On Jan 9, 2020, at 12:10 PM, Steve French <smfrench@xxxxxxxxx> wrote:
>
> 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).
The whole point of not being able to change ctime and btime as a regular
user is so that it is possible to determine when a file was actually
created on the filesystem and last modified. That is often useful for
debugging or forensics reasons.
I think if this is something that SMB/CIFS wants to do, it should save
these attributes into an xattr of its own (e.g. user.dos or whatever),
rather than using the ctime and btime(crtime) fields in the filesystem.
Cheers, Andreas
> 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
Cheers, Andreas
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