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uaccess: Selectively open read or write user access 

When opening user access to only perform reads, only open read access.
When opening user access to only perform writes, only open write
access.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2e73bc57125c2c6ab12a587586a4eed3a47105fc.1585898438.git.christophe.leroy@c-s.fr
alistair/sunxi64-5.8
Christophe Leroy 2020-04-03 07:20:51 +00:00 committed by Michael Ellerman
parent 999a22890c
commit 41cd780524
6 changed files with 25 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/readdir.c
View File

@ -242,7 +242,7 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen,
return -EINTR;
dirent = buf->current_dir;
prev = (void __user *) dirent - prev_reclen;
if (!user_access_begin(prev, reclen + prev_reclen))
if (!user_write_access_begin(prev, reclen + prev_reclen))
goto efault;
/* This might be 'dirent->d_off', but if so it will get overwritten */
@ -251,14 +251,14 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen,
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
user_write_access_end();
buf->current_dir = (void __user *)dirent + reclen;
buf->prev_reclen = reclen;
buf->count -= reclen;
return 0;
efault_end:
user_access_end();
user_write_access_end();
efault:
buf->error = -EFAULT;
return -EFAULT;
@ -327,7 +327,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
return -EINTR;
dirent = buf->current_dir;
prev = (void __user *)dirent - prev_reclen;
if (!user_access_begin(prev, reclen + prev_reclen))
if (!user_write_access_begin(prev, reclen + prev_reclen))
goto efault;
/* This might be 'dirent->d_off', but if so it will get overwritten */
@ -336,7 +336,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, &dirent->d_type, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
user_write_access_end();
buf->prev_reclen = reclen;
buf->current_dir = (void __user *)dirent + reclen;
@ -344,7 +344,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
return 0;
efault_end:
user_access_end();
user_write_access_end();
efault:
buf->error = -EFAULT;
return -EFAULT;

12
kernel/compat.c
View File

@ -199,7 +199,7 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
if (!user_access_begin(umask, bitmap_size / 8))
if (!user_read_access_begin(umask, bitmap_size / 8))
return -EFAULT;
while (nr_compat_longs > 1) {
@ -211,11 +211,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
}
if (nr_compat_longs)
unsafe_get_user(*mask, umask++, Efault);
user_access_end();
user_read_access_end();
return 0;
Efault:
user_access_end();
user_read_access_end();
return -EFAULT;
}
@ -228,7 +228,7 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
if (!user_access_begin(umask, bitmap_size / 8))
if (!user_write_access_begin(umask, bitmap_size / 8))
return -EFAULT;
while (nr_compat_longs > 1) {
@ -239,10 +239,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
}
if (nr_compat_longs)
unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
user_access_end();
user_write_access_end();
return 0;
Efault:
user_access_end();
user_write_access_end();
return -EFAULT;
}

12
kernel/exit.c
View File

@ -1557,7 +1557,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
if (!infop)
return err;
if (!user_access_begin(infop, sizeof(*infop)))
if (!user_write_access_begin(infop, sizeof(*infop)))
return -EFAULT;
unsafe_put_user(signo, &infop->si_signo, Efault);
@ -1566,10 +1566,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
unsafe_put_user(info.pid, &infop->si_pid, Efault);
unsafe_put_user(info.uid, &infop->si_uid, Efault);
unsafe_put_user(info.status, &infop->si_status, Efault);
user_access_end();
user_write_access_end();
return err;
Efault:
user_access_end();
user_write_access_end();
return -EFAULT;
}
@ -1684,7 +1684,7 @@ COMPAT_SYSCALL_DEFINE5(waitid,
if (!infop)
return err;
if (!user_access_begin(infop, sizeof(*infop)))
if (!user_write_access_begin(infop, sizeof(*infop)))
return -EFAULT;
unsafe_put_user(signo, &infop->si_signo, Efault);
@ -1693,10 +1693,10 @@ COMPAT_SYSCALL_DEFINE5(waitid,
unsafe_put_user(info.pid, &infop->si_pid, Efault);
unsafe_put_user(info.uid, &infop->si_uid, Efault);
unsafe_put_user(info.status, &infop->si_status, Efault);
user_access_end();
user_write_access_end();
return err;
Efault:
user_access_end();
user_write_access_end();
return -EFAULT;
}
#endif

4
lib/strncpy_from_user.c
View File

@ -116,9 +116,9 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
kasan_check_write(dst, count);
check_object_size(dst, count, false);
if (user_access_begin(src, max)) {
if (user_read_access_begin(src, max)) {
retval = do_strncpy_from_user(dst, src, count, max);
user_access_end();
user_read_access_end();
return retval;
}
}

4
lib/strnlen_user.c
View File

@ -109,9 +109,9 @@ long strnlen_user(const char __user *str, long count)
if (max > count)
max = count;
if (user_access_begin(str, max)) {
if (user_read_access_begin(str, max)) {
retval = do_strnlen_user(str, count, max);
user_access_end();
user_read_access_end();
return retval;
}
}

6
lib/usercopy.c
View File

@ -58,7 +58,7 @@ int check_zeroed_user(const void __user *from, size_t size)
from -= align;
size += align;
if (!user_access_begin(from, size))
if (!user_read_access_begin(from, size))
return -EFAULT;
unsafe_get_user(val, (unsigned long __user *) from, err_fault);
@ -79,10 +79,10 @@ int check_zeroed_user(const void __user *from, size_t size)
val &= aligned_byte_mask(size);
done:
user_access_end();
user_read_access_end();
return (val == 0);
err_fault:
user_access_end();
user_read_access_end();
return -EFAULT;
}
EXPORT_SYMBOL(check_zeroed_user);