diff options
Diffstat (limited to 'kernel/user_namespace.c')
| -rw-r--r-- | kernel/user_namespace.c | 128 |
1 files changed, 127 insertions, 1 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 86602316422d..456a6b9fba34 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -19,6 +19,7 @@ #include <linux/fs.h> #include <linux/uaccess.h> #include <linux/ctype.h> +#include <linux/projid.h> static struct kmem_cache *user_ns_cachep __read_mostly; @@ -295,6 +296,75 @@ gid_t from_kgid_munged(struct user_namespace *targ, kgid_t kgid) } EXPORT_SYMBOL(from_kgid_munged); +/** + * make_kprojid - Map a user-namespace projid pair into a kprojid. + * @ns: User namespace that the projid is in + * @projid: Project identifier + * + * Maps a user-namespace uid pair into a kernel internal kuid, + * and returns that kuid. + * + * When there is no mapping defined for the user-namespace projid + * pair INVALID_PROJID is returned. Callers are expected to test + * for and handle handle INVALID_PROJID being returned. INVALID_PROJID + * may be tested for using projid_valid(). + */ +kprojid_t make_kprojid(struct user_namespace *ns, projid_t projid) +{ + /* Map the uid to a global kernel uid */ + return KPROJIDT_INIT(map_id_down(&ns->projid_map, projid)); +} +EXPORT_SYMBOL(make_kprojid); + +/** + * from_kprojid - Create a projid from a kprojid user-namespace pair. + * @targ: The user namespace we want a projid in. + * @kprojid: The kernel internal project identifier to start with. + * + * Map @kprojid into the user-namespace specified by @targ and + * return the resulting projid. + * + * There is always a mapping into the initial user_namespace. + * + * If @kprojid has no mapping in @targ (projid_t)-1 is returned. + */ +projid_t from_kprojid(struct user_namespace *targ, kprojid_t kprojid) +{ + /* Map the uid from a global kernel uid */ + return map_id_up(&targ->projid_map, __kprojid_val(kprojid)); +} +EXPORT_SYMBOL(from_kprojid); + +/** + * from_kprojid_munged - Create a projiid from a kprojid user-namespace pair. + * @targ: The user namespace we want a projid in. + * @kprojid: The kernel internal projid to start with. + * + * Map @kprojid into the user-namespace specified by @targ and + * return the resulting projid. + * + * There is always a mapping into the initial user_namespace. + * + * Unlike from_kprojid from_kprojid_munged never fails and always + * returns a valid projid. This makes from_kprojid_munged + * appropriate for use in syscalls like stat and where + * failing the system call and failing to provide a valid projid are + * not an options. + * + * If @kprojid has no mapping in @targ OVERFLOW_PROJID is returned. + */ +projid_t from_kprojid_munged(struct user_namespace *targ, kprojid_t kprojid) +{ + projid_t projid; + projid = from_kprojid(targ, kprojid); + + if (projid == (projid_t) -1) + projid = OVERFLOW_PROJID; + return projid; +} +EXPORT_SYMBOL(from_kprojid_munged); + + static int uid_m_show(struct seq_file *seq, void *v) { struct user_namespace *ns = seq->private; @@ -337,6 +407,27 @@ static int gid_m_show(struct seq_file *seq, void *v) return 0; } +static int projid_m_show(struct seq_file *seq, void *v) +{ + struct user_namespace *ns = seq->private; + struct uid_gid_extent *extent = v; + struct user_namespace *lower_ns; + projid_t lower; + + lower_ns = seq_user_ns(seq); + if ((lower_ns == ns) && lower_ns->parent) + lower_ns = lower_ns->parent; + + lower = from_kprojid(lower_ns, KPROJIDT_INIT(extent->lower_first)); + + seq_printf(seq, "%10u %10u %10u\n", + extent->first, + lower, + extent->count); + + return 0; +} + static void *m_start(struct seq_file *seq, loff_t *ppos, struct uid_gid_map *map) { struct uid_gid_extent *extent = NULL; @@ -362,6 +453,13 @@ static void *gid_m_start(struct seq_file *seq, loff_t *ppos) return m_start(seq, ppos, &ns->gid_map); } +static void *projid_m_start(struct seq_file *seq, loff_t *ppos) +{ + struct user_namespace *ns = seq->private; + + return m_start(seq, ppos, &ns->projid_map); +} + static void *m_next(struct seq_file *seq, void *v, loff_t *pos) { (*pos)++; @@ -387,6 +485,13 @@ struct seq_operations proc_gid_seq_operations = { .show = gid_m_show, }; +struct seq_operations proc_projid_seq_operations = { + .start = projid_m_start, + .stop = m_stop, + .next = m_next, + .show = projid_m_show, +}; + static DEFINE_MUTEX(id_map_mutex); static ssize_t map_write(struct file *file, const char __user *buf, @@ -434,7 +539,7 @@ static ssize_t map_write(struct file *file, const char __user *buf, /* Require the appropriate privilege CAP_SETUID or CAP_SETGID * over the user namespace in order to set the id mapping. */ - if (!ns_capable(ns, cap_setid)) + if (cap_valid(cap_setid) && !ns_capable(ns, cap_setid)) goto out; /* Get a buffer */ @@ -584,9 +689,30 @@ ssize_t proc_gid_map_write(struct file *file, const char __user *buf, size_t siz &ns->gid_map, &ns->parent->gid_map); } +ssize_t proc_projid_map_write(struct file *file, const char __user *buf, size_t size, loff_t *ppos) +{ + struct seq_file *seq = file->private_data; + struct user_namespace *ns = seq->private; + struct user_namespace *seq_ns = seq_user_ns(seq); + + if (!ns->parent) + return -EPERM; + + if ((seq_ns != ns) && (seq_ns != ns->parent)) + return -EPERM; + + /* Anyone can set any valid project id no capability needed */ + return map_write(file, buf, size, ppos, -1, + &ns->projid_map, &ns->parent->projid_map); +} + static bool new_idmap_permitted(struct user_namespace *ns, int cap_setid, struct uid_gid_map *new_map) { + /* Allow anyone to set a mapping that doesn't require privilege */ + if (!cap_valid(cap_setid)) + return true; + /* Allow the specified ids if we have the appropriate capability * (CAP_SETUID or CAP_SETGID) over the parent user namespace. */ |