On Mon, Jul 27, 2020 at 09:23:34AM -0400, Mimi Zohar wrote: > On Fri, 2020-07-24 at 14:36 -0700, Kees Cook wrote: > > From: Scott Branden <scott.branden@xxxxxxxxxxxx> > > > > When the kernel_read_file LSM hook is called with contents=false, IMA > > can appraise the file directly, without requiring a filled buffer. When > > such a buffer is available, though, IMA can continue to use it instead > > of forcing a double read here. > > > > Signed-off-by: Scott Branden <scott.branden@xxxxxxxxxxxx> > > Link: https://lore.kernel.org/lkml/20200706232309.12010-10-scott.branden@xxxxxxxxxxxx/ > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > After adjusting the comment below. > > Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> Sure! Greg, shall I send a v4 with added Reviews and the comment change or is that minor enough that you're able to do it? Thanks for the reviews Mimi! -Kees > > > --- > > security/integrity/ima/ima_main.c | 22 ++++++++++++++++------ > > 1 file changed, 16 insertions(+), 6 deletions(-) > > > > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > > index dc4f90660aa6..459e50526a12 100644 > > --- a/security/integrity/ima/ima_main.c > > +++ b/security/integrity/ima/ima_main.c > > @@ -613,11 +613,8 @@ void ima_post_path_mknod(struct dentry *dentry) > > int ima_read_file(struct file *file, enum kernel_read_file_id read_id, > > bool contents) > > { > > - /* Reject all partial reads during appraisal. */ > > - if (!contents) { > > - if (ima_appraise & IMA_APPRAISE_ENFORCE) > > - return -EACCES; > > - } > > + enum ima_hooks func; > > + u32 secid; > > > > /* > > * Do devices using pre-allocated memory run the risk of the > > @@ -626,7 +623,20 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id, > > * buffers? It may be desirable to include the buffer address > > * in this API and walk all the dma_map_single() mappings to check. > > */ > > - return 0; > > + > > + /* > > + * There will be a call made to ima_post_read_file() with > > + * a filled buffer, so we don't need to perform an extra > > + * read early here. > > + */ > > + if (contents) > > + return 0; > > + > > + /* Read entire file for all partial reads during appraisal. */ > > In addition to verifying the file signature, the file might be > included in the IMA measurement list or the file hash may be used to > augment the audit record. Please remove "during appraisal" from the > comment. > > > + func = read_idmap[read_id] ?: FILE_CHECK; > > + security_task_getsecid(current, &secid); > > + return process_measurement(file, current_cred(), secid, NULL, > > + 0, MAY_READ, func); > > } > > > > const int read_idmap[READING_MAX_ID] = { > -- Kees Cook
