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user-record-nss: check if strings from pwd/spwd/grp/sgrp are valid utf-8

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strv_extend_strv_utf8_only() uses a temporary buffer to make the implementation
conscise. Otherwise we'd have to rewrite all of strv_extend_strv() which didn't
seem worth the trouble for this one use outside of a hot path.

If the data is not serializable, we just pretend it doesn't exists.
This fixes #16683 and https://bugs.gentoo.org/735072 in a second way.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2020-08-30 20:34:12 +02:00
parent e60775cb7b
commit 5c0b738012
1 changed files with 37 additions and 11 deletions
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48
src/shared/user-record-nss.c
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@ -6,10 +6,35 @@
#include "strv.h"
#include "user-record-nss.h"
#include "user-util.h"
#include "utf8.h"
#define SET_IF(field, condition, value, fallback) \
field = (condition) ? (value) : (fallback)
static inline const char* utf8_only(const char *s) {
return s && utf8_is_valid(s) ? s : NULL;
}
static inline int strv_extend_strv_utf8_only(char ***dst, char **src, bool filter_duplicates) {
_cleanup_free_ char **t = NULL;
size_t l, j = 0;
/* First, do a shallow copy of s, filtering for only valid utf-8 strings */
l = strv_length(src);
t = new(char*, l + 1);
if (!t)
return -ENOMEM;
for (size_t i = 0; i < l; i++)
if (utf8_is_valid(src[i]))
t[j++] = src[i];
if (j == 0)
return 0;
t[j] = NULL;
return strv_extend_strv(dst, t, filter_duplicates);
}
int nss_passwd_to_user_record(
const struct passwd *pwd,
const struct spwd *spwd,
@ -55,18 +80,19 @@ int nss_passwd_to_user_record(
free_and_replace(hr->real_name, mangled);
}
r = free_and_strdup(&hr->home_directory, empty_to_null(pwd->pw_dir));
r = free_and_strdup(&hr->home_directory, utf8_only(empty_to_null(pwd->pw_dir)));
if (r < 0)
return r;
r = free_and_strdup(&hr->shell, empty_to_null(pwd->pw_shell));
r = free_and_strdup(&hr->shell, utf8_only(empty_to_null(pwd->pw_shell)));
if (r < 0)
return r;
hr->uid = pwd->pw_uid;
hr->gid = pwd->pw_gid;
if (spwd && looks_like_hashed_password(spwd->sp_pwdp)) {
if (spwd &&
looks_like_hashed_password(utf8_only(spwd->sp_pwdp))) { /* Ignore locked, disabled, and mojibake passwords */
strv_free_erase(hr->hashed_password);
hr->hashed_password = strv_new(spwd->sp_pwdp);
if (!hr->hashed_password)
@ -316,26 +342,26 @@ int nss_group_to_group_record(
if (!g->group_name)
return -ENOMEM;
g->members = strv_copy(grp->gr_mem);
if (!g->members)
return -ENOMEM;
r = strv_extend_strv_utf8_only(&g->members, grp->gr_mem, false);
if (r < 0)
return r;
g->gid = grp->gr_gid;
if (sgrp) {
if (looks_like_hashed_password(sgrp->sg_passwd)) {
if (looks_like_hashed_password(utf8_only(sgrp->sg_passwd))) {
g->hashed_password = strv_new(sgrp->sg_passwd);
if (!g->hashed_password)
return -ENOMEM;
}
r = strv_extend_strv(&g->members, sgrp->sg_mem, 1);
r = strv_extend_strv_utf8_only(&g->members, sgrp->sg_mem, true);
if (r < 0)
return r;
g->administrators = strv_copy(sgrp->sg_adm);
if (!g->administrators)
return -ENOMEM;
r = strv_extend_strv_utf8_only(&g->administrators, sgrp->sg_adm, false);
if (r < 0)
return r;
}
r = json_build(&g->json, JSON_BUILD_OBJECT(