ovl: fix corner case of conflicting lower layer uuid
This fixes ovl_lower_uuid_ok() to correctly detect the corner case: - two filesystems, A and B, both have null uuid - upper layer is on A - lower layer 1 is also on A - lower layer 2 is on B In this case, bad_uuid would not have been set for B, because the check only involved the list of lower fs. Hence we'll try to decode a layer 2 origin on layer 1 and fail. We check for conflicting (and null) uuid among all lower layers, including those layers that are on the same fs as the upper layer. Reported-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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@ -24,6 +24,8 @@ struct ovl_sb {
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dev_t pseudo_dev;
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dev_t pseudo_dev;
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/* Unusable (conflicting) uuid */
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/* Unusable (conflicting) uuid */
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bool bad_uuid;
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bool bad_uuid;
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/* Used as a lower layer (but maybe also as upper) */
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bool is_lower;
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};
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};
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struct ovl_layer {
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struct ovl_layer {
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@ -1260,7 +1260,7 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
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if (!ofs->config.nfs_export && !ofs->upper_mnt)
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if (!ofs->config.nfs_export && !ofs->upper_mnt)
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return true;
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return true;
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for (i = 1; i < ofs->numfs; i++) {
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for (i = 0; i < ofs->numfs; i++) {
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/*
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/*
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* We use uuid to associate an overlay lower file handle with a
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* We use uuid to associate an overlay lower file handle with a
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* lower layer, so we can accept lower fs with null uuid as long
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* lower layer, so we can accept lower fs with null uuid as long
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@ -1268,7 +1268,8 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
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* if we detect multiple lower fs with the same uuid, we
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* if we detect multiple lower fs with the same uuid, we
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* disable lower file handle decoding on all of them.
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* disable lower file handle decoding on all of them.
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*/
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*/
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if (uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
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if (ofs->fs[i].is_lower &&
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uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
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ofs->fs[i].bad_uuid = true;
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ofs->fs[i].bad_uuid = true;
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return false;
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return false;
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}
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}
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@ -1342,10 +1343,12 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
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/*
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/*
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* All lower layers that share the same fs as upper layer, use the real
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* All lower layers that share the same fs as upper layer, use the real
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* upper st_dev.
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* upper st_dev.
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* is_lower will be set if upper fs is shared with a lower layer.
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*/
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*/
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if (ofs->upper_mnt) {
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if (ofs->upper_mnt) {
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ofs->fs[0].sb = ofs->upper_mnt->mnt_sb;
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ofs->fs[0].sb = ofs->upper_mnt->mnt_sb;
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ofs->fs[0].pseudo_dev = ofs->upper_mnt->mnt_sb->s_dev;
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ofs->fs[0].pseudo_dev = ofs->upper_mnt->mnt_sb->s_dev;
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ofs->fs[0].is_lower = false;
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}
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}
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for (i = 0; i < numlower; i++) {
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for (i = 0; i < numlower; i++) {
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@ -1387,6 +1390,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
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ofs->layers[ofs->numlayer].fsid = fsid;
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ofs->layers[ofs->numlayer].fsid = fsid;
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ofs->layers[ofs->numlayer].fs = &ofs->fs[fsid];
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ofs->layers[ofs->numlayer].fs = &ofs->fs[fsid];
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ofs->numlayer++;
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ofs->numlayer++;
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ofs->fs[fsid].is_lower = true;
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}
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}
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/*
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/*
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