On Mon, Apr 18, 2016 at 12:09 PM, Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote:
> A string representation of the kernel_read_file_id enumeration is
> needed for displaying messages (eg. pr_info, auditing) that can be
> used by multiple LSMs and the integrity subsystem. To simplify
> keeping the list of strings up to date with the enumeration, this
> patch defines two new preprocessing macros named __fid_enumify and
> __fid_stringify to create the enumeration and an array of strings.
> kernel_read_file_id_str() returns a string based on the enumeration.
>
> Changelog:
> - redefined the macros and simplified their usage - James Bottomley
>
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
This works for me! I'll add it to my LSM series to replace my
implementation of kernel_read_file_id_str.
Thanks!
-Kees
> ---
> fs/exec.c | 19 -------------------
> include/linux/fs.h | 32 +++++++++++++++++++++++++-------
> 2 files changed, 25 insertions(+), 26 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 05e71b6..c4010b8 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -819,25 +819,6 @@ struct file *open_exec(const char *name)
> }
> EXPORT_SYMBOL(open_exec);
>
> -const char *kernel_read_file_id_str(enum kernel_read_file_id id)
> -{
> - switch (id) {
> - case READING_FIRMWARE:
> - return "firmware";
> - case READING_MODULE:
> - return "kernel-module";
> - case READING_KEXEC_IMAGE:
> - return "kexec-image";
> - case READING_KEXEC_INITRAMFS:
> - return "kexec-initramfs";
> - case READING_POLICY:
> - return "security-policy";
> - default:
> - return "unknown";
> - }
> -}
> -EXPORT_SYMBOL(kernel_read_file_id_str);
> -
> int kernel_read(struct file *file, loff_t offset,
> char *addr, unsigned long count)
> {
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 23ea886..497c17f 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2580,16 +2580,34 @@ static inline void i_readcount_inc(struct inode *inode)
> #endif
> extern int do_pipe_flags(int *, int);
>
> +#define __kernel_read_file_id(id) \
> + id(UNKNOWN, unknown) \
> + id(FIRMWARE, firmware) \
> + id(MODULE, kernel-module) \
> + id(KEXEC_IMAGE, kexec-image) \
> + id(KEXEC_INITRAMFS, kexec-initramfs) \
> + id(POLICY, security-policy) \
> + id(MAX_ID, )
> +
> +#define __fid_enumify(ENUM, dummy) READING_ ## ENUM,
> +#define __fid_stringify(dummy, str) #str,
> +
> enum kernel_read_file_id {
> - READING_FIRMWARE = 1,
> - READING_MODULE,
> - READING_KEXEC_IMAGE,
> - READING_KEXEC_INITRAMFS,
> - READING_POLICY,
> - READING_MAX_ID
> + __kernel_read_file_id(__fid_enumify)
> +};
> +
> +static const char *kernel_read_file_str[] = {
> + __kernel_read_file_id(__fid_stringify)
> };
>
> -extern const char *kernel_read_file_id_str(enum kernel_read_file_id id);
> +static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
> +{
> + if (id < 0 || id >= READING_MAX_ID)
> + return kernel_read_file_str[READING_UNKNOWN];
> +
> + return kernel_read_file_str[id];
> +}
> +
> extern int kernel_read(struct file *, loff_t, char *, unsigned long);
> extern int kernel_read_file(struct file *, void **, loff_t *, loff_t,
> enum kernel_read_file_id);
> --
> 2.1.0
>
--
Kees Cook
Chrome OS & Brillo Security
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