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sched: Remove __rcu annotation from cred pointer

PATCH RESEND In review Amol Grover 3 participants 13 messages Apr 2, 2020 – May 26, 2020

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#0 lore raw

PATCH RESEND 1/3 sched: Remove __rcu annotation from cred pointer

task_struct::cred (subjective credentials) is *always* used task-synchronously, hence, does not require RCU semantics.

task_struct::real_cred (objective credentials) can be used in RCU context and its __rcu annotation is retained.

However, task_struct::cred and task_struct::real_cred *may* point to the same object, hence, the object pointed to by task_struct::cred *may* have RCU delayed freeing.

---
 include/linux/sched.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
include/linux/sched.h +5 -2
index 716ad1d8d95e..39924e6e0cf2 100644
@@ -879,8 +879,11 @@ struct task_struct {
 	/* Objective and real subjective task credentials (COW): */
 	const struct cred __rcu		*real_cred;
 
-	/* Effective (overridable) subjective task credentials (COW): */
-	const struct cred __rcu		*cred;
+	/*
+	 * Effective (overridable) subjective task credentials (COW)
+	 * which is used task-synchronously
+	 */
+	const struct cred		*cred;
 
 #ifdef CONFIG_KEYS
 	/* Cached requested key. */
Signature · 1 line
2.24.1
#1 lore raw

PATCH RESEND 2/3 cred: Do not use RCU primitives to access cred pointer

Since task_struct::cred can only be used task-synchronously, and is not visible to other threads under RCU context, we do not require RCU primitives to read/write to it and incur heavy barriers.

---
 include/linux/cred.h | 5 ++---
 kernel/cred.c        | 6 +++---
 2 files changed, 5 insertions(+), 6 deletions(-)
include/linux/cred.h +2 -3
index 18639c069263..5973791e5fe4 100644
@@ -291,11 +291,10 @@ static inline void put_cred(const struct cred *_cred)
 /**
  * current_cred - Access the current task's subjective credentials
  *
- * Access the subjective credentials of the current task.  RCU-safe,
- * since nobody else can modify it.
+ * Access the subjective credentials of the current task.
  */
 #define current_cred() \
-	rcu_dereference_protected(current->cred, 1)
+	(current->cred)
 
 /**
  * current_real_cred - Access the current task's objective credentials
kernel/cred.c +3 -3
index 809a985b1793..3956c31d068d 100644
@@ -485,7 +485,7 @@ int commit_creds(struct cred *new)
 	if (new->user != old->user)
 		atomic_inc(&new->user->processes);
 	rcu_assign_pointer(task->real_cred, new);
-	rcu_assign_pointer(task->cred, new);
+	task->cred = new;
 	if (new->user != old->user)
 		atomic_dec(&old->user->processes);
 	alter_cred_subscribers(old, -2);
@@ -562,7 +562,7 @@ const struct cred *override_creds(const struct cred *new)
 	 */
 	get_new_cred((struct cred *)new);
 	alter_cred_subscribers(new, 1);
-	rcu_assign_pointer(current->cred, new);
+	current->cred = new;
 	alter_cred_subscribers(old, -1);
 
 	kdebug("override_creds() = %p{%d,%d}", old,
@@ -590,7 +590,7 @@ void revert_creds(const struct cred *old)
 	validate_creds(old);
 	validate_creds(override);
 	alter_cred_subscribers(old, 1);
-	rcu_assign_pointer(current->cred, old);
+	current->cred = old;
 	alter_cred_subscribers(override, -1);
 	put_cred(override);
 }
Signature · 1 line
2.24.1
#2 lore raw

PATCH RESEND 3/3 auditsc: Do not use RCU primitive to read from cred pointer

In reply to Amol Grover

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.

---
 kernel/auditsc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)
kernel/auditsc.c +5 -10
index 4effe01ebbe2..d3510513cdd1 100644
@@ -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;
 		}
Signature · 6 lines
2.24.1

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maintainer
#3 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

Quoted 11 lines · Amol Grover

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.

---
 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

Quoted 60 lines
kernel/auditsc.c +5 -11
index 4effe01ebbe2..d3510513cdd1 100644
@@ -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

Signature · 2 lines
paul moore
www.paul-moore.com
#4 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

Quoted 13 lines · Paul Moore
Quoted 11 lines · Amol Grover

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.

---
 kernel/auditsc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)
Quoted 4 lines

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?

Thanks
Amol

Quoted 51 lines
Quoted 51 lines
kernel/auditsc.c +4 -9
index 4effe01ebbe2..d3510513cdd1 100644
@@ -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,
 
Quoted 13 lines
Quoted 9 lines
kernel/auditsc.c +1 -2
        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

Signature · 2 lines
paul moore
www.paul-moore.com

_______________________________________________
Linux-kernel-mentees mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

maintainer Acked-by
#5 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

Quoted 19 lines · Amol Grover
Quoted 13 lines · Paul Moore
Quoted 11 lines · Amol Grover

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.

---
 kernel/auditsc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)
Quoted 4 lines

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

Quoted 6 lines

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?

If you hadn't changed the patch at all, and it doesn't look like you did, you could have (and likely should have) just carried over my ACK. Regardless, I'll re-ACK it now (below). As far as the other two patches are concerned, they look okay to me but I would defer my ACK to maintainer of that code.

Signature · 2 lines
paul moore
www.paul-moore.com
#6 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

In reply to Amol Grover
Quoted 19 lines · Amol Grover
Quoted 13 lines · Paul Moore
Quoted 11 lines · Amol Grover

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.

---
 kernel/auditsc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)
Quoted 4 lines

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

Quoted 6 lines

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?

Quoted 65 lines

Thanks
Amol

Quoted 62 lines
Quoted 59 lines
kernel/auditsc.c +5 -11
index 4effe01ebbe2..d3510513cdd1 100644
@@ -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;
                }
--
Quoted 1 line

2.24.1

paul moore

- RGB

--
Richard Guy Briggs <[email protected]>
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

maintainer
#7 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

Quoted 20 lines · Richard Guy Briggs
Quoted 19 lines · Amol Grover
Quoted 17 lines · Paul Moore
Quoted 11 lines · Amol Grover

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.

---
 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

Quoted 8 lines
Quoted 6 lines

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?

When I asked a similar question back in February the response was basically not the audit tree.

Signature · 2 lines
paul moore
www.paul-moore.com
#8 lore raw

Re: [PATCH 3/3 RESEND] auditsc: Do not use RCU primitive to read from cred pointer

Quoted 28 lines · Paul Moore
Quoted 27 lines · Richard Guy Briggs
Quoted 25 lines · Amol Grover
Quoted 13 lines · Paul Moore
Quoted 11 lines · Amol Grover

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.

---
 kernel/auditsc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)
Quoted 4 lines

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?

Quoted 4 lines
Quoted 1 line

Via who's tree are you expecting this will make it upstream?

When I asked a similar question back in February the response was basically not the audit tree.

Well, I went checking mingo and akpm's trees and didn't find 1/3 and 2/3 there even though I thought 3/3 was in audit/stable-5.6. I was mistaken, that patch in audit/stable-5.6 is a previous rcu fix for auditd_conn and not 3/3.

Quoted 1 line

paul moore

- RGB

--
Richard Guy Briggs <[email protected]>
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
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

#9 lore raw
In reply to Amol Grover
Quoted 6 lines · Amol Grover

task_struct::cred (subjective credentials) is *always* used task-synchronously, hence, does not require RCU semantics.

task_struct::real_cred (objective credentials) can be used in RCU context and its __rcu annotation is retained.

Quoted 8 lines

However, task_struct::cred and task_struct::real_cred *may* point to the same object, hence, the object pointed to by task_struct::cred *may* have RCU delayed freeing.

Hello everyone,

Could you please go through patches 1/3 and 2/3 and if deemed OK, give your acks. I sent the original patch in beginning of February (~4 months back) and resent the patches again in beginning of April due to lack of traffic. Paul Moore was kind enough to ack twice - the 3/3 and its resend patch. However these 2 patches still remain. I'd really appreciate if someone reviewed them.

Thanks
Amol
_______________________________________________
Linux-kernel-mentees mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

#10 lore raw
Quoted 16 lines · Amol Grover
Quoted 6 lines · Amol Grover

task_struct::cred (subjective credentials) is *always* used task-synchronously, hence, does not require RCU semantics.

task_struct::real_cred (objective credentials) can be used in RCU context and its __rcu annotation is retained.

Quoted 8 lines

However, task_struct::cred and task_struct::real_cred *may* point to the same object, hence, the object pointed to by task_struct::cred *may* have RCU delayed freeing.

Quoted 8 lines

Hello everyone,

Could you please go through patches 1/3 and 2/3 and if deemed OK, give your acks. I sent the original patch in beginning of February (~4 months back) and resent the patches again in beginning of April due to lack of traffic. Paul Moore was kind enough to ack twice - the 3/3 and its resend patch. However these 2 patches still remain. I'd really appreciate if someone reviewed them.

I asked on April 3 which upstream tree you expect this patchset to go through and I did not see a reply. Do you have a specific target or is the large addressee list assuming someone else is taking this set? All we have seen is that it is not intended to go through the audit tree.

Quoted 2 lines

Thanks
Amol

- RGB

--
Richard Guy Briggs <[email protected]>
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
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

#11 lore raw
Quoted 26 lines · Richard Guy Briggs
Quoted 16 lines · Amol Grover
Quoted 6 lines · Amol Grover

task_struct::cred (subjective credentials) is *always* used task-synchronously, hence, does not require RCU semantics.

task_struct::real_cred (objective credentials) can be used in RCU context and its __rcu annotation is retained.

Quoted 8 lines

However, task_struct::cred and task_struct::real_cred *may* point to the same object, hence, the object pointed to by task_struct::cred *may* have RCU delayed freeing.

Quoted 8 lines

Hello everyone,

Could you please go through patches 1/3 and 2/3 and if deemed OK, give your acks. I sent the original patch in beginning of February (~4 months back) and resent the patches again in beginning of April due to lack of traffic. Paul Moore was kind enough to ack twice - the 3/3 and its resend patch. However these 2 patches still remain. I'd really appreciate if someone reviewed them.

Quoted 5 lines

I asked on April 3 which upstream tree you expect this patchset to go through and I did not see a reply. Do you have a specific target or is the large addressee list assuming someone else is taking this set? All we have seen is that it is not intended to go through the audit tree.

Apologies for it. As Paul Moore replied, initially I assumed this patchset to not go through the audit tree as the audit specific changes were secondary to the main change (though certainly I did not think which upstream tree the patchset would go through). But now I am okay with the patchset making it to upstream via audit tree if it is fine by the maintainers.

Thanks
Amol

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Quoted 2 lines

Thanks
Amol

- RGB

--
Richard Guy Briggs <[email protected]>
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

maintainer
#12 lore raw
Quoted 33 lines · Amol Grover
Quoted 26 lines · Richard Guy Briggs
Quoted 16 lines · Amol Grover
Quoted 6 lines · Amol Grover

task_struct::cred (subjective credentials) is *always* used task-synchronously, hence, does not require RCU semantics.

task_struct::real_cred (objective credentials) can be used in RCU context and its __rcu annotation is retained.

Quoted 8 lines

However, task_struct::cred and task_struct::real_cred *may* point to the same object, hence, the object pointed to by task_struct::cred *may* have RCU delayed freeing.

Quoted 8 lines

Hello everyone,

Could you please go through patches 1/3 and 2/3 and if deemed OK, give your acks. I sent the original patch in beginning of February (~4 months back) and resent the patches again in beginning of April due to lack of traffic. Paul Moore was kind enough to ack twice - the 3/3 and its resend patch. However these 2 patches still remain. I'd really appreciate if someone reviewed them.

Quoted 5 lines

I asked on April 3 which upstream tree you expect this patchset to go through and I did not see a reply. Do you have a specific target or is the large addressee list assuming someone else is taking this set? All we have seen is that it is not intended to go through the audit tree.

Quoted 6 lines

Apologies for it. As Paul Moore replied, initially I assumed this patchset to not go through the audit tree as the audit specific changes were secondary to the main change (though certainly I did not think which upstream tree the patchset would go through). But now I am okay with the patchset making it to upstream via audit tree if it is fine by the maintainers.

This patchset is not appropriate for the audit tree as the most significant changes are not audit related.

My ACK on patch 3/3 was, and is, conditional on the previous patches being acceptable to the greater kernel community; this is the main reason why I didn't ACK patch 1/3 or 2/3.

Signature · 2 lines
paul moore
www.paul-moore.com