From: Baokun Li libaokun1@huawei.com
[ Upstream commit a26dc49df37e996876f50a0210039b2d211fdd6f ]
This prevents malicious processes from completing random copen/cread requests and crashing the system. Added checks are listed below:
* Generic, copen can only complete open requests, and cread can only complete read requests. * For copen, ondemand_id must not be 0, because this indicates that the request has not been read by the daemon. * For cread, the object corresponding to fd and req should be the same.
Signed-off-by: Baokun Li libaokun1@huawei.com Link: https://lore.kernel.org/r/20240522114308.2402121-7-libaokun@huaweicloud.com Acked-by: Jeff Layton jlayton@kernel.org Reviewed-by: Jingbo Xu jefflexu@linux.alibaba.com Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cachefiles/ondemand.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 89f118d68d125..6f815e7c50867 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -97,12 +97,12 @@ static loff_t cachefiles_ondemand_fd_llseek(struct file *filp, loff_t pos, }
static long cachefiles_ondemand_fd_ioctl(struct file *filp, unsigned int ioctl, - unsigned long arg) + unsigned long id) { struct cachefiles_object *object = filp->private_data; struct cachefiles_cache *cache = object->volume->cache; struct cachefiles_req *req; - unsigned long id; + XA_STATE(xas, &cache->reqs, id);
if (ioctl != CACHEFILES_IOC_READ_COMPLETE) return -EINVAL; @@ -110,10 +110,15 @@ static long cachefiles_ondemand_fd_ioctl(struct file *filp, unsigned int ioctl, if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags)) return -EOPNOTSUPP;
- id = arg; - req = xa_erase(&cache->reqs, id); - if (!req) + xa_lock(&cache->reqs); + req = xas_load(&xas); + if (!req || req->msg.opcode != CACHEFILES_OP_READ || + req->object != object) { + xa_unlock(&cache->reqs); return -EINVAL; + } + xas_store(&xas, NULL); + xa_unlock(&cache->reqs);
trace_cachefiles_ondemand_cread(object, id); complete(&req->done); @@ -142,6 +147,7 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) unsigned long id; long size; int ret; + XA_STATE(xas, &cache->reqs, 0);
if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags)) return -EOPNOTSUPP; @@ -165,9 +171,16 @@ int cachefiles_ondemand_copen(struct cachefiles_cache *cache, char *args) if (ret) return ret;
- req = xa_erase(&cache->reqs, id); - if (!req) + xa_lock(&cache->reqs); + xas.xa_index = id; + req = xas_load(&xas); + if (!req || req->msg.opcode != CACHEFILES_OP_OPEN || + !req->object->ondemand->ondemand_id) { + xa_unlock(&cache->reqs); return -EINVAL; + } + xas_store(&xas, NULL); + xa_unlock(&cache->reqs);
/* fail OPEN request if copen format is invalid */ ret = kstrtol(psize, 0, &size);