diff options
| -rw-r--r-- | fs/kernfs/file.c | 17 | ||||
| -rw-r--r-- | fs/sysfs/mount.c | 3 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 19 |
3 files changed, 30 insertions, 9 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index e01ea4a14a01..5e9a80cfc3d8 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -610,6 +610,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn, static int kernfs_fop_open(struct inode *inode, struct file *file) { struct kernfs_node *kn = file->f_path.dentry->d_fsdata; + struct kernfs_root *root = kernfs_root(kn); const struct kernfs_ops *ops; struct kernfs_open_file *of; bool has_read, has_write, has_mmap; @@ -624,14 +625,16 @@ static int kernfs_fop_open(struct inode *inode, struct file *file) has_write = ops->write || ops->mmap; has_mmap = ops->mmap; - /* check perms and supported operations */ - if ((file->f_mode & FMODE_WRITE) && - (!(inode->i_mode & S_IWUGO) || !has_write)) - goto err_out; + /* see the flag definition for details */ + if (root->flags & KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK) { + if ((file->f_mode & FMODE_WRITE) && + (!(inode->i_mode & S_IWUGO) || !has_write)) + goto err_out; - if ((file->f_mode & FMODE_READ) && - (!(inode->i_mode & S_IRUGO) || !has_read)) - goto err_out; + if ((file->f_mode & FMODE_READ) && + (!(inode->i_mode & S_IRUGO) || !has_read)) + goto err_out; + } /* allocate a kernfs_open_file for the file */ error = -ENOMEM; diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index a66ad6196f59..8794423f7efb 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -63,7 +63,8 @@ int __init sysfs_init(void) { int err; - sysfs_root = kernfs_create_root(NULL, 0, NULL); + sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK, + NULL); if (IS_ERR(sysfs_root)) return PTR_ERR(sysfs_root); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index b0122dc6f96a..ca1be5c9136c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -50,7 +50,24 @@ enum kernfs_node_flag { /* @flags for kernfs_create_root() */ enum kernfs_root_flag { - KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001, + /* + * kernfs_nodes are created in the deactivated state and invisible. + * They require explicit kernfs_activate() to become visible. This + * can be used to make related nodes become visible atomically + * after all nodes are created successfully. + */ + KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001, + + /* + * For regular flies, if the opener has CAP_DAC_OVERRIDE, open(2) + * succeeds regardless of the RW permissions. sysfs had an extra + * layer of enforcement where open(2) fails with -EACCES regardless + * of CAP_DAC_OVERRIDE if the permission doesn't have the + * respective read or write access at all (none of S_IRUGO or + * S_IWUGO) or the respective operation isn't implemented. The + * following flag enables that behavior. + */ + KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002, }; /* type-specific structures for kernfs_node union members */ |