diff options
| author | Dave Hansen <haveblue@us.ibm.com> | 2008-02-15 14:37:38 -0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2008-04-19 00:29:15 -0400 |
| commit | 18f335aff86913de3c76f88d32c8135c1da62ce6 (patch) | |
| tree | bf541547b9774137a161d200bace04ad152e80e3 /fs/xattr.c | |
| parent | 9079b1eb1753f217c3de9f1b7dd7fd549cc3f0cf (diff) | |
| download | lwn-18f335aff86913de3c76f88d32c8135c1da62ce6.tar.gz lwn-18f335aff86913de3c76f88d32c8135c1da62ce6.zip | |
[PATCH] r/o bind mounts: elevate write count for xattr_permission() callers
This basically audits the callers of xattr_permission(), which calls
permission() and can perform writes to the filesystem.
[AV: add missing parts - removexattr() and nfsd posix acls, plug for a leak
spotted by Miklos]
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/xattr.c')
| -rw-r--r-- | fs/xattr.c | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/fs/xattr.c b/fs/xattr.c index 3acab1615460..f7062da505d4 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -11,6 +11,7 @@ #include <linux/slab.h> #include <linux/file.h> #include <linux/xattr.h> +#include <linux/mount.h> #include <linux/namei.h> #include <linux/security.h> #include <linux/syscalls.h> @@ -32,8 +33,6 @@ xattr_permission(struct inode *inode, const char *name, int mask) * filesystem or on an immutable / append-only inode. */ if (mask & MAY_WRITE) { - if (IS_RDONLY(inode)) - return -EROFS; if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) return -EPERM; } @@ -262,7 +261,11 @@ sys_setxattr(char __user *path, char __user *name, void __user *value, error = user_path_walk(path, &nd); if (error) return error; - error = setxattr(nd.path.dentry, name, value, size, flags); + error = mnt_want_write(nd.path.mnt); + if (!error) { + error = setxattr(nd.path.dentry, name, value, size, flags); + mnt_drop_write(nd.path.mnt); + } path_put(&nd.path); return error; } @@ -277,7 +280,11 @@ sys_lsetxattr(char __user *path, char __user *name, void __user *value, error = user_path_walk_link(path, &nd); if (error) return error; - error = setxattr(nd.path.dentry, name, value, size, flags); + error = mnt_want_write(nd.path.mnt); + if (!error) { + error = setxattr(nd.path.dentry, name, value, size, flags); + mnt_drop_write(nd.path.mnt); + } path_put(&nd.path); return error; } @@ -295,7 +302,12 @@ sys_fsetxattr(int fd, char __user *name, void __user *value, return error; dentry = f->f_path.dentry; audit_inode(NULL, dentry); - error = setxattr(dentry, name, value, size, flags); + error = mnt_want_write(f->f_path.mnt); + if (!error) { + error = setxattr(dentry, name, value, size, flags); + mnt_drop_write(f->f_path.mnt); + } +out_fput: fput(f); return error; } @@ -482,7 +494,11 @@ sys_removexattr(char __user *path, char __user *name) error = user_path_walk(path, &nd); if (error) return error; - error = removexattr(nd.path.dentry, name); + error = mnt_want_write(nd.path.mnt); + if (!error) { + error = removexattr(nd.path.dentry, name); + mnt_drop_write(nd.path.mnt); + } path_put(&nd.path); return error; } @@ -496,7 +512,11 @@ sys_lremovexattr(char __user *path, char __user *name) error = user_path_walk_link(path, &nd); if (error) return error; - error = removexattr(nd.path.dentry, name); + error = mnt_want_write(nd.path.mnt); + if (!error) { + error = removexattr(nd.path.dentry, name); + mnt_drop_write(nd.path.mnt); + } path_put(&nd.path); return error; } @@ -513,7 +533,11 @@ sys_fremovexattr(int fd, char __user *name) return error; dentry = f->f_path.dentry; audit_inode(NULL, dentry); - error = removexattr(dentry, name); + error = mnt_want_write(f->f_path.mnt); + if (!error) { + error = removexattr(dentry, name); + mnt_drop_write(f->f_path.mnt); + } fput(f); return error; } |