One loosely related question ...
Your patch adds the ability to set creation time (birth time) which
can be useful for backup/restore cases, but doesn't address the other
hole in Linux (the inability to restore a files ctime).
In Linux the ability to set timestamps seems quite limited (utimes
only allows setting mtime and atime).
Since setting all 4 timestamps is allowed over SMB3 (and all older
dialects as well), should we extend this to allow setting ctime not
just creation time over SMB3/CIFS mounts?
On Thu, Dec 19, 2019 at 10:53 AM Boris Protopopov
<boris.v.protopopov@xxxxxxxxx> wrote:
>
> Add extended attribute "system.cifs_ntsd" (and alias "system.smb3_ntsd")
> to allow for setting owner and DACL in the security descriptor. This is in
> addition to the existing "system.cifs_acl" and "system.smb3_acl" attributes
> that allow for setting DACL only. Add support for setting creation time and
> dos attributes using set_file_info() calls to complement the existing
> support for getting these attributes via query_path_info() calls.
>
> Signed-off-by: Boris Protopopov <bprotopopov@xxxxxxxxxxx>
> ---
> fs/cifs/xattr.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 117 insertions(+), 11 deletions(-)
>
> diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c
> index 9076150758d8..c41856e6fa22 100644
> --- a/fs/cifs/xattr.c
> +++ b/fs/cifs/xattr.c
> @@ -32,7 +32,8 @@
> #include "cifs_unicode.h"
>
> #define MAX_EA_VALUE_SIZE CIFSMaxBufSize
> -#define CIFS_XATTR_CIFS_ACL "system.cifs_acl"
> +#define CIFS_XATTR_CIFS_ACL "system.cifs_acl" /* DACL only */
> +#define CIFS_XATTR_CIFS_NTSD "system.cifs_ntsd" /* owner plus DACL */
> #define CIFS_XATTR_ATTRIB "cifs.dosattrib" /* full name: user.cifs.dosattrib */
> #define CIFS_XATTR_CREATETIME "cifs.creationtime" /* user.cifs.creationtime */
> /*
> @@ -40,12 +41,62 @@
> * confusing users and using the 20+ year old term 'cifs' when it is no longer
> * secure, replaced by SMB2 (then even more highly secure SMB3) many years ago
> */
> -#define SMB3_XATTR_CIFS_ACL "system.smb3_acl"
> +#define SMB3_XATTR_CIFS_ACL "system.smb3_acl" /* DACL only */
> +#define SMB3_XATTR_CIFS_NTSD "system.smb3_ntsd" /* owner plus DACL */
> #define SMB3_XATTR_ATTRIB "smb3.dosattrib" /* full name: user.smb3.dosattrib */
> #define SMB3_XATTR_CREATETIME "smb3.creationtime" /* user.smb3.creationtime */
> /* BB need to add server (Samba e.g) support for security and trusted prefix */
>
> -enum { XATTR_USER, XATTR_CIFS_ACL, XATTR_ACL_ACCESS, XATTR_ACL_DEFAULT };
> +enum { XATTR_USER, XATTR_CIFS_ACL, XATTR_ACL_ACCESS, XATTR_ACL_DEFAULT,
> + XATTR_CIFS_NTSD };
> +
> +static int cifs_attrib_set(unsigned int xid, struct cifs_tcon *pTcon,
> + struct inode *inode, char *full_path,
> + const void *value, size_t size)
> +{
> + ssize_t rc = -EOPNOTSUPP;
> + __u32 *pattrib = (__u32 *)value;
> + __u32 attrib;
> + FILE_BASIC_INFO info_buf;
> +
> + if ((value == NULL) || (size != sizeof(__u32)))
> + return -ERANGE;
> +
> + memset(&info_buf, 0, sizeof(info_buf));
> + info_buf.Attributes = attrib = cpu_to_le32(*pattrib);
> +
> + if (pTcon->ses->server->ops->set_file_info)
> + rc = pTcon->ses->server->ops->set_file_info(inode, full_path,
> + &info_buf, xid);
> + if (rc == 0)
> + CIFS_I(inode)->cifsAttrs = attrib;
> +
> + return rc;
> +}
> +
> +static int cifs_creation_time_set(unsigned int xid, struct cifs_tcon *pTcon,
> + struct inode *inode, char *full_path,
> + const void *value, size_t size)
> +{
> + ssize_t rc = -EOPNOTSUPP;
> + __u64 *pcreation_time = (__u64 *)value;
> + __u64 creation_time;
> + FILE_BASIC_INFO info_buf;
> +
> + if ((value == NULL) || (size != sizeof(__u64)))
> + return -ERANGE;
> +
> + memset(&info_buf, 0, sizeof(info_buf));
> + info_buf.CreationTime = creation_time = cpu_to_le64(*pcreation_time);
> +
> + if (pTcon->ses->server->ops->set_file_info)
> + rc = pTcon->ses->server->ops->set_file_info(inode, full_path,
> + &info_buf, xid);
> + if (rc == 0)
> + CIFS_I(inode)->createtime = creation_time;
> +
> + return rc;
> +}
>
> static int cifs_xattr_set(const struct xattr_handler *handler,
> struct dentry *dentry, struct inode *inode,
> @@ -86,6 +137,23 @@ static int cifs_xattr_set(const struct xattr_handler *handler,
>
> switch (handler->flags) {
> case XATTR_USER:
> + cifs_dbg(FYI, "%s:setting user xattr %s\n", __func__, name);
> + if ((strcmp(name, CIFS_XATTR_ATTRIB) == 0) ||
> + (strcmp(name, SMB3_XATTR_ATTRIB) == 0)) {
> + rc = cifs_attrib_set(xid, pTcon, inode, full_path,
> + value, size);
> + if (rc == 0) /* force revalidate of the inode */
> + CIFS_I(inode)->time = 0;
> + break;
> + } else if ((strcmp(name, CIFS_XATTR_CREATETIME) == 0) ||
> + (strcmp(name, SMB3_XATTR_CREATETIME) == 0)) {
> + rc = cifs_creation_time_set(xid, pTcon, inode,
> + full_path, value, size);
> + if (rc == 0) /* force revalidate of the inode */
> + CIFS_I(inode)->time = 0;
> + break;
> + }
> +
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_XATTR)
> goto out;
>
> @@ -95,7 +163,8 @@ static int cifs_xattr_set(const struct xattr_handler *handler,
> cifs_sb->local_nls, cifs_sb);
> break;
>
> - case XATTR_CIFS_ACL: {
> + case XATTR_CIFS_ACL:
> + case XATTR_CIFS_NTSD: {
> struct cifs_ntsd *pacl;
>
> if (!value)
> @@ -106,12 +175,25 @@ static int cifs_xattr_set(const struct xattr_handler *handler,
> } else {
> memcpy(pacl, value, size);
> if (value &&
> - pTcon->ses->server->ops->set_acl)
> - rc = pTcon->ses->server->ops->set_acl(pacl,
> - size, inode,
> - full_path, CIFS_ACL_DACL);
> - else
> + pTcon->ses->server->ops->set_acl) {
> + rc = 0;
> + if (handler->flags == XATTR_CIFS_NTSD) {
> + /* set owner and DACL */
> + rc = pTcon->ses->server->ops->set_acl(
> + pacl, size, inode,
> + full_path,
> + CIFS_ACL_OWNER);
> + }
> + if (rc == 0) {
> + /* set DACL */
> + rc = pTcon->ses->server->ops->set_acl(
> + pacl, size, inode,
> + full_path,
> + CIFS_ACL_DACL);
> + }
> + } else {
> rc = -EOPNOTSUPP;
> + }
> if (rc == 0) /* force revalidate of the inode */
> CIFS_I(inode)->time = 0;
> kfree(pacl);
> @@ -179,7 +261,7 @@ static int cifs_creation_time_get(struct dentry *dentry, struct inode *inode,
> void *value, size_t size)
> {
> ssize_t rc;
> - __u64 * pcreatetime;
> + __u64 *pcreatetime;
>
> rc = cifs_revalidate_dentry_attr(dentry);
> if (rc)
> @@ -244,7 +326,9 @@ static int cifs_xattr_get(const struct xattr_handler *handler,
> full_path, name, value, size, cifs_sb);
> break;
>
> - case XATTR_CIFS_ACL: {
> + case XATTR_CIFS_ACL:
> + case XATTR_CIFS_NTSD: {
> + /* the whole ntsd is fetched regardless */
> u32 acllen;
> struct cifs_ntsd *pacl;
>
> @@ -382,6 +466,26 @@ static const struct xattr_handler smb3_acl_xattr_handler = {
> .set = cifs_xattr_set,
> };
>
> +static const struct xattr_handler cifs_cifs_ntsd_xattr_handler = {
> + .name = CIFS_XATTR_CIFS_NTSD,
> + .flags = XATTR_CIFS_NTSD,
> + .get = cifs_xattr_get,
> + .set = cifs_xattr_set,
> +};
> +
> +/*
> + * Although this is just an alias for the above, need to move away from
> + * confusing users and using the 20 year old term 'cifs' when it is no
> + * longer secure and was replaced by SMB2/SMB3 a long time ago, and
> + * SMB3 and later are highly secure.
> + */
> +static const struct xattr_handler smb3_ntsd_xattr_handler = {
> + .name = SMB3_XATTR_CIFS_NTSD,
> + .flags = XATTR_CIFS_NTSD,
> + .get = cifs_xattr_get,
> + .set = cifs_xattr_set,
> +};
> +
> static const struct xattr_handler cifs_posix_acl_access_xattr_handler = {
> .name = XATTR_NAME_POSIX_ACL_ACCESS,
> .flags = XATTR_ACL_ACCESS,
> @@ -401,6 +505,8 @@ const struct xattr_handler *cifs_xattr_handlers[] = {
> &cifs_os2_xattr_handler,
> &cifs_cifs_acl_xattr_handler,
> &smb3_acl_xattr_handler, /* alias for above since avoiding "cifs" */
> + &cifs_cifs_ntsd_xattr_handler,
> + &smb3_ntsd_xattr_handler, /* alias for above since avoiding "cifs" */
> &cifs_posix_acl_access_xattr_handler,
> &cifs_posix_acl_default_xattr_handler,
> NULL
> --
> 2.14.5
>
--
Thanks,
Steve
