From 9e1f1de02c2275d7172e18dc4e7c2065777611bf Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 3 Jun 2011 18:24:58 -0400 Subject: [PATCH] more conservative S_NOSEC handling Caching "we have already removed suid/caps" was overenthusiastic as merged. On network filesystems we might have had suid/caps set on another client, silently picked by this client on revalidate, all of that *without* clearing the S_NOSEC flag. AFAICS, the only reasonably sane way to deal with that is * new superblock flag; unless set, S_NOSEC is not going to be set. * local block filesystems set it in their ->mount() (more accurately, mount_bdev() does, so does btrfs ->mount(), users of mount_bdev() other than local block ones clear it) * if any network filesystem (or a cluster one) wants to use S_NOSEC, it'll need to set MS_NOSEC in sb->s_flags *AND* take care to clear S_NOSEC when inode attribute changes are picked from other clients. It's not an earth-shattering hole (anybody that can set suid on another client will almost certainly be able to write to the file before doing that anyway), but it's a bug that needs fixing. Signed-off-by: Al Viro --- fs/btrfs/super.c | 2 +- fs/fuse/inode.c | 2 ++ fs/ocfs2/super.c | 2 +- fs/super.c | 2 +- include/linux/fs.h | 3 ++- mm/filemap.c | 2 +- 6 files changed, 8 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 9b2e7e5bc3ef..d158b672a2d2 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -819,7 +819,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, } else { char b[BDEVNAME_SIZE]; - s->s_flags = flags; + s->s_flags = flags | MS_NOSEC; strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); error = btrfs_fill_super(s, fs_devices, data, flags & MS_SILENT ? 1 : 0); diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index cc6ec4b2f0ff..38f84cd48b67 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -921,6 +921,8 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) if (sb->s_flags & MS_MANDLOCK) goto err; + sb->s_flags &= ~MS_NOSEC; + if (!parse_fuse_opt((char *) data, &d, is_bdev)) goto err; diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index cdbaf5e97308..56f61027236b 100644 --- a/fs/ocfs2/super.c +++ b/fs/ocfs2/super.c @@ -1072,7 +1072,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent) sb->s_magic = OCFS2_SUPER_MAGIC; - sb->s_flags = (sb->s_flags & ~MS_POSIXACL) | + sb->s_flags = (sb->s_flags & ~(MS_POSIXACL | MS_NOSEC)) | ((osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0); /* Hard readonly mode only if: bdev_read_only, MS_RDONLY, diff --git a/fs/super.c b/fs/super.c index c75593953c52..ab3d672db0de 100644 --- a/fs/super.c +++ b/fs/super.c @@ -822,7 +822,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type, } else { char b[BDEVNAME_SIZE]; - s->s_flags = flags; + s->s_flags = flags | MS_NOSEC; s->s_mode = mode; strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); sb_set_blocksize(s, block_size(bdev)); diff --git a/include/linux/fs.h b/include/linux/fs.h index c55d6b7cd5d6..646a1836152a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -208,6 +208,7 @@ struct inodes_stat_t { #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ #define MS_I_VERSION (1<<23) /* Update inode I_version field */ #define MS_STRICTATIME (1<<24) /* Always perform atime updates */ +#define MS_NOSEC (1<<28) #define MS_BORN (1<<29) #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) @@ -2591,7 +2592,7 @@ static inline int is_sxid(mode_t mode) static inline void inode_has_no_xattr(struct inode *inode) { - if (!is_sxid(inode->i_mode)) + if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & MS_NOSEC)) inode->i_flags |= S_NOSEC; } diff --git a/mm/filemap.c b/mm/filemap.c index d7b10578a64b..a8251a8d3457 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2000,7 +2000,7 @@ int file_remove_suid(struct file *file) error = security_inode_killpriv(dentry); if (!error && killsuid) error = __remove_suid(dentry, killsuid); - if (!error) + if (!error && (inode->i_sb->s_flags & MS_NOSEC)) inode->i_flags |= S_NOSEC; return error; -- 2.34.1