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McKenney" , Jann Horn , Steven Rostedt , Shakeel Butt , Thomas Gleixner , Dietmar Eggemann , David Howells , linux-kernel@vger.kernel.org, linux-audit@redhat.com, "Eric W . Biederman" , Andrew Morton Subject: Re: [Linux-kernel-mentees] [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" On 2020-04-03 13:26, Amol Grover wrote: > On Thu, Apr 02, 2020 at 08:56:36AM -0400, Paul Moore wrote: > > On Thu, Apr 2, 2020 at 1:57 AM Amol Grover wrote: > > > task_struct::cred is only used task-synchronously and does > > > not require any RCU locks, hence, rcu_dereference_check is > > > not required to read from it. > > > > > > Suggested-by: Jann Horn > > > Co-developed-by: Joel Fernandes (Google) > > > Signed-off-by: Joel Fernandes (Google) > > > Signed-off-by: Amol Grover > > > --- > > > kernel/auditsc.c | 15 +++++---------- > > > 1 file changed, 5 insertions(+), 10 deletions(-) > > > > This is the exact same patch I ACK'd back in February, yes? > > > > https://lore.kernel.org/linux-audit/CAHC9VhQCbg1V290bYEZM+izDPRpr=XYXakohnDaMphkBBFgUaA@mail.gmail.com > > > > Hi Paul, > > That's correct. I've resend the series out of the fear that the first 2 > patches might've gotten lost as it's been almost a month since I last > sent them. Could you please ack this again, and if you don't mind could > you please go through the other 2 patches and ack them aswell? Via who's tree are you expecting this will make it upstream? > Thanks > Amol > > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > > index 4effe01ebbe2..d3510513cdd1 100644 > > > --- a/kernel/auditsc.c > > > +++ b/kernel/auditsc.c > > > @@ -430,24 +430,19 @@ static int audit_field_compare(struct task_struct *tsk, > > > /* Determine if any context name data matches a rule's watch data */ > > > /* Compare a task_struct with an audit_rule. Return 1 on match, 0 > > > * otherwise. > > > - * > > > - * If task_creation is true, this is an explicit indication that we are > > > - * filtering a task rule at task creation time. This and tsk == current are > > > - * the only situations where tsk->cred may be accessed without an rcu read lock. > > > */ > > > static int audit_filter_rules(struct task_struct *tsk, > > > struct audit_krule *rule, > > > struct audit_context *ctx, > > > struct audit_names *name, > > > - enum audit_state *state, > > > - bool task_creation) > > > + enum audit_state *state) > > > { > > > const struct cred *cred; > > > int i, need_sid = 1; > > > u32 sid; > > > unsigned int sessionid; > > > > > > - cred = rcu_dereference_check(tsk->cred, tsk == current || task_creation); > > > + cred = tsk->cred; > > > > > > for (i = 0; i < rule->field_count; i++) { > > > struct audit_field *f = &rule->fields[i]; > > > @@ -745,7 +740,7 @@ static enum audit_state audit_filter_task(struct task_struct *tsk, char **key) > > > rcu_read_lock(); > > > list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TASK], list) { > > > if (audit_filter_rules(tsk, &e->rule, NULL, NULL, > > > - &state, true)) { > > > + &state)) { > > > if (state == AUDIT_RECORD_CONTEXT) > > > *key = kstrdup(e->rule.filterkey, GFP_ATOMIC); > > > rcu_read_unlock(); > > > @@ -791,7 +786,7 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk, > > > list_for_each_entry_rcu(e, list, list) { > > > if (audit_in_mask(&e->rule, ctx->major) && > > > audit_filter_rules(tsk, &e->rule, ctx, NULL, > > > - &state, false)) { > > > + &state)) { > > > rcu_read_unlock(); > > > ctx->current_state = state; > > > return state; > > > @@ -815,7 +810,7 @@ static int audit_filter_inode_name(struct task_struct *tsk, > > > > > > list_for_each_entry_rcu(e, list, list) { > > > if (audit_in_mask(&e->rule, ctx->major) && > > > - audit_filter_rules(tsk, &e->rule, ctx, n, &state, false)) { > > > + audit_filter_rules(tsk, &e->rule, ctx, n, &state)) { > > > ctx->current_state = state; > > > return 1; > > > } > > > -- > > > 2.24.1 > > > > paul moore - RGB -- Richard Guy Briggs Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees