cifs: Handle extended attribute name cifs_acl to generate cifs acl blob (try #4)

Add extended attribute name system.cifs_acl

Get/generate cifs/ntfs acl blob and hand over to the invoker however
it wants to parse/process it under experimental configurable option CIFS_ACL.

Do not get CIFS/NTFS ACL for xattr for attribute system.posix_acl_access

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

4 files changed, 40 insertions, 26 deletions

diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 3bdbfb026b6b..ee45648b0d1a 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -144,6 +144,13 @@ config CIFS_FSCACHE
             to be cached locally on disk through the general filesystem cache
             manager. If unsure, say N.
 
+config CIFS_ACL
+          bool "Provide CIFS ACL support (EXPERIMENTAL)"
+          depends on EXPERIMENTAL && CIFS_XATTR
+          help
+            Allows to fetch CIFS/NTFS ACL from the server.  The DACL blob
+            is handed over to the application/caller.
+
 config CIFS_EXPERIMENTAL
           bool "CIFS Experimental Features (EXPERIMENTAL)"
           depends on CIFS && EXPERIMENTAL
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index c15e3ee730c6..c6ebea088ac7 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -608,7 +608,7 @@ static struct cifs_ntsd *get_cifs_acl_by_path(struct cifs_sb_info *cifs_sb,
 }
 
 /* Retrieve an ACL from the server */
-static struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
+struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
                                       struct inode *inode, const char *path,
                                       u32 *pacllen)
 {
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index b498731852d4..db961dc4fd3d 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -134,6 +134,8 @@ extern int cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb,
                               struct cifs_fattr *fattr, struct inode *inode,
                               const char *path, const __u16 *pfid);
 extern int mode_to_cifs_acl(struct inode *inode, const char *path, __u64);
+extern struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *, struct inode *,
+                                        const char *, u32 *);
 
 extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,
                         const char *);
diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c
index a264b744bb41..eae2a1491608 100644
--- a/fs/cifs/xattr.c
+++ b/fs/cifs/xattr.c
@@ -30,10 +30,11 @@
 
 #define MAX_EA_VALUE_SIZE 65535
 #define CIFS_XATTR_DOS_ATTRIB "user.DosAttrib"
+#define CIFS_XATTR_CIFS_ACL "system.cifs_acl"
 #define CIFS_XATTR_USER_PREFIX "user."
 #define CIFS_XATTR_SYSTEM_PREFIX "system."
 #define CIFS_XATTR_OS2_PREFIX "os2."
-#define CIFS_XATTR_SECURITY_PREFIX ".security"
+#define CIFS_XATTR_SECURITY_PREFIX "security."
 #define CIFS_XATTR_TRUSTED_PREFIX "trusted."
 #define XATTR_TRUSTED_PREFIX_LEN  8
 #define XATTR_SECURITY_PREFIX_LEN 9
@@ -277,29 +278,8 @@ ssize_t cifs_getxattr(struct dentry *direntry, const char *ea_name,
                                 cifs_sb->local_nls,
                                 cifs_sb->mnt_cifs_flags &
                                         CIFS_MOUNT_MAP_SPECIAL_CHR);
-#ifdef CONFIG_CIFS_EXPERIMENTAL
-                else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) {
-                        __u16 fid;
-                        int oplock = 0;
-                        struct cifs_ntsd *pacl = NULL;
-                        __u32 buflen = 0;
-                        if (experimEnabled)
-                                rc = CIFSSMBOpen(xid, pTcon, full_path,
-                                        FILE_OPEN, GENERIC_READ, 0, &fid,
-                                        &oplock, NULL, cifs_sb->local_nls,
-                                        cifs_sb->mnt_cifs_flags &
-                                        CIFS_MOUNT_MAP_SPECIAL_CHR);
-                        /* else rc is EOPNOTSUPP from above */
-
-                        if (rc == 0) {
-                                rc = CIFSSMBGetCIFSACL(xid, pTcon, fid, &pacl,
-                                                      &buflen);
-                                CIFSSMBClose(xid, pTcon, fid);
-                        }
-                }
-#endif /* EXPERIMENTAL */
 #else
-                cFYI(1, "query POSIX ACL not supported yet");
+                cFYI(1, "Query POSIX ACL not supported yet");
 #endif /* CONFIG_CIFS_POSIX */
         } else if (strncmp(ea_name, POSIX_ACL_XATTR_DEFAULT,
                           strlen(POSIX_ACL_XATTR_DEFAULT)) == 0) {
@@ -311,8 +291,33 @@ ssize_t cifs_getxattr(struct dentry *direntry, const char *ea_name,
                                 cifs_sb->mnt_cifs_flags &
                                         CIFS_MOUNT_MAP_SPECIAL_CHR);
 #else
-                cFYI(1, "query POSIX default ACL not supported yet");
-#endif
+                cFYI(1, "Query POSIX default ACL not supported yet");
+#endif /* CONFIG_CIFS_POSIX */
+        } else if (strncmp(ea_name, CIFS_XATTR_CIFS_ACL,
+                                strlen(CIFS_XATTR_CIFS_ACL)) == 0) {
+#ifdef CONFIG_CIFS_ACL
+                        u32 acllen;
+                        struct cifs_ntsd *pacl;
+
+                        pacl = get_cifs_acl(cifs_sb, direntry->d_inode,
+                                                full_path, &acllen);
+                        if (IS_ERR(pacl)) {
+                                rc = PTR_ERR(pacl);
+                                cERROR(1, "%s: error %zd getting sec desc",
+                                                __func__, rc);
+                        } else {
+                                if (ea_value) {
+                                        if (acllen > buf_size)
+                                                acllen = -ERANGE;
+                                        else
+                                                memcpy(ea_value, pacl, acllen);
+                                }
+                                rc = acllen;
+                                kfree(pacl);
+                        }
+#else
+                cFYI(1, "Query CIFS ACL not supported yet");
+#endif /* CONFIG_CIFS_ACL */
         } else if (strncmp(ea_name,
                   CIFS_XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) == 0) {
                 cFYI(1, "Trusted xattr namespace not supported yet");