From 628ff7c1d8d8466a5ad8078bd0206a130f8b8a51 Mon Sep 17 00:00:00 2001
From: Roland Dreier <rdreier@cisco.com>
Date: Fri, 18 Dec 2009 09:41:24 -0800
Subject: [PATCH] anonfd: Allow making anon files read-only
It seems a couple places such as arch/ia64/kernel/perfmon.c and
drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile()
instead of a private pseudo-fs + alloc_file(), if only there were a way
to get a read-only file. So provide this by having anon_inode_getfile()
create a read-only file if we pass O_RDONLY in flags.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/anon_inodes.c | 12 ++++++++++--
fs/eventfd.c | 2 +-
fs/eventpoll.c | 2 +-
fs/signalfd.c | 2 +-
fs/timerfd.c | 2 +-
kernel/perf_event.c | 2 +-
virt/kvm/kvm_main.c | 4 ++--
7 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 2c994591f4d7a..598237e972212 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -89,11 +89,19 @@ struct file *anon_inode_getfile(const char *name,
struct qstr this;
struct path path;
struct file *file;
+ fmode_t mode;
int error;
if (IS_ERR(anon_inode_inode))
return ERR_PTR(-ENODEV);
+ switch (flags & O_ACCMODE) {
+ case O_RDONLY: mode = FMODE_READ; break;
+ case O_WRONLY: mode = FMODE_WRITE; break;
+ case O_RDWR: mode = FMODE_READ | FMODE_WRITE; break;
+ default: return ERR_PTR(-EINVAL);
+ }
+
if (fops->owner && !try_module_get(fops->owner))
return ERR_PTR(-ENOENT);
@@ -121,13 +129,13 @@ struct file *anon_inode_getfile(const char *name,
d_instantiate(path.dentry, anon_inode_inode);
error = -ENFILE;
- file = alloc_file(&path, FMODE_READ | FMODE_WRITE, fops);
+ file = alloc_file(&path, mode, fops);
if (!file)
goto err_dput;
file->f_mapping = anon_inode_inode->i_mapping;
file->f_pos = 0;
- file->f_flags = O_RDWR | (flags & O_NONBLOCK);
+ file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
file->f_version = 0;
file->private_data = priv;
diff --git a/fs/eventfd.c b/fs/eventfd.c
index 8b47e4200e65e..d26402ff06eaa 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -339,7 +339,7 @@ struct file *eventfd_file_create(unsigned int count, int flags)
ctx->flags = flags;
file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx,
- flags & EFD_SHARED_FCNTL_FLAGS);
+ O_RDWR | (flags & EFD_SHARED_FCNTL_FLAGS));
if (IS_ERR(file))
eventfd_free_ctx(ctx);
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 366c503f96573..bd056a5b4efc5 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1206,7 +1206,7 @@ SYSCALL_DEFINE1(epoll_create1, int, flags)
* a file structure and a free file descriptor.
*/
error = anon_inode_getfd("[eventpoll]", &eventpoll_fops, ep,
- flags & O_CLOEXEC);
+ O_RDWR | (flags & O_CLOEXEC));
if (error < 0)
ep_free(ep);
diff --git a/fs/signalfd.c b/fs/signalfd.c
index b07565c943867..1dabe4ee02fe9 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -236,7 +236,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
* anon_inode_getfd() will install the fd.
*/
ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx,
- flags & (O_CLOEXEC | O_NONBLOCK));
+ O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK)));
if (ufd < 0)
kfree(ctx);
} else {
diff --git a/fs/timerfd.c b/fs/timerfd.c
index b042bd7034b1f..1bfc95ad5f716 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -200,7 +200,7 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
hrtimer_init(&ctx->tmr, clockid, HRTIMER_MODE_ABS);
ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
- flags & TFD_SHARED_FCNTL_FLAGS);
+ O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
if (ufd < 0)
kfree(ctx);
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index e0eb4a2fe1833..1f38270f08c7d 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -4724,7 +4724,7 @@ SYSCALL_DEFINE5(perf_event_open,
if (IS_ERR(event))
goto err_put_context;
- err = anon_inode_getfd("[perf_event]", &perf_fops, event, 0);
+ err = anon_inode_getfd("[perf_event]", &perf_fops, event, O_RDWR);
if (err < 0)
goto err_free_put_context;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e1f2bf8d7b1e0..b5af88167613d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1177,7 +1177,7 @@ static struct file_operations kvm_vcpu_fops = {
*/
static int create_vcpu_fd(struct kvm_vcpu *vcpu)
{
- return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0);
+ return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, O_RDWR);
}
/*
@@ -1638,7 +1638,7 @@ static int kvm_dev_ioctl_create_vm(void)
kvm = kvm_create_vm();
if (IS_ERR(kvm))
return PTR_ERR(kvm);
- fd = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, 0);
+ fd = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
if (fd < 0)
kvm_put_kvm(kvm);
--
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