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userfaultfd: use secure anon inodes for userfaultfd 

This change gives userfaultfd file descriptors a real security
context, allowing policy to act on them.

Signed-off-by: Daniel Colascione <dancol@google.com>
[LG: Remove owner inode from userfaultfd_ctx]
[LG: Use anon_inode_getfd_secure() in userfaultfd syscall]
[LG: Use inode of file in userfaultfd_read() in resolve_userfault_fork()]
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Daniel Colascione 2021-01-08 14:22:23 -08:00 committed by Paul Moore
parent 29cd6591ab
commit b537900f15
1 changed files with 10 additions and 9 deletions
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19
fs/userfaultfd.c
View File

@ -979,14 +979,14 @@ static __poll_t userfaultfd_poll(struct file *file, poll_table *wait)
static const struct file_operations userfaultfd_fops;
static int resolve_userfault_fork(struct userfaultfd_ctx *ctx,
struct userfaultfd_ctx *new,
static int resolve_userfault_fork(struct userfaultfd_ctx *new,
struct inode *inode,
struct uffd_msg *msg)
{
int fd;
fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new,
O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS));
fd = anon_inode_getfd_secure("[userfaultfd]", &userfaultfd_fops, new,
O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS), inode);
if (fd < 0)
return fd;
@ -996,7 +996,7 @@ static int resolve_userfault_fork(struct userfaultfd_ctx *ctx,
}
static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
struct uffd_msg *msg)
struct uffd_msg *msg, struct inode *inode)
{
ssize_t ret;
DECLARE_WAITQUEUE(wait, current);
@ -1107,7 +1107,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
spin_unlock_irq(&ctx->fd_wqh.lock);
if (!ret && msg->event == UFFD_EVENT_FORK) {
ret = resolve_userfault_fork(ctx, fork_nctx, msg);
ret = resolve_userfault_fork(fork_nctx, inode, msg);
spin_lock_irq(&ctx->event_wqh.lock);
if (!list_empty(&fork_event)) {
/*
@ -1167,6 +1167,7 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf,
ssize_t _ret, ret = 0;
struct uffd_msg msg;
int no_wait = file->f_flags & O_NONBLOCK;
struct inode *inode = file_inode(file);
if (ctx->state == UFFD_STATE_WAIT_API)
return -EINVAL;
@ -1174,7 +1175,7 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf,
for (;;) {
if (count < sizeof(msg))
return ret ? ret : -EINVAL;
_ret = userfaultfd_ctx_read(ctx, no_wait, &msg);
_ret = userfaultfd_ctx_read(ctx, no_wait, &msg, inode);
if (_ret < 0)
return ret ? ret : _ret;
if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg)))
@ -1999,8 +2000,8 @@ SYSCALL_DEFINE1(userfaultfd, int, flags)
/* prevent the mm struct to be freed */
mmgrab(ctx->mm);
fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx,
O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS));
fd = anon_inode_getfd_secure("[userfaultfd]", &userfaultfd_fops, ctx,
O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS), NULL);
if (fd < 0) {
mmdrop(ctx->mm);
kmem_cache_free(userfaultfd_ctx_cachep, ctx);