Author: kib
Date: Fri Feb 15 11:13:39 2019
New Revision: 344152
URL: https://svnweb.freebsd.org/changeset/base/344152

Log:
  MFC r343891:
  Fix renameat(2) for CAPABILITIES kernelsi.
  
  MFC Note: Layout of the struct nameidata is changed.  I specifically
  decided to not move the new field to the end of the new structure since
  it would mostly make the corruption silent.  __FreeBSD_version is bumped.

Modified:
  stable/12/sys/kern/vfs_lookup.c
  stable/12/sys/kern/vfs_syscalls.c
  stable/12/sys/sys/namei.h
  stable/12/sys/sys/param.h
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/vfs_lookup.c
==============================================================================
--- stable/12/sys/kern/vfs_lookup.c     Fri Feb 15 10:40:41 2019        
(r344151)
+++ stable/12/sys/kern/vfs_lookup.c     Fri Feb 15 11:13:39 2019        
(r344152)
@@ -388,6 +388,7 @@ namei(struct nameidata *ndp)
        dp = NULL;
        cnp->cn_nameptr = cnp->cn_pnbuf;
        if (cnp->cn_pnbuf[0] == '/') {
+               ndp->ni_resflags |= NIRES_ABS;
                error = namei_handle_root(ndp, &dp);
        } else {
                if (ndp->ni_startdir != NULL) {
@@ -1252,6 +1253,7 @@ NDINIT_ALL(struct nameidata *ndp, u_long op, u_long fl
        ndp->ni_dirp = namep;
        ndp->ni_dirfd = dirfd;
        ndp->ni_startdir = startdir;
+       ndp->ni_resflags = 0;
        if (rightsp != NULL)
                ndp->ni_rightsneeded = *rightsp;
        else

Modified: stable/12/sys/kern/vfs_syscalls.c
==============================================================================
--- stable/12/sys/kern/vfs_syscalls.c   Fri Feb 15 10:40:41 2019        
(r344151)
+++ stable/12/sys/kern/vfs_syscalls.c   Fri Feb 15 11:13:39 2019        
(r344152)
@@ -3511,10 +3511,10 @@ again:
                        goto out;
                }
 #ifdef CAPABILITIES
-               if (newfd != AT_FDCWD) {
+               if (newfd != AT_FDCWD && (tond.ni_resflags & NIRES_ABS) == 0) {
                        /*
                         * If the target already exists we require CAP_UNLINKAT
-                        * from 'newfd'.
+                        * from 'newfd', when newfd was used for the lookup.
                         */
                        error = cap_check(&tond.ni_filecaps.fc_rights,
                            &cap_unlinkat_rights);

Modified: stable/12/sys/sys/namei.h
==============================================================================
--- stable/12/sys/sys/namei.h   Fri Feb 15 10:40:41 2019        (r344151)
+++ stable/12/sys/sys/namei.h   Fri Feb 15 11:13:39 2019        (r344152)
@@ -88,6 +88,10 @@ struct nameidata {
        struct  vnode *ni_vp;           /* vnode of result */
        struct  vnode *ni_dvp;          /* vnode of intermediate directory */
        /*
+        * Results: flags returned from namei
+        */
+       u_int   ni_resflags;
+       /*
         * Shared between namei and lookup/commit routines.
         */
        size_t  ni_pathlen;             /* remaining chars in path */
@@ -156,6 +160,11 @@ struct nameidata {
 #define        TRAILINGSLASH   0x10000000 /* path ended in a slash */
 #define        NOCAPCHECK      0x20000000 /* do not perform capability checks 
*/
 #define        PARAMASK        0x3ffffe00 /* mask of parameter descriptors */
+
+/*
+ * Namei results flags
+ */
+#define        NIRES_ABS       0x00000001 /* Path was absolute */
 
 /*
  * Flags in ni_lcf, valid for the duration of the namei call.

Modified: stable/12/sys/sys/param.h
==============================================================================
--- stable/12/sys/sys/param.h   Fri Feb 15 10:40:41 2019        (r344151)
+++ stable/12/sys/sys/param.h   Fri Feb 15 11:13:39 2019        (r344152)
@@ -60,7 +60,7 @@
  *             in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1200502      /* Master, propagated to newvers */
+#define __FreeBSD_version 1200503      /* Master, propagated to newvers */
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
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