From c6fbba0546d3ead18d4a623e76e28bcbaa66a325 Mon Sep 17 00:00:00 2001 From: Steve French Date: Thu, 18 Dec 2008 01:41:20 +0000 Subject: [CIFS] make sure that DFS pathnames are properly formed The paths in a DFS request are supposed to only have a single preceding backslash, but we are sending them with a double backslash. This is exposing a bug in Windows where it also sends a path in the response that has a double backslash. The existing code that builds the mount option string however expects a double backslash prefix in a couple of places when it tries to use the path returned by build_path_from_dentry. Fix compose_mount_options to expect properly formed DFS paths (single backslash at front). Also clean up error handling in that function. There was a possible NULL pointer dereference and situations where a partially built option string would be returned. Tested against Samba 3.0.28-ish server and Samba 3.3 and Win2k8. CC: Stable Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/CHANGES | 3 ++- fs/cifs/cifs_dfs_ref.c | 48 ++++++++++++++++++++++++++++++++++++------------ 2 files changed, 38 insertions(+), 13 deletions(-) (limited to 'fs/cifs') diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES index 5ab6bcce880..080703a15f4 100644 --- a/fs/cifs/CHANGES +++ b/fs/cifs/CHANGES @@ -4,7 +4,8 @@ Add "forcemandatorylock" mount option to allow user to use mandatory rather than posix (advisory) byte range locks, even though server would support posix byte range locks. Fix query of root inode when prefixpath specified and user does not have access to query information about the -top of the share. +top of the share. Fix problem in 2.6.28 resolving DFS paths to +Samba servers (worked to Windows). Version 1.55 ------------ diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c index e1c18362ba4..85c0a74d034 100644 --- a/fs/cifs/cifs_dfs_ref.c +++ b/fs/cifs/cifs_dfs_ref.c @@ -122,7 +122,7 @@ static char *compose_mount_options(const char *sb_mountdata, char **devname) { int rc; - char *mountdata; + char *mountdata = NULL; int md_len; char *tkn_e; char *srvIP = NULL; @@ -136,10 +136,9 @@ static char *compose_mount_options(const char *sb_mountdata, *devname = cifs_get_share_name(ref->node_name); rc = dns_resolve_server_name_to_ip(*devname, &srvIP); if (rc != 0) { - cERROR(1, ("%s: Failed to resolve server part of %s to IP", - __func__, *devname)); - mountdata = ERR_PTR(rc); - goto compose_mount_options_out; + cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d", + __func__, *devname, rc));; + goto compose_mount_options_err; } /* md_len = strlen(...) + 12 for 'sep+prefixpath=' * assuming that we have 'unc=' and 'ip=' in @@ -149,8 +148,8 @@ static char *compose_mount_options(const char *sb_mountdata, strlen(ref->node_name) + 12; mountdata = kzalloc(md_len+1, GFP_KERNEL); if (mountdata == NULL) { - mountdata = ERR_PTR(-ENOMEM); - goto compose_mount_options_out; + rc = -ENOMEM; + goto compose_mount_options_err; } /* copy all options except of unc,ip,prefixpath */ @@ -197,18 +196,32 @@ static char *compose_mount_options(const char *sb_mountdata, /* find & copy prefixpath */ tkn_e = strchr(ref->node_name + 2, '\\'); - if (tkn_e == NULL) /* invalid unc, missing share name*/ - goto compose_mount_options_out; + if (tkn_e == NULL) { + /* invalid unc, missing share name*/ + rc = -EINVAL; + goto compose_mount_options_err; + } + /* + * this function gives us a path with a double backslash prefix. We + * require a single backslash for DFS. Temporarily increment fullpath + * to put it in the proper form and decrement before freeing it. + */ fullpath = build_path_from_dentry(dentry); + if (!fullpath) { + rc = -ENOMEM; + goto compose_mount_options_err; + } + ++fullpath; tkn_e = strchr(tkn_e + 1, '\\'); - if (tkn_e || strlen(fullpath) - (ref->path_consumed)) { + if (tkn_e || (strlen(fullpath) - ref->path_consumed)) { strncat(mountdata, &sep, 1); strcat(mountdata, "prefixpath="); if (tkn_e) strcat(mountdata, tkn_e + 1); - strcat(mountdata, fullpath + (ref->path_consumed)); + strcat(mountdata, fullpath + ref->path_consumed); } + --fullpath; kfree(fullpath); /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/ @@ -217,6 +230,11 @@ static char *compose_mount_options(const char *sb_mountdata, compose_mount_options_out: kfree(srvIP); return mountdata; + +compose_mount_options_err: + kfree(mountdata); + mountdata = ERR_PTR(rc); + goto compose_mount_options_out; } @@ -309,13 +327,19 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) goto out_err; } + /* + * The MSDFS spec states that paths in DFS referral requests and + * responses must be prefixed by a single '\' character instead of + * the double backslashes usually used in the UNC. This function + * gives us the latter, so we must adjust the result. + */ full_path = build_path_from_dentry(dentry); if (full_path == NULL) { rc = -ENOMEM; goto out_err; } - rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls, + rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls, &num_referrals, &referrals, cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR); -- cgit v1.2.3-18-g5258