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fs: remove various compat readv/writev helpers
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Now that import_iovec handles compat iovecs as well, all the duplicated
code in the compat readv/writev helpers is not needed.  Remove them
and switch the compat syscall handlers to use the native helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Christoph Hellwig authored and Al Viro committed Oct 3, 2020
1 parent 89cd35c commit 3523a9d
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Showing 2 changed files with 40 additions and 159 deletions.
179 changes: 30 additions & 149 deletions fs/read_write.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1068,226 +1068,107 @@ SYSCALL_DEFINE6(pwritev2, unsigned long, fd, const struct iovec __user *, vec,
return do_pwritev(fd, vec, vlen, pos, flags);
}

/*
* Various compat syscalls. Note that they all pretend to take a native
* iovec - import_iovec will properly treat those as compat_iovecs based on
* in_compat_syscall().
*/
#ifdef CONFIG_COMPAT
static size_t compat_readv(struct file *file,
const struct compat_iovec __user *vec,
unsigned long vlen, loff_t *pos, rwf_t flags)
{
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
ssize_t ret;

ret = import_iovec(READ, (const struct iovec __user *)vec, vlen,
UIO_FASTIOV, &iov, &iter);
if (ret >= 0) {
ret = do_iter_read(file, &iter, pos, flags);
kfree(iov);
}
if (ret > 0)
add_rchar(current, ret);
inc_syscr(current);
return ret;
}

static size_t do_compat_readv(compat_ulong_t fd,
const struct compat_iovec __user *vec,
compat_ulong_t vlen, rwf_t flags)
{
struct fd f = fdget_pos(fd);
ssize_t ret;
loff_t pos;

if (!f.file)
return -EBADF;
pos = f.file->f_pos;
ret = compat_readv(f.file, vec, vlen, &pos, flags);
if (ret >= 0)
f.file->f_pos = pos;
fdput_pos(f);
return ret;

}

COMPAT_SYSCALL_DEFINE3(readv, compat_ulong_t, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
compat_ulong_t, vlen)
{
return do_compat_readv(fd, vec, vlen, 0);
}

static long do_compat_preadv64(unsigned long fd,
const struct compat_iovec __user *vec,
unsigned long vlen, loff_t pos, rwf_t flags)
{
struct fd f;
ssize_t ret;

if (pos < 0)
return -EINVAL;
f = fdget(fd);
if (!f.file)
return -EBADF;
ret = -ESPIPE;
if (f.file->f_mode & FMODE_PREAD)
ret = compat_readv(f.file, vec, vlen, &pos, flags);
fdput(f);
return ret;
return do_readv(fd, vec, vlen, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
COMPAT_SYSCALL_DEFINE4(preadv64, unsigned long, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
unsigned long, vlen, loff_t, pos)
{
return do_compat_preadv64(fd, vec, vlen, pos, 0);
return do_preadv(fd, vec, vlen, pos, 0);
}
#endif

COMPAT_SYSCALL_DEFINE5(preadv, compat_ulong_t, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
{
loff_t pos = ((loff_t)pos_high << 32) | pos_low;

return do_compat_preadv64(fd, vec, vlen, pos, 0);
return do_preadv(fd, vec, vlen, pos, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
unsigned long, vlen, loff_t, pos, rwf_t, flags)
{
if (pos == -1)
return do_compat_readv(fd, vec, vlen, flags);

return do_compat_preadv64(fd, vec, vlen, pos, flags);
return do_readv(fd, vec, vlen, flags);
return do_preadv(fd, vec, vlen, pos, flags);
}
#endif

COMPAT_SYSCALL_DEFINE6(preadv2, compat_ulong_t, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
compat_ulong_t, vlen, u32, pos_low, u32, pos_high,
rwf_t, flags)
{
loff_t pos = ((loff_t)pos_high << 32) | pos_low;

if (pos == -1)
return do_compat_readv(fd, vec, vlen, flags);

return do_compat_preadv64(fd, vec, vlen, pos, flags);
}

static size_t compat_writev(struct file *file,
const struct compat_iovec __user *vec,
unsigned long vlen, loff_t *pos, rwf_t flags)
{
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct iov_iter iter;
ssize_t ret;

ret = import_iovec(WRITE, (const struct iovec __user *)vec, vlen,
UIO_FASTIOV, &iov, &iter);
if (ret >= 0) {
file_start_write(file);
ret = do_iter_write(file, &iter, pos, flags);
file_end_write(file);
kfree(iov);
}
if (ret > 0)
add_wchar(current, ret);
inc_syscw(current);
return ret;
}

static size_t do_compat_writev(compat_ulong_t fd,
const struct compat_iovec __user* vec,
compat_ulong_t vlen, rwf_t flags)
{
struct fd f = fdget_pos(fd);
ssize_t ret;
loff_t pos;

if (!f.file)
return -EBADF;
pos = f.file->f_pos;
ret = compat_writev(f.file, vec, vlen, &pos, flags);
if (ret >= 0)
f.file->f_pos = pos;
fdput_pos(f);
return ret;
return do_readv(fd, vec, vlen, flags);
return do_preadv(fd, vec, vlen, pos, flags);
}

COMPAT_SYSCALL_DEFINE3(writev, compat_ulong_t, fd,
const struct compat_iovec __user *, vec,
const struct iovec __user *, vec,
compat_ulong_t, vlen)
{
return do_compat_writev(fd, vec, vlen, 0);
}

static long do_compat_pwritev64(unsigned long fd,
const struct compat_iovec __user *vec,
unsigned long vlen, loff_t pos, rwf_t flags)
{
struct fd f;
ssize_t ret;

if (pos < 0)
return -EINVAL;
f = fdget(fd);
if (!f.file)
return -EBADF;
ret = -ESPIPE;
if (f.file->f_mode & FMODE_PWRITE)
ret = compat_writev(f.file, vec, vlen, &pos, flags);
fdput(f);
return ret;
return do_writev(fd, vec, vlen, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
COMPAT_SYSCALL_DEFINE4(pwritev64, unsigned long, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
unsigned long, vlen, loff_t, pos)
{
return do_compat_pwritev64(fd, vec, vlen, pos, 0);
return do_pwritev(fd, vec, vlen, pos, 0);
}
#endif

COMPAT_SYSCALL_DEFINE5(pwritev, compat_ulong_t, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *,vec,
compat_ulong_t, vlen, u32, pos_low, u32, pos_high)
{
loff_t pos = ((loff_t)pos_high << 32) | pos_low;

return do_compat_pwritev64(fd, vec, vlen, pos, 0);
return do_pwritev(fd, vec, vlen, pos, 0);
}

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *, vec,
unsigned long, vlen, loff_t, pos, rwf_t, flags)
{
if (pos == -1)
return do_compat_writev(fd, vec, vlen, flags);

return do_compat_pwritev64(fd, vec, vlen, pos, flags);
return do_writev(fd, vec, vlen, flags);
return do_pwritev(fd, vec, vlen, pos, flags);
}
#endif

COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
const struct compat_iovec __user *,vec,
const struct iovec __user *,vec,
compat_ulong_t, vlen, u32, pos_low, u32, pos_high, rwf_t, flags)
{
loff_t pos = ((loff_t)pos_high << 32) | pos_low;

if (pos == -1)
return do_compat_writev(fd, vec, vlen, flags);

return do_compat_pwritev64(fd, vec, vlen, pos, flags);
return do_writev(fd, vec, vlen, flags);
return do_pwritev(fd, vec, vlen, pos, flags);
}

#endif
#endif /* CONFIG_COMPAT */

static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
size_t count, loff_t max)
Expand Down
20 changes: 10 additions & 10 deletions include/linux/compat.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -546,25 +546,25 @@ asmlinkage long compat_sys_getdents(unsigned int fd,
/* fs/read_write.c */
asmlinkage long compat_sys_lseek(unsigned int, compat_off_t, unsigned int);
asmlinkage ssize_t compat_sys_readv(compat_ulong_t fd,
const struct compat_iovec __user *vec, compat_ulong_t vlen);
const struct iovec __user *vec, compat_ulong_t vlen);
asmlinkage ssize_t compat_sys_writev(compat_ulong_t fd,
const struct compat_iovec __user *vec, compat_ulong_t vlen);
const struct iovec __user *vec, compat_ulong_t vlen);
/* No generic prototype for pread64 and pwrite64 */
asmlinkage ssize_t compat_sys_preadv(compat_ulong_t fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
compat_ulong_t vlen, u32 pos_low, u32 pos_high);
asmlinkage ssize_t compat_sys_pwritev(compat_ulong_t fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
compat_ulong_t vlen, u32 pos_low, u32 pos_high);
#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64
asmlinkage long compat_sys_preadv64(unsigned long fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
unsigned long vlen, loff_t pos);
#endif

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64
asmlinkage long compat_sys_pwritev64(unsigned long fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
unsigned long vlen, loff_t pos);
#endif

Expand Down Expand Up @@ -800,20 +800,20 @@ asmlinkage long compat_sys_execveat(int dfd, const char __user *filename,
const compat_uptr_t __user *argv,
const compat_uptr_t __user *envp, int flags);
asmlinkage ssize_t compat_sys_preadv2(compat_ulong_t fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
compat_ulong_t vlen, u32 pos_low, u32 pos_high, rwf_t flags);
asmlinkage ssize_t compat_sys_pwritev2(compat_ulong_t fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
compat_ulong_t vlen, u32 pos_low, u32 pos_high, rwf_t flags);
#ifdef __ARCH_WANT_COMPAT_SYS_PREADV64V2
asmlinkage long compat_sys_preadv64v2(unsigned long fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
unsigned long vlen, loff_t pos, rwf_t flags);
#endif

#ifdef __ARCH_WANT_COMPAT_SYS_PWRITEV64V2
asmlinkage long compat_sys_pwritev64v2(unsigned long fd,
const struct compat_iovec __user *vec,
const struct iovec __user *vec,
unsigned long vlen, loff_t pos, rwf_t flags);
#endif

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