Only exchange source and destination filenames
if flags contain RENAME_EXCHANGE.
In case if executable file was running and replaced by
other file /proc/PID/exe should still show correct file name,
not the old name of the file by which it was replaced.
The scenario when this bug manifests itself was like this:
* ALT Linux uses rpm and start-stop-daemon;
* during a package upgrade rpm creates a temporary file
for an executable to rename it upon successful unpacking;
* start-stop-daemon is run subsequently and it obtains
the (nonexistant) temporary filename via /proc/PID/exe
thus failing to identify the running process.
Cc: Miklos Szeredi <mszer...@suse.cz>
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: linux-fsde...@vger.kernel.org
Fixes: da1ce0670c14 "vfs: add cross-rename"
Signed-off-by: Mikhail Efremov <s...@altlinux.org>
---
fs/dcache.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 7a5b514..3218570 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2372,7 +2372,8 @@ void dentry_update_name_case(struct dentry *dentry,
struct qstr *name)
}
EXPORT_SYMBOL(dentry_update_name_case);
-static void switch_names(struct dentry *dentry, struct dentry *target)
+static void switch_names(struct dentry *dentry, struct dentry *target,
+ bool exchange)
{
if (dname_external(target)) {
if (dname_external(dentry)) {
@@ -2404,11 +2405,21 @@ static void switch_names(struct dentry *dentry, struct
dentry *target)
/*
* Both are internal.
*/
- unsigned int i;
- BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN,
sizeof(long)));
- for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
- swap(((long *) &dentry->d_iname)[i],
- ((long *) &target->d_iname)[i]);
+ if (exchange) {
+ unsigned int i;
+
+ BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN,
+ sizeof(long)));
+ for (i = 0; i < DNAME_INLINE_LEN / sizeof(long);
+ i++) {
+ swap(((long *) &dentry->d_iname)[i],
+ ((long *) &target->d_iname)[i]);
+ }
+ } else {
+ memcpy(dentry->d_iname, target->d_name.name,
+ target->d_name.len + 1);
+ dentry->d_name.len = target->d_name.len;
+ return;
}
}
}
@@ -2510,7 +2521,7 @@ static void __d_move(struct dentry *dentry, struct dentry
*target,
list_del(&target->d_u.d_child);
/* Switch the names.. */
- switch_names(dentry, target);
+ switch_names(dentry, target, exchange);
swap(dentry->d_name.hash, target->d_name.hash);
/* ... and switch the parents */
@@ -2649,7 +2660,7 @@ static void __d_materialise_dentry(struct dentry *dentry,
struct dentry *anon)
dparent = dentry->d_parent;
- switch_names(dentry, anon);
+ switch_names(dentry, anon, false);
swap(dentry->d_name.hash, anon->d_name.hash);
dentry->d_parent = dentry;
--
1.8.5.5
--
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