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552 lines
14 KiB
552 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/fs/readdir.c |
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* |
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* Copyright (C) 1995 Linus Torvalds |
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*/ |
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|
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#include <linux/stddef.h> |
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#include <linux/kernel.h> |
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#include <linux/export.h> |
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#include <linux/time.h> |
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#include <linux/mm.h> |
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#include <linux/errno.h> |
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#include <linux/stat.h> |
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#include <linux/file.h> |
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#include <linux/fs.h> |
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#include <linux/fsnotify.h> |
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#include <linux/dirent.h> |
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#include <linux/security.h> |
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#include <linux/syscalls.h> |
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#include <linux/unistd.h> |
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#include <linux/compat.h> |
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#include <linux/uaccess.h> |
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#include <asm/unaligned.h> |
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|
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/* |
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* Note the "unsafe_put_user() semantics: we goto a |
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* label for errors. |
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*/ |
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#define unsafe_copy_dirent_name(_dst, _src, _len, label) do { \ |
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char __user *dst = (_dst); \ |
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const char *src = (_src); \ |
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size_t len = (_len); \ |
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unsafe_put_user(0, dst+len, label); \ |
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unsafe_copy_to_user(dst, src, len, label); \ |
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} while (0) |
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int iterate_dir(struct file *file, struct dir_context *ctx) |
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{ |
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struct inode *inode = file_inode(file); |
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bool shared = false; |
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int res = -ENOTDIR; |
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if (file->f_op->iterate_shared) |
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shared = true; |
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else if (!file->f_op->iterate) |
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goto out; |
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res = security_file_permission(file, MAY_READ); |
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if (res) |
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goto out; |
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if (shared) |
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res = down_read_killable(&inode->i_rwsem); |
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else |
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res = down_write_killable(&inode->i_rwsem); |
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if (res) |
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goto out; |
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res = -ENOENT; |
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if (!IS_DEADDIR(inode)) { |
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ctx->pos = file->f_pos; |
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if (shared) |
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res = file->f_op->iterate_shared(file, ctx); |
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else |
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res = file->f_op->iterate(file, ctx); |
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file->f_pos = ctx->pos; |
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fsnotify_access(file); |
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file_accessed(file); |
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} |
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if (shared) |
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inode_unlock_shared(inode); |
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else |
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inode_unlock(inode); |
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out: |
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return res; |
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} |
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EXPORT_SYMBOL(iterate_dir); |
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/* |
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* POSIX says that a dirent name cannot contain NULL or a '/'. |
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* |
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* It's not 100% clear what we should really do in this case. |
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* The filesystem is clearly corrupted, but returning a hard |
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* error means that you now don't see any of the other names |
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* either, so that isn't a perfect alternative. |
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* |
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* And if you return an error, what error do you use? Several |
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* filesystems seem to have decided on EUCLEAN being the error |
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* code for EFSCORRUPTED, and that may be the error to use. Or |
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* just EIO, which is perhaps more obvious to users. |
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* |
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* In order to see the other file names in the directory, the |
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* caller might want to make this a "soft" error: skip the |
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* entry, and return the error at the end instead. |
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* |
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* Note that this should likely do a "memchr(name, 0, len)" |
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* check too, since that would be filesystem corruption as |
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* well. However, that case can't actually confuse user space, |
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* which has to do a strlen() on the name anyway to find the |
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* filename length, and the above "soft error" worry means |
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* that it's probably better left alone until we have that |
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* issue clarified. |
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* |
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* Note the PATH_MAX check - it's arbitrary but the real |
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* kernel limit on a possible path component, not NAME_MAX, |
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* which is the technical standard limit. |
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*/ |
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static int verify_dirent_name(const char *name, int len) |
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{ |
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if (len <= 0 || len >= PATH_MAX) |
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return -EIO; |
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if (memchr(name, '/', len)) |
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return -EIO; |
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return 0; |
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} |
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/* |
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* Traditional linux readdir() handling.. |
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* |
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* "count=1" is a special case, meaning that the buffer is one |
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* dirent-structure in size and that the code can't handle more |
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* anyway. Thus the special "fillonedir()" function for that |
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* case (the low-level handlers don't need to care about this). |
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*/ |
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#ifdef __ARCH_WANT_OLD_READDIR |
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struct old_linux_dirent { |
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unsigned long d_ino; |
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unsigned long d_offset; |
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unsigned short d_namlen; |
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char d_name[1]; |
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}; |
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struct readdir_callback { |
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struct dir_context ctx; |
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struct old_linux_dirent __user * dirent; |
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int result; |
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}; |
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static int fillonedir(struct dir_context *ctx, const char *name, int namlen, |
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loff_t offset, u64 ino, unsigned int d_type) |
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{ |
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struct readdir_callback *buf = |
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container_of(ctx, struct readdir_callback, ctx); |
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struct old_linux_dirent __user * dirent; |
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unsigned long d_ino; |
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if (buf->result) |
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return -EINVAL; |
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buf->result = verify_dirent_name(name, namlen); |
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if (buf->result < 0) |
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return buf->result; |
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d_ino = ino; |
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if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { |
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buf->result = -EOVERFLOW; |
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return -EOVERFLOW; |
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} |
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buf->result++; |
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dirent = buf->dirent; |
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if (!user_write_access_begin(dirent, |
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(unsigned long)(dirent->d_name + namlen + 1) - |
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(unsigned long)dirent)) |
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goto efault; |
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unsafe_put_user(d_ino, &dirent->d_ino, efault_end); |
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unsafe_put_user(offset, &dirent->d_offset, efault_end); |
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unsafe_put_user(namlen, &dirent->d_namlen, efault_end); |
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unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); |
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user_write_access_end(); |
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return 0; |
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efault_end: |
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user_write_access_end(); |
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efault: |
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buf->result = -EFAULT; |
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return -EFAULT; |
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} |
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SYSCALL_DEFINE3(old_readdir, unsigned int, fd, |
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struct old_linux_dirent __user *, dirent, unsigned int, count) |
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{ |
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int error; |
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struct fd f = fdget_pos(fd); |
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struct readdir_callback buf = { |
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.ctx.actor = fillonedir, |
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.dirent = dirent |
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}; |
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if (!f.file) |
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return -EBADF; |
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error = iterate_dir(f.file, &buf.ctx); |
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if (buf.result) |
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error = buf.result; |
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fdput_pos(f); |
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return error; |
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} |
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#endif /* __ARCH_WANT_OLD_READDIR */ |
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/* |
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* New, all-improved, singing, dancing, iBCS2-compliant getdents() |
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* interface. |
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*/ |
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struct linux_dirent { |
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unsigned long d_ino; |
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unsigned long d_off; |
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unsigned short d_reclen; |
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char d_name[1]; |
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}; |
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struct getdents_callback { |
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struct dir_context ctx; |
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struct linux_dirent __user * current_dir; |
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int prev_reclen; |
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int count; |
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int error; |
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}; |
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static int filldir(struct dir_context *ctx, const char *name, int namlen, |
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loff_t offset, u64 ino, unsigned int d_type) |
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{ |
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struct linux_dirent __user *dirent, *prev; |
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struct getdents_callback *buf = |
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container_of(ctx, struct getdents_callback, ctx); |
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unsigned long d_ino; |
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int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, |
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sizeof(long)); |
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int prev_reclen; |
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buf->error = verify_dirent_name(name, namlen); |
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if (unlikely(buf->error)) |
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return buf->error; |
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buf->error = -EINVAL; /* only used if we fail.. */ |
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if (reclen > buf->count) |
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return -EINVAL; |
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d_ino = ino; |
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if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { |
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buf->error = -EOVERFLOW; |
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return -EOVERFLOW; |
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} |
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prev_reclen = buf->prev_reclen; |
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if (prev_reclen && signal_pending(current)) |
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return -EINTR; |
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dirent = buf->current_dir; |
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prev = (void __user *) dirent - prev_reclen; |
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if (!user_write_access_begin(prev, reclen + prev_reclen)) |
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goto efault; |
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/* This might be 'dirent->d_off', but if so it will get overwritten */ |
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unsafe_put_user(offset, &prev->d_off, efault_end); |
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unsafe_put_user(d_ino, &dirent->d_ino, efault_end); |
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unsafe_put_user(reclen, &dirent->d_reclen, efault_end); |
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unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); |
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unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); |
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user_write_access_end(); |
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buf->current_dir = (void __user *)dirent + reclen; |
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buf->prev_reclen = reclen; |
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buf->count -= reclen; |
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return 0; |
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efault_end: |
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user_write_access_end(); |
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efault: |
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buf->error = -EFAULT; |
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return -EFAULT; |
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} |
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SYSCALL_DEFINE3(getdents, unsigned int, fd, |
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struct linux_dirent __user *, dirent, unsigned int, count) |
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{ |
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struct fd f; |
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struct getdents_callback buf = { |
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.ctx.actor = filldir, |
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.count = count, |
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.current_dir = dirent |
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}; |
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int error; |
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f = fdget_pos(fd); |
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if (!f.file) |
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return -EBADF; |
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error = iterate_dir(f.file, &buf.ctx); |
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if (error >= 0) |
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error = buf.error; |
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if (buf.prev_reclen) { |
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struct linux_dirent __user * lastdirent; |
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lastdirent = (void __user *)buf.current_dir - buf.prev_reclen; |
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if (put_user(buf.ctx.pos, &lastdirent->d_off)) |
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error = -EFAULT; |
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else |
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error = count - buf.count; |
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} |
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fdput_pos(f); |
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return error; |
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} |
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struct getdents_callback64 { |
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struct dir_context ctx; |
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struct linux_dirent64 __user * current_dir; |
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int prev_reclen; |
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int count; |
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int error; |
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}; |
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static int filldir64(struct dir_context *ctx, const char *name, int namlen, |
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loff_t offset, u64 ino, unsigned int d_type) |
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{ |
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struct linux_dirent64 __user *dirent, *prev; |
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struct getdents_callback64 *buf = |
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container_of(ctx, struct getdents_callback64, ctx); |
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int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, |
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sizeof(u64)); |
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int prev_reclen; |
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buf->error = verify_dirent_name(name, namlen); |
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if (unlikely(buf->error)) |
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return buf->error; |
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buf->error = -EINVAL; /* only used if we fail.. */ |
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if (reclen > buf->count) |
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return -EINVAL; |
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prev_reclen = buf->prev_reclen; |
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if (prev_reclen && signal_pending(current)) |
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return -EINTR; |
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dirent = buf->current_dir; |
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prev = (void __user *)dirent - prev_reclen; |
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if (!user_write_access_begin(prev, reclen + prev_reclen)) |
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goto efault; |
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/* This might be 'dirent->d_off', but if so it will get overwritten */ |
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unsafe_put_user(offset, &prev->d_off, efault_end); |
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unsafe_put_user(ino, &dirent->d_ino, efault_end); |
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unsafe_put_user(reclen, &dirent->d_reclen, efault_end); |
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unsafe_put_user(d_type, &dirent->d_type, efault_end); |
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unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); |
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user_write_access_end(); |
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buf->prev_reclen = reclen; |
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buf->current_dir = (void __user *)dirent + reclen; |
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buf->count -= reclen; |
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return 0; |
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efault_end: |
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user_write_access_end(); |
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efault: |
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buf->error = -EFAULT; |
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return -EFAULT; |
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} |
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SYSCALL_DEFINE3(getdents64, unsigned int, fd, |
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struct linux_dirent64 __user *, dirent, unsigned int, count) |
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{ |
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struct fd f; |
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struct getdents_callback64 buf = { |
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.ctx.actor = filldir64, |
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.count = count, |
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.current_dir = dirent |
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}; |
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int error; |
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f = fdget_pos(fd); |
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if (!f.file) |
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return -EBADF; |
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error = iterate_dir(f.file, &buf.ctx); |
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if (error >= 0) |
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error = buf.error; |
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if (buf.prev_reclen) { |
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struct linux_dirent64 __user * lastdirent; |
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typeof(lastdirent->d_off) d_off = buf.ctx.pos; |
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lastdirent = (void __user *) buf.current_dir - buf.prev_reclen; |
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if (put_user(d_off, &lastdirent->d_off)) |
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error = -EFAULT; |
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else |
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error = count - buf.count; |
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} |
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fdput_pos(f); |
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return error; |
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} |
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#ifdef CONFIG_COMPAT |
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struct compat_old_linux_dirent { |
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compat_ulong_t d_ino; |
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compat_ulong_t d_offset; |
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unsigned short d_namlen; |
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char d_name[1]; |
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}; |
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struct compat_readdir_callback { |
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struct dir_context ctx; |
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struct compat_old_linux_dirent __user *dirent; |
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int result; |
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}; |
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static int compat_fillonedir(struct dir_context *ctx, const char *name, |
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int namlen, loff_t offset, u64 ino, |
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unsigned int d_type) |
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{ |
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struct compat_readdir_callback *buf = |
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container_of(ctx, struct compat_readdir_callback, ctx); |
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struct compat_old_linux_dirent __user *dirent; |
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compat_ulong_t d_ino; |
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if (buf->result) |
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return -EINVAL; |
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buf->result = verify_dirent_name(name, namlen); |
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if (buf->result < 0) |
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return buf->result; |
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d_ino = ino; |
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if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { |
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buf->result = -EOVERFLOW; |
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return -EOVERFLOW; |
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} |
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buf->result++; |
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dirent = buf->dirent; |
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if (!user_write_access_begin(dirent, |
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(unsigned long)(dirent->d_name + namlen + 1) - |
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(unsigned long)dirent)) |
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goto efault; |
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unsafe_put_user(d_ino, &dirent->d_ino, efault_end); |
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unsafe_put_user(offset, &dirent->d_offset, efault_end); |
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unsafe_put_user(namlen, &dirent->d_namlen, efault_end); |
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unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); |
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user_write_access_end(); |
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return 0; |
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efault_end: |
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user_write_access_end(); |
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efault: |
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buf->result = -EFAULT; |
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return -EFAULT; |
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} |
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COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd, |
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struct compat_old_linux_dirent __user *, dirent, unsigned int, count) |
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{ |
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int error; |
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struct fd f = fdget_pos(fd); |
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struct compat_readdir_callback buf = { |
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.ctx.actor = compat_fillonedir, |
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.dirent = dirent |
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}; |
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if (!f.file) |
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return -EBADF; |
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error = iterate_dir(f.file, &buf.ctx); |
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if (buf.result) |
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error = buf.result; |
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fdput_pos(f); |
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return error; |
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} |
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struct compat_linux_dirent { |
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compat_ulong_t d_ino; |
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compat_ulong_t d_off; |
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unsigned short d_reclen; |
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char d_name[1]; |
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}; |
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struct compat_getdents_callback { |
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struct dir_context ctx; |
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struct compat_linux_dirent __user *current_dir; |
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int prev_reclen; |
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int count; |
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int error; |
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}; |
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static int compat_filldir(struct dir_context *ctx, const char *name, int namlen, |
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loff_t offset, u64 ino, unsigned int d_type) |
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{ |
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struct compat_linux_dirent __user *dirent, *prev; |
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struct compat_getdents_callback *buf = |
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container_of(ctx, struct compat_getdents_callback, ctx); |
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compat_ulong_t d_ino; |
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int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) + |
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namlen + 2, sizeof(compat_long_t)); |
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int prev_reclen; |
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buf->error = verify_dirent_name(name, namlen); |
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if (unlikely(buf->error)) |
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return buf->error; |
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buf->error = -EINVAL; /* only used if we fail.. */ |
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if (reclen > buf->count) |
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return -EINVAL; |
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d_ino = ino; |
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if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { |
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buf->error = -EOVERFLOW; |
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return -EOVERFLOW; |
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} |
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prev_reclen = buf->prev_reclen; |
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if (prev_reclen && signal_pending(current)) |
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return -EINTR; |
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dirent = buf->current_dir; |
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prev = (void __user *) dirent - prev_reclen; |
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if (!user_write_access_begin(prev, reclen + prev_reclen)) |
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goto efault; |
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unsafe_put_user(offset, &prev->d_off, efault_end); |
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unsafe_put_user(d_ino, &dirent->d_ino, efault_end); |
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unsafe_put_user(reclen, &dirent->d_reclen, efault_end); |
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unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); |
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unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); |
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user_write_access_end(); |
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buf->prev_reclen = reclen; |
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buf->current_dir = (void __user *)dirent + reclen; |
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buf->count -= reclen; |
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return 0; |
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efault_end: |
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user_write_access_end(); |
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efault: |
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buf->error = -EFAULT; |
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return -EFAULT; |
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} |
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COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd, |
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struct compat_linux_dirent __user *, dirent, unsigned int, count) |
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{ |
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struct fd f; |
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struct compat_getdents_callback buf = { |
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.ctx.actor = compat_filldir, |
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.current_dir = dirent, |
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.count = count |
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}; |
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int error; |
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f = fdget_pos(fd); |
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if (!f.file) |
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return -EBADF; |
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error = iterate_dir(f.file, &buf.ctx); |
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if (error >= 0) |
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error = buf.error; |
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if (buf.prev_reclen) { |
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struct compat_linux_dirent __user * lastdirent; |
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lastdirent = (void __user *)buf.current_dir - buf.prev_reclen; |
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|
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if (put_user(buf.ctx.pos, &lastdirent->d_off)) |
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error = -EFAULT; |
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else |
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error = count - buf.count; |
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} |
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fdput_pos(f); |
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return error; |
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} |
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#endif
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