146 lines
4.4 KiB
Diff
146 lines
4.4 KiB
Diff
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From: Andreas Gruenbacher <agruen@suse.de>
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Subject: VFS hooks for per-filesystem permission models
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Patch-mainline: Not yet
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Add may_create and may_delete inode operations that filesystems can
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implement in order to override the vfs provided default behavior.
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This is required for implementing permission models which go beyond
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the traditional UNIX semantics.
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If a filesystem does not implement these hooks, the behavior is
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unchanged.
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Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
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---
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fs/namei.c | 48 +++++++++++++++++++++++++++++++++++++-----------
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include/linux/fs.h | 2 ++
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2 files changed, 39 insertions(+), 11 deletions(-)
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--- a/fs/namei.c
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+++ b/fs/namei.c
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@@ -1320,13 +1320,24 @@ static int may_delete(struct inode *dir,
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BUG_ON(victim->d_parent->d_inode != dir);
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audit_inode_child(victim, dir);
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- error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ if (dir->i_op->may_delete) {
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+ if (IS_RDONLY(dir))
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+ return -EROFS;
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+ if (IS_IMMUTABLE(dir))
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+ return -EACCES;
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+ error = dir->i_op->may_delete(dir, victim->d_inode);
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+ if (!error)
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+ error = security_inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ } else {
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+ error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ if (!error && check_sticky(dir, victim->d_inode))
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+ error = -EPERM;
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+ }
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if (error)
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return error;
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if (IS_APPEND(dir))
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return -EPERM;
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- if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
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- IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
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+ if (IS_APPEND(victim->d_inode) || IS_IMMUTABLE(victim->d_inode))
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return -EPERM;
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if (isdir) {
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if (!S_ISDIR(victim->d_inode->i_mode))
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@@ -1350,13 +1361,28 @@ static int may_delete(struct inode *dir,
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* 3. We should have write and exec permissions on dir
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* 4. We can't do it if dir is immutable (done in permission())
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*/
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-static inline int may_create(struct inode *dir, struct dentry *child)
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+static inline int may_create(struct inode *dir, struct dentry *child,
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+ int isdir)
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{
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+ int error;
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+
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if (child->d_inode)
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return -EEXIST;
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if (IS_DEADDIR(dir))
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return -ENOENT;
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- return inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+
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+ if (dir->i_op->may_create) {
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+ if (IS_RDONLY(dir))
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+ return -EROFS;
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+ if (IS_IMMUTABLE(dir))
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+ return -EACCES;
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+ error = dir->i_op->may_create(dir, isdir);
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+ if (!error)
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+ error = security_inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ } else
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+ error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+
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+ return error;
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}
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/*
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@@ -1404,7 +1430,7 @@ void unlock_rename(struct dentry *p1, st
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int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
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struct nameidata *nd)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -1963,7 +1989,7 @@ EXPORT_SYMBOL_GPL(lookup_create);
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int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -2067,7 +2093,7 @@ SYSCALL_DEFINE3(mknod, const char __user
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int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 1);
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if (error)
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return error;
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@@ -2350,7 +2376,7 @@ SYSCALL_DEFINE1(unlink, const char __use
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int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -2423,7 +2449,7 @@ int vfs_link(struct dentry *old_dentry,
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if (!inode)
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return -ENOENT;
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- error = may_create(dir, new_dentry);
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+ error = may_create(dir, new_dentry, S_ISDIR(inode->i_mode));
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if (error)
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return error;
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@@ -2636,7 +2662,7 @@ int vfs_rename(struct inode *old_dir, st
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return error;
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if (!new_dentry->d_inode)
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- error = may_create(new_dir, new_dentry);
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+ error = may_create(new_dir, new_dentry, is_dir);
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else
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error = may_delete(new_dir, new_dentry, is_dir);
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if (error)
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--- a/include/linux/fs.h
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+++ b/include/linux/fs.h
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@@ -1531,6 +1531,8 @@ struct inode_operations {
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void (*truncate) (struct inode *);
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int (*permission) (struct inode *, int);
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int (*check_acl)(struct inode *, int);
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+ int (*may_create) (struct inode *, int);
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+ int (*may_delete) (struct inode *, struct inode *);
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int (*setattr) (struct dentry *, struct iattr *);
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int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *);
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int (*setxattr) (struct dentry *, const char *,const void *,size_t,int);
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