6.15-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara pc@manguebit.org
[ Upstream commit 3363da82e02f1bddc54faa92ea430c6532e2cd2e ]
We've seen customers having shares mounted in paths like /??/C:/ or /??/UNC/foo.example.com/share in order to get their native SMB symlinks successfully followed from different mounts.
After commit 12b466eb52d9 ("cifs: Fix creating and resolving absolute NT-style symlinks"), the client would then convert absolute paths from "/??/C:/" to "/mnt/c/" by default. The absolute paths would vary depending on the value of symlinkroot= mount option.
Fix this by restoring old behavior of not trying to convert absolute paths by default. Only do this if symlinkroot= was _explicitly_ set.
Before patch:
$ mount.cifs //w22-fs0/test2 /mnt/1 -o vers=3.1.1,username=xxx,password=yyy $ ls -l /mnt/1/symlink2 lrwxr-xr-x 1 root root 15 Jun 20 14:22 /mnt/1/symlink2 -> /mnt/c/testfile $ mkdir -p /??/C:; echo foo > //??/C:/testfile $ cat /mnt/1/symlink2 cat: /mnt/1/symlink2: No such file or directory
After patch:
$ mount.cifs //w22-fs0/test2 /mnt/1 -o vers=3.1.1,username=xxx,password=yyy $ ls -l /mnt/1/symlink2 lrwxr-xr-x 1 root root 15 Jun 20 14:22 /mnt/1/symlink2 -> '/??/C:/testfile' $ mkdir -p /??/C:; echo foo > //??/C:/testfile $ cat /mnt/1/symlink2 foo
Cc: linux-cifs@vger.kernel.org Reported-by: Pierguido Lambri plambri@redhat.com Cc: David Howells dhowells@redhat.com Cc: Stefan Metzmacher metze@samba.org Fixes: 12b466eb52d9 ("cifs: Fix creating and resolving absolute NT-style symlinks") Signed-off-by: Paulo Alcantara (Red Hat) pc@manguebit.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/fs_context.c | 17 +++++++---------- fs/smb/client/reparse.c | 22 +++++++++++++--------- 2 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c index a634a34d4086a..59ccc2229ab30 100644 --- a/fs/smb/client/fs_context.c +++ b/fs/smb/client/fs_context.c @@ -1824,10 +1824,14 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, cifs_errorf(fc, "symlinkroot mount options must be absolute path\n"); goto cifs_parse_mount_err; } - kfree(ctx->symlinkroot); - ctx->symlinkroot = kstrdup(param->string, GFP_KERNEL); - if (!ctx->symlinkroot) + if (strnlen(param->string, PATH_MAX) == PATH_MAX) { + cifs_errorf(fc, "symlinkroot path too long (max path length: %u)\n", + PATH_MAX - 1); goto cifs_parse_mount_err; + } + kfree(ctx->symlinkroot); + ctx->symlinkroot = param->string; + param->string = NULL; break; } /* case Opt_ignore: - is ignored as expected ... */ @@ -1837,13 +1841,6 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, goto cifs_parse_mount_err; }
- /* - * By default resolve all native absolute symlinks relative to "/mnt/". - * Same default has drvfs driver running in WSL for resolving SMB shares. - */ - if (!ctx->symlinkroot) - ctx->symlinkroot = kstrdup("/mnt/", GFP_KERNEL); - return 0;
cifs_parse_mount_err: diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c index 1c40e42e4d897..5fa29a97ac154 100644 --- a/fs/smb/client/reparse.c +++ b/fs/smb/client/reparse.c @@ -57,6 +57,7 @@ static int create_native_symlink(const unsigned int xid, struct inode *inode, struct reparse_symlink_data_buffer *buf = NULL; struct cifs_open_info_data data = {}; struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); + const char *symroot = cifs_sb->ctx->symlinkroot; struct inode *new; struct kvec iov; __le16 *path = NULL; @@ -82,7 +83,8 @@ static int create_native_symlink(const unsigned int xid, struct inode *inode, .symlink_target = symlink_target, };
- if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) && symname[0] == '/') { + if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) && + symroot && symname[0] == '/') { /* * This is a request to create an absolute symlink on the server * which does not support POSIX paths, and expects symlink in @@ -92,7 +94,7 @@ static int create_native_symlink(const unsigned int xid, struct inode *inode, * ensure compatibility of this symlink stored in absolute form * on the SMB server. */ - if (!strstarts(symname, cifs_sb->ctx->symlinkroot)) { + if (!strstarts(symname, symroot)) { /* * If the absolute Linux symlink target path is not * inside "symlinkroot" location then there is no way @@ -101,12 +103,12 @@ static int create_native_symlink(const unsigned int xid, struct inode *inode, cifs_dbg(VFS, "absolute symlink '%s' cannot be converted to NT format " "because it is outside of symlinkroot='%s'\n", - symname, cifs_sb->ctx->symlinkroot); + symname, symroot); rc = -EINVAL; goto out; } - len = strlen(cifs_sb->ctx->symlinkroot); - if (cifs_sb->ctx->symlinkroot[len-1] != '/') + len = strlen(symroot); + if (symroot[len - 1] != '/') len++; if (symname[len] >= 'a' && symname[len] <= 'z' && (symname[len+1] == '/' || symname[len+1] == '\0')) { @@ -782,6 +784,7 @@ int smb2_parse_native_symlink(char **target, const char *buf, unsigned int len, const char *full_path, struct cifs_sb_info *cifs_sb) { + const char *symroot = cifs_sb->ctx->symlinkroot; char sep = CIFS_DIR_SEP(cifs_sb); char *linux_target = NULL; char *smb_target = NULL; @@ -815,7 +818,8 @@ int smb2_parse_native_symlink(char **target, const char *buf, unsigned int len, goto out; }
- if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) && !relative) { + if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) && + symroot && !relative) { /* * This is an absolute symlink from the server which does not * support POSIX paths, so the symlink is in NT-style path. @@ -907,15 +911,15 @@ int smb2_parse_native_symlink(char **target, const char *buf, unsigned int len, }
abs_path_len = strlen(abs_path)+1; - symlinkroot_len = strlen(cifs_sb->ctx->symlinkroot); - if (cifs_sb->ctx->symlinkroot[symlinkroot_len-1] == '/') + symlinkroot_len = strlen(symroot); + if (symroot[symlinkroot_len - 1] == '/') symlinkroot_len--; linux_target = kmalloc(symlinkroot_len + 1 + abs_path_len, GFP_KERNEL); if (!linux_target) { rc = -ENOMEM; goto out; } - memcpy(linux_target, cifs_sb->ctx->symlinkroot, symlinkroot_len); + memcpy(linux_target, symroot, symlinkroot_len); linux_target[symlinkroot_len] = '/'; memcpy(linux_target + symlinkroot_len + 1, abs_path, abs_path_len); } else if (smb_target[0] == sep && relative) {