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From efe0be279901006f939cd357ccee47b651c786da Mon Sep 17 00:00:00 2001
From: Seebs <seebs@seebs.net>
Date: Fri, 24 Feb 2017 12:47:38 -0600
Subject: Don't try to record 0-length posix_acl_default xattrs
Based on a submission from Anton Gerasimov <anton@advancedtelematic.com>
On some systems, with some kernel configs, "cp -a" apparently tries to
set an empty ACL list, with a valid header but no contents, which causes
strange and mysterious behavior later if we actually create such an entry.
So filter that out, also sanity-check a couple of other things.
Signed-off-by: Seebs <seebs@seebs.net>
Upstream-Status: Backport
diff --git a/ChangeLog.txt b/ChangeLog.txt
index ae2a6e9..a2d30e9 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -1,3 +1,6 @@
+2017-02-24:
+ * (seebs) import posix_acl_default fix from Anton Gerasimov
+ <anton@advancedtelematic.com>
2017-02-01:
* (seebs) handle xattr deletion slightly more carefully.
* (seebs) tag this as 1.8.2
diff --git a/ports/linux/xattr/pseudo_wrappers.c b/ports/linux/xattr/pseudo_wrappers.c
index 46bc053..d69d53e 100644
--- a/ports/linux/xattr/pseudo_wrappers.c
+++ b/ports/linux/xattr/pseudo_wrappers.c
@@ -62,9 +62,9 @@ static int
posix_permissions(const acl_header *header, int entries, int *extra, int *mode) {
int acl_seen = 0;
if (le32(header->version) != 2) {
- pseudo_diag("Fatal: ACL support no available for header version %d.\n",
+ pseudo_diag("Fatal: ACL support not available for header version %d.\n",
le32(header->version));
- return 1;
+ return -1;
}
*mode = 0;
*extra = 0;
@@ -140,12 +140,38 @@ static int shared_setxattr(const char *path, int fd, const char *name, const voi
pseudo_debug(PDBGF_XATTR, "setxattr(%s [fd %d], %s => '%.*s')\n",
path ? path : "<no path>", fd, name, (int) size, (char *) value);
+ /* Filter out erroneous sizes for POSIX ACL
+ * see posix_acl_xattr_count in include/linux/posix_acl_xattr.h of Linux source code */
+ /* I don't think there's any posix_acl_* values that aren't in this format */
+ if (!strncmp(name, "system.posix_acl_", 17)) {
+ // ACL is corrupt, issue an error
+ if(size < sizeof(acl_header) || (size - sizeof(acl_header)) % sizeof(acl_entry) != 0) {
+ pseudo_debug(PDBGF_XATTR, "invalid data size for %s: %d\n",
+ name, (int) size);
+ errno = EINVAL;
+ return -1;
+ }
+
+ // ACL is empty, do nothing
+ if((size - sizeof(acl_header)) / sizeof(acl_entry) == 0) {
+ /* on some systems, "cp -a" will attempt to clone the
+ * posix_acl_default entry for a directory (which would specify
+ * default ACLs for new files in that directory), but if the
+ * original was empty, we get a header but no entries. With
+ * real xattr, that ends up being silently discarded, apparently,
+ * so we discard it too.
+ */
+ pseudo_debug(PDBGF_XATTR, "0-length ACL entry %s.\n", name);
+ return 0;
+ }
+ }
/* this may be a plain chmod */
if (!strcmp(name, "system.posix_acl_access")) {
int extra;
int mode;
int entries = (size - sizeof(acl_header)) / sizeof(acl_entry);
- if (!posix_permissions(value, entries, &extra, &mode)) {
+ int res = posix_permissions(value, entries, &extra, &mode);
+ if (res == 0) {
pseudo_debug(PDBGF_XATTR, "posix_acl_access translated to mode %04o. Remaining attribute(s): %d.\n",
mode, extra);
buf.st_mode = mode;
@@ -164,8 +190,12 @@ static int shared_setxattr(const char *path, int fd, const char *name, const voi
if (!extra) {
return 0;
}
+ } else if (res == -1) {
+ errno = EOPNOTSUPP;
+ return -1;
}
}
+
if (!strcmp(name, "user.pseudo_data")) {
pseudo_debug(PDBGF_XATTR | PDBGF_XATTRDB, "user.pseudo_data xattribute does not get to go in database.\n");
return -1;
--
cgit v0.10.2
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