From: Paulo Alcantara pc@cjr.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@cjr.nz Signed-off-by: Steve French stfrench@microsoft.com [apanyaki: backport to v6.1-stable] Signed-off-by: Andrew Paniakin apanyaki@amazon.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