From a207516776769404dfa8ae89003efba1004a55df Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 9 Sep 2020 20:05:58 +0900 Subject: tomoyo: Loosen pathname/domainname validation. Since commit e2dc9bf3f5275ca3 ("umd: Transform fork_usermode_blob into fork_usermode_driver") started calling execve() on a program written in a local mount which is not connected to mount tree, tomoyo_realpath_from_path() started returning a pathname in "$fsname:/$pathname" format which violates TOMOYO's domainname rule that it must start with "<$namespace>" followed by zero or more repetitions of pathnames which start with '/'. Since $fsname must not contain '.' since commit 79c0b2df79eb56fc ("add filesystem subtype support"), tomoyo_correct_path() can recognize a token which appears '/' before '.' appears (e.g. proc:/self/exe ) as a pathname while rejecting a token which appears '.' before '/' appears (e.g. exec.realpath="/bin/bash" ) as a condition parameter. Therefore, accept domainnames which contain pathnames which do not start with '/' but contain '/' before '.' (e.g. tmpfs:/bpfilter_umh ). Signed-off-by: Tetsuo Handa --- security/tomoyo/util.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c index eba0b3395851..a40abb0b91ee 100644 --- a/security/tomoyo/util.c +++ b/security/tomoyo/util.c @@ -143,6 +143,8 @@ char *tomoyo_read_token(struct tomoyo_acl_param *param) return pos; } +static bool tomoyo_correct_path2(const char *filename, const size_t len); + /** * tomoyo_get_domainname - Read a domainname from a line. * @@ -157,10 +159,10 @@ const struct tomoyo_path_info *tomoyo_get_domainname char *pos = start; while (*pos) { - if (*pos++ != ' ' || *pos++ == '/') + if (*pos++ != ' ' || + tomoyo_correct_path2(pos, strchrnul(pos, ' ') - pos)) continue; - pos -= 2; - *pos++ = '\0'; + *(pos - 1) = '\0'; break; } param->data = pos; @@ -513,6 +515,22 @@ bool tomoyo_correct_word(const char *string) return tomoyo_correct_word2(string, strlen(string)); } +/** + * tomoyo_correct_path2 - Check whether the given pathname follows the naming rules. + * + * @filename: The pathname to check. + * @len: Length of @filename. + * + * Returns true if @filename follows the naming rules, false otherwise. + */ +static bool tomoyo_correct_path2(const char *filename, const size_t len) +{ + const char *cp1 = memchr(filename, '/', len); + const char *cp2 = memchr(filename, '.', len); + + return cp1 && (!cp2 || (cp1 < cp2)) && tomoyo_correct_word2(filename, len); +} + /** * tomoyo_correct_path - Validate a pathname. * @@ -523,7 +541,7 @@ bool tomoyo_correct_word(const char *string) */ bool tomoyo_correct_path(const char *filename) { - return *filename == '/' && tomoyo_correct_word(filename); + return tomoyo_correct_path2(filename, strlen(filename)); } /** @@ -545,8 +563,7 @@ bool tomoyo_correct_domain(const unsigned char *domainname) if (!cp) break; - if (*domainname != '/' || - !tomoyo_correct_word2(domainname, cp - domainname)) + if (!tomoyo_correct_path2(domainname, cp - domainname)) return false; domainname = cp + 1; } -- cgit v1.2.3