From 18f335aff86913de3c76f88d32c8135c1da62ce6 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 15 Feb 2008 14:37:38 -0800 Subject: [PATCH] [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 Signed-off-by: Christoph Hellwig Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- fs/nfsd/nfs4proc.c | 7 ++++++- fs/nfsd/vfs.c | 4 ++++ fs/xattr.c | 40 ++++++++++++++++++++++++++++++++-------- 3 files changed, 42 insertions(+), 9 deletions(-) diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index c593db047d8..c309c881bd4 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -658,14 +658,19 @@ nfsd4_setattr(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, return status; } } + status = mnt_want_write(cstate->current_fh.fh_export->ex_path.mnt); + if (status) + return status; status = nfs_ok; if (setattr->sa_acl != NULL) status = nfsd4_set_nfs4_acl(rqstp, &cstate->current_fh, setattr->sa_acl); if (status) - return status; + goto out; status = nfsd_setattr(rqstp, &cstate->current_fh, &setattr->sa_iattr, 0, (time_t)0); +out: + mnt_drop_write(cstate->current_fh.fh_export->ex_path.mnt); return status; } diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 18a4cc9feeb..626dfd38528 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -2086,6 +2086,9 @@ nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl) } else size = 0; + error = mnt_want_write(fhp->fh_export->ex_path.mnt); + if (error) + goto getout; if (size) error = vfs_setxattr(fhp->fh_dentry, name, value, size, 0); else { @@ -2097,6 +2100,7 @@ nfsd_set_posix_acl(struct svc_fh *fhp, int type, struct posix_acl *acl) error = 0; } } + mnt_drop_write(fhp->fh_export->ex_path.mnt); getout: kfree(value); diff --git a/fs/xattr.c b/fs/xattr.c index 3acab161546..f7062da505d 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -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; } -- 2.39.3