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 de2eceffdee8baf97f584bf644872822fdef8ef3..ed6aaad451aa4f90aa5dd96c2054bf0304b676cf 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 843dd17e6078b6d530ecc46260703b390f9abbe4..b8d2800bb4b719eb8ad5407823415fe1e0daa8d9 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 389a88cb308192babd68abfb4f2022803c3346c1..2d97cbba512dbda01ecd7e0ea2957d16154c08b7 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 706020b06617ce6fae8e0e9517259a6a0fcfcb78..b90ec550183ae82196467bf161ec7de1f4eee877 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 41670d4a5816530d7b948fe29f0fad20a44ec2ed..1616710b8a82cf93f3ad4f1fa41f6ea35167dae1 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 cbb4d9ec00f207a8156cab8a4aa52fb8a49ff43e..ca2a697a206181803531691db196c5475fb57959 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);