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Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c151
1 files changed, 94 insertions, 57 deletions
diff --git a/fs/open.c b/fs/open.c
index 3fa4e4ffce4c..7af1f05d5978 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -244,21 +244,21 @@ static long do_sys_truncate(const char __user * path, loff_t length)
if (!S_ISREG(inode->i_mode))
goto dput_and_out;
- error = vfs_permission(&nd, MAY_WRITE);
+ error = mnt_want_write(nd.path.mnt);
if (error)
goto dput_and_out;
- error = -EROFS;
- if (IS_RDONLY(inode))
- goto dput_and_out;
+ error = vfs_permission(&nd, MAY_WRITE);
+ if (error)
+ goto mnt_drop_write_and_out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
error = get_write_access(inode);
if (error)
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
/*
* Make sure that there are no leases. get_write_access() protects
@@ -276,6 +276,8 @@ static long do_sys_truncate(const char __user * path, loff_t length)
put_write_and_out:
put_write_access(inode);
+mnt_drop_write_and_out:
+ mnt_drop_write(nd.path.mnt);
dput_and_out:
path_put(&nd.path);
out:
@@ -457,8 +459,17 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
if(res || !(mode & S_IWOTH) ||
special_file(nd.path.dentry->d_inode->i_mode))
goto out_path_release;
-
- if(IS_RDONLY(nd.path.dentry->d_inode))
+ /*
+ * This is a rare case where using __mnt_is_readonly()
+ * is OK without a mnt_want/drop_write() pair. Since
+ * no actual write to the fs is performed here, we do
+ * not need to telegraph to that to anyone.
+ *
+ * By doing this, we accept that this access is
+ * inherently racy and know that the fs may change
+ * state before we even see this result.
+ */
+ if (__mnt_is_readonly(nd.path.mnt))
res = -EROFS;
out_path_release:
@@ -567,12 +578,12 @@ asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
audit_inode(NULL, dentry);
- err = -EROFS;
- if (IS_RDONLY(inode))
+ err = mnt_want_write(file->f_path.mnt);
+ if (err)
goto out_putf;
err = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto out_putf;
+ goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -581,6 +592,8 @@ asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
err = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
+out_drop_write:
+ mnt_drop_write(file->f_path.mnt);
out_putf:
fput(file);
out:
@@ -600,13 +613,13 @@ asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
goto out;
inode = nd.path.dentry->d_inode;
- error = -EROFS;
- if (IS_RDONLY(inode))
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
goto dput_and_out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto dput_and_out;
+ goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
@@ -616,6 +629,8 @@ asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
error = notify_change(nd.path.dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
+out_drop_write:
+ mnt_drop_write(nd.path.mnt);
dput_and_out:
path_put(&nd.path);
out:
@@ -638,9 +653,6 @@ static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
printk(KERN_ERR "chown_common: NULL inode\n");
goto out;
}
- error = -EROFS;
- if (IS_RDONLY(inode))
- goto out;
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out;
@@ -671,7 +683,12 @@ asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
error = user_path_walk(filename, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.path.dentry, user, group);
+ mnt_drop_write(nd.path.mnt);
+out_release:
path_put(&nd.path);
out:
return error;
@@ -691,7 +708,12 @@ asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
error = __user_walk_fd(dfd, filename, follow, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.path.dentry, user, group);
+ mnt_drop_write(nd.path.mnt);
+out_release:
path_put(&nd.path);
out:
return error;
@@ -705,7 +727,12 @@ asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group
error = user_path_walk_link(filename, &nd);
if (error)
goto out;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto out_release;
error = chown_common(nd.path.dentry, user, group);
+ mnt_drop_write(nd.path.mnt);
+out_release:
path_put(&nd.path);
out:
return error;
@@ -722,14 +749,48 @@ asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
if (!file)
goto out;
+ error = mnt_want_write(file->f_path.mnt);
+ if (error)
+ goto out_fput;
dentry = file->f_path.dentry;
audit_inode(NULL, dentry);
error = chown_common(dentry, user, group);
+ mnt_drop_write(file->f_path.mnt);
+out_fput:
fput(file);
out:
return error;
}
+/*
+ * You have to be very careful that these write
+ * counts get cleaned up in error cases and
+ * upon __fput(). This should probably never
+ * be called outside of __dentry_open().
+ */
+static inline int __get_file_write_access(struct inode *inode,
+ struct vfsmount *mnt)
+{
+ int error;
+ error = get_write_access(inode);
+ if (error)
+ return error;
+ /*
+ * Do not take mount writer counts on
+ * special files since no writes to
+ * the mount itself will occur.
+ */
+ if (!special_file(inode->i_mode)) {
+ /*
+ * Balanced in __fput()
+ */
+ error = mnt_want_write(mnt);
+ if (error)
+ put_write_access(inode);
+ }
+ return error;
+}
+
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
int flags, struct file *f,
int (*open)(struct inode *, struct file *))
@@ -742,9 +803,11 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
FMODE_PREAD | FMODE_PWRITE;
inode = dentry->d_inode;
if (f->f_mode & FMODE_WRITE) {
- error = get_write_access(inode);
+ error = __get_file_write_access(inode, mnt);
if (error)
goto cleanup_file;
+ if (!special_file(inode->i_mode))
+ file_take_write(f);
}
f->f_mapping = inode->i_mapping;
@@ -774,7 +837,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
if (f->f_flags & O_DIRECT) {
if (!f->f_mapping->a_ops ||
((!f->f_mapping->a_ops->direct_IO) &&
- (!f->f_mapping->a_ops->get_xip_page))) {
+ (!f->f_mapping->a_ops->get_xip_mem))) {
fput(f);
f = ERR_PTR(-EINVAL);
}
@@ -784,8 +847,19 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
cleanup_all:
fops_put(f->f_op);
- if (f->f_mode & FMODE_WRITE)
+ if (f->f_mode & FMODE_WRITE) {
put_write_access(inode);
+ if (!special_file(inode->i_mode)) {
+ /*
+ * We don't consider this a real
+ * mnt_want/drop_write() pair
+ * because it all happenend right
+ * here, so just reset the state.
+ */
+ file_reset_write(f);
+ mnt_drop_write(mnt);
+ }
+ }
file_kill(f);
f->f_path.dentry = NULL;
f->f_path.mnt = NULL;
@@ -796,43 +870,6 @@ cleanup_file:
return ERR_PTR(error);
}
-/*
- * Note that while the flag value (low two bits) for sys_open means:
- * 00 - read-only
- * 01 - write-only
- * 10 - read-write
- * 11 - special
- * it is changed into
- * 00 - no permissions needed
- * 01 - read-permission
- * 10 - write-permission
- * 11 - read-write
- * for the internal routines (ie open_namei()/follow_link() etc). 00 is
- * used by symlinks.
- */
-static struct file *do_filp_open(int dfd, const char *filename, int flags,
- int mode)
-{
- int namei_flags, error;
- struct nameidata nd;
-
- namei_flags = flags;
- if ((namei_flags+1) & O_ACCMODE)
- namei_flags++;
-
- error = open_namei(dfd, filename, namei_flags, mode, &nd);
- if (!error)
- return nameidata_to_filp(&nd, flags);
-
- return ERR_PTR(error);
-}
-
-struct file *filp_open(const char *filename, int flags, int mode)
-{
- return do_filp_open(AT_FDCWD, filename, flags, mode);
-}
-EXPORT_SYMBOL(filp_open);
-
/**
* lookup_instantiate_filp - instantiates the open intent filp
* @nd: pointer to nameidata
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-19 09:40:44 +0100