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smb3: fix mode passed in on create for modetosid mount option
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When using the special SID to store the mode bits in an ACE (See
http://technet.microsoft.com/en-us/library/hh509017(v=ws.10).aspx)
which is enabled with mount parm "modefromsid" we were not
passing in the mode via SMB3 create (although chmod was enabled).
SMB3 create allows a security descriptor context to be passed
in (which is more atomic and thus preferable to setting the mode
bits after create via a setinfo).

This patch enables setting the mode bits on create when using
modefromsid mount option.  In addition it fixes an endian
error in the definition of the Control field flags in the SMB3
security descriptor. It also makes the ACE type of the special
SID better match the documentation (and behavior of servers
which use this to store mode bits in SMB3 ACLs).

Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
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Steve French committed Dec 6, 2019
1 parent 9a7d5a9 commit fdef665
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Showing 5 changed files with 122 additions and 34 deletions.
42 changes: 26 additions & 16 deletions fs/cifs/cifsacl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -802,6 +802,31 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
return;
}

/*
* Fill in the special SID based on the mode. See
* http://technet.microsoft.com/en-us/library/hh509017(v=ws.10).aspx
*/
unsigned int setup_special_mode_ACE(struct cifs_ace *pntace, __u64 nmode)
{
int i;
unsigned int ace_size = 28;

pntace->type = ACCESS_DENIED_ACE_TYPE;
pntace->flags = 0x0;
pntace->access_req = 0;
pntace->sid.num_subauth = 3;
pntace->sid.revision = 1;
for (i = 0; i < NUM_AUTHS; i++)
pntace->sid.authority[i] = sid_unix_NFS_mode.authority[i];

pntace->sid.sub_auth[0] = sid_unix_NFS_mode.sub_auth[0];
pntace->sid.sub_auth[1] = sid_unix_NFS_mode.sub_auth[1];
pntace->sid.sub_auth[2] = cpu_to_le32(nmode & 07777);

/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
pntace->size = cpu_to_le16(ace_size);
return ace_size;
}

static int set_chmod_dacl(struct cifs_acl *pndacl, struct cifs_sid *pownersid,
struct cifs_sid *pgrpsid, __u64 nmode, bool modefromsid)
Expand All @@ -815,23 +840,8 @@ static int set_chmod_dacl(struct cifs_acl *pndacl, struct cifs_sid *pownersid,
if (modefromsid) {
struct cifs_ace *pntace =
(struct cifs_ace *)((char *)pnndacl + size);
int i;

pntace->type = ACCESS_ALLOWED;
pntace->flags = 0x0;
pntace->access_req = 0;
pntace->sid.num_subauth = 3;
pntace->sid.revision = 1;
for (i = 0; i < NUM_AUTHS; i++)
pntace->sid.authority[i] =
sid_unix_NFS_mode.authority[i];
pntace->sid.sub_auth[0] = sid_unix_NFS_mode.sub_auth[0];
pntace->sid.sub_auth[1] = sid_unix_NFS_mode.sub_auth[1];
pntace->sid.sub_auth[2] = cpu_to_le32(nmode & 07777);

/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
pntace->size = cpu_to_le16(28);
size += 28;
size += setup_special_mode_ACE(pntace, nmode);
num_aces++;
}

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32 changes: 16 additions & 16 deletions fs/cifs/cifsacl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -147,22 +147,22 @@ struct smb3_sd {
} __packed;

/* Meaning of 'Control' field flags */
#define ACL_CONTROL_SR 0x0001 /* Self relative */
#define ACL_CONTROL_RM 0x0002 /* Resource manager control bits */
#define ACL_CONTROL_PS 0x0004 /* SACL protected from inherits */
#define ACL_CONTROL_PD 0x0008 /* DACL protected from inherits */
#define ACL_CONTROL_SI 0x0010 /* SACL Auto-Inherited */
#define ACL_CONTROL_DI 0x0020 /* DACL Auto-Inherited */
#define ACL_CONTROL_SC 0x0040 /* SACL computed through inheritance */
#define ACL_CONTROL_DC 0x0080 /* DACL computed through inheritence */
#define ACL_CONTROL_SS 0x0100 /* Create server ACL */
#define ACL_CONTROL_DT 0x0200 /* DACL provided by trusteed source */
#define ACL_CONTROL_SD 0x0400 /* SACL defaulted */
#define ACL_CONTROL_SP 0x0800 /* SACL is present on object */
#define ACL_CONTROL_DD 0x1000 /* DACL defaulted */
#define ACL_CONTROL_DP 0x2000 /* DACL is present on object */
#define ACL_CONTROL_GD 0x4000 /* Group was defaulted */
#define ACL_CONTROL_OD 0x8000 /* User was defaulted */
#define ACL_CONTROL_SR 0x8000 /* Self relative */
#define ACL_CONTROL_RM 0x4000 /* Resource manager control bits */
#define ACL_CONTROL_PS 0x2000 /* SACL protected from inherits */
#define ACL_CONTROL_PD 0x1000 /* DACL protected from inherits */
#define ACL_CONTROL_SI 0x0800 /* SACL Auto-Inherited */
#define ACL_CONTROL_DI 0x0400 /* DACL Auto-Inherited */
#define ACL_CONTROL_SC 0x0200 /* SACL computed through inheritance */
#define ACL_CONTROL_DC 0x0100 /* DACL computed through inheritence */
#define ACL_CONTROL_SS 0x0080 /* Create server ACL */
#define ACL_CONTROL_DT 0x0040 /* DACL provided by trusted source */
#define ACL_CONTROL_SD 0x0020 /* SACL defaulted */
#define ACL_CONTROL_SP 0x0010 /* SACL is present on object */
#define ACL_CONTROL_DD 0x0008 /* DACL defaulted */
#define ACL_CONTROL_DP 0x0004 /* DACL is present on object */
#define ACL_CONTROL_GD 0x0002 /* Group was defaulted */
#define ACL_CONTROL_OD 0x0001 /* User was defaulted */

/* Meaning of AclRevision flags */
#define ACL_REVISION 0x02 /* See section 2.4.4.1 of MS-DTYP */
Expand Down
1 change: 1 addition & 0 deletions fs/cifs/cifsproto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,7 @@ extern struct cifs_ntsd *get_cifs_acl_by_fid(struct cifs_sb_info *,
const struct cifs_fid *, u32 *);
extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
const char *, int);
extern unsigned int setup_special_mode_ACE(struct cifs_ace *pace, __u64 nmode);

extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
Expand Down
71 changes: 69 additions & 2 deletions fs/cifs/smb2pdu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2191,6 +2191,72 @@ add_twarp_context(struct kvec *iov, unsigned int *num_iovec, __u64 timewarp)
return 0;
}

/* See MS-SMB2 2.2.13.2.2 and MS-DTYP 2.4.6 */
static struct crt_sd_ctxt *
create_sd_buf(umode_t mode, unsigned int *len)
{
struct crt_sd_ctxt *buf;
struct cifs_ace *pace;
unsigned int sdlen, acelen;

*len = roundup(sizeof(struct crt_sd_ctxt) + sizeof(struct cifs_ace), 8);
buf = kzalloc(*len, GFP_KERNEL);
if (buf == NULL)
return buf;

sdlen = sizeof(struct smb3_sd) + sizeof(struct smb3_acl) +
sizeof(struct cifs_ace);

buf->ccontext.DataOffset = cpu_to_le16(offsetof
(struct crt_sd_ctxt, sd));
buf->ccontext.DataLength = cpu_to_le32(sdlen);
buf->ccontext.NameOffset = cpu_to_le16(offsetof
(struct crt_sd_ctxt, Name));
buf->ccontext.NameLength = cpu_to_le16(4);
/* SMB2_CREATE_SD_BUFFER_TOKEN is "SecD" */
buf->Name[0] = 'S';
buf->Name[1] = 'e';
buf->Name[2] = 'c';
buf->Name[3] = 'D';
buf->sd.Revision = 1; /* Must be one see MS-DTYP 2.4.6 */
/*
* ACL is "self relative" ie ACL is stored in contiguous block of memory
* and "DP" ie the DACL is present
*/
buf->sd.Control = cpu_to_le16(ACL_CONTROL_SR | ACL_CONTROL_DP);

/* offset owner, group and Sbz1 and SACL are all zero */
buf->sd.OffsetDacl = cpu_to_le32(sizeof(struct smb3_sd));
buf->acl.AclRevision = ACL_REVISION; /* See 2.4.4.1 of MS-DTYP */

/* create one ACE to hold the mode embedded in reserved special SID */
pace = (struct cifs_ace *)(sizeof(struct crt_sd_ctxt) + (char *)buf);
acelen = setup_special_mode_ACE(pace, (__u64)mode);
buf->acl.AclSize = cpu_to_le16(sizeof(struct cifs_acl) + acelen);
buf->acl.AceCount = cpu_to_le16(1);
return buf;
}

static int
add_sd_context(struct kvec *iov, unsigned int *num_iovec, umode_t mode)
{
struct smb2_create_req *req = iov[0].iov_base;
unsigned int num = *num_iovec;
unsigned int len = 0;

iov[num].iov_base = create_sd_buf(mode, &len);
if (iov[num].iov_base == NULL)
return -ENOMEM;
iov[num].iov_len = len;
if (!req->CreateContextsOffset)
req->CreateContextsOffset = cpu_to_le32(
sizeof(struct smb2_create_req) +
iov[num - 1].iov_len);
le32_add_cpu(&req->CreateContextsLength, len);
*num_iovec = num + 1;
return 0;
}

static struct crt_query_id_ctxt *
create_query_id_buf(void)
{
Expand Down Expand Up @@ -2563,7 +2629,7 @@ SMB2_open_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, __u8 *oplock,
return rc;
}

if ((oparms->disposition == FILE_CREATE) &&
if ((oparms->disposition != FILE_OPEN) &&
(oparms->mode != ACL_NO_MODE)) {
if (n_iov > 2) {
struct create_context *ccontext =
Expand All @@ -2572,7 +2638,8 @@ SMB2_open_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, __u8 *oplock,
cpu_to_le32(iov[n_iov-1].iov_len);
}

/* rc = add_sd_context(iov, &n_iov, oparms->mode); */
cifs_dbg(FYI, "add sd with mode 0x%x\n", oparms->mode);
rc = add_sd_context(iov, &n_iov, oparms->mode);
if (rc)
return rc;
}
Expand Down
10 changes: 10 additions & 0 deletions fs/cifs/smb2pdu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#define _SMB2PDU_H

#include <net/sock.h>
#include <cifsacl.h>

/*
* Note that, due to trying to use names similar to the protocol specifications,
Expand Down Expand Up @@ -855,6 +856,15 @@ struct crt_query_id_ctxt {
__u8 Name[8];
} __packed;

struct crt_sd_ctxt {
struct create_context ccontext;
__u8 Name[8];
struct smb3_sd sd;
struct smb3_acl acl;
/* Followed by at least 4 ACEs */
} __packed;


#define COPY_CHUNK_RES_KEY_SIZE 24
struct resume_key_req {
char ResumeKey[COPY_CHUNK_RES_KEY_SIZE];
Expand Down

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