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basic/user-util: avoid filesystem access check

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The check of u==UID_NOBODY is just a register comparison, but
synthesize_nobody() requires a system call, so let's invert the order in the
condition. Since most calls into this module are not for nobody, we should
save one syscall in the common case.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2022-08-24 10:02:46 +02:00
parent 4c795066b6
commit 36bac2dcba
1 changed files with 9 additions and 12 deletions
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src/basic/user-util.c
+9 -12
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@@ -196,8 +196,8 @@ static int synthesize_user_creds(
return 0;
}
if (synthesize_nobody() &&
STR_IN_SET(*username, NOBODY_USER_NAME, "65534")) {
if (STR_IN_SET(*username, NOBODY_USER_NAME, "65534") &&
synthesize_nobody()) {
*username = NOBODY_USER_NAME;
if (uid)
@@ -341,8 +341,8 @@ int get_group_creds(const char **groupname, gid_t *gid, UserCredsFlags flags) {
return 0;
}
if (synthesize_nobody() &&
STR_IN_SET(*groupname, NOBODY_GROUP_NAME, "65534")) {
if (STR_IN_SET(*groupname, NOBODY_GROUP_NAME, "65534") &&
synthesize_nobody()) {
*groupname = NOBODY_GROUP_NAME;
if (gid)
@@ -388,8 +388,7 @@ char* uid_to_name(uid_t uid) {
/* Shortcut things to avoid NSS lookups */
if (uid == 0)
return strdup("root");
if (synthesize_nobody() &&
uid == UID_NOBODY)
if (uid == UID_NOBODY && synthesize_nobody())
return strdup(NOBODY_USER_NAME);
if (uid_is_valid(uid)) {
@@ -432,8 +431,7 @@ char* gid_to_name(gid_t gid) {
if (gid == 0)
return strdup("root");
if (synthesize_nobody() &&
gid == GID_NOBODY)
if (gid == GID_NOBODY && synthesize_nobody())
return strdup(NOBODY_GROUP_NAME);
if (gid_is_valid(gid)) {
@@ -600,8 +598,8 @@ int get_home_dir(char **_h) {
*_h = h;
return 0;
}
if (synthesize_nobody() &&
u == UID_NOBODY) {
if (u == UID_NOBODY && synthesize_nobody()) {
h = strdup("/");
if (!h)
return -ENOMEM;
@@ -657,8 +655,7 @@ int get_shell(char **_s) {
*_s = s;
return 0;
}
if (synthesize_nobody() &&
u == UID_NOBODY) {
if (u == UID_NOBODY && synthesize_nobody()) {
s = strdup(NOLOGIN);
if (!s)
return -ENOMEM;