From 4a59015372840a6fc35d7fd40638a9d5dc3ec958 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Sun, 13 Nov 2016 21:23:34 +0100 Subject: [PATCH] xattr: Fix setting security xattrs on sockfs The IOP_XATTR flag is set on sockfs because sockfs supports getting the "system.sockprotoname" xattr. Since commit 6c6ef9f2, this flag is checked for setxattr support as well. This is wrong on sockfs because security xattr support there is supposed to be provided by security_inode_setsecurity. The smack security module relies on socket labels (xattrs). Fix this by adding a security xattr handler on sockfs that returns -EAGAIN, and by checking for -EAGAIN in setxattr. We cannot simply check for -EOPNOTSUPP in setxattr because there are filesystems that neither have direct security xattr support nor support via security_inode_setsecurity. A more proper fix might be to move the call to security_inode_setsecurity into sockfs, but it's not clear to me if that is safe: we would end up calling security_inode_post_setxattr after that as well. Signed-off-by: Andreas Gruenbacher Signed-off-by: Al Viro --- fs/xattr.c | 22 ++++++++++++++-------- net/socket.c | 15 +++++++++++++++ 2 files changed, 29 insertions(+), 8 deletions(-) diff --git a/fs/xattr.c b/fs/xattr.c index 3368659c471e..2d13b4e62fae 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -170,7 +170,7 @@ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { struct inode *inode = dentry->d_inode; - int error = -EOPNOTSUPP; + int error = -EAGAIN; int issec = !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN); @@ -183,15 +183,21 @@ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, security_inode_post_setxattr(dentry, name, value, size, flags); } - } else if (issec) { - const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; - + } else { if (unlikely(is_bad_inode(inode))) return -EIO; - error = security_inode_setsecurity(inode, suffix, value, - size, flags); - if (!error) - fsnotify_xattr(dentry); + } + if (error == -EAGAIN) { + error = -EOPNOTSUPP; + + if (issec) { + const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; + + error = security_inode_setsecurity(inode, suffix, value, + size, flags); + if (!error) + fsnotify_xattr(dentry); + } } return error; diff --git a/net/socket.c b/net/socket.c index 272518b087c8..73dc69f9681e 100644 --- a/net/socket.c +++ b/net/socket.c @@ -341,8 +341,23 @@ static const struct xattr_handler sockfs_xattr_handler = { .get = sockfs_xattr_get, }; +static int sockfs_security_xattr_set(const struct xattr_handler *handler, + struct dentry *dentry, struct inode *inode, + const char *suffix, const void *value, + size_t size, int flags) +{ + /* Handled by LSM. */ + return -EAGAIN; +} + +static const struct xattr_handler sockfs_security_xattr_handler = { + .prefix = XATTR_SECURITY_PREFIX, + .set = sockfs_security_xattr_set, +}; + static const struct xattr_handler *sockfs_xattr_handlers[] = { &sockfs_xattr_handler, + &sockfs_security_xattr_handler, NULL };