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authorEric W. Biederman <ebiederm@xmission.com>2012-02-07 18:52:57 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-09-18 01:01:35 -0700
commit2f6f0654ab61961fd0f7701fe3be89ea111f0cda (patch)
treea96703c892bd374b5ef7b102c52a5ec596970027 /fs/xattr_acl.c
parentd20b92ab668cc44fc84bba0001839c5a8013a5cd (diff)
userns: Convert vfs posix_acl support to use kuids and kgids
- In setxattr if we are setting a posix acl convert uids and gids from the current user namespace into the initial user namespace, before the xattrs are passed to the underlying filesystem. Untranslatable uids and gids are represented as -1 which posix_acl_from_xattr will represent as INVALID_UID or INVALID_GID. posix_acl_valid will fail if an acl from userspace has any INVALID_UID or INVALID_GID values. In net this guarantees that untranslatable posix acls will not be stored by filesystems. - In getxattr if we are reading a posix acl convert uids and gids from the initial user namespace into the current user namespace. Uids and gids that can not be tranlsated into the current user namespace will be represented as -1. - Replace e_id in struct posix_acl_entry with an anymouns union of e_uid and e_gid. For the short term retain the e_id field until all of the users are converted. - Don't set struct posix_acl.e_id in the cases where the acl type does not use e_id. Greatly reducing the use of ACL_UNDEFINED_ID. - Rework the ordering checks in posix_acl_valid so that I use kuid_t and kgid_t types throughout the code, and so that I don't need arithmetic on uid and gid types. Cc: Theodore Tso <tytso@mit.edu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jan Kara <jack@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/xattr_acl.c')
-rw-r--r--fs/xattr_acl.c90
1 files changed, 85 insertions, 5 deletions
diff --git a/fs/xattr_acl.c b/fs/xattr_acl.c
index 69d06b07b16..bf472ca1b34 100644
--- a/fs/xattr_acl.c
+++ b/fs/xattr_acl.c
@@ -9,7 +9,65 @@
#include <linux/fs.h>
#include <linux/posix_acl_xattr.h>
#include <linux/gfp.h>
+#include <linux/user_namespace.h>
+/*
+ * Fix up the uids and gids in posix acl extended attributes in place.
+ */
+static void posix_acl_fix_xattr_userns(
+ struct user_namespace *to, struct user_namespace *from,
+ void *value, size_t size)
+{
+ posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
+ posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
+ int count;
+ kuid_t uid;
+ kgid_t gid;
+
+ if (!value)
+ return;
+ if (size < sizeof(posix_acl_xattr_header))
+ return;
+ if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
+ return;
+
+ count = posix_acl_xattr_count(size);
+ if (count < 0)
+ return;
+ if (count == 0)
+ return;
+
+ for (end = entry + count; entry != end; entry++) {
+ switch(le16_to_cpu(entry->e_tag)) {
+ case ACL_USER:
+ uid = make_kuid(from, le32_to_cpu(entry->e_id));
+ entry->e_id = cpu_to_le32(from_kuid(to, uid));
+ break;
+ case ACL_GROUP:
+ gid = make_kgid(from, le32_to_cpu(entry->e_id));
+ entry->e_id = cpu_to_le32(from_kuid(to, uid));
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+void posix_acl_fix_xattr_from_user(void *value, size_t size)
+{
+ struct user_namespace *user_ns = current_user_ns();
+ if (user_ns == &init_user_ns)
+ return;
+ posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size);
+}
+
+void posix_acl_fix_xattr_to_user(void *value, size_t size)
+{
+ struct user_namespace *user_ns = current_user_ns();
+ if (user_ns == &init_user_ns)
+ return;
+ posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size);
+}
/*
* Convert from extended attribute to in-memory representation.
@@ -50,12 +108,21 @@ posix_acl_from_xattr(const void *value, size_t size)
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
- acl_e->e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
+ acl_e->e_uid =
+ make_kuid(&init_user_ns,
+ le32_to_cpu(entry->e_id));
+ if (!uid_valid(acl_e->e_uid))
+ goto fail;
+ break;
case ACL_GROUP:
- acl_e->e_id = le32_to_cpu(entry->e_id);
+ acl_e->e_gid =
+ make_kgid(&init_user_ns,
+ le32_to_cpu(entry->e_id));
+ if (!gid_valid(acl_e->e_gid))
+ goto fail;
break;
default:
@@ -89,9 +156,22 @@ posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size)
ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
for (n=0; n < acl->a_count; n++, ext_entry++) {
- ext_entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
- ext_entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
- ext_entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
+ const struct posix_acl_entry *acl_e = &acl->a_entries[n];
+ ext_entry->e_tag = cpu_to_le16(acl_e->e_tag);
+ ext_entry->e_perm = cpu_to_le16(acl_e->e_perm);
+ switch(acl_e->e_tag) {
+ case ACL_USER:
+ ext_entry->e_id =
+ cpu_to_le32(from_kuid(&init_user_ns, acl_e->e_uid));
+ break;
+ case ACL_GROUP:
+ ext_entry->e_id =
+ cpu_to_le32(from_kgid(&init_user_ns, acl_e->e_gid));
+ break;
+ default:
+ ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID);
+ break;
+ }
}
return real_size;
}