>#include <linux/uio.h>#include <linux/uaccess.h>#include <linux/security.h>
#define DEVMEM_MINOR 1#define DEVPORT_MINOR 4
static inline unsigned long size_inside_page(unsigned long start, unsigned long size){ unsigned long sz;
sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
return min(sz, size);}
#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGEstatic inline int valid_phys_addr_range(phys_addr_t addr, size_t count){ return addr + count <= __pa(high_memory);}
static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size){ return 1;}#endif
#ifdef CONFIG_STRICT_DEVMEMstatic inline int page_is_allowed(unsigned long pfn){ return devmem_is_allowed(pfn);}#elsestatic inline int page_is_allowed(unsigned long pfn){ return 1;}#endif
static inline bool should_stop_iteration(void){ if (need_resched()) cond_resched(); return signal_pending(current);}
/* * This funcion reads the *physical* memory. The f_pos points directly to the * memory location. */static ssize_t read_mem(struct file *file, char __user *buf, size_t count, loff_t *ppos){ phys_addr_t p = *ppos; ssize_t read, sz; void *ptr; char *bounce; int err;
if (p != *ppos) return 0;
if (!valid_phys_addr_range(p, count)) return -EFAULT; read = 0;#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE) { sz = size_inside_page(p, count); if (sz > 0) { if (clear_user(buf, sz)) return -EFAULT; buf += sz; p += sz; count -= sz; read += sz; } }#endif
bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!bounce) return -ENOMEM;
while (count > 0) { unsigned long remaining; int allowed, probe;
sz = size_inside_page(p, count);
err = -EPERM; allowed = page_is_allowed(p >> PAGE_SHIFT); if (!allowed) goto failed;
err = -EFAULT; if (allowed == 2) { /* Show zeros for restricted memory. */ remaining = clear_user(buf, sz); } else { /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur. */ ptr = xlate_dev_mem_ptr(p); if (!ptr) goto failed;
probe = copy_from_kernel_nofault(bounce, ptr, sz); unxlate_dev_mem_ptr(p, ptr); if (probe) goto failed;
remaining = copy_to_user(buf, bounce, sz); }
if (remaining) goto failed;
buf += sz; p += sz; count -= sz; read += sz; if (should_stop_iteration()) break; } kfree(bounce);
*ppos += read; return read;
failed: kfree(bounce); return err;}
static ssize_t write_mem(struct file *file, const char __user *buf, size_t count, loff_t *ppos){ phys_addr_t p = *ppos; ssize_t written, sz; unsigned long copied; void *ptr;
if (p != *ppos) return -EFBIG;
if (!valid_phys_addr_range(p, count)) return -EFAULT;
written = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE) { sz = size_inside_page(p, count); /* Hmm. Do something? */ buf += sz; p += sz; count -= sz; written += sz; }#endif
while (count > 0) { int allowed;
sz = size_inside_page(p, count);
allowed = page_is_allowed(p >> PAGE_SHIFT); if (!allowed) return -EPERM;
/* Skip actual writing when a page is marked as restricted. */ if (allowed == 1) { /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur. */ ptr = xlate_dev_mem_ptr(p); if (!ptr) { if (written) break; return -EFAULT; }
copied = copy_from_user(ptr, buf, sz); unxlate_dev_mem_ptr(p, ptr); if (copied) { written += sz - copied; if (written) break; return -EFAULT; } }
buf += sz; p += sz; count -= sz; written += sz; if (should_stop_iteration()) break; }
*ppos += written; return written;}
int __weak phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot){ return 1;}
#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
/* * Architectures vary in how they handle caching for addresses * outside of main memory. * */#ifdef pgprot_noncachedstatic int uncached_access(struct file *file, phys_addr_t addr){ /* * Accessing memory above the top the kernel knows about or through a * file pointer * that was marked O_DSYNC will be done non-cached. */ if (file->f_flags & O_DSYNC) return 1; return addr >= __pa(high_memory);}#endif
static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot){#ifdef pgprot_noncached phys_addr_t offset = pfn << PAGE_SHIFT;
if (uncached_access(file, offset)) return pgprot_noncached(vma_prot);#endif return vma_prot;}#endif
#ifndef CONFIG_MMUstatic unsigned long get_unmapped_area_mem(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags){ if (!valid_mmap_phys_addr_range(pgoff, len)) return (unsigned long) -EINVAL; return pgoff << PAGE_SHIFT;}
/* permit direct mmap, for read, write or exec */static unsigned memory_mmap_capabilities(struct file *file){ return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC;}
static unsigned zero_mmap_capabilities(struct file *file){ return NOMMU_MAP_COPY;}
/* can't do an in-place private mapping if there's no MMU */static inline int private_mapping_ok(struct vm_area_desc *desc){ return is_nommu_shared_vma_flags(&desc->vma_flags);}#else
static inline int private_mapping_ok(struct vm_area_desc *desc){ return 1;}#endif
static const struct vm_operations_struct mmap_mem_ops = {#ifdef CONFIG_HAVE_IOREMAP_PROT .access = generic_access_phys#endif};
static int mmap_mem_prepare(struct vm_area_desc *desc){ struct file *file = desc->file; const size_t size = vma_desc_size(desc); const phys_addr_t offset = (phys_addr_t)desc->pgoff << PAGE_SHIFT;
/* Does it even fit in phys_addr_t? */ if (offset >> PAGE_SHIFT != desc->pgoff) return -EINVAL;
/* It's illegal to wrap around the end of the physical address space. */ if (offset + (phys_addr_t)size - 1 < offset) return -EINVAL;
if (!valid_mmap_phys_addr_range(desc->pgoff, size)) return -EINVAL;
if (!private_mapping_ok(desc)) return -ENOSYS;
if (!range_is_allowed(desc->pgoff, size)) return -EPERM;
if (!phys_mem_access_prot_allowed(file, desc->pgoff, size, &desc->page_prot)) return -EINVAL;
desc->page_prot = phys_mem_access_prot(file, desc->pgoff, size, desc->page_prot);
desc->vm_ops = &mmap_mem_ops;
/* Remap-pfn-range will mark the range with the I/O flag. */ mmap_action_remap_full(desc, desc->pgoff); desc->action.error_override = -EAGAIN;
return 0;}
#ifdef CONFIG_DEVPORTstatic ssize_t read_port(struct file *file, char __user *buf, size_t count, loff_t *ppos){ unsigned long i = *ppos; char __user *tmp = buf;
if (!access_ok(buf, count)) return -EFAULT; while (count-- > 0 && i < 65536) { if (__put_user(inb(i), tmp) < 0) return -EFAULT; i++; tmp++; } *ppos = i; return tmp-buf;}
static ssize_t write_port(struct file *file, const char __user *buf, size_t count, loff_t *ppos){ unsigned long i = *ppos; const char __user *tmp = buf;
if (!access_ok(buf, count)) return -EFAULT; while (count-- > 0 && i < 65536) { char c;
if (__get_user(c, tmp)) { if (tmp > buf) break; return -EFAULT; } outb(c, i); i++; tmp++; } *ppos = i; return tmp-buf;}#endif
static ssize_t read_null(struct file *file, char __user *buf, size_t count, loff_t *ppos){ return 0;}
static ssize_t write_null(struct file *file, const char __user *buf, size_t count, loff_t *ppos){ return count;}
static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to){ return 0;}
static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from){ size_t count = iov_iter_count(from); iov_iter_advance(from, count); return count;}
static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, struct splice_desc *sd){ return sd->len;}
static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags){ return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);}
static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags){ return 0;}
static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter){ size_t written = 0;
while (iov_iter_count(iter)) { size_t chunk = iov_iter_count(iter), n;
if (chunk > PAGE_SIZE) chunk = PAGE_SIZE; /* Just for latency reasons */ n = iov_iter_zero(chunk, iter); if (!n && iov_iter_count(iter)) return written ? written : -EFAULT; written += n; if (signal_pending(current)) return written ? written : -ERESTARTSYS; if (!need_resched()) continue; if (iocb->ki_flags & IOCB_NOWAIT) return written ? written : -EAGAIN; cond_resched(); } return written;}
static ssize_t read_zero(struct file *file, char __user *buf, size_t count, loff_t *ppos){ size_t cleared = 0;
while (count) { size_t chunk = min_t(size_t, count, PAGE_SIZE); size_t left;
left = clear_user(buf + cleared, chunk); if (unlikely(left)) { cleared += (chunk - left); if (!cleared) return -EFAULT; break; } cleared += chunk; count -= chunk;
if (signal_pending(current)) break; cond_resched(); }
return cleared;}
static int mmap_zero_prepare(struct vm_area_desc *desc){#ifndef CONFIG_MMU return -ENOSYS;#endif if (vma_desc_test(desc, VMA_SHARED_BIT)) return shmem_zero_setup_desc(desc);
/* * This is a highly unique situation where we mark a MAP_PRIVATE mapping * of /dev/zero anonymous, despite it not being. */ vma_desc_set_anonymous(desc); return 0;}
#ifndef CONFIG_MMUstatic unsigned long get_unmapped_area_zero(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags){ return -ENOSYS;}#elsestatic unsigned long get_unmapped_area_zero(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags){ if (flags & MAP_SHARED) { /* * mmap_zero_prepare() will call shmem_zero_setup() to create a * file, so use shmem's get_unmapped_area in case it can be * huge; and pass NULL for file as in mmap.c's * get_unmapped_area(), so as not to confuse shmem with our * handle on "/dev/zero". */ return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); }
/* * Otherwise flags & MAP_PRIVATE: with no shmem object beneath it, * attempt to map aligned to huge page size if possible, otherwise we * fall back to system page size mappings. */#ifdef CONFIG_TRANSPARENT_HUGEPAGE return thp_get_unmapped_area(file, addr, len, pgoff, flags);#else return mm_get_unmapped_area(file, addr, len, pgoff, flags);#endif}#endif /* CONFIG_MMU */
static ssize_t write_full(struct file *file, const char __user *buf, size_t count, loff_t *ppos){ return -ENOSPC;}
/* * Special lseek() function for /dev/null and /dev/zero. Most notably, you * can fopen() both devices with "a" now. This was previously impossible. * -- SRB. */static loff_t null_lseek(struct file *file, loff_t offset, int orig){ return file->f_pos = 0;}
/* * The memory devices use the full 32/64 bits of the offset, and so we cannot * check against negative addresses: they are ok. The return value is weird, * though, in that case (0). * * also note that seeking relative to the "end of file" isn't supported: * it has no meaning, so it returns -EINVAL. */static loff_t memory_lseek(struct file *file, loff_t offset, int orig){ loff_t ret;
inode_lock(file_inode(file)); switch (orig) { case SEEK_CUR: offset += file->f_pos; fallthrough; case SEEK_SET: /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ if ((unsigned long long)offset >= -MAX_ERRNO) { ret = -EOVERFLOW; break; } file->f_pos = offset; ret = file->f_pos; force_successful_syscall_return(); break; default: ret = -EINVAL; } inode_unlock(file_inode(file)); return ret;}
static int open_port(struct inode *inode, struct file *filp){ int rc;
if (!capable(CAP_SYS_RAWIO)) return -EPERM;
rc = security_locked_down(LOCKDOWN_DEV_MEM); if (rc) return rc;
if (iminor(inode) != DEVMEM_MINOR) return 0;
/* * Use a unified address space to have a single point to manage * revocations when drivers want to take over a /dev/mem mapped * range. */ filp->f_mapping = iomem_get_mapping();
return 0;}
#define zero_lseek null_lseek#define full_lseek null_lseek#define write_zero write_null#define write_iter_zero write_iter_null#define splice_write_zero splice_write_null#define open_mem open_port
static const struct file_operations __maybe_unused mem_fops = { .llseek = memory_lseek, .read = read_mem, .write = write_mem, .mmap_prepare = mmap_mem_prepare, .open = open_mem,#ifndef CONFIG_MMU .get_unmapped_area = get_unmapped_area_mem, .mmap_capabilities = memory_mmap_capabilities,#endif .fop_flags = FOP_UNSIGNED_OFFSET,};
static const struct file_operations null_fops = { .llseek = null_lseek, .read = read_null, .write = write_null, .read_iter = read_iter_null, .write_iter = write_iter_null, .splice_write = splice_write_null, .uring_cmd = uring_cmd_null,};
#ifdef CONFIG_DEVPORTstatic const struct file_operations port_fops = { .llseek = memory_lseek, .read = read_port, .write = write_port, .open = open_port,};#endif
static const struct file_operations zero_fops = { .llseek = zero_lseek, .write = write_zero, .read_iter = read_iter_zero, .read = read_zero, .write_iter = write_iter_zero, .splice_read = copy_splice_read, .splice_write = splice_write_zero, .mmap_prepare = mmap_zero_prepare, .get_unmapped_area = get_unmapped_area_zero,#ifndef CONFIG_MMU .mmap_capabilities = zero_mmap_capabilities,#endif};
static const struct file_operations full_fops = { .llseek = full_lseek, .read_iter = read_iter_zero, .write = write_full, .splice_read = copy_splice_read,};
static const struct memdev { const char *name; const struct file_operations *fops; fmode_t fmode; umode_t mode;} devlist[] = {#ifdef CONFIG_DEVMEM [DEVMEM_MINOR] = { "mem", &mem_fops, 0, 0 },#endif [3] = { "null", &null_fops, FMODE_NOWAIT, 0666 },#ifdef CONFIG_DEVPORT [4] = { "port", &port_fops, 0, 0 },#endif [5] = { "zero", &zero_fops, FMODE_NOWAIT, 0666 }, [7] = { "full", &full_fops, 0, 0666 }, [8] = { "random", &random_fops, FMODE_NOWAIT, 0666 }, [9] = { "urandom", &urandom_fops, FMODE_NOWAIT, 0666 },#ifdef CONFIG_PRINTK [11] = { "kmsg", &kmsg_fops, 0, 0644 },#endif};
static int memory_open(struct inode *inode, struct file *filp){ int minor; const struct memdev *dev;
minor = iminor(inode); if (minor >= ARRAY_SIZE(devlist)) return -ENXIO;
dev = &devlist[minor]; if (!dev->fops) return -ENXIO;
filp->f_op = dev->fops; filp->f_mode |= dev->fmode;
if (dev->fops->open) return dev->fops->open(inode, filp);
return 0;}
static const struct file_operations memory_fops = { .open = memory_open, .llseek = noop_llseek,};
static char *mem_devnode(const struct device *dev, umode_t *mode){ if (mode && devlist[MINOR(dev->devt)].mode) *mode = devlist[MINOR(dev->devt)].mode; return NULL;}
static const struct class mem_class = { .name = "mem", .devnode = mem_devnode,};
static int __init chr_dev_init(void){ int retval; int minor;
if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) printk("unable to get major %d for memory devs\n", MEM_MAJOR);
retval = class_register(&mem_class); if (retval) return retval;
for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { if (!devlist[minor].name) continue;
/* * Create /dev/port? */ if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) continue;
device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor), NULL, devlist[minor].name); }
return tty_init();}
fs_initcall(chr_dev_init);