[RFC PATCH 1/8] KEYS: Change the type of key->quotalen to unsigned int

[RFC PATCH 1/8] KEYS: Change the type of key->quotalen to unsigned int

[Jarkko Sakkinen]

key_alloc() and key_payload_reserve() set key->quotalen with values,
which can be larger than USHRT_MAX.

Change the type from unsigned short to unsigned int.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 include/linux/key.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index e40b5267658f..6729536a76b2 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -216,7 +216,7 @@ struct key {
 	kuid_t			uid;
 	kgid_t			gid;
 	key_perm_t		perm;		/* access permissions */
-	unsigned short		quotalen;	/* length added to quota */
+	unsigned int		quotalen;	/* length added to quota */
 	unsigned short		datalen;	/* payload data length
 						 * - may not match RCU dereferenced payload
 						 * - payload should contain own length
-- 
2.47.3

[RFC PATCH 2/8] KEYS: Change the type of key->datalen to unsigned int

[Jarkko Sakkinen]

key_alloc() and key_payload_reserve() set key->datalen with values,
which can be larger than USHRT_MAX.

Change the type from unsigned short to unsigned int.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 include/linux/key.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index 6729536a76b2..26139c3adf62 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -217,7 +217,7 @@ struct key {
 	kgid_t			gid;
 	key_perm_t		perm;		/* access permissions */
 	unsigned int		quotalen;	/* length added to quota */
-	unsigned short		datalen;	/* payload data length
+	unsigned int		datalen;	/* payload data length
 						 * - may not match RCU dereferenced payload
 						 * - payload should contain own length
 						 */
-- 
2.47.3

Re: [RFC PATCH 2/8] KEYS: Change the type of key->datalen to unsigned int

[David Howells]

I would merge this with patch 1.

Apart from that:

	Reviewed-by: David Howells <dhowells@redhat.com>

on both 1 & 2.

David

Re: [RFC PATCH 2/8] KEYS: Change the type of key->datalen to unsigned int

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:33:32PM +0100, David Howells wrote:
> I would merge this with patch 1.
> 
> Apart from that:
> 
> 	Reviewed-by: David Howells <dhowells@redhat.com>
> 
> on both 1 & 2.
> 
> David
> 

I can do that. I went a little over the top with sanity checking
the slop :-)

Br, Jarkko

[RFC PATCH 3/8] KEYS: Reject @desclen values over U16_MAX in key_alloc()

[Jarkko Sakkinen]

@desclen in key_alloc() is saved to the 16-bit wide desc_len field in
struct keyring_index_key.

Reject @desclen values over U16_MAX with -EINVAL in order to prevent
integer overflow.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: f771fde82051 ("keys: Simplify key description management")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/key.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/keys/key.c b/security/keys/key.c
index 6ebb8691551f..7888c0c6a772 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -245,6 +245,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 	}
 
 	desclen = strlen(desc);
+	if (desclen > U16_MAX)
+		goto error;
 	quotalen = desclen + 1 + type->def_datalen;
 
 	/* get hold of the key tracking for this user */
-- 
2.47.3

Re: [RFC PATCH 3/8] KEYS: Reject @desclen values over U16_MAX in key_alloc()

[David Howells]

Jarkko Sakkinen <jarkko@kernel.org> wrote:

> Reject @desclen values over U16_MAX with -EINVAL in order to prevent
> integer overflow.

KEY_MAX_DESC_SIZE.

David

Re: [RFC PATCH 3/8] KEYS: Reject @desclen values over U16_MAX in key_alloc()

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:35:19PM +0100, David Howells wrote:
> Jarkko Sakkinen <jarkko@kernel.org> wrote:
> 
> > Reject @desclen values over U16_MAX with -EINVAL in order to prevent
> > integer overflow.
> 
> KEY_MAX_DESC_SIZE.
> 
> David

Good catch, thanks.

Br, Jarkko

[RFC PATCH 4/8] KEYS: Prevent overflow of user->qnkeys in key_alloc()

[Jarkko Sakkinen]

Add the missing check rejecting allocations when user->qnkeys has reached
INT_MAX.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 7e047ef5fe2d ("[PATCH] keys: sort out key quota system")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/key.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/security/keys/key.c b/security/keys/key.c
index 7888c0c6a772..30f8a8dea206 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -263,6 +263,9 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 			key_quota_root_maxbytes : key_quota_maxbytes;
 
 		spin_lock_irqsave(&user->lock, irqflags);
+		if (user->qnkeys == INT_MAX)
+			goto no_quota;
+
 		if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
 			if (user->qnkeys + 1 > maxkeys ||
 			    user->qnbytes + quotalen > maxbytes ||
-- 
2.47.3

[RFC PATCH 5/8] KEYS: Prevent overflow of quota in key_alloc()

[Jarkko Sakkinen]

Check that the calculated quota length does not go over INT_MAX.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 7e047ef5fe2d ("[PATCH] keys: sort out key quota system")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/key.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 30f8a8dea206..18043251365f 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -245,7 +245,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 	}
 
 	desclen = strlen(desc);
-	if (desclen > U16_MAX)
+	if (desclen > U16_MAX || type->def_datalen > INT_MAX - desclen - 1)
 		goto error;
 	quotalen = desclen + 1 + type->def_datalen;
 
-- 
2.47.3

Re: [RFC PATCH 5/8] KEYS: Prevent overflow of quota in key_alloc()

[David Howells]

Jarkko Sakkinen <jarkko@kernel.org> wrote:

> -	if (desclen > U16_MAX)

This should also be KEY_MAX_DESC_SIZE.

> +	if (desclen > U16_MAX || type->def_datalen > INT_MAX - desclen - 1)

That looks awkward, but I can see why you did it.

Reviewed-by: David Howells <dhowells@redhat.com>

Re: [RFC PATCH 5/8] KEYS: Prevent overflow of quota in key_alloc()

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:40:47PM +0100, David Howells wrote:
> Jarkko Sakkinen <jarkko@kernel.org> wrote:
> 
> > -	if (desclen > U16_MAX)
> 
> This should also be KEY_MAX_DESC_SIZE.
> 
> > +	if (desclen > U16_MAX || type->def_datalen > INT_MAX - desclen - 1)
> 
> That looks awkward, but I can see why you did it.
> 
> Reviewed-by: David Howells <dhowells@redhat.com>
> 

Do you mind if I do search-replace and apply these with
KEY_MAX_DESC_SIZE fixup?

Br, Jarkko

[RFC PATCH 6/8] KEYS: Prevent overflow of user->qnbytes in key_alloc()

[Jarkko Sakkinen]

Add the missing check rejecting resulting byte counts above INT_MAX.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 7e047ef5fe2d ("[PATCH] keys: sort out key quota system")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/key.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 18043251365f..5afc16425daf 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -263,7 +263,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
 			key_quota_root_maxbytes : key_quota_maxbytes;
 
 		spin_lock_irqsave(&user->lock, irqflags);
-		if (user->qnkeys == INT_MAX)
+		if (user->qnkeys == INT_MAX ||
+		    quotalen > INT_MAX - user->qnbytes)
 			goto no_quota;
 
 		if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
-- 
2.47.3

Re: [RFC PATCH 6/8] KEYS: Prevent overflow of user->qnbytes in key_alloc()

[David Howells]

I suggest merging patches 4 and 6, then add:

	Reviewed-by: David Howells <dhowells@redhat.com>

Re: [RFC PATCH 6/8] KEYS: Prevent overflow of user->qnbytes in key_alloc()

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:41:45PM +0100, David Howells wrote:
> I suggest merging patches 4 and 6, then add:
> 
> 	Reviewed-by: David Howells <dhowells@redhat.com>

Ok, I'll merge 1-2 and 4-6 both and apply, thanks.

Br, Jarkko

[RFC PATCH 7/8] KEYS: Reject @datalen values over INT_MAX

[Jarkko Sakkinen]

Protect quota from overflowing by rejecting @datalen values that
surpass over INT_MAX.

Cc: stable@vger.kernel.org
Assisted-by: LLM
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/key.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 5afc16425daf..5718ae7b80e5 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -379,11 +379,16 @@ EXPORT_SYMBOL(key_alloc);
  */
 int key_payload_reserve(struct key *key, size_t datalen)
 {
-	int delta = (int)datalen - key->datalen;
+	int delta;
 	int ret = 0;
 
 	key_check(key);
 
+	if (datalen > INT_MAX)
+		return -EINVAL;
+
+	delta = (int)datalen - key->datalen;
+
 	/* contemplate the quota adjustment */
 	if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 		unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
-- 
2.47.3

Re: [RFC PATCH 7/8] KEYS: Reject @datalen values over INT_MAX

[David Howells]

Jarkko Sakkinen <jarkko@kernel.org> wrote:

> -	int delta = (int)datalen - key->datalen;
> +	int delta;
>  	int ret = 0;
>  
>  	key_check(key);
>  
> +	if (datalen > INT_MAX)
> +		return -EINVAL;
> +
> +	delta = (int)datalen - key->datalen;
> +

You don't actually need to move the subtraction.

But apart from that:

Signed-off-by: David Howells <dhowells@redhat.com>

Re: [RFC PATCH 7/8] KEYS: Reject @datalen values over INT_MAX

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:43:27PM +0100, David Howells wrote:
> Jarkko Sakkinen <jarkko@kernel.org> wrote:
> 
> > -	int delta = (int)datalen - key->datalen;
> > +	int delta;
> >  	int ret = 0;
> >  
> >  	key_check(key);
> >  
> > +	if (datalen > INT_MAX)
> > +		return -EINVAL;
> > +
> > +	delta = (int)datalen - key->datalen;
> > +
> 
> You don't actually need to move the subtraction.

Ouch, you're right, I'll fixup that.

> 
> But apart from that:
> 
> Signed-off-by: David Howells <dhowells@redhat.com>

Br, Jarkko

[RFC PATCH 8/8] KEYS: Verify the key identity in __keyctl_unlink

[Jarkko Sakkinen]

Let's define the following preconditions:

- Two keys: A and B.
- R is a keyring.
- Both have the same type/description/domain.

Then:

1. KEYCTL_LINK(A, R) => {A}
1. KEYCTL_LINK(B, R) => {B}
2. KEYCTL_UNLINK(A, R) => {}

Instead, verify key tidentity before unlinking, and return -ENOENT on
mismatch.

Cc: stable@vger.kernel.org
Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring")
Assisted-by: LLM
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 security/keys/keyring.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 7143f3079d20..b025331488c5 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1501,9 +1501,15 @@ static int __key_unlink_begin(struct key *keyring, struct key *key,
 			      struct assoc_array_edit **_edit)
 {
 	struct assoc_array_edit *edit;
+	const void *object;
 
 	BUG_ON(*_edit != NULL);
 
+	object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
+				  &key->index_key);
+	if (!object || keyring_ptr_to_key(object) != key)
+		return -ENOENT;
+
 	edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
 				  &key->index_key);
 	if (IS_ERR(edit))
-- 
2.47.3

Re: [RFC PATCH 8/8] KEYS: Verify the key identity in __keyctl_unlink

[David Howells]

This will show it:

	keyctl newring ring_a @s
	keyctl newring ring_b @s
	A=`keyctl add user A ss %:ring_a`
	B=`keyctl add user A qq %:ring_b`
	keyctl newring R @s
	keyctl show
	keyctl link $A %:R
	keyctl show
	keyctl link $B %:R
	keyctl show
	keyctl unlink $A %:R
	keyctl show  # R is now incorrectly empty

Reviewed-by: David Howells <dhowells@redhat.com>

Re: [RFC PATCH 8/8] KEYS: Verify the key identity in __keyctl_unlink

[Jarkko Sakkinen]

On Mon, Oct 19, 2026 at 04:55:13PM +0100, David Howells wrote:
> This will show it:
> 
> 	keyctl newring ring_a @s
> 	keyctl newring ring_b @s
> 	A=`keyctl add user A ss %:ring_a`
> 	B=`keyctl add user A qq %:ring_b`
> 	keyctl newring R @s
> 	keyctl show
> 	keyctl link $A %:R
> 	keyctl show
> 	keyctl link $B %:R
> 	keyctl show
> 	keyctl unlink $A %:R
> 	keyctl show  # R is now incorrectly empty
> 
> Reviewed-by: David Howells <dhowells@redhat.com>

I'll actually add this to my own test harness, thanks.

I'm a slightly worried of this patch given that you can
technically interpret it as a uapi change. I guess here it
is acceptable, and if a tree falls down, we'll respond
to that.

Br, Jarkko