2021년 7월 13일 (화) 오전 11:49, Paul Moore <paul@xxxxxxxxxxxxxx>님이 작성: > > On Mon, Jul 12, 2021 at 7:48 PM Austin Kim <austindh.kim@xxxxxxxxx> wrote: > > From: Austin Kim <austin.kim@xxxxxxx> > > > > It is possible for audit_log_start() to return NULL on error. > > So add exception handling for possible NULL audit buffers where > > return value can be handled from callers. > > Hi. > > The patch looks fine to me, but I think the description doesn't tell > the full story and I'm worried that people might misunderstand why > this patch is worthwhile. I would suggest you revise the commit > description to explain that in these cases it is safe to return early > when audit_log_start() returns NULL because the only non-cleanup > processing left in these functions is to generate an audit record. Thanks for valuable feedback. Let me resend the patch with revised 'commit description', as you recommended. > Returning early in these cases is a performance optimization and not a > correctness issue; the audit_log_*() functions can support being > passed a NULL audit_buffer argument. > > > Signed-off-by: Austin Kim <austin.kim@xxxxxxx> > > --- > > security/selinux/hooks.c | 4 ++++ > > security/selinux/ss/services.c | 2 ++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > > index b0032c42333e..9e84e6635f2f 100644 > > --- a/security/selinux/hooks.c > > +++ b/security/selinux/hooks.c > > @@ -3325,6 +3325,8 @@ static int selinux_inode_setxattr(struct user_namespace *mnt_userns, > > } > > ab = audit_log_start(audit_context(), > > GFP_ATOMIC, AUDIT_SELINUX_ERR); > > + if (!ab) > > + return rc; > > audit_log_format(ab, "op=setxattr invalid_context="); > > audit_log_n_untrustedstring(ab, value, audit_size); > > audit_log_end(ab); > > @@ -6552,6 +6554,8 @@ static int selinux_setprocattr(const char *name, void *value, size_t size) > > ab = audit_log_start(audit_context(), > > GFP_ATOMIC, > > AUDIT_SELINUX_ERR); > > + if (!ab) > > + return error; > > audit_log_format(ab, "op=fscreate invalid_context="); > > audit_log_n_untrustedstring(ab, value, audit_size); > > audit_log_end(ab); > > diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c > > index d84c77f370dc..e5f1b2757a83 100644 > > --- a/security/selinux/ss/services.c > > +++ b/security/selinux/ss/services.c > > @@ -1673,6 +1673,8 @@ static int compute_sid_handle_invalid_context( > > if (context_struct_to_string(policydb, newcontext, &n, &nlen)) > > goto out; > > ab = audit_log_start(audit_context(), GFP_ATOMIC, AUDIT_SELINUX_ERR); > > + if (!ab) > > + goto out; > > audit_log_format(ab, > > "op=security_compute_sid invalid_context="); > > /* no need to record the NUL with untrusted strings */ > > -- > > 2.20.1 > > -- > paul moore > www.paul-moore.com
