crypto: Enable context analysis

Enable context analysis for crypto subsystem.

This demonstrates a larger conversion to use Clang's context
analysis. The benefit is additional static checking of locking rules,
along with better documentation.

Note the use of the __acquire_ret macro how to define an API where a
function returns a pointer to an object (struct scomp_scratch) with a
lock held. Additionally, the analysis only resolves aliases where the
analysis unambiguously sees that a variable was not reassigned after
initialization, requiring minor code changes.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-36-elver@google.com

diff --git a/crypto/Makefile b/crypto/Makefile
index 16a35649dd912663199d9e65820f51eb2389f3b1..db264feab7e74b19c7b78e02628a090a472bb0ad 100644 (file)
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -3,6 +3,8 @@
 # Cryptographic API
 #
 
+CONTEXT_ANALYSIS := y
+
 obj-$(CONFIG_CRYPTO) += crypto.o
 crypto-y := api.o cipher.o
 

diff --git a/crypto/acompress.c b/crypto/acompress.c
index be28cbfd22e32d95bcc8f3de313c995cdee086c4..25df368df098b10b82df9ad3c8f2feeb1ce825ea 100644 (file)
--- a/crypto/acompress.c
+++ b/crypto/acompress.c
@@ -449,8 +449,8 @@ int crypto_acomp_alloc_streams(struct crypto_acomp_streams *s)
 }
 EXPORT_SYMBOL_GPL(crypto_acomp_alloc_streams);
 
-struct crypto_acomp_stream *crypto_acomp_lock_stream_bh(
-       struct crypto_acomp_streams *s) __acquires(stream)
+struct crypto_acomp_stream *_crypto_acomp_lock_stream_bh(
+       struct crypto_acomp_streams *s)
 {
        struct crypto_acomp_stream __percpu *streams = s->streams;
        int cpu = raw_smp_processor_id();
@@ -469,7 +469,7 @@ struct crypto_acomp_stream *crypto_acomp_lock_stream_bh(
        spin_lock(&ps->lock);
        return ps;
 }
-EXPORT_SYMBOL_GPL(crypto_acomp_lock_stream_bh);
+EXPORT_SYMBOL_GPL(_crypto_acomp_lock_stream_bh);
 
 void acomp_walk_done_src(struct acomp_walk *walk, int used)
 {

diff --git a/crypto/algapi.c b/crypto/algapi.c
index e604d0d8b7b410e05df7b8c17e0aff92fbfa40a7..abc9333327d48efaaff1b953786f62d2172ff607 100644 (file)
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -244,6 +244,7 @@ EXPORT_SYMBOL_GPL(crypto_remove_spawns);
 
 static void crypto_alg_finish_registration(struct crypto_alg *alg,
                                           struct list_head *algs_to_put)
+       __must_hold(&crypto_alg_sem)
 {
        struct crypto_alg *q;
 
@@ -299,6 +300,7 @@ static struct crypto_larval *crypto_alloc_test_larval(struct crypto_alg *alg)
 
 static struct crypto_larval *
 __crypto_register_alg(struct crypto_alg *alg, struct list_head *algs_to_put)
+       __must_hold(&crypto_alg_sem)
 {
        struct crypto_alg *q;
        struct crypto_larval *larval;

diff --git a/crypto/api.c b/crypto/api.c
index 5724d62e9d0780a3d56d1d136b0e6124b3269b4d..05629644a688e4285ef14b6127ba160dda61e3a3 100644 (file)
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -57,6 +57,7 @@ EXPORT_SYMBOL_GPL(crypto_mod_put);
 
 static struct crypto_alg *__crypto_alg_lookup(const char *name, u32 type,
                                              u32 mask)
+       __must_hold_shared(&crypto_alg_sem)
 {
        struct crypto_alg *q, *alg = NULL;
        int best = -2;

diff --git a/crypto/crypto_engine.c b/crypto/crypto_engine.c
index 18e1689efe127ca29b8faf4f9dee775d92046745..1653a4bf5b317a7adb2060432f78f0461de951c0 100644 (file)
--- a/crypto/crypto_engine.c
+++ b/crypto/crypto_engine.c
@@ -453,8 +453,8 @@ struct crypto_engine *crypto_engine_alloc_init_and_set(struct device *dev,
        snprintf(engine->name, sizeof(engine->name),
                 "%s-engine", dev_name(dev));
 
-       crypto_init_queue(&engine->queue, qlen);
        spin_lock_init(&engine->queue_lock);
+       crypto_init_queue(&engine->queue, qlen);
 
        engine->kworker = kthread_run_worker(0, "%s", engine->name);
        if (IS_ERR(engine->kworker)) {

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 1d433dae9955793c5420f635f872e36fb0c494d6..0a6f6c05a78fefbdba3b066f089a0ebe69e07869 100644 (file)
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -232,6 +232,7 @@ static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
  */
 static int drbg_fips_continuous_test(struct drbg_state *drbg,
                                     const unsigned char *entropy)
+       __must_hold(&drbg->drbg_mutex)
 {
        unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
        int ret = 0;
@@ -848,6 +849,7 @@ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
 static inline int drbg_get_random_bytes(struct drbg_state *drbg,
                                        unsigned char *entropy,
                                        unsigned int entropylen)
+       __must_hold(&drbg->drbg_mutex)
 {
        int ret;
 
@@ -862,6 +864,7 @@ static inline int drbg_get_random_bytes(struct drbg_state *drbg,
 }
 
 static int drbg_seed_from_random(struct drbg_state *drbg)
+       __must_hold(&drbg->drbg_mutex)
 {
        struct drbg_string data;
        LIST_HEAD(seedlist);
@@ -919,6 +922,7 @@ static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg)
  */
 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
                     bool reseed)
+       __must_hold(&drbg->drbg_mutex)
 {
        int ret;
        unsigned char entropy[((32 + 16) * 2)];
@@ -1153,6 +1157,7 @@ err:
 static int drbg_generate(struct drbg_state *drbg,
                         unsigned char *buf, unsigned int buflen,
                         struct drbg_string *addtl)
+       __must_hold(&drbg->drbg_mutex)
 {
        int len = 0;
        LIST_HEAD(addtllist);

diff --git a/crypto/internal.h b/crypto/internal.h
index b9afd68767c199a5601dbfaec63703a737b8b727..8fbe0226d48e2e6b757a57f576124452cc4a67d2 100644 (file)
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -61,8 +61,8 @@ enum {
 /* Maximum number of (rtattr) parameters for each template. */
 #define CRYPTO_MAX_ATTRS 32
 
-extern struct list_head crypto_alg_list;
 extern struct rw_semaphore crypto_alg_sem;
+extern struct list_head crypto_alg_list __guarded_by(&crypto_alg_sem);
 extern struct blocking_notifier_head crypto_chain;
 
 int alg_test(const char *driver, const char *alg, u32 type, u32 mask);

diff --git a/crypto/proc.c b/crypto/proc.c
index 82f15b967e85f9ba50fa70164f8bdf16e8157949..5fb9fe86d02377695217f349d586b90a724cd0b7 100644 (file)
--- a/crypto/proc.c
+++ b/crypto/proc.c
@@ -19,17 +19,20 @@
 #include "internal.h"
 
 static void *c_start(struct seq_file *m, loff_t *pos)
+       __acquires_shared(&crypto_alg_sem)
 {
        down_read(&crypto_alg_sem);
        return seq_list_start(&crypto_alg_list, *pos);
 }
 
 static void *c_next(struct seq_file *m, void *p, loff_t *pos)
+       __must_hold_shared(&crypto_alg_sem)
 {
        return seq_list_next(p, &crypto_alg_list, pos);
 }
 
 static void c_stop(struct seq_file *m, void *p)
+       __releases_shared(&crypto_alg_sem)
 {
        up_read(&crypto_alg_sem);
 }

diff --git a/crypto/scompress.c b/crypto/scompress.c
index 1a7ed8ae65b074d6a040ecac489277f6b7c0a449..7aee1d50e148a7fcbabfbe2417df6a49cf9a1256 100644 (file)
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -28,8 +28,8 @@
 struct scomp_scratch {
        spinlock_t      lock;
        union {
-               void    *src;
-               unsigned long saddr;
+               void    *src __guarded_by(&lock);
+               unsigned long saddr __guarded_by(&lock);
        };
 };
 
@@ -38,8 +38,8 @@ static DEFINE_PER_CPU(struct scomp_scratch, scomp_scratch) = {
 };
 
 static const struct crypto_type crypto_scomp_type;
-static int scomp_scratch_users;
 static DEFINE_MUTEX(scomp_lock);
+static int scomp_scratch_users __guarded_by(&scomp_lock);
 
 static cpumask_t scomp_scratch_want;
 static void scomp_scratch_workfn(struct work_struct *work);
@@ -67,6 +67,7 @@ static void crypto_scomp_show(struct seq_file *m, struct crypto_alg *alg)
 }
 
 static void crypto_scomp_free_scratches(void)
+       __context_unsafe(/* frees @scratch */)
 {
        struct scomp_scratch *scratch;
        int i;
@@ -101,7 +102,7 @@ static void scomp_scratch_workfn(struct work_struct *work)
                struct scomp_scratch *scratch;
 
                scratch = per_cpu_ptr(&scomp_scratch, cpu);
-               if (scratch->src)
+               if (context_unsafe(scratch->src))
                        continue;
                if (scomp_alloc_scratch(scratch, cpu))
                        break;
@@ -111,6 +112,7 @@ static void scomp_scratch_workfn(struct work_struct *work)
 }
 
 static int crypto_scomp_alloc_scratches(void)
+       __context_unsafe(/* allocates @scratch */)
 {
        unsigned int i = cpumask_first(cpu_possible_mask);
        struct scomp_scratch *scratch;
@@ -139,7 +141,8 @@ unlock:
        return ret;
 }
 
-static struct scomp_scratch *scomp_lock_scratch(void) __acquires(scratch)
+#define scomp_lock_scratch(...) __acquire_ret(_scomp_lock_scratch(__VA_ARGS__), &__ret->lock)
+static struct scomp_scratch *_scomp_lock_scratch(void) __acquires_ret
 {
        int cpu = raw_smp_processor_id();
        struct scomp_scratch *scratch;
@@ -159,7 +162,7 @@ static struct scomp_scratch *scomp_lock_scratch(void) __acquires(scratch)
 }
 
 static inline void scomp_unlock_scratch(struct scomp_scratch *scratch)
-       __releases(scratch)
+       __releases(&scratch->lock)
 {
        spin_unlock(&scratch->lock);
 }
@@ -171,8 +174,6 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
        bool src_isvirt = acomp_request_src_isvirt(req);
        bool dst_isvirt = acomp_request_dst_isvirt(req);
        struct crypto_scomp *scomp = *tfm_ctx;
-       struct crypto_acomp_stream *stream;
-       struct scomp_scratch *scratch;
        unsigned int slen = req->slen;
        unsigned int dlen = req->dlen;
        struct page *spage, *dpage;
@@ -232,13 +233,12 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
                } while (0);
        }
 
-       stream = crypto_acomp_lock_stream_bh(&crypto_scomp_alg(scomp)->streams);
+       struct crypto_acomp_stream *stream = crypto_acomp_lock_stream_bh(&crypto_scomp_alg(scomp)->streams);
 
        if (!src_isvirt && !src) {
-               const u8 *src;
+               struct scomp_scratch *scratch = scomp_lock_scratch();
+               const u8 *src = scratch->src;
 
-               scratch = scomp_lock_scratch();
-               src = scratch->src;
                memcpy_from_sglist(scratch->src, req->src, 0, slen);
 
                if (dir)

diff --git a/include/crypto/internal/acompress.h b/include/crypto/internal/acompress.h
index 2d97440028ffd7bf3ae1c2c69ebb955c523838bb..9a3f28baa8043b1e1964b9b3a4327d163275566d 100644 (file)
--- a/include/crypto/internal/acompress.h
+++ b/include/crypto/internal/acompress.h
@@ -191,11 +191,12 @@ static inline bool crypto_acomp_req_virt(struct crypto_acomp *tfm)
 void crypto_acomp_free_streams(struct crypto_acomp_streams *s);
 int crypto_acomp_alloc_streams(struct crypto_acomp_streams *s);
 
-struct crypto_acomp_stream *crypto_acomp_lock_stream_bh(
-       struct crypto_acomp_streams *s) __acquires(stream);
+#define crypto_acomp_lock_stream_bh(...) __acquire_ret(_crypto_acomp_lock_stream_bh(__VA_ARGS__), &__ret->lock);
+struct crypto_acomp_stream *_crypto_acomp_lock_stream_bh(
+               struct crypto_acomp_streams *s) __acquires_ret;
 
 static inline void crypto_acomp_unlock_stream_bh(
-       struct crypto_acomp_stream *stream) __releases(stream)
+       struct crypto_acomp_stream *stream) __releases(&stream->lock)
 {
        spin_unlock_bh(&stream->lock);
 }

diff --git a/include/crypto/internal/engine.h b/include/crypto/internal/engine.h
index f19ef376833f391d8dfb98d20c387c45c59bdd58..6a1d27880615507ed7a8765859f3be6ae3fbb1d3 100644 (file)
--- a/include/crypto/internal/engine.h
+++ b/include/crypto/internal/engine.h
@@ -45,7 +45,7 @@ struct crypto_engine {
 
        struct list_head        list;
        spinlock_t              queue_lock;
-       struct crypto_queue     queue;
+       struct crypto_queue     queue __guarded_by(&queue_lock);
        struct device           *dev;
 
        struct kthread_worker           *kworker;