9b54bf9d6a
Using this helper allows us to avoid the in-kernel calls to the
compat_sys_{f,}statfs64() sycalls, as are necessary for parameter
mangling in arm64's compat handling.
Following the example of ksys_* functions, kcompat_sys_* functions are
intended to be a drop-in replacement for their compat_sys_*
counterparts, with the same calling convention.
This is necessary to enable conversion of arm64's syscall handling to
use pt_regs wrappers.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Will Deacon <will.deacon@arm.com>
396 lines
9.7 KiB
C
396 lines
9.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/syscalls.h>
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#include <linux/export.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/statfs.h>
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#include <linux/security.h>
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#include <linux/uaccess.h>
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#include <linux/compat.h>
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#include "internal.h"
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static int flags_by_mnt(int mnt_flags)
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{
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int flags = 0;
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if (mnt_flags & MNT_READONLY)
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flags |= ST_RDONLY;
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if (mnt_flags & MNT_NOSUID)
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flags |= ST_NOSUID;
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if (mnt_flags & MNT_NODEV)
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flags |= ST_NODEV;
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if (mnt_flags & MNT_NOEXEC)
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flags |= ST_NOEXEC;
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if (mnt_flags & MNT_NOATIME)
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flags |= ST_NOATIME;
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if (mnt_flags & MNT_NODIRATIME)
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flags |= ST_NODIRATIME;
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if (mnt_flags & MNT_RELATIME)
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flags |= ST_RELATIME;
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return flags;
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}
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static int flags_by_sb(int s_flags)
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{
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int flags = 0;
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if (s_flags & SB_SYNCHRONOUS)
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flags |= ST_SYNCHRONOUS;
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if (s_flags & SB_MANDLOCK)
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flags |= ST_MANDLOCK;
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if (s_flags & SB_RDONLY)
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flags |= ST_RDONLY;
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return flags;
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}
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static int calculate_f_flags(struct vfsmount *mnt)
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{
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return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
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flags_by_sb(mnt->mnt_sb->s_flags);
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}
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static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
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{
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int retval;
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if (!dentry->d_sb->s_op->statfs)
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return -ENOSYS;
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memset(buf, 0, sizeof(*buf));
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retval = security_sb_statfs(dentry);
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if (retval)
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return retval;
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retval = dentry->d_sb->s_op->statfs(dentry, buf);
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if (retval == 0 && buf->f_frsize == 0)
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buf->f_frsize = buf->f_bsize;
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return retval;
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}
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int vfs_statfs(const struct path *path, struct kstatfs *buf)
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{
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int error;
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error = statfs_by_dentry(path->dentry, buf);
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if (!error)
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buf->f_flags = calculate_f_flags(path->mnt);
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return error;
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}
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EXPORT_SYMBOL(vfs_statfs);
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int user_statfs(const char __user *pathname, struct kstatfs *st)
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{
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struct path path;
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int error;
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unsigned int lookup_flags = LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT;
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retry:
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error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
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if (!error) {
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error = vfs_statfs(&path, st);
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path_put(&path);
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if (retry_estale(error, lookup_flags)) {
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lookup_flags |= LOOKUP_REVAL;
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goto retry;
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}
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}
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return error;
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}
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int fd_statfs(int fd, struct kstatfs *st)
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{
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struct fd f = fdget_raw(fd);
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int error = -EBADF;
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if (f.file) {
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error = vfs_statfs(&f.file->f_path, st);
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fdput(f);
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}
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return error;
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}
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static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
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{
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struct statfs buf;
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if (sizeof(buf) == sizeof(*st))
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memcpy(&buf, st, sizeof(*st));
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else {
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if (sizeof buf.f_blocks == 4) {
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if ((st->f_blocks | st->f_bfree | st->f_bavail |
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st->f_bsize | st->f_frsize) &
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0xffffffff00000000ULL)
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return -EOVERFLOW;
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/*
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* f_files and f_ffree may be -1; it's okay to stuff
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* that into 32 bits
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*/
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if (st->f_files != -1 &&
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(st->f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (st->f_ffree != -1 &&
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(st->f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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buf.f_type = st->f_type;
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buf.f_bsize = st->f_bsize;
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buf.f_blocks = st->f_blocks;
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buf.f_bfree = st->f_bfree;
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buf.f_bavail = st->f_bavail;
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buf.f_files = st->f_files;
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buf.f_ffree = st->f_ffree;
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buf.f_fsid = st->f_fsid;
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buf.f_namelen = st->f_namelen;
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buf.f_frsize = st->f_frsize;
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buf.f_flags = st->f_flags;
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memset(buf.f_spare, 0, sizeof(buf.f_spare));
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}
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if (copy_to_user(p, &buf, sizeof(buf)))
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return -EFAULT;
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return 0;
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}
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static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
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{
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struct statfs64 buf;
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if (sizeof(buf) == sizeof(*st))
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memcpy(&buf, st, sizeof(*st));
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else {
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buf.f_type = st->f_type;
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buf.f_bsize = st->f_bsize;
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buf.f_blocks = st->f_blocks;
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buf.f_bfree = st->f_bfree;
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buf.f_bavail = st->f_bavail;
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buf.f_files = st->f_files;
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buf.f_ffree = st->f_ffree;
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buf.f_fsid = st->f_fsid;
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buf.f_namelen = st->f_namelen;
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buf.f_frsize = st->f_frsize;
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buf.f_flags = st->f_flags;
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memset(buf.f_spare, 0, sizeof(buf.f_spare));
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}
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if (copy_to_user(p, &buf, sizeof(buf)))
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return -EFAULT;
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return 0;
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}
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SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
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{
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struct kstatfs st;
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int error = user_statfs(pathname, &st);
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if (!error)
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error = do_statfs_native(&st, buf);
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return error;
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}
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SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
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{
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struct kstatfs st;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = user_statfs(pathname, &st);
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if (!error)
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error = do_statfs64(&st, buf);
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return error;
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}
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SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
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{
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struct kstatfs st;
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int error = fd_statfs(fd, &st);
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if (!error)
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error = do_statfs_native(&st, buf);
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return error;
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}
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SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
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{
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struct kstatfs st;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = fd_statfs(fd, &st);
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if (!error)
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error = do_statfs64(&st, buf);
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return error;
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}
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static int vfs_ustat(dev_t dev, struct kstatfs *sbuf)
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{
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struct super_block *s = user_get_super(dev);
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int err;
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if (!s)
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return -EINVAL;
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err = statfs_by_dentry(s->s_root, sbuf);
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drop_super(s);
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return err;
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}
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SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
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{
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struct ustat tmp;
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struct kstatfs sbuf;
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int err = vfs_ustat(new_decode_dev(dev), &sbuf);
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if (err)
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return err;
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memset(&tmp,0,sizeof(struct ustat));
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tmp.f_tfree = sbuf.f_bfree;
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tmp.f_tinode = sbuf.f_ffree;
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return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
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}
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#ifdef CONFIG_COMPAT
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static int put_compat_statfs(struct compat_statfs __user *ubuf, struct kstatfs *kbuf)
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{
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struct compat_statfs buf;
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if (sizeof ubuf->f_blocks == 4) {
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if ((kbuf->f_blocks | kbuf->f_bfree | kbuf->f_bavail |
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kbuf->f_bsize | kbuf->f_frsize) & 0xffffffff00000000ULL)
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return -EOVERFLOW;
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/* f_files and f_ffree may be -1; it's okay
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* to stuff that into 32 bits */
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if (kbuf->f_files != 0xffffffffffffffffULL
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&& (kbuf->f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (kbuf->f_ffree != 0xffffffffffffffffULL
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&& (kbuf->f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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memset(&buf, 0, sizeof(struct compat_statfs));
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buf.f_type = kbuf->f_type;
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buf.f_bsize = kbuf->f_bsize;
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buf.f_blocks = kbuf->f_blocks;
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buf.f_bfree = kbuf->f_bfree;
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buf.f_bavail = kbuf->f_bavail;
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buf.f_files = kbuf->f_files;
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buf.f_ffree = kbuf->f_ffree;
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buf.f_namelen = kbuf->f_namelen;
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buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
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buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
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buf.f_frsize = kbuf->f_frsize;
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buf.f_flags = kbuf->f_flags;
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if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs)))
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return -EFAULT;
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return 0;
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}
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/*
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* The following statfs calls are copies of code from fs/statfs.c and
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* should be checked against those from time to time
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*/
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COMPAT_SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct compat_statfs __user *, buf)
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{
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struct kstatfs tmp;
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int error = user_statfs(pathname, &tmp);
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if (!error)
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error = put_compat_statfs(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct compat_statfs __user *, buf)
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{
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struct kstatfs tmp;
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int error = fd_statfs(fd, &tmp);
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if (!error)
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error = put_compat_statfs(buf, &tmp);
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return error;
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}
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static int put_compat_statfs64(struct compat_statfs64 __user *ubuf, struct kstatfs *kbuf)
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{
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struct compat_statfs64 buf;
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if (sizeof(ubuf->f_bsize) == 4) {
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if ((kbuf->f_type | kbuf->f_bsize | kbuf->f_namelen |
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kbuf->f_frsize | kbuf->f_flags) & 0xffffffff00000000ULL)
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return -EOVERFLOW;
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/* f_files and f_ffree may be -1; it's okay
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* to stuff that into 32 bits */
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if (kbuf->f_files != 0xffffffffffffffffULL
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&& (kbuf->f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (kbuf->f_ffree != 0xffffffffffffffffULL
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&& (kbuf->f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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memset(&buf, 0, sizeof(struct compat_statfs64));
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buf.f_type = kbuf->f_type;
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buf.f_bsize = kbuf->f_bsize;
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buf.f_blocks = kbuf->f_blocks;
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buf.f_bfree = kbuf->f_bfree;
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buf.f_bavail = kbuf->f_bavail;
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buf.f_files = kbuf->f_files;
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buf.f_ffree = kbuf->f_ffree;
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buf.f_namelen = kbuf->f_namelen;
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buf.f_fsid.val[0] = kbuf->f_fsid.val[0];
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buf.f_fsid.val[1] = kbuf->f_fsid.val[1];
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buf.f_frsize = kbuf->f_frsize;
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buf.f_flags = kbuf->f_flags;
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if (copy_to_user(ubuf, &buf, sizeof(struct compat_statfs64)))
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return -EFAULT;
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return 0;
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}
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int kcompat_sys_statfs64(const char __user * pathname, compat_size_t sz, struct compat_statfs64 __user * buf)
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{
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struct kstatfs tmp;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = user_statfs(pathname, &tmp);
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if (!error)
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error = put_compat_statfs64(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE3(statfs64, const char __user *, pathname, compat_size_t, sz, struct compat_statfs64 __user *, buf)
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{
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return kcompat_sys_statfs64(pathname, sz, buf);
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}
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int kcompat_sys_fstatfs64(unsigned int fd, compat_size_t sz, struct compat_statfs64 __user * buf)
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{
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struct kstatfs tmp;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = fd_statfs(fd, &tmp);
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if (!error)
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error = put_compat_statfs64(buf, &tmp);
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return error;
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}
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COMPAT_SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, compat_size_t, sz, struct compat_statfs64 __user *, buf)
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{
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return kcompat_sys_fstatfs64(fd, sz, buf);
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}
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/*
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* This is a copy of sys_ustat, just dealing with a structure layout.
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* Given how simple this syscall is that apporach is more maintainable
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* than the various conversion hacks.
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*/
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COMPAT_SYSCALL_DEFINE2(ustat, unsigned, dev, struct compat_ustat __user *, u)
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{
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struct compat_ustat tmp;
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struct kstatfs sbuf;
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int err = vfs_ustat(new_decode_dev(dev), &sbuf);
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if (err)
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return err;
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memset(&tmp, 0, sizeof(struct compat_ustat));
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tmp.f_tfree = sbuf.f_bfree;
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tmp.f_tinode = sbuf.f_ffree;
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if (copy_to_user(u, &tmp, sizeof(struct compat_ustat)))
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return -EFAULT;
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return 0;
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}
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#endif
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