From: Herbert Xu <[email protected]> random: Add hook to override device reads and getrandom(2)
Upstream Status: RHEL only Restore the changes to /dev/random which were reverted after 5.18. This reverts commit 900f11e054896bae7b0146055698656e3d1e20a6. This also brings the code up-to-date with respect to centos-stream commit 9de3a7339793d3c516b9305a8854267156f90c53 so that changes that were made after the kernel-ark revert have been brought in. Signed-off-by: Herbert Xu <[email protected]> diff --git a/drivers/char/random.c b/drivers/char/random.c index blahblah..blahblah 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -51,6 +51,7 @@ #include <linux/completion.h> #include <linux/uuid.h> #include <linux/uaccess.h> +#include <linux/rcupdate.h> #include <linux/suspend.h> #include <linux/siphash.h> #include <linux/sched/isolation.h> @@ -309,6 +310,11 @@ static void crng_fast_key_erasure(u8 key[CHACHA_KEY_SIZE], memzero_explicit(first_block, sizeof(first_block)); } +/* + * Hook for external RNG. + */ +static const struct random_extrng __rcu *extrng; + /* * This function returns a ChaCha state that you may use for generating * random data. It also returns up to 32 bytes on its own of random data @@ -739,6 +745,9 @@ static void __cold _credit_init_bits(size_t bits) } +static const struct file_operations extrng_random_fops; +static const struct file_operations extrng_urandom_fops; + /********************************************************************** * * Entropy collection routines. @@ -956,6 +965,19 @@ void __init add_bootloader_randomness(const void *buf, size_t len) credit_init_bits(len * 8); } +void random_register_extrng(const struct random_extrng *rng) +{ + rcu_assign_pointer(extrng, rng); +} +EXPORT_SYMBOL_GPL(random_register_extrng); + +void random_unregister_extrng(void) +{ + RCU_INIT_POINTER(extrng, NULL); + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(random_unregister_extrng); + #if IS_ENABLED(CONFIG_VMGENID) static BLOCKING_NOTIFIER_HEAD(vmfork_chain); @@ -1366,6 +1388,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags struct iov_iter iter; struct iovec iov; int ret; + const struct random_extrng *rng; if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) return -EINVAL; @@ -1377,6 +1400,21 @@ SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) return -EINVAL; + rcu_read_lock(); + rng = rcu_dereference(extrng); + if (rng && !try_module_get(rng->owner)) + rng = NULL; + rcu_read_unlock(); + + if (rng) { + ret = import_single_range(ITER_DEST, ubuf, len, &iov, &iter); + if (unlikely(ret)) + return ret; + ret = rng->extrng_read_iter(&iter, !!(flags & GRND_RANDOM)); + module_put(rng->owner); + return ret; + } + if (!crng_ready() && !(flags & GRND_INSECURE)) { if (flags & GRND_NONBLOCK) return -EAGAIN; @@ -1397,6 +1435,12 @@ static __poll_t random_poll(struct file *file, poll_table *wait) return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM; } +static __poll_t extrng_poll(struct file *file, poll_table * wait) +{ + /* extrng pool is always full, always read, no writes */ + return EPOLLIN | EPOLLRDNORM; +} + static ssize_t write_pool_user(struct iov_iter *iter) { u8 block[BLAKE2S_BLOCK_SIZE]; @@ -1538,7 +1582,58 @@ static int random_fasync(int fd, struct file *filp, int on) return fasync_helper(fd, filp, on, &fasync); } +static int random_open(struct inode *inode, struct file *filp) +{ + const struct random_extrng *rng; + + rcu_read_lock(); + rng = rcu_dereference(extrng); + if (rng && !try_module_get(rng->owner)) + rng = NULL; + rcu_read_unlock(); + + if (!rng) + return 0; + + filp->f_op = &extrng_random_fops; + filp->private_data = rng->owner; + + return 0; +} + +static int urandom_open(struct inode *inode, struct file *filp) +{ + const struct random_extrng *rng; + + rcu_read_lock(); + rng = rcu_dereference(extrng); + if (rng && !try_module_get(rng->owner)) + rng = NULL; + rcu_read_unlock(); + + if (!rng) + return 0; + + filp->f_op = &extrng_urandom_fops; + filp->private_data = rng->owner; + + return 0; +} + +static int extrng_release(struct inode *inode, struct file *filp) +{ + module_put(filp->private_data); + return 0; +} + +static ssize_t +extrng_read_iter(struct kiocb *kiocb, struct iov_iter *iter) +{ + return rcu_dereference_raw(extrng)->extrng_read_iter(iter, false); +} + const struct file_operations random_fops = { + .open = random_open, .read_iter = random_read_iter, .write_iter = random_write_iter, .poll = random_poll, @@ -1551,6 +1646,7 @@ const struct file_operations random_fops = { }; const struct file_operations urandom_fops = { + .open = urandom_open, .read_iter = urandom_read_iter, .write_iter = random_write_iter, .unlocked_ioctl = random_ioctl, @@ -1561,6 +1657,32 @@ const struct file_operations urandom_fops = { .splice_write = iter_file_splice_write, }; +static const struct file_operations extrng_random_fops = { + .open = random_open, + .read_iter = extrng_read_iter, + .write_iter = random_write_iter, + .poll = extrng_poll, + .unlocked_ioctl = random_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .fasync = random_fasync, + .llseek = noop_llseek, + .release = extrng_release, + .splice_read = copy_splice_read, + .splice_write = iter_file_splice_write, +}; + +static const struct file_operations extrng_urandom_fops = { + .open = urandom_open, + .read_iter = extrng_read_iter, + .write_iter = random_write_iter, + .unlocked_ioctl = random_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .fasync = random_fasync, + .llseek = noop_llseek, + .release = extrng_release, + .splice_read = copy_splice_read, + .splice_write = iter_file_splice_write, +}; /******************************************************************** * diff --git a/include/linux/random.h b/include/linux/random.h index blahblah..blahblah 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -9,6 +9,13 @@ #include <uapi/linux/random.h> +struct iov_iter; + +struct random_extrng { + ssize_t (*extrng_read_iter)(struct iov_iter *iter, bool reseed); + struct module *owner; +}; + struct notifier_block; void add_device_randomness(const void *buf, size_t len); @@ -157,6 +164,9 @@ int random_prepare_cpu(unsigned int cpu); int random_online_cpu(unsigned int cpu); #endif +void random_register_extrng(const struct random_extrng *rng); +void random_unregister_extrng(void); + #ifndef MODULE extern const struct file_operations random_fops, urandom_fops; #endif -- https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2757 _______________________________________________ kernel mailing list -- [email protected] To unsubscribe send an email to [email protected] Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/[email protected] Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
