From: Hyunchul Lee hyc.lee@gmail.com
mainline inclusion from mainline-5.15-rc3 commit f58eae6c5fa882d6d0a6b7587a099602a59d57b5 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G CVE: NA
Reference: https://git.kernel.org/torvalds/linux/c/f58eae6c5fa8
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Because of .., files outside the share directory could be accessed. To prevent this, normalize the given path and remove all . and .. components.
In addition to the usual large set of regression tests (smbtorture and xfstests), ran various tests on this to specifically check path name validation including libsmb2 tests to verify path normalization:
./examples/smb2-ls-async smb://172.30.1.15/homes2/../ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/../ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/../../ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/../ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/..bar/ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/bar../ ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/bar.. ./examples/smb2-ls-async smb://172.30.1.15/homes2/foo/bar../../../../
Signed-off-by: Hyunchul Lee hyc.lee@gmail.com Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Jason Yan yanaijie@huawei.com Signed-off-by: Zhong Jinghua zhongjinghua@huawei.com --- fs/ksmbd/misc.c | 76 ++++++++++++++++++++++++++++++++++++++++------ fs/ksmbd/misc.h | 3 +- fs/ksmbd/smb2pdu.c | 14 ++++++--- 3 files changed, 77 insertions(+), 16 deletions(-)
diff --git a/fs/ksmbd/misc.c b/fs/ksmbd/misc.c index 0b307ca28a19..3eac3c01749f 100644 --- a/fs/ksmbd/misc.c +++ b/fs/ksmbd/misc.c @@ -191,19 +191,77 @@ int get_nlink(struct kstat *st) return nlink; }
-void ksmbd_conv_path_to_unix(char *path) +char *ksmbd_conv_path_to_unix(char *path) { + size_t path_len, remain_path_len, out_path_len; + char *out_path, *out_next; + int i, pre_dotdot_cnt = 0, slash_cnt = 0; + bool is_last; + strreplace(path, '\', '/'); -} + path_len = strlen(path); + remain_path_len = path_len; + if (path_len == 0) + return ERR_PTR(-EINVAL);
-void ksmbd_strip_last_slash(char *path) -{ - int len = strlen(path); + out_path = kzalloc(path_len + 2, GFP_KERNEL); + if (!out_path) + return ERR_PTR(-ENOMEM); + out_path_len = 0; + out_next = out_path; + + do { + char *name = path + path_len - remain_path_len; + char *next = strchrnul(name, '/'); + size_t name_len = next - name; + + is_last = !next[0]; + if (name_len == 2 && name[0] == '.' && name[1] == '.') { + pre_dotdot_cnt++; + /* handle the case that path ends with "/.." */ + if (is_last) + goto follow_dotdot; + } else { + if (pre_dotdot_cnt) { +follow_dotdot: + slash_cnt = 0; + for (i = out_path_len - 1; i >= 0; i--) { + if (out_path[i] == '/' && + ++slash_cnt == pre_dotdot_cnt + 1) + break; + } + + if (i < 0 && + slash_cnt != pre_dotdot_cnt) { + kfree(out_path); + return ERR_PTR(-EINVAL); + } + + out_next = &out_path[i+1]; + *out_next = '\0'; + out_path_len = i + 1;
- while (len && path[len - 1] == '/') { - path[len - 1] = '\0'; - len--; - } + } + + if (name_len != 0 && + !(name_len == 1 && name[0] == '.') && + !(name_len == 2 && name[0] == '.' && name[1] == '.')) { + next[0] = '\0'; + sprintf(out_next, "%s/", name); + out_next += name_len + 1; + out_path_len += name_len + 1; + next[0] = '/'; + } + pre_dotdot_cnt = 0; + } + + remain_path_len -= name_len + 1; + } while (!is_last); + + if (out_path_len > 0) + out_path[out_path_len-1] = '\0'; + path[path_len] = '\0'; + return out_path; }
void ksmbd_conv_path_to_windows(char *path) diff --git a/fs/ksmbd/misc.h b/fs/ksmbd/misc.h index af8717d4d85b..b7b10139ada2 100644 --- a/fs/ksmbd/misc.h +++ b/fs/ksmbd/misc.h @@ -16,8 +16,7 @@ int ksmbd_validate_filename(char *filename); int parse_stream_name(char *filename, char **stream_name, int *s_type); char *convert_to_nt_pathname(char *filename, char *sharepath); int get_nlink(struct kstat *st); -void ksmbd_conv_path_to_unix(char *path); -void ksmbd_strip_last_slash(char *path); +char *ksmbd_conv_path_to_unix(char *path); void ksmbd_conv_path_to_windows(char *path); char *ksmbd_extract_sharename(char *treename); char *convert_to_unix_name(struct ksmbd_share_config *share, char *name); diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c index 2fa4584df93e..acb13fbc7713 100644 --- a/fs/ksmbd/smb2pdu.c +++ b/fs/ksmbd/smb2pdu.c @@ -634,7 +634,7 @@ static char * smb2_get_name(struct ksmbd_share_config *share, const char *src, const int maxlen, struct nls_table *local_nls) { - char *name, *unixname; + char *name, *norm_name, *unixname;
name = smb_strndup_from_utf16(src, maxlen, 1, local_nls); if (IS_ERR(name)) { @@ -643,11 +643,15 @@ smb2_get_name(struct ksmbd_share_config *share, const char *src, }
/* change it to absolute unix name */ - ksmbd_conv_path_to_unix(name); - ksmbd_strip_last_slash(name); - - unixname = convert_to_unix_name(share, name); + norm_name = ksmbd_conv_path_to_unix(name); + if (IS_ERR(norm_name)) { + kfree(name); + return norm_name; + } kfree(name); + + unixname = convert_to_unix_name(share, norm_name); + kfree(norm_name); if (!unixname) { pr_err("can not convert absolute name\n"); return ERR_PTR(-ENOMEM);