Messages in this thread Patch in this message | | | From | Alban Crequy <> | Subject | [PATCH] [RFC] cgroup: reject cgroup names with non-printing characters | Date | Mon, 21 Jul 2014 16:11:56 +0100 |
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/proc/<pid>/cgroup contains one cgroup path on each line. If cgroup names are allowed to contain "\n", applications cannot parse /proc/<pid>/cgroup safely.
I use < 0x20 as seen in vfat_bad_char; is it safe to use isprint()?
Signed-off-by: Alban Crequy <alban.crequy@collabora.co.uk> --- kernel/cgroup.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 70776ae..e2df5e7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4378,6 +4378,20 @@ err_free_css: return err; } +/* Inspired by vfat_bad_char: do not accept non-printing characters. In + * particular, reject '\n' to prevent making /proc/<pid>/cgroup unparsable. + */ +static inline int cgroup_is_used_badchars(const char *s) +{ + int i; + + for (i = 0; s[i] != '\0'; i++) + if (s[i] < 0x20) + return -EINVAL; + + return 0; +} + static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode) { @@ -4387,6 +4401,11 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, struct kernfs_node *kn; int ssid, ret; + /* do not create cgroups with bad names */ + ret = cgroup_is_used_badchars(name); + if (ret) + return ret; + parent = cgroup_kn_lock_live(parent_kn); if (!parent) return -ENODEV; -- 1.8.5.3
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