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Message-ID: <20250331235023.107494-1-apanyaki@amazon.com>
Date: Mon, 31 Mar 2025 23:50:22 +0000
From: Andrew Paniakin <apanyaki@...zon.com>
To: <stable@...r.kernel.org>
CC: Benjamin Herrenschmidt <benh@...zon.com>, Hazem Mohamed Abuelfotoh
<abuehaze@...zon.com>, Paulo Alcantara <pc@...guebit.com>, Paulo Alcantara
<pc@....nz>, Steve French <stfrench@...rosoft.com>, Andrew Paniakin
<apanyaki@...zon.com>, Steve French <sfrench@...ba.org>, Ronnie Sahlberg
<lsahlber@...hat.com>, Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey
<tom@...pey.com>, "open list:COMMON INTERNET FILE SYSTEM CLIENT (CIFS and
SMB3)" <linux-cifs@...r.kernel.org>, "moderated list:COMMON INTERNET FILE
SYSTEM CLIENT (CIFS and SMB3)" <samba-technical@...ts.samba.org>, open list
<linux-kernel@...r.kernel.org>
Subject: [PATCH 6.1 V2] cifs: use origin fullpath for automounts
From: Paulo Alcantara <pc@....nz>
commit 7ad54b98fc1f141cfb70cfe2a3d6def5a85169ff upstream.
Use TCP_Server_Info::origin_fullpath instead of cifs_tcon::tree_name
when building source paths for automounts as it will be useful for
domain-based DFS referrals where the connections and referrals would
get either re-used from the cache or re-created when chasing the dfs
link.
Signed-off-by: Paulo Alcantara (SUSE) <pc@....nz>
Signed-off-by: Steve French <stfrench@...rosoft.com>
[apanyaki: backport to v6.1-stable]
Signed-off-by: Andrew Paniakin <apanyaki@...zon.com>
---
Please do not include follow-up fix d5a863a153e9 ("cifs: avoid dup
prefix path in dfs_get_automount_devname()"). It works correctly only
when all patches applied in a following order:
1. 7ad54b98fc1f1 ("cifs: use origin fullpath for automounts")
2. a1c0d00572fc ("cifs: share dfs connections and supers") (not ported to linux-6.1)
3. d5a863a153e9 ("cifs: avoid dup prefix path in dfs_get_automount_devname()")
The reason is that patch a1c0d00572fc ("cifs: share dfs connections and
supers") changes origin_fullpath contents from just a namespace root to
a full path eg. from '//corp.fsxtest.local/namespace/' to
'//corp.fsxtest.local/namespace/folderA/fs1-folder/'. But the prefix
path '/folderA/' is also stored in a cifs superblock info and it was
copied twice. With patch d5a863a153e9 ("cifs: avoid dup prefix path in
dfs_get_automount_devname()") prepath string from superblock info is not
used in path construction and result is correct.
But the patch a1c0d00572fc ("cifs: share dfs connections and supers")
was not ported to linux-6.1, probably because it's a part of huge cifs
driver update series merged in linux-6.2, not just a bug fix. So if we
apply patches in following order:
1. 7ad54b98fc1f1 ("cifs: use origin fullpath for automounts")
2. d5a863a153e9 ("cifs: avoid dup prefix path in dfs_get_automount_devname()")
then constructed fullpath will be '//corp.fsxtest.local/namespace/fs1-folder/'
instead of '//corp.fsxtest.local/namespace/folderA/fs1-folder/' because prefix
path was not copied from the superblock info.
Changelog:
v2:
- added CONFIG_CIFS_DFS_UPCALL wrapper to fix build issue [1]
v1: (updates made to upstream version of this patch)
- set_dest_addr() converts DFS address to sockaddr differently: in
kernel 6.1 dns_resolve_server_name_to_ip() returns a string which
needs to be converted to sockaddr with cifs_convert_address().
- removed hunk to init tmp.leaf_fullpath, it was introduced later in
a1c0d00572fc ("cifs: share dfs connections and supers")
- __build_path_from_dentry_optional_prefix() and
dfs_get_automount_devname() functions were added to
fs/smb/client/cifsproto.h instead of fs/cifs/dfs.h as it doesn't exist
in 6.1
- Link to v1: https://lore.kernel.org/all/20240713031147.20332-1-apanyaki@amazon.com/
Testing:
1. tested that these steps do not work without this backport and work
with it:
- mount DFS namespace root:
mount -t cifs -o cred=/mnt/creds,noserverino //corp.fsxtest.local
- shutdown the namespace server that is in use
- access DFS link (triggers automount):
ls /mnt/dfs-namespace/fs1-folder
Reported verbose logs which demonstrate backport correctness in
regression ML thread [2].
2. build kernel with debug options listed in the patch submission
checklist[3], executed cifs test suite of the xfstests [4], no errors.
3. confirmed compilation works with all y/m/n combinations for
CONFIG_CIFS and CONFIG_CIFS_DFS_UPCALL.
4. confirmed allmodconfig and allnoconfig cross-compilation works on
arm, arm64, mips, powerpc, risc.
[1] https://lore.kernel.org/all/aaccd8cc-2bfe-4b2e-b690-be50540f9965@gmail.com/
[2] https://lore.kernel.org/all/Z9cZuBxOscqybcMy@3c06303d853a.ant.amazon.com/
[3] https://www.kernel.org/doc/html/latest/process/submit-checklist.html
[4] https://web.git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git
fs/smb/client/cifs_dfs_ref.c | 34 ++++++++++++++++++++++++++++++++--
fs/smb/client/cifsproto.h | 21 +++++++++++++++++++++
fs/smb/client/dir.c | 21 +++++++++++++++------
3 files changed, 68 insertions(+), 8 deletions(-)
diff --git a/fs/smb/client/cifs_dfs_ref.c b/fs/smb/client/cifs_dfs_ref.c
index 020e71fe1454..876f9a43a99d 100644
--- a/fs/smb/client/cifs_dfs_ref.c
+++ b/fs/smb/client/cifs_dfs_ref.c
@@ -258,6 +258,31 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
goto compose_mount_options_out;
}
+static int set_dest_addr(struct smb3_fs_context *ctx, const char *full_path)
+{
+ struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;
+ char *str_addr = NULL;
+ int rc;
+
+ rc = dns_resolve_server_name_to_ip(full_path, &str_addr, NULL);
+ if (rc < 0)
+ goto out;
+
+ rc = cifs_convert_address(addr, str_addr, strlen(str_addr));
+ if (!rc) {
+ cifs_dbg(FYI, "%s: failed to convert ip address\n", __func__);
+ rc = -EINVAL;
+ goto out;
+ }
+
+ cifs_set_port(addr, ctx->port);
+ rc = 0;
+
+out:
+ kfree(str_addr);
+ return rc;
+}
+
/*
* Create a vfsmount that we can automount
*/
@@ -295,8 +320,7 @@ static struct vfsmount *cifs_dfs_do_automount(struct path *path)
ctx = smb3_fc2context(fc);
page = alloc_dentry_path();
- /* always use tree name prefix */
- full_path = build_path_from_dentry_optional_prefix(mntpt, page, true);
+ full_path = dfs_get_automount_devname(mntpt, page);
if (IS_ERR(full_path)) {
mnt = ERR_CAST(full_path);
goto out;
@@ -315,6 +339,12 @@ static struct vfsmount *cifs_dfs_do_automount(struct path *path)
goto out;
}
+ rc = set_dest_addr(ctx, full_path);
+ if (rc) {
+ mnt = ERR_PTR(rc);
+ goto out;
+ }
+
rc = smb3_parse_devname(full_path, ctx);
if (!rc)
mnt = fc_mount(fc);
diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index f37e4da0fe40..81d2761cd00a 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -57,8 +57,29 @@ extern void exit_cifs_idmap(void);
extern int init_cifs_spnego(void);
extern void exit_cifs_spnego(void);
extern const char *build_path_from_dentry(struct dentry *, void *);
+char *__build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+ const char *tree, int tree_len,
+ bool prefix);
extern char *build_path_from_dentry_optional_prefix(struct dentry *direntry,
void *page, bool prefix);
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page)
+{
+ struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
+ struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+ struct TCP_Server_Info *server = tcon->ses->server;
+
+ if (unlikely(!server->origin_fullpath))
+ return ERR_PTR(-EREMOTE);
+
+ return __build_path_from_dentry_optional_prefix(dentry, page,
+ server->origin_fullpath,
+ strlen(server->origin_fullpath),
+ true);
+}
+#endif
+
static inline void *alloc_dentry_path(void)
{
return __getname();
diff --git a/fs/smb/client/dir.c b/fs/smb/client/dir.c
index 863c7bc3db86..477302157ab3 100644
--- a/fs/smb/client/dir.c
+++ b/fs/smb/client/dir.c
@@ -78,14 +78,13 @@ build_path_from_dentry(struct dentry *direntry, void *page)
prefix);
}
-char *
-build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
- bool prefix)
+char *__build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+ const char *tree, int tree_len,
+ bool prefix)
{
int dfsplen;
int pplen = 0;
struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
- struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
char dirsep = CIFS_DIR_SEP(cifs_sb);
char *s;
@@ -93,7 +92,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
return ERR_PTR(-ENOMEM);
if (prefix)
- dfsplen = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1);
+ dfsplen = strnlen(tree, tree_len + 1);
else
dfsplen = 0;
@@ -123,7 +122,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
}
if (dfsplen) {
s -= dfsplen;
- memcpy(s, tcon->tree_name, dfsplen);
+ memcpy(s, tree, dfsplen);
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
int i;
for (i = 0; i < dfsplen; i++) {
@@ -135,6 +134,16 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
return s;
}
+char *build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
+ bool prefix)
+{
+ struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
+ struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+
+ return __build_path_from_dentry_optional_prefix(direntry, page, tcon->tree_name,
+ MAX_TREE_SIZE, prefix);
+}
+
/*
* Don't allow path components longer than the server max.
* Don't allow the separator character in a path component.
base-commit: 8e60a714ba3bb083b7321385054fa39ceb876914
--
2.43.0
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