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uaccess: Selectively open read or write user access

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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
This commit is contained in:
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
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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);