Clean up the snapshot code so that it no longer depends on the use of
the SF_IMMUTABLE flag to prevent writing. Instead put in explicit checking for the SF_SNAPSHOT flag in the appropriate places. With this change, it is now possible to rename and link to snapshot files. It is also possible to set or clear any of the owner, group, or other read bits on the file, though none of the write or execute bits can be set. There is also an explicit test to prevent the setting or clearing of the SF_SNAPSHOT flag via chflags() or fchflags(). Note also that the modify time cannot be changed as it needs to accurately reflect the time that the snapshot was taken. Submitted by: Robert Watson <rwatson@FreeBSD.org>
This commit is contained in:
parent
3ce7b7aa84
commit
3592b7155c
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=63897
@ -45,6 +45,7 @@
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#include <sys/vnode.h>
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#include <sys/malloc.h>
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#include <sys/resourcevar.h>
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#include <sys/stat.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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@ -174,6 +175,8 @@ ffs_truncate(vp, length, flags, cred, p)
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if (error)
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return (error);
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#endif
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if ((oip->i_flags & SF_SNAPSHOT) != 0)
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ffs_snapremove(ovp);
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ovp->v_lasta = ovp->v_clen = ovp->v_cstart = ovp->v_lastw = 0;
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if (DOINGSOFTDEP(ovp)) {
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if (length > 0) {
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@ -241,7 +241,7 @@ ffs_snapshot(mp, snapfile)
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/*
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* Change inode to snapshot type file.
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*/
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ip->i_flags |= SF_IMMUTABLE | SF_SNAPSHOT;
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ip->i_flags |= SF_SNAPSHOT;
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ip->i_flag |= IN_CHANGE | IN_UPDATE;
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/*
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* Ensure that the snapshot is completely on disk.
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@ -414,7 +414,7 @@ ffs_snapshot(mp, snapfile)
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ino_to_fsbo(fs, xp->i_number);
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dip->di_size = 0;
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dip->di_blocks = 0;
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dip->di_flags &= ~(SF_IMMUTABLE | SF_SNAPSHOT);
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dip->di_flags &= ~SF_SNAPSHOT;
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bzero(&dip->di_db[0], (NDADDR + NIADDR) * sizeof(ufs_daddr_t));
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nbp->b_flags |= B_VALIDSUSPWRT;
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bdwrite(nbp);
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@ -636,11 +636,9 @@ ffs_snapremove(vp)
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ip->i_copyonwrite = 0;
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break;
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}
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if (xp == 0) {
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if (xp == 0)
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printf("ffs_snapremove: lost snapshot vnode %d\n",
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ip->i_number);
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vref(vp);
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}
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if (VTOI(devvp)->i_copyonwrite == 0)
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devvp->v_flag &= ~VCOPYONWRITE;
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/*
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@ -673,9 +671,8 @@ ffs_snapremove(vp)
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/*
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* Clear snapshot flag and drop reference.
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*/
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ip->i_flags &= ~(SF_IMMUTABLE | SF_SNAPSHOT);
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ip->i_flags &= ~SF_SNAPSHOT;
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ip->i_flag |= IN_CHANGE | IN_UPDATE;
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vrele(vp);
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}
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/*
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@ -905,7 +902,8 @@ ffs_snapshot_unmount(mp)
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while ((xp = devip->i_copyonwrite) != 0) {
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devip->i_copyonwrite = xp->i_copyonwrite;
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xp->i_copyonwrite = 0;
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vrele(ITOV(xp));
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if (xp->i_effnlink > 0)
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vrele(ITOV(xp));
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}
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ump->um_devvp->v_flag &= ~VCOPYONWRITE;
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}
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@ -923,6 +923,13 @@ ufs_dirremove(dvp, ip, flags, isrmdir)
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error = bowrite(bp);
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}
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dp->i_flag |= IN_CHANGE | IN_UPDATE;
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/*
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* If the last named reference to a snapshot goes away,
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* drop its snapshot reference so that it will be reclaimed
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* when last open reference goes away.
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*/
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if (ip != 0 && (ip->i_flags & SF_SNAPSHOT) != 0 && ip->i_effnlink == 0)
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vrele(ITOV(ip));
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return (error);
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}
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@ -965,6 +972,13 @@ ufs_dirrewrite(dp, oip, newinum, newtype, isrmdir)
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}
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}
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dp->i_flag |= IN_CHANGE | IN_UPDATE;
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/*
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* If the last named reference to a snapshot goes away,
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* drop its snapshot reference so that it will be reclaimed
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* when last open reference goes away.
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*/
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if ((oip->i_flags & SF_SNAPSHOT) != 0 && oip->i_effnlink == 0)
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vrele(ITOV(oip));
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return (error);
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}
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@ -331,7 +331,7 @@ ufs_access(ap)
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}
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/* If immutable bit set, nobody gets to write it. */
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if ((mode & VWRITE) && (ip->i_flags & IMMUTABLE))
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if ((mode & VWRITE) && (ip->i_flags & (IMMUTABLE | SF_SNAPSHOT)))
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return (EPERM);
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/* Otherwise, user id 0 always gets access. */
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@ -454,6 +454,12 @@ ufs_setattr(ap)
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& (SF_NOUNLINK | SF_IMMUTABLE | SF_APPEND)) &&
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securelevel > 0)
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return (EPERM);
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/* Snapshot flag cannot be set or cleared */
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if (((vap->va_flags & SF_SNAPSHOT) != 0 &&
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(ip->i_flags & SF_SNAPSHOT) == 0) ||
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((vap->va_flags & SF_SNAPSHOT) == 0 &&
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(ip->i_flags & SF_SNAPSHOT) != 0))
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return (EPERM);
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ip->i_flags = vap->va_flags;
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} else {
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if (ip->i_flags
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@ -491,6 +497,8 @@ ufs_setattr(ap)
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case VREG:
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if (vp->v_mount->mnt_flag & MNT_RDONLY)
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return (EROFS);
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if ((ip->i_flags & SF_SNAPSHOT) != 0)
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return (EPERM);
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break;
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default:
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break;
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@ -498,10 +506,11 @@ ufs_setattr(ap)
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if ((error = UFS_TRUNCATE(vp, vap->va_size, 0, cred, p)) != 0)
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return (error);
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}
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ip = VTOI(vp);
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if (vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL) {
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if (vp->v_mount->mnt_flag & MNT_RDONLY)
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return (EROFS);
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if ((ip->i_flags & SF_SNAPSHOT) != 0)
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return (EPERM);
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if (cred->cr_uid != ip->i_uid &&
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(error = suser_xxx(cred, p, PRISON_ROOT)) &&
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((vap->va_vaflags & VA_UTIMES_NULL) == 0 ||
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@ -528,6 +537,9 @@ ufs_setattr(ap)
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if (vap->va_mode != (mode_t)VNOVAL) {
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if (vp->v_mount->mnt_flag & MNT_RDONLY)
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return (EROFS);
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if ((ip->i_flags & SF_SNAPSHOT) != 0 && (vap->va_mode &
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(S_IXUSR | S_IWUSR | S_IXGRP | S_IWGRP | S_IXOTH | S_IWOTH)))
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return (EPERM);
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error = ufs_chmod(vp, (int)vap->va_mode, cred, p);
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}
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VN_KNOTE(vp, NOTE_ATTRIB);
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@ -702,8 +714,6 @@ ufs_remove(ap)
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int error;
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ip = VTOI(vp);
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if ((ip->i_flags & SF_SNAPSHOT) != 0)
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ffs_snapremove(vp);
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if ((ip->i_flags & (NOUNLINK | IMMUTABLE | APPEND)) ||
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(VTOI(dvp)->i_flags & APPEND)) {
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error = EPERM;
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@ -358,7 +358,7 @@ mmap(p, uap)
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p->p_ucred, p)))
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return (error);
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if ((va.va_flags &
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(IMMUTABLE|APPEND)) == 0)
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(SF_SNAPSHOT|IMMUTABLE|APPEND)) == 0)
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maxprot |= VM_PROT_WRITE;
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else if (prot & PROT_WRITE)
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return (EPERM);
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