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From bbe9ac11d8d4a8511214605509a593fb9f04ffaa Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Fri, 19 Oct 2018 11:28:40 +0200
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Subject: [PATCH] chown-recursive: also drop ACLs when recursively chown()ing
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Let's better be safe than sorry and also drop ACLs.
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(cherry-picked from commit f89bc84f3242449cbc308892c87573b131f121df)
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Related: #1643368
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---
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 src/core/chown-recursive.c | 16 ++++++++++++----
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 1 file changed, 12 insertions(+), 4 deletions(-)
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diff --git a/src/core/chown-recursive.c b/src/core/chown-recursive.c
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index 27c64489b5..447b771267 100644
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--- a/src/core/chown-recursive.c
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+++ b/src/core/chown-recursive.c
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@@ -3,6 +3,7 @@
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 #include <fcntl.h>
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 #include <sys/stat.h>
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 #include <sys/types.h>
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+#include <sys/xattr.h>
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 #include "chown-recursive.h"
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 #include "dirent-util.h"
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@@ -14,6 +15,7 @@
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 static int chown_one(int fd, const struct stat *st, uid_t uid, gid_t gid) {
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         char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
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+        const char *n;
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         assert(fd >= 0);
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         assert(st);
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@@ -26,13 +28,19 @@ static int chown_one(int fd, const struct stat *st, uid_t uid, gid_t gid) {
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          * O_PATH. (Note: fchown() and fchmod() do not work with O_PATH, the kernel refuses that. */
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         xsprintf(procfs_path, "/proc/self/fd/%i", fd);
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+        /* Drop any ACL if there is one */
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+        FOREACH_STRING(n, "system.posix_acl_access", "system.posix_acl_default")
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+                if (removexattr(procfs_path, n) < 0)
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+                        if (!IN_SET(errno, ENODATA, EOPNOTSUPP, ENOSYS, ENOTTY))
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+                                return -errno;
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+
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         if (chown(procfs_path, uid, gid) < 0)
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                 return -errno;
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-        /* The linux kernel alters the mode in some cases of chown(). Let's undo this. We do this only for non-symlinks
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-         * however. That's because for symlinks the access mode is ignored anyway and because on some kernels/file
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-         * systems trying to change the access mode will succeed but has no effect while on others it actively
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-         * fails. */
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+        /* The linux kernel alters the mode in some cases of chown(), as well when we change ACLs. Let's undo this. We
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+         * do this only for non-symlinks however. That's because for symlinks the access mode is ignored anyway and
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+         * because on some kernels/file systems trying to change the access mode will succeed but has no effect while
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+         * on others it actively fails. */
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         if (!S_ISLNK(st->st_mode))
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                 if (chmod(procfs_path, st->st_mode & 07777) < 0)
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                         return -errno;