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

diff --git a/fs/readdir.c b/fs/readdir.c
index de2ecef..ed6aaad 100644 (file)
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -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;

diff --git a/kernel/compat.c b/kernel/compat.c
index 843dd17..b8d2800 100644 (file)
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -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;
 }
 

diff --git a/kernel/exit.c b/kernel/exit.c
index 389a88c..2d97cbb 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -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

diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 706020b..b90ec55 100644 (file)
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -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;
                }
        }

diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index 41670d4..1616710 100644 (file)
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -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;
                }
        }

diff --git a/lib/usercopy.c b/lib/usercopy.c
index cbb4d9e..ca2a697 100644 (file)
--- a/lib/usercopy.c
+++ b/lib/usercopy.c
@@ -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);