| Message ID | 20240821123616.60401-7-dhowells@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | keys: Add tracepoints | expand |
On Wed Aug 21, 2024 at 3:36 PM EEST, David Howells wrote: > Add a key_try_get() function to try to get a ref on a key and switch code > that's manipulating the key refcount directly to use it. This will allow a > tracepoint to be emplaced there later. > > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Jarkko Sakkinen <jarkko@kernel.org> > cc: keyrings@vger.kernel.org > cc: linux-security-module@vger.kernel.org > --- > include/linux/key.h | 1 + > security/keys/key.c | 16 +++++++++++++++- > security/keys/keyring.c | 2 +- > 3 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/include/linux/key.h b/include/linux/key.h > index 80d736813b89..4e5baf3e7286 100644 > --- a/include/linux/key.h > +++ b/include/linux/key.h > @@ -300,6 +300,7 @@ extern struct key *key_alloc(struct key_type *type, > extern void key_revoke(struct key *key); > extern void key_invalidate(struct key *key); > struct key *key_get(struct key *key); > +struct key *key_try_get(struct key *key); > extern void key_put(struct key *key); > extern bool key_put_tag(struct key_tag *tag); > extern void key_remove_domain(struct key_tag *domain_tag); > diff --git a/security/keys/key.c b/security/keys/key.c > index 14c7ee77ea15..59cffb6f9b94 100644 > --- a/security/keys/key.c > +++ b/security/keys/key.c > @@ -649,6 +649,20 @@ struct key *key_get(struct key *key) > } > EXPORT_SYMBOL(key_get); > > +/** > + * key_try_get - Get a ref on a key if its refcount is not non-zero. > + * @key: The key to get a reference on. > + * > + * Get a reference on a key unless it has no references and return true if > + * successful. @key must not be NULL. > + */ > +struct key *key_try_get(struct key *key) > +{ > + if (!refcount_inc_not_zero(&key->usage)) > + return NULL; > + return key; > +} > + > /** > * key_put - Discard a reference to a key. > * @key: The key to discard a reference from. > @@ -709,7 +723,7 @@ struct key *key_lookup(key_serial_t id) > /* A key is allowed to be looked up only if someone still owns a > * reference to it - otherwise it's awaiting the gc. > */ > - if (!refcount_inc_not_zero(&key->usage)) > + if (!key_try_get(key)) > goto not_found; > > error: > diff --git a/security/keys/keyring.c b/security/keys/keyring.c > index e77d927f1d4d..a09a4c2b1bcb 100644 > --- a/security/keys/keyring.c > +++ b/security/keys/keyring.c > @@ -1174,7 +1174,7 @@ struct key *find_keyring_by_name(const char *name, bool uid_keyring) > /* we've got a match but we might end up racing with > * key_cleanup() if the keyring is currently 'dead' > * (ie. it has a zero usage count) */ > - if (!refcount_inc_not_zero(&keyring->usage)) > + if (!key_try_get(keyring)) > continue; > keyring->last_used_at = ktime_get_real_seconds(); > goto out; Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> BR, Jarkko
diff --git a/include/linux/key.h b/include/linux/key.h index 80d736813b89..4e5baf3e7286 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -300,6 +300,7 @@ extern struct key *key_alloc(struct key_type *type, extern void key_revoke(struct key *key); extern void key_invalidate(struct key *key); struct key *key_get(struct key *key); +struct key *key_try_get(struct key *key); extern void key_put(struct key *key); extern bool key_put_tag(struct key_tag *tag); extern void key_remove_domain(struct key_tag *domain_tag); diff --git a/security/keys/key.c b/security/keys/key.c index 14c7ee77ea15..59cffb6f9b94 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -649,6 +649,20 @@ struct key *key_get(struct key *key) } EXPORT_SYMBOL(key_get); +/** + * key_try_get - Get a ref on a key if its refcount is not non-zero. + * @key: The key to get a reference on. + * + * Get a reference on a key unless it has no references and return true if + * successful. @key must not be NULL. + */ +struct key *key_try_get(struct key *key) +{ + if (!refcount_inc_not_zero(&key->usage)) + return NULL; + return key; +} + /** * key_put - Discard a reference to a key. * @key: The key to discard a reference from. @@ -709,7 +723,7 @@ struct key *key_lookup(key_serial_t id) /* A key is allowed to be looked up only if someone still owns a * reference to it - otherwise it's awaiting the gc. */ - if (!refcount_inc_not_zero(&key->usage)) + if (!key_try_get(key)) goto not_found; error: diff --git a/security/keys/keyring.c b/security/keys/keyring.c index e77d927f1d4d..a09a4c2b1bcb 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -1174,7 +1174,7 @@ struct key *find_keyring_by_name(const char *name, bool uid_keyring) /* we've got a match but we might end up racing with * key_cleanup() if the keyring is currently 'dead' * (ie. it has a zero usage count) */ - if (!refcount_inc_not_zero(&keyring->usage)) + if (!key_try_get(keyring)) continue; keyring->last_used_at = ktime_get_real_seconds(); goto out;
Add a key_try_get() function to try to get a ref on a key and switch code that's manipulating the key refcount directly to use it. This will allow a tracepoint to be emplaced there later. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jarkko Sakkinen <jarkko@kernel.org> cc: keyrings@vger.kernel.org cc: linux-security-module@vger.kernel.org --- include/linux/key.h | 1 + security/keys/key.c | 16 +++++++++++++++- security/keys/keyring.c | 2 +- 3 files changed, 17 insertions(+), 2 deletions(-)