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top: Do not default to the cwd in configs_read().

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If the HOME environment variable is not set, or not absolute, use the
home directory returned by getpwuid(getuid()), if set and absolute
(instead of the cwd "."); otherwise, set p_home to NULL.

To keep the changes to a minimum, we rely on POSIX, which requires that
fopen() fails with ENOENT if the pathname (Rc_name) is an empty string.
This integrates well into the existing code, and makes write_rcfile()
work without a change.

Also, it makes the code in configs_read() easier to follow: only set and
use p_home if safe, and only set Rc_name if safe (in all the other cases
it is the empty string, and the fopen() calls fail). Plus, check for
snprintf() truncation (and if it happens, reset Rc_name to the empty
string).

Important note: top.1 should probably be updated, since it mentions the
fallback to the current working directory.
This commit is contained in:
Qualys Security Advisory - committed by Craig Small
parent e877d4f4c4
commit b45c4803dd
1 changed files with 28 additions and 5 deletions
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33
top/top.c
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@ -3810,6 +3810,20 @@ error Hey, fix the above fscanf 'PFLAGSSIZ' dependency !
} // end: config_file } // end: config_file
static int snprintf_Rc_name (const char *const format, ...) __attribute__((format(printf,1,2)));
static int snprintf_Rc_name (const char *const format, ...) {
int len;
va_list ap;
va_start(ap, format);
len = vsnprintf(Rc_name, sizeof(Rc_name), format, ap);
va_end(ap);
if (len <= 0 || (size_t)len >= sizeof(Rc_name)) {
Rc_name[0] = '\0';
return 0;
}
return len;
}
/* /*
* Try reading up to 3 rcfiles * Try reading up to 3 rcfiles
* 1. 'SYS_RCRESTRICT' contains two lines consisting of the secure * 1. 'SYS_RCRESTRICT' contains two lines consisting of the secure
@ -3842,23 +3856,31 @@ static void configs_read (void) {
fclose(fp); fclose(fp);
} }
Rc_name[0] = '\0'; // "fopen() shall fail if pathname is an empty string."
// attempt to use the legacy file first, if we cannot access that file, use // attempt to use the legacy file first, if we cannot access that file, use
// the new XDG basedir locations (XDG_CONFIG_HOME or HOME/.config) instead. // the new XDG basedir locations (XDG_CONFIG_HOME or HOME/.config) instead.
p_home = getenv("HOME"); p_home = getenv("HOME");
if (!p_home || p_home[0] == '\0') if (!p_home || p_home[0] != '/') {
p_home = "."; const struct passwd *const pwd = getpwuid(getuid());
snprintf(Rc_name, sizeof(Rc_name), "%s/.%src", p_home, Myname); if (!pwd || !(p_home = pwd->pw_dir) || p_home[0] != '/') {
p_home = NULL;
}
}
if (p_home) {
snprintf_Rc_name("%s/.%src", p_home, Myname);
}
if (!(fp = fopen(Rc_name, "r"))) { if (!(fp = fopen(Rc_name, "r"))) {
p = getenv("XDG_CONFIG_HOME"); p = getenv("XDG_CONFIG_HOME");
// ensure the path we get is absolute, fallback otherwise. // ensure the path we get is absolute, fallback otherwise.
if (!p || p[0] != '/') { if (!p || p[0] != '/') {
if (!p_home) goto system_default;
p = fmtmk("%s/.config", p_home); p = fmtmk("%s/.config", p_home);
(void)mkdir(p, 0700); (void)mkdir(p, 0700);
} }
snprintf(Rc_name, sizeof(Rc_name), "%s/procps", p); if (!snprintf_Rc_name("%s/procps", p)) goto system_default;
(void)mkdir(Rc_name, 0700); (void)mkdir(Rc_name, 0700);
snprintf(Rc_name, sizeof(Rc_name), "%s/procps/%src", p, Myname); if (!snprintf_Rc_name("%s/procps/%src", p, Myname)) goto system_default;
fp = fopen(Rc_name, "r"); fp = fopen(Rc_name, "r");
} }
@ -3867,6 +3889,7 @@ static void configs_read (void) {
fclose(fp); fclose(fp);
if (p) goto default_or_error; if (p) goto default_or_error;
} else { } else {
system_default:
fp = fopen(SYS_RCDEFAULTS, "r"); fp = fopen(SYS_RCDEFAULTS, "r");
if (fp) { if (fp) {
p = config_file(fp, SYS_RCDEFAULTS, &tmp_delay); p = config_file(fp, SYS_RCDEFAULTS, &tmp_delay);