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    Subject[PATCH v7 1/7] exec: Change uselib(2) IS_SREG() failure to EACCES
    Date
    From: Kees Cook <keescook@chromium.org>

    Change uselib(2)' S_ISREG() error return to EACCES instead of EINVAL so
    the behavior matches execve(2), and the seemingly documented value.
    The "not a regular file" failure mode of execve(2) is explicitly
    documented[1], but it is not mentioned in uselib(2)[2] which does,
    however, say that open(2) and mmap(2) errors may apply. The documentation
    for open(2) does not include a "not a regular file" error[3], but mmap(2)
    does[4], and it is EACCES.

    [1] http://man7.org/linux/man-pages/man2/execve.2.html#ERRORS
    [2] http://man7.org/linux/man-pages/man2/uselib.2.html#ERRORS
    [3] http://man7.org/linux/man-pages/man2/open.2.html#ERRORS
    [4] http://man7.org/linux/man-pages/man2/mmap.2.html#ERRORS

    Signed-off-by: Mickaël Salaün <mic@digikod.net>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
    Link: https://lore.kernel.org/r/20200605160013.3954297-2-keescook@chromium.org
    ---
    fs/exec.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index e6e8a9a70327..d7c937044d10 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -141,11 +141,10 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
    if (IS_ERR(file))
    goto out;

    - error = -EINVAL;
    + error = -EACCES;
    if (!S_ISREG(file_inode(file)->i_mode))
    goto exit;

    - error = -EACCES;
    if (path_noexec(&file->f_path))
    goto exit;

    --
    2.27.0
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