Message ID | 20220823150035.711534-6-roberto.sassu@huaweicloud.com (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | bpf: Add kfuncs for PKCS#7 signature verification | expand |
On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu <roberto.sassu@huaweicloud.com> wrote: > > From: Roberto Sassu <roberto.sassu@huawei.com> > > Add the bpf_lookup_user_key(), bpf_lookup_system_key() and bpf_key_put() > kfuncs, to respectively search a key with a given key handle serial number > and flags, obtain a key from a pre-determined ID defined in > include/linux/verification.h, and cleanup. > > Introduce system_keyring_id_check() to validate the keyring ID parameter of > bpf_lookup_system_key(). > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > --- > include/linux/bpf.h | 6 ++ > include/linux/verification.h | 8 +++ > kernel/trace/bpf_trace.c | 135 +++++++++++++++++++++++++++++++++++ > 3 files changed, 149 insertions(+) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 6041304b402e..991da09a5858 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} > static inline void bpf_cgroup_atype_put(int cgroup_atype) {} > #endif /* CONFIG_BPF_LSM */ > > +#ifdef CONFIG_KEYS Do we need to declare struct key here? > +struct bpf_key { > + struct key *key; > + bool has_ref; > +}; > +#endif /* CONFIG_KEYS */ > #endif /* _LINUX_BPF_H */ >
On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote: > On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu > <roberto.sassu@huaweicloud.com> wrote: > > From: Roberto Sassu <roberto.sassu@huawei.com> > > > > Add the bpf_lookup_user_key(), bpf_lookup_system_key() and > > bpf_key_put() > > kfuncs, to respectively search a key with a given key handle serial > > number > > and flags, obtain a key from a pre-determined ID defined in > > include/linux/verification.h, and cleanup. > > > > Introduce system_keyring_id_check() to validate the keyring ID > > parameter of > > bpf_lookup_system_key(). > > > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > > --- > > include/linux/bpf.h | 6 ++ > > include/linux/verification.h | 8 +++ > > kernel/trace/bpf_trace.c | 135 > > +++++++++++++++++++++++++++++++++++ > > 3 files changed, 149 insertions(+) > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index 6041304b402e..991da09a5858 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 > > attach_btf_id, int cgroup_atype) {} > > static inline void bpf_cgroup_atype_put(int cgroup_atype) {} > > #endif /* CONFIG_BPF_LSM */ > > > > +#ifdef CONFIG_KEYS > > Do we need to declare struct key here? > > > +struct bpf_key { > > + struct key *key; > > + bool has_ref; > > +}; > > +#endif /* CONFIG_KEYS */ > > #endif /* _LINUX_BPF_H */ > > If there is a better place, I will move there. Thanks Roberto
On Fri, Aug 26, 2022 at 12:22 AM Roberto Sassu <roberto.sassu@huaweicloud.com> wrote: > > On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote: > > On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu > > <roberto.sassu@huaweicloud.com> wrote: > > > From: Roberto Sassu <roberto.sassu@huawei.com> > > > > > > Add the bpf_lookup_user_key(), bpf_lookup_system_key() and > > > bpf_key_put() > > > kfuncs, to respectively search a key with a given key handle serial > > > number > > > and flags, obtain a key from a pre-determined ID defined in > > > include/linux/verification.h, and cleanup. > > > > > > Introduce system_keyring_id_check() to validate the keyring ID > > > parameter of > > > bpf_lookup_system_key(). > > > > > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > > > --- > > > include/linux/bpf.h | 6 ++ > > > include/linux/verification.h | 8 +++ > > > kernel/trace/bpf_trace.c | 135 > > > +++++++++++++++++++++++++++++++++++ > > > 3 files changed, 149 insertions(+) > > > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > > index 6041304b402e..991da09a5858 100644 > > > --- a/include/linux/bpf.h > > > +++ b/include/linux/bpf.h > > > @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 > > > attach_btf_id, int cgroup_atype) {} > > > static inline void bpf_cgroup_atype_put(int cgroup_atype) {} > > > #endif /* CONFIG_BPF_LSM */ > > > > > > +#ifdef CONFIG_KEYS > > > > Do we need to declare struct key here? > > > > > +struct bpf_key { > > > + struct key *key; > > > + bool has_ref; > > > +}; > > > +#endif /* CONFIG_KEYS */ > > > #endif /* _LINUX_BPF_H */ > > > > > If there is a better place, I will move there. I guess you misunderstood. I meant we need struct key; struct bpf_key { struct key *key; bool has_ref; }; Otherwise, we may get some warning with certain config. Thanks, Song
On Fri, 2022-08-26 at 00:25 -0700, Song Liu wrote: > On Fri, Aug 26, 2022 at 12:22 AM Roberto Sassu > <roberto.sassu@huaweicloud.com> wrote: > > On Thu, 2022-08-25 at 22:56 -0700, Song Liu wrote: > > > On Tue, Aug 23, 2022 at 8:02 AM Roberto Sassu > > > <roberto.sassu@huaweicloud.com> wrote: > > > > From: Roberto Sassu <roberto.sassu@huawei.com> > > > > > > > > Add the bpf_lookup_user_key(), bpf_lookup_system_key() and > > > > bpf_key_put() > > > > kfuncs, to respectively search a key with a given key handle > > > > serial > > > > number > > > > and flags, obtain a key from a pre-determined ID defined in > > > > include/linux/verification.h, and cleanup. > > > > > > > > Introduce system_keyring_id_check() to validate the keyring ID > > > > parameter of > > > > bpf_lookup_system_key(). > > > > > > > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > > > > --- > > > > include/linux/bpf.h | 6 ++ > > > > include/linux/verification.h | 8 +++ > > > > kernel/trace/bpf_trace.c | 135 > > > > +++++++++++++++++++++++++++++++++++ > > > > 3 files changed, 149 insertions(+) > > > > > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > > > index 6041304b402e..991da09a5858 100644 > > > > --- a/include/linux/bpf.h > > > > +++ b/include/linux/bpf.h > > > > @@ -2586,4 +2586,10 @@ static inline void > > > > bpf_cgroup_atype_get(u32 > > > > attach_btf_id, int cgroup_atype) {} > > > > static inline void bpf_cgroup_atype_put(int cgroup_atype) {} > > > > #endif /* CONFIG_BPF_LSM */ > > > > > > > > +#ifdef CONFIG_KEYS > > > > > > Do we need to declare struct key here? > > > > > > > +struct bpf_key { > > > > + struct key *key; > > > > + bool has_ref; > > > > +}; > > > > +#endif /* CONFIG_KEYS */ > > > > #endif /* _LINUX_BPF_H */ > > > > > > > > If there is a better place, I will move there. > > I guess you misunderstood. I meant we need > > struct key; > > struct bpf_key { > struct key *key; > bool has_ref; > }; > > Otherwise, we may get some warning with certain config. Argh, thanks! Will add it. Roberto
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6041304b402e..991da09a5858 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2586,4 +2586,10 @@ static inline void bpf_cgroup_atype_get(u32 attach_btf_id, int cgroup_atype) {} static inline void bpf_cgroup_atype_put(int cgroup_atype) {} #endif /* CONFIG_BPF_LSM */ +#ifdef CONFIG_KEYS +struct bpf_key { + struct key *key; + bool has_ref; +}; +#endif /* CONFIG_KEYS */ #endif /* _LINUX_BPF_H */ diff --git a/include/linux/verification.h b/include/linux/verification.h index a655923335ae..f34e50ebcf60 100644 --- a/include/linux/verification.h +++ b/include/linux/verification.h @@ -17,6 +17,14 @@ #define VERIFY_USE_SECONDARY_KEYRING ((struct key *)1UL) #define VERIFY_USE_PLATFORM_KEYRING ((struct key *)2UL) +static inline int system_keyring_id_check(u64 id) +{ + if (id > (unsigned long)VERIFY_USE_PLATFORM_KEYRING) + return -EINVAL; + + return 0; +} + /* * The use to which an asymmetric key is being put. */ diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 68e5cdd24cef..dfea85c7f4f0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -20,6 +20,8 @@ #include <linux/fprobe.h> #include <linux/bsearch.h> #include <linux/sort.h> +#include <linux/key.h> +#include <linux/verification.h> #include <net/bpf_sk_storage.h> @@ -1181,6 +1183,139 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = { .arg1_type = ARG_PTR_TO_CTX, }; +#ifdef CONFIG_KEYS +__diag_push(); +__diag_ignore_all("-Wmissing-prototypes", + "kfuncs which will be used in BPF programs"); + +/** + * bpf_lookup_user_key - lookup a key by its serial + * @serial: key handle serial number + * @flags: lookup-specific flags + * + * Search a key with a given *serial* and the provided *flags*. + * If found, increment the reference count of the key by one, and + * return it in the bpf_key structure. + * + * The bpf_key structure must be passed to bpf_key_put() when done + * with it, so that the key reference count is decremented and the + * bpf_key structure is freed. + * + * Permission checks are deferred to the time the key is used by + * one of the available key-specific kfuncs. + * + * Set *flags* with KEY_LOOKUP_CREATE, to attempt creating a requested + * special keyring (e.g. session keyring), if it doesn't yet exist. + * Set *flags* with KEY_LOOKUP_PARTIAL, to lookup a key without waiting + * for the key construction, and to retrieve uninstantiated keys (keys + * without data attached to them). + * + * Return: a bpf_key pointer with a valid key pointer if the key is found, a + * NULL pointer otherwise. + */ +struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) +{ + key_ref_t key_ref; + struct bpf_key *bkey; + + if (key_lookup_flags_check(flags) < 0) + return NULL; + + /* + * Permission check is deferred until the key is used, as the + * intent of the caller is unknown here. + */ + key_ref = lookup_user_key(serial, flags, KEY_DEFER_PERM_CHECK); + if (IS_ERR(key_ref)) + return NULL; + + bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC); + if (!bkey) { + key_put(key_ref_to_ptr(key_ref)); + return NULL; + } + + bkey->key = key_ref_to_ptr(key_ref); + bkey->has_ref = true; + + return bkey; +} + +/** + * bpf_lookup_system_key - lookup a key by a system-defined ID + * @id: key ID + * + * Obtain a bpf_key structure with a key pointer set to the passed key ID. + * The key pointer is marked as invalid, to prevent bpf_key_put() from + * attempting to decrement the key reference count on that pointer. The key + * pointer set in such way is currently understood only by + * verify_pkcs7_signature(). + * + * Set *id* to one of the values defined in include/linux/verification.h: + * 0 for the primary keyring (immutable keyring of system keys); + * VERIFY_USE_SECONDARY_KEYRING for both the primary and secondary keyring + * (where keys can be added only if they are vouched for by existing keys + * in those keyrings); VERIFY_USE_PLATFORM_KEYRING for the platform + * keyring (primarily used by the integrity subsystem to verify a kexec'ed + * kerned image and, possibly, the initramfs signature). + * + * Return: a bpf_key pointer with an invalid key pointer set from the + * pre-determined ID on success, a NULL pointer otherwise + */ +struct bpf_key *bpf_lookup_system_key(u64 id) +{ + struct bpf_key *bkey; + + if (system_keyring_id_check(id) < 0) + return NULL; + + bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC); + if (!bkey) + return NULL; + + bkey->key = (struct key *)(unsigned long)id; + bkey->has_ref = false; + + return bkey; +} + +/** + * bpf_key_put - decrement key reference count if key is valid and free bpf_key + * @bkey: bpf_key structure + * + * Decrement the reference count of the key inside *bkey*, if the pointer + * is valid, and free *bkey*. + */ +void bpf_key_put(struct bpf_key *bkey) +{ + if (bkey->has_ref) + key_put(bkey->key); + + kfree(bkey); +} + +__diag_pop(); + +BTF_SET8_START(key_sig_kfunc_set) +BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL) +BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE) +BTF_SET8_END(key_sig_kfunc_set) + +static const struct btf_kfunc_id_set bpf_key_sig_kfunc_set = { + .owner = THIS_MODULE, + .set = &key_sig_kfunc_set, +}; + +static int __init bpf_key_sig_kfuncs_init(void) +{ + return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, + &bpf_key_sig_kfunc_set); +} + +late_initcall(bpf_key_sig_kfuncs_init); +#endif /* CONFIG_KEYS */ + static const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) {