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cachefiles: add consistency check for copen/cread

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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>
This commit is contained in:
Baokun Li 2024-05-22 19:43:02 +08:00 committed by Christian Brauner
parent 3e6d704f02
commit a26dc49df3
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 20 additions and 7 deletions
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27
fs/cachefiles/ondemand.c
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@ -82,12 +82,12 @@ 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;
@ -95,10 +95,15 @@ 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);
@ -126,6 +131,7 @@ 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;
@ -149,9 +155,16 @@ 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);