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systemd/src/core/condition.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/capability.h>
#include <sys/statvfs.h>
#include <fnmatch.h>
#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#endif
#include <systemd/sd-id128.h>
#include "util.h"
#include "condition.h"
#include "virt.h"
#include "path-util.h"
Condition* condition_new(ConditionType type, const char *parameter, bool trigger, bool negate) {
Condition *c;
assert(type < _CONDITION_TYPE_MAX);
c = new0(Condition, 1);
if (!c)
return NULL;
c->type = type;
c->trigger = trigger;
c->negate = negate;
if (parameter) {
c->parameter = strdup(parameter);
if (!c->parameter) {
free(c);
return NULL;
}
}
return c;
}
void condition_free(Condition *c) {
assert(c);
free(c->parameter);
free(c);
}
void condition_free_list(Condition *first) {
Condition *c, *n;
LIST_FOREACH_SAFE(conditions, c, n, first)
condition_free(c);
}
static bool test_kernel_command_line(const char *parameter) {
char *line, *w, *state, *word = NULL;
bool equal;
int r;
size_t l, pl;
bool found = false;
assert(parameter);
if (detect_container(NULL) > 0)
return false;
r = read_one_line_file("/proc/cmdline", &line);
if (r < 0) {
log_warning("Failed to read /proc/cmdline, ignoring: %s", strerror(-r));
return false;
}
equal = !!strchr(parameter, '=');
pl = strlen(parameter);
FOREACH_WORD_QUOTED(w, l, line, state) {
free(word);
word = strndup(w, l);
if (!word)
break;
if (equal) {
if (streq(word, parameter)) {
found = true;
break;
}
} else {
if (startswith(word, parameter) && (word[pl] == '=' || word[pl] == 0)) {
found = true;
break;
}
}
}
free(word);
free(line);
return found;
}
static bool test_virtualization(const char *parameter) {
int b;
Virtualization v;
const char *id;
assert(parameter);
v = detect_virtualization(&id);
if (v < 0) {
log_warning("Failed to detect virtualization, ignoring: %s", strerror(-v));
return false;
}
/* First, compare with yes/no */
b = parse_boolean(parameter);
if (v > 0 && b > 0)
return true;
if (v == 0 && b == 0)
return true;
/* Then, compare categorization */
if (v == VIRTUALIZATION_VM && streq(parameter, "vm"))
return true;
if (v == VIRTUALIZATION_CONTAINER && streq(parameter, "container"))
return true;
/* Finally compare id */
return v > 0 && streq(parameter, id);
}
static bool test_security(const char *parameter) {
#ifdef HAVE_SELINUX
if (streq(parameter, "selinux"))
return is_selinux_enabled() > 0;
#endif
return false;
}
static bool test_capability(const char *parameter) {
cap_value_t value;
FILE *f;
char line[LINE_MAX];
unsigned long long capabilities = (unsigned long long) -1;
/* If it's an invalid capability, we don't have it */
if (cap_from_name(parameter, &value) < 0)
return false;
/* If it's a valid capability we default to assume
* that we have it */
f = fopen("/proc/self/status", "re");
if (!f)
return true;
while (fgets(line, sizeof(line), f)) {
truncate_nl(line);
if (startswith(line, "CapBnd:")) {
(void) sscanf(line+7, "%llx", &capabilities);
break;
}
}
fclose(f);
return !!(capabilities & (1ULL << value));
}
static bool test_host(const char *parameter) {
sd_id128_t x, y;
char *h;
int r;
bool b;
if (sd_id128_from_string(parameter, &x) >= 0) {
r = sd_id128_get_machine(&y);
if (r < 0)
return false;
return sd_id128_equal(x, y);
}
h = gethostname_malloc();
if (!h)
return false;
b = fnmatch(parameter, h, FNM_CASEFOLD) == 0;
free(h);
return b;
}
bool condition_test(Condition *c) {
assert(c);
switch(c->type) {
case CONDITION_PATH_EXISTS:
return (access(c->parameter, F_OK) >= 0) == !c->negate;
case CONDITION_PATH_EXISTS_GLOB:
return (glob_exists(c->parameter) > 0) == !c->negate;
case CONDITION_PATH_IS_DIRECTORY: {
struct stat st;
if (stat(c->parameter, &st) < 0)
return c->negate;
return S_ISDIR(st.st_mode) == !c->negate;
}
case CONDITION_PATH_IS_SYMBOLIC_LINK: {
struct stat st;
if (lstat(c->parameter, &st) < 0)
return c->negate;
return S_ISLNK(st.st_mode) == !c->negate;
}
case CONDITION_PATH_IS_MOUNT_POINT:
return (path_is_mount_point(c->parameter, true) > 0) == !c->negate;
case CONDITION_PATH_IS_READ_WRITE:
return (path_is_read_only_fs(c->parameter) > 0) == c->negate;
case CONDITION_DIRECTORY_NOT_EMPTY: {
int k;
k = dir_is_empty(c->parameter);
return !(k == -ENOENT || k > 0) == !c->negate;
}
case CONDITION_FILE_NOT_EMPTY: {
struct stat st;
if (stat(c->parameter, &st) < 0)
return c->negate;
return (S_ISREG(st.st_mode) && st.st_size > 0) == !c->negate;
}
case CONDITION_FILE_IS_EXECUTABLE: {
struct stat st;
if (stat(c->parameter, &st) < 0)
return c->negate;
return (S_ISREG(st.st_mode) && (st.st_mode & 0111)) == !c->negate;
}
case CONDITION_KERNEL_COMMAND_LINE:
return test_kernel_command_line(c->parameter) == !c->negate;
case CONDITION_VIRTUALIZATION:
return test_virtualization(c->parameter) == !c->negate;
case CONDITION_SECURITY:
return test_security(c->parameter) == !c->negate;
case CONDITION_CAPABILITY:
return test_capability(c->parameter) == !c->negate;
case CONDITION_HOST:
return test_host(c->parameter) == !c->negate;
case CONDITION_NULL:
return !c->negate;
default:
assert_not_reached("Invalid condition type.");
}
}
bool condition_test_list(Condition *first) {
Condition *c;
int triggered = -1;
/* If the condition list is empty, then it is true */
if (!first)
return true;
/* Otherwise, if all of the non-trigger conditions apply and
* if any of the trigger conditions apply (unless there are
* none) we return true */
LIST_FOREACH(conditions, c, first) {
bool b;
b = condition_test(c);
if (!c->trigger && !b)
return false;
if (c->trigger && triggered <= 0)
triggered = b;
}
return triggered != 0;
}
void condition_dump(Condition *c, FILE *f, const char *prefix) {
assert(c);
assert(f);
if (!prefix)
prefix = "";
fprintf(f,
"%s\t%s: %s%s%s\n",
prefix,
condition_type_to_string(c->type),
c->trigger ? "|" : "",
c->negate ? "!" : "",
c->parameter);
}
void condition_dump_list(Condition *first, FILE *f, const char *prefix) {
Condition *c;
LIST_FOREACH(conditions, c, first)
condition_dump(c, f, prefix);
}
static const char* const condition_type_table[_CONDITION_TYPE_MAX] = {
[CONDITION_PATH_EXISTS] = "ConditionPathExists",
[CONDITION_PATH_EXISTS_GLOB] = "ConditionPathExistsGlob",
[CONDITION_PATH_IS_DIRECTORY] = "ConditionPathIsDirectory",
[CONDITION_PATH_IS_SYMBOLIC_LINK] = "ConditionPathIsSymbolicLink",
[CONDITION_PATH_IS_MOUNT_POINT] = "ConditionPathIsMountPoint",
[CONDITION_PATH_IS_READ_WRITE] = "ConditionPathIsReadWrite",
[CONDITION_DIRECTORY_NOT_EMPTY] = "ConditionDirectoryNotEmpty",
[CONDITION_FILE_NOT_EMPTY] = "ConditionFileNotEmpty",
[CONDITION_KERNEL_COMMAND_LINE] = "ConditionKernelCommandLine",
[CONDITION_VIRTUALIZATION] = "ConditionVirtualization",
[CONDITION_SECURITY] = "ConditionSecurity",
[CONDITION_HOST] = "ConditionHost",
[CONDITION_NULL] = "ConditionNull"
};
DEFINE_STRING_TABLE_LOOKUP(condition_type, ConditionType);
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