As ls_get() is non-tail recursive we face the inherent danger of blowing up the
stack at some level of nesting. To have at least some security we define
MAX_NESTLVL to be 5. That should be sufficient for most users. The argument lvl
to ls_get() can be used to keep track of the level of nesting we are at. If lvl
is greater than the allowed default level return (without error) and unwind the
stack.
--nesting gains an optional numeric argument. This allows the user to specify
the maximum level of nesting she/he wants to see. Fair warning: If your nesting
level is really deep and/or you have a lot of containers your might run into
trouble.
Signed-off-by: Christian Brauner <christian.brau...@mailbox.org>
---
src/lxc/arguments.h | 2 +-
src/lxc/lxc_ls.c | 37 ++++++++++++++++++++++++++++++++++---
2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/src/lxc/arguments.h b/src/lxc/arguments.h
index 898a9ce..a3d2932 100644
--- a/src/lxc/arguments.h
+++ b/src/lxc/arguments.h
@@ -124,11 +124,11 @@ struct lxc_arguments {
char *ls_fancy_format;
char *ls_groups;
char *ls_regex;
+ unsigned int ls_nesting; /* maximum allowed nesting level */
bool ls_active;
bool ls_fancy;
bool ls_frozen;
bool ls_line;
- bool ls_nesting;
bool ls_running;
bool ls_stopped;
diff --git a/src/lxc/lxc_ls.c b/src/lxc/lxc_ls.c
index 3a7fa15..a4ab9b6 100644
--- a/src/lxc/lxc_ls.c
+++ b/src/lxc/lxc_ls.c
@@ -40,6 +40,10 @@
lxc_log_define(lxc_ls, lxc);
#define LINELEN 1024
+/* Per default we only allow five levels of recursion to protect the stack at
+ * least a little bit. */
+#define MAX_NESTLVL 5
+
#define LS_FROZEN 1
#define LS_STOPPED 2
#define LS_ACTIVE 3
@@ -154,7 +158,7 @@ static const struct option my_longopts[] = {
{"running", no_argument, 0, LS_RUNNING},
{"frozen", no_argument, 0, LS_FROZEN},
{"stopped", no_argument, 0, LS_STOPPED},
- {"nesting", no_argument, 0, LS_NESTING},
+ {"nesting", optional_argument, 0, LS_NESTING},
{"groups", required_argument, 0, 'g'},
{"regex", required_argument, 0, 'r'},
LXC_COMMON_OPTIONS
@@ -177,11 +181,12 @@ Options :\n\
--running list only running containers\n\
--frozen list only frozen containers\n\
--stopped list only stopped containers\n\
- --nesting list nested containers\n\
+ --nesting=NUM list nested containers up to NUM (default is 5) levels of
nesting\n\
-r --regex filter container names by regular expression\n\
-g --groups comma separated list of groups a container must have to
be displayed\n",
.options = my_longopts,
.parser = my_parser,
+ .ls_nesting = MAX_NESTLVL,
};
int main(int argc, char *argv[])
@@ -300,6 +305,16 @@ static int ls_get(struct ls **m, size_t *size, const
struct lxc_arguments *args,
struct lengths *lht, const char *basepath, const char *parent,
unsigned int lvl)
{
+ /* As ls_get() is non-tail recursive we face the inherent danger of
+ * blowing up the stack at some level of nesting. To have at least some
+ * security we define MAX_NESTLVL to be 5. That should be sufficient for
+ * most users. The argument lvl can be used to keep track of the level
+ * of nesting we are at. If lvl is greater than the allowed default
+ * level or the level the user specified on the command line we return
+ * and unwind the stack. */
+ if (lvl > args->ls_nesting)
+ return 0;
+
int num = 0, ret = -1;
char **containers = NULL;
/* If we, at some level of nesting, encounter a stopped container but
@@ -855,6 +870,8 @@ static void ls_print_table(struct ls *l, struct lengths
*lht,
static int my_parser(struct lxc_arguments *args, int c, char *arg)
{
+ char *invalid;
+ unsigned long int m, n = MAX_NESTLVL;
switch (c) {
case '1':
args->ls_line = true;
@@ -875,7 +892,21 @@ static int my_parser(struct lxc_arguments *args, int c,
char *arg)
args->ls_stopped = true;
break;
case LS_NESTING:
- args->ls_nesting = true;
+ /* In case strtoul() receives a string that represents a
+ * negative number it will return ULONG_MAX - the number that
+ * string represents if the number the string represents is <
+ * ULONG_MAX and ULONG_MAX otherwise. But it will consider this
+ * valid input and not set errno. So we check manually if the
+ * first character of num_string == '-'. Otherwise the default
+ * level remains set. */
+ if (arg && !(*arg == '-')) {
+ errno = 0;
+ m = strtoul(arg, &invalid, 0);
+ /* ls_nesting has type unsigned int. */
+ if (!errno && (*invalid == '\0') && (m <= UINT_MAX))
+ n = m;
+ }
+ args->ls_nesting = n;
break;
case 'g':
args->groups = arg;
--
2.7.0
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