proxmox-mirrors/mirror_lxc
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_lxc synced 2025-08-15 08:05:20 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

lxccontainer: do_lxcapi_save_config()

Browse Source 
If liblxc is used multi-threaded do_lxcapi_save_config() could be called from
threads that fork() which to not risk ending up with invalid locking states we
should avoid using functions like fopen() that internally allocate memory and
use locking. Let's replace it with the async-signal safe combination of
open() + write().

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner 2018-02-23 15:43:50 +01:00
parent a30b9023a0
commit 0e1a60b0fb
No known key found for this signature in database
GPG Key ID: 8EB056D53EECB12D
3 changed files with 37 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
src/lxc/confile.c
View File

@ -2417,17 +2417,21 @@ signed long lxc_config_parse_arch(const char *arch)
}
/* Write out a configuration file. */
void write_config(FILE *fout, struct lxc_conf *c)
int write_config(int fd, const struct lxc_conf *conf)
{
int ret;
size_t len = c->unexpanded_len;
size_t len = conf->unexpanded_len;
if (!len)
return;
if (len == 0)
return 0;
ret = fwrite(c->unexpanded_config, 1, len, fout);
if (ret != len)
ret = lxc_write_nointr(fd, conf->unexpanded_config, len);
if (ret < 0) {
SYSERROR("Failed to write configuration file");
return -1;
}
return 0;
}
bool do_append_unexp_config_line(struct lxc_conf *conf, const char *key,

2
src/lxc/confile.h
View File

@ -93,7 +93,7 @@ extern signed long lxc_config_parse_arch(const char *arch);
extern int lxc_clear_config_item(struct lxc_conf *c, const char *key);
extern void write_config(FILE *fout, struct lxc_conf *c);
extern int write_config(int fd, const struct lxc_conf *conf);
extern bool do_append_unexp_config_line(struct lxc_conf *conf, const char *key,
const char *v);

44
src/lxc/lxccontainer.c
View File

@ -2418,9 +2418,8 @@ WRAP_API_3(int, lxcapi_get_keys, const char *, char *, int)
static bool do_lxcapi_save_config(struct lxc_container *c, const char *alt_file)
{
FILE *fout;
int fd, lret;
bool ret = false, need_disklock = false;
int lret;
if (!alt_file)
alt_file = c->configfile;
@ -2430,7 +2429,10 @@ static bool do_lxcapi_save_config(struct lxc_container *c, const char *alt_file)
/* If we haven't yet loaded a config, load the stock config. */
if (!c->lxc_conf) {
if (!do_lxcapi_load_config(c, lxc_global_config_value("lxc.default_config"))) {
ERROR("Error loading default configuration file %s while saving %s", lxc_global_config_value("lxc.default_config"), c->name);
ERROR("Error loading default configuration file %s "
"while saving %s",
lxc_global_config_value("lxc.default_config"),
c->name);
return false;
}
}
@ -2453,18 +2455,24 @@ static bool do_lxcapi_save_config(struct lxc_container *c, const char *alt_file)
if (lret)
return false;
fout = fopen(alt_file, "w");
if (!fout)
goto out;
write_config(fout, c->lxc_conf);
fclose(fout);
fd = open(alt_file, O_WRONLY | O_CREAT | O_CLOEXEC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
if (fd < 0)
goto on_error;
lret = write_config(fd, c->lxc_conf);
close(fd);
if (lret < 0)
goto on_error;
ret = true;
out:
on_error:
if (need_disklock)
container_disk_unlock(c);
else
container_mem_unlock(c);
return ret;
}
@ -3515,10 +3523,9 @@ static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char
char **hookargs)
{
char newpath[MAXPATHLEN];
int ret;
int fd, ret;
struct clone_update_data data;
size_t saved_unexp_len;
FILE *fout;
pid_t pid;
int storage_copied = 0;
char *origroot = NULL, *saved_unexp_conf = NULL;
@ -3562,9 +3569,11 @@ static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char
origroot = c->lxc_conf->rootfs.path;
c->lxc_conf->rootfs.path = NULL;
}
fout = fopen(newpath, "w");
if (!fout) {
SYSERROR("open %s", newpath);
fd = open(newpath, O_WRONLY | O_CREAT | O_CLOEXEC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
if (fd < 0) {
SYSERROR("Failed to open \"%s\"", newpath);
goto out;
}
@ -3572,14 +3581,13 @@ static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char
saved_unexp_len = c->lxc_conf->unexpanded_len;
c->lxc_conf->unexpanded_config = strdup(saved_unexp_conf);
if (!c->lxc_conf->unexpanded_config) {
ERROR("Out of memory");
fclose(fout);
close(fd);
goto out;
}
clear_unexp_config_line(c->lxc_conf, "lxc.rootfs.path", false);
write_config(fout, c->lxc_conf);
fclose(fout);
write_config(fd, c->lxc_conf);
close(fd);
c->lxc_conf->rootfs.path = origroot;
free(c->lxc_conf->unexpanded_config);
c->lxc_conf->unexpanded_config = saved_unexp_conf;