With handle_killpriv_v2, server needs to kill suid/sgid on truncate (setattr) but it does not know if caller has CAP_FSETID or not. So like write, send killpriv information in fuse_setattr_in and add a flag FUSE_SETATTR_KILL_PRIV.
Signed-off-by: Vivek Goyal <[email protected]> --- fs/fuse/dir.c | 11 ++++++++--- include/uapi/linux/fuse.h | 11 ++++++++++- 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 26f028bc760b..82747ca4c5c8 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1437,13 +1437,15 @@ void fuse_release_nowrite(struct inode *inode) static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args, struct inode *inode, struct fuse_setattr_in *inarg_p, - struct fuse_attr_out *outarg_p) + struct fuse_attr_out *outarg_p, + uint32_t setattr_flags) { args->opcode = FUSE_SETATTR; args->nodeid = get_node_id(inode); args->in_numargs = 1; args->in_args[0].size = sizeof(*inarg_p); args->in_args[0].value = inarg_p; + inarg_p->setattr_flags = setattr_flags; args->out_numargs = 1; args->out_args[0].size = sizeof(*outarg_p); args->out_args[0].value = outarg_p; @@ -1474,7 +1476,7 @@ int fuse_flush_times(struct inode *inode, struct fuse_file *ff) inarg.valid |= FATTR_FH; inarg.fh = ff->fh; } - fuse_setattr_fill(fc, &args, inode, &inarg, &outarg); + fuse_setattr_fill(fc, &args, inode, &inarg, &outarg, 0); return fuse_simple_request(fc, &args); } @@ -1501,6 +1503,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr, loff_t oldsize; int err; bool trust_local_cmtime = is_wb && S_ISREG(inode->i_mode); + uint32_t setattr_flags = 0; if (!fc->default_permissions) attr->ia_valid |= ATTR_FORCE; @@ -1529,6 +1532,8 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr, if (attr->ia_valid & ATTR_SIZE) { if (WARN_ON(!S_ISREG(inode->i_mode))) return -EIO; + if (fc->handle_killpriv_v2 && !capable(CAP_FSETID)) + setattr_flags |= FUSE_SETATTR_KILL_PRIV; is_truncate = true; } @@ -1565,7 +1570,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr, inarg.valid |= FATTR_LOCKOWNER; inarg.lock_owner = fuse_lock_owner_id(fc, current->files); } - fuse_setattr_fill(fc, &args, inode, &inarg, &outarg); + fuse_setattr_fill(fc, &args, inode, &inarg, &outarg, setattr_flags); err = fuse_simple_request(fc, &args); if (err) { if (err == -EINTR) diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 960ba8af5cf4..4b275653ac2e 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -173,6 +173,7 @@ * - add FUSE_SETUPMAPPING and FUSE_REMOVEMAPPING * - add map_alignment to fuse_init_out, add FUSE_MAP_ALIGNMENT flag * - add FUSE_HANDLE_KILLPRIV_V2 + * - add FUSE_SETATTR_KILL_PRIV */ #ifndef _LINUX_FUSE_H @@ -368,6 +369,14 @@ struct fuse_file_lock { */ #define FUSE_GETATTR_FH (1 << 0) +/** + * Setattr flags + * FUSE_SETATTR_KILL_PRIV: kill suid and sgid bits. sgid should be killed + * only if group execute bit (S_IXGRP) is set. Meant to be used together + * with FUSE_HANDLE_KILLPRIV_V2. + */ +#define FUSE_SETATTR_KILL_PRIV (1 << 0) + /** * Lock flags */ @@ -566,7 +575,7 @@ struct fuse_link_in { struct fuse_setattr_in { uint32_t valid; - uint32_t padding; + uint32_t setattr_flags; uint64_t fh; uint64_t size; uint64_t lock_owner; -- 2.25.4 _______________________________________________ Virtio-fs mailing list [email protected] https://www.redhat.com/mailman/listinfo/virtio-fs
