From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Miklos Szeredi <mszeredi@redhat.com>
Subject: [RFC][PATCH 37/42] do_shmat(): grab shp->shm_file earlier, switch to alloc_file_clone()
Date: Wed, 11 Jul 2018 03:22:01 +0100 [thread overview]
Message-ID: <20180711022206.12571-37-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20180711022206.12571-1-viro@ZenIV.linux.org.uk>
From: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
ipc/shm.c | 39 ++++++++++++++++++---------------------
1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/ipc/shm.c b/ipc/shm.c
index 051a3e1fb8df..0cebcf74b669 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1354,14 +1354,13 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
struct shmid_kernel *shp;
unsigned long addr = (unsigned long)shmaddr;
unsigned long size;
- struct file *file;
+ struct file *file, *base;
int err;
unsigned long flags = MAP_SHARED;
unsigned long prot;
int acc_mode;
struct ipc_namespace *ns;
struct shm_file_data *sfd;
- struct path path;
fmode_t f_mode;
unsigned long populate = 0;
@@ -1435,46 +1434,44 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg,
goto out_unlock;
}
- path = shp->shm_file->f_path;
- path_get(&path);
+ /*
+ * We need to take a reference to the real shm file to prevent the
+ * pointer from becoming stale in cases where the lifetime of the outer
+ * file extends beyond that of the shm segment. It's not usually
+ * possible, but it can happen during remap_file_pages() emulation as
+ * that unmaps the memory, then does ->mmap() via file reference only.
+ * We'll deny the ->mmap() if the shm segment was since removed, but to
+ * detect shm ID reuse we need to compare the file pointers.
+ */
+ base = get_file(shp->shm_file);
shp->shm_nattch++;
- size = i_size_read(d_inode(path.dentry));
+ size = i_size_read(file_inode(base));
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();
err = -ENOMEM;
sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
if (!sfd) {
- path_put(&path);
+ fput(base);
goto out_nattch;
}
- file = alloc_file(&path, f_mode,
- is_file_hugepages(shp->shm_file) ?
+ file = alloc_file_clone(base, f_mode,
+ is_file_hugepages(base) ?
&shm_file_operations_huge :
&shm_file_operations);
err = PTR_ERR(file);
if (IS_ERR(file)) {
kfree(sfd);
- path_put(&path);
+ fput(base);
goto out_nattch;
}
- file->private_data = sfd;
- file->f_mapping = shp->shm_file->f_mapping;
sfd->id = shp->shm_perm.id;
sfd->ns = get_ipc_ns(ns);
- /*
- * We need to take a reference to the real shm file to prevent the
- * pointer from becoming stale in cases where the lifetime of the outer
- * file extends beyond that of the shm segment. It's not usually
- * possible, but it can happen during remap_file_pages() emulation as
- * that unmaps the memory, then does ->mmap() via file reference only.
- * We'll deny the ->mmap() if the shm segment was since removed, but to
- * detect shm ID reuse we need to compare the file pointers.
- */
- sfd->file = get_file(shp->shm_file);
+ sfd->file = base;
sfd->vm_ops = NULL;
+ file->private_data = sfd;
err = security_mmap_file(file, prot, flags);
if (err)
--
2.11.0
next prev parent reply other threads:[~2018-07-11 2:22 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180710101736.32d6cc6c@canb.auug.org.au>
[not found] ` <20180710150455.GK30522@ZenIV.linux.org.uk>
2018-07-11 2:11 ` linux-next: manual merge of the vfs tree with the overlayfs tree Al Viro
2018-07-11 2:21 ` [RFC][PATCH 01/42] drm_mode_create_lease_ioctl(): fix open-coded filp_clone_open() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 02/42] cxl_getfile(): fix double-iput() on alloc_file() failures Al Viro
2018-07-11 2:21 ` [RFC][PATCH 03/42] ocxlflash_getfile(): " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 04/42] make get_empty_filp() to call file_free_rcu() directly Al Viro
2018-07-11 2:35 ` Linus Torvalds
2018-07-11 2:43 ` Al Viro
2018-07-11 2:21 ` [RFC][PATCH 05/42] fold security_file_free() into file_free() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 06/42] turn filp_clone_open() into inline wrapper for dentry_open() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 07/42] create_pipe_files(): use fput() if allocation of the second file fails Al Viro
2018-07-11 2:21 ` [RFC][PATCH 08/42] make sure do_dentry_open() won't return positive as an error Al Viro
2018-07-11 2:39 ` Linus Torvalds
2018-07-11 2:41 ` Al Viro
2018-07-11 2:21 ` [RFC][PATCH 09/42] pass creds to get_empty_filp(), make sure dentry_open() passes the right creds Al Viro
2018-07-11 2:21 ` [RFC][PATCH 10/42] get rid of cred argument of vfs_open() and do_dentry_open() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 11/42] security_file_open(): lose cred argument Al Viro
2018-07-11 2:21 ` [RFC][PATCH 12/42] ->file_open(): " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 13/42] introduce FMODE_OPENED Al Viro
2018-07-11 2:21 ` [RFC][PATCH 14/42] fold put_filp() into fput() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 15/42] lift fput() on late failures into path_openat() Al Viro
2018-07-11 5:43 ` Amir Goldstein
2018-07-11 2:21 ` [RFC][PATCH 16/42] now we can fold open_check_o_direct() into do_dentry_open() Al Viro
2018-07-11 2:44 ` Linus Torvalds
2018-07-11 2:59 ` Al Viro
2018-07-11 3:13 ` Linus Torvalds
2018-07-11 2:21 ` [RFC][PATCH 17/42] switch all remaining checks for FILE_OPENED to FMODE_OPENED Al Viro
2018-07-11 2:21 ` [RFC][PATCH 18/42] introduce FMODE_CREATED and switch to it Al Viro
2018-07-11 2:21 ` [RFC][PATCH 19/42] IMA: don't propagate opened through the entire thing Al Viro
2018-07-11 2:21 ` [RFC][PATCH 20/42] getting rid of 'opened' argument of ->atomic_open() - step 1 Al Viro
2018-07-11 2:21 ` [RFC][PATCH 21/42] getting rid of 'opened' argument of ->atomic_open() - part 2 Al Viro
2018-07-11 2:21 ` [RFC][PATCH 22/42] get rid of 'opened' argument of ->atomic_open() - part 3 Al Viro
2018-07-11 2:21 ` [RFC][PATCH 23/42] get rid of 'opened' in path_openat() and the helpers downstream Al Viro
2018-07-11 2:21 ` [RFC][PATCH 24/42] ->atomic_open(): return 0 in all success cases Al Viro
2018-07-11 2:21 ` [RFC][PATCH 25/42] document ->atomic_open() changes Al Viro
2018-07-11 2:21 ` [RFC][PATCH 26/42] switch atomic_open() and lookup_open() to returning 0 in all success cases Al Viro
2018-07-11 2:21 ` [RFC][PATCH 27/42] kill FILE_{CREATED,OPENED} Al Viro
2018-07-11 2:21 ` [RFC][PATCH 28/42] new wrapper: alloc_file_pseudo() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 29/42] __shmem_file_setup(): reorder allocations Al Viro
2018-07-11 2:21 ` [RFC][PATCH 30/42] ... and switch shmem_file_setup() to alloc_file_pseudo() Al Viro
2018-07-11 2:21 ` [RFC][PATCH 31/42] cxl_getfile(): switch " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 32/42] ocxlflash_getfile(): " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 33/42] hugetlb_file_setup(): " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 34/42] anon_inode_getfile(): " Al Viro
2018-07-11 2:21 ` [RFC][PATCH 35/42] create_pipe_files(): switch the first allocation " Al Viro
2018-07-11 2:22 ` [RFC][PATCH 36/42] new helper: alloc_file_clone() Al Viro
2018-07-11 2:22 ` Al Viro [this message]
2018-07-11 2:22 ` [RFC][PATCH 38/42] make alloc_file() static Al Viro
2018-07-11 2:22 ` [RFC][PATCH 39/42] document alloc_file() changes Al Viro
2018-07-11 2:22 ` [RFC][PATCH 40/42] make path_init() unconditionally paired with terminate_walk() Al Viro
2018-07-11 2:22 ` [RFC][PATCH 41/42] allow link_path_walk() to take ERR_PTR() Al Viro
2018-07-11 2:22 ` [RFC][PATCH 42/42] few more cleanups of link_path_walk() callers Al Viro
2018-07-11 2:56 ` [RFC][PATCH 01/42] drm_mode_create_lease_ioctl(): fix open-coded filp_clone_open() Linus Torvalds
2018-07-11 15:25 ` Al Viro
2018-07-11 16:15 ` Al Viro
2018-07-12 12:43 ` Al Viro
2018-07-12 15:05 ` Linus Torvalds
2018-07-12 15:53 ` vfs / overlayfs conflict resolution for linux-next Al Viro
2018-07-18 2:56 ` Al Viro
2018-07-18 3:29 ` Stephen Rothwell
2018-07-18 7:25 ` Miklos Szeredi
2018-07-18 12:10 ` Miklos Szeredi
2018-07-18 12:43 ` Al Viro
2018-07-18 13:46 ` Al Viro
2018-07-18 15:46 ` Miklos Szeredi
2018-07-18 18:12 ` [RFC] call_with_creds() Al Viro
2018-07-18 18:19 ` Linus Torvalds
2018-07-18 19:46 ` Al Viro
2018-07-18 19:53 ` Linus Torvalds
2018-07-18 20:04 ` Al Viro
2018-07-18 20:15 ` Al Viro
2018-07-18 20:43 ` Linus Torvalds
2018-07-18 21:22 ` Al Viro
2018-07-18 23:06 ` Linus Torvalds
2018-07-18 21:27 ` David Howells
2018-07-18 23:16 ` Linus Torvalds
2018-07-18 21:28 ` David Howells
2018-07-18 23:13 ` Linus Torvalds
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