From 90c0ad07bd2bb71e6d283f4debc9b01acf5369d1 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 21 Dec 2020 12:14:35 +0100 Subject: [PATCH] Revert "FROMLIST: overlayfs: override_creds=off option bypass creator_cred" This reverts commit 6120a4d78045cc741f04ed6bcd3d6f553115278d as it did not make it into 5.11-rc1 and causes massive merge issues. If needed, please forward-port and add it back. Cc: Mark Salyzyn Bug: 133515582 Bug: 136124883 Bug: 129319403 Change-Id: Ib896e744640d570918af498e1f2bd42d66c33471 Signed-off-by: Greg Kroah-Hartman --- Documentation/filesystems/overlayfs.rst | 23 ----------------------- fs/overlayfs/copy_up.c | 2 +- fs/overlayfs/dir.c | 17 +++++++---------- fs/overlayfs/file.c | 25 ++++++++++++------------- fs/overlayfs/inode.c | 18 +++++++++--------- fs/overlayfs/namei.c | 6 +++--- fs/overlayfs/overlayfs.h | 1 - fs/overlayfs/ovl_entry.h | 1 - fs/overlayfs/readdir.c | 8 ++++---- fs/overlayfs/super.c | 22 +--------------------- fs/overlayfs/util.c | 12 ++---------- 11 files changed, 39 insertions(+), 96 deletions(-) diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index 18ac7d35c145..580ab9a0fe31 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -137,29 +137,6 @@ Only the lists of names from directories are merged. Other content such as metadata and extended attributes are reported for the upper directory only. These attributes of the lower directory are hidden. -credentials ------------ - -By default, all access to the upper, lower and work directories is the -recorded mounter's MAC and DAC credentials. The incoming accesses are -checked against the caller's credentials. - -In the case where caller MAC or DAC credentials do not overlap, a -use case available in older versions of the driver, the -override_creds mount flag can be turned off and help when the use -pattern has caller with legitimate credentials where the mounter -does not. Several unintended side effects will occur though. The -caller without certain key capabilities or lower privilege will not -always be able to delete files or directories, create nodes, or -search some restricted directories. The ability to search and read -a directory entry is spotty as a result of the cache mechanism not -retesting the credentials because of the assumption, a privileged -caller can fill cache, then a lower privilege can read the directory -cache. The uneven security model where cache, upperdir and workdir -are opened at privilege, but accessed without creating a form of -privilege escalation, should only be used with strict understanding -of the side effects and of the security policies. - whiteouts and opaque directories -------------------------------- diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b9d97e7efd5c..955ecd4030f0 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -962,7 +962,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int flags) dput(parent); dput(next); } - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return err; } diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 3c6f5f6648b8..28a075b5f5b2 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -565,7 +565,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr, bool origin) { int err; - const struct cred *old_cred, *hold_cred = NULL; + const struct cred *old_cred; struct cred *override_cred; struct dentry *parent = dentry->d_parent; @@ -592,15 +592,14 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, override_cred->fsgid = inode->i_gid; if (!attr->hardlink) { err = security_dentry_create_files_as(dentry, - attr->mode, &dentry->d_name, - old_cred ? old_cred : current_cred(), + attr->mode, &dentry->d_name, old_cred, override_cred); if (err) { put_cred(override_cred); goto out_revert_creds; } } - hold_cred = override_creds(override_cred); + put_cred(override_creds(override_cred)); put_cred(override_cred); if (!ovl_dentry_is_whiteout(dentry)) @@ -609,9 +608,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, err = ovl_create_over_whiteout(dentry, inode, attr); } out_revert_creds: - ovl_revert_creds(dentry->d_sb, old_cred ?: hold_cred); - if (old_cred && hold_cred) - put_cred(hold_cred); + revert_creds(old_cred); return err; } @@ -687,7 +684,7 @@ static int ovl_set_link_redirect(struct dentry *dentry) old_cred = ovl_override_creds(dentry->d_sb); err = ovl_set_redirect(dentry, false); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return err; } @@ -906,7 +903,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir) err = ovl_remove_upper(dentry, is_dir, &list); else err = ovl_remove_and_whiteout(dentry, &list); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); if (!err) { if (is_dir) clear_nlink(dentry->d_inode); @@ -1276,7 +1273,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old, out_unlock: unlock_rename(new_upperdir, old_upperdir); out_revert_creds: - ovl_revert_creds(old->d_sb, old_cred); + revert_creds(old_cred); if (update_nlink) ovl_nlink_end(new); out_drop_write: diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 660b1629c7c8..efccb7c1f9bc 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -59,7 +59,7 @@ static struct file *ovl_open_realfile(const struct file *file, realfile = open_with_fake_path(&file->f_path, flags, realinode, current_cred()); } - ovl_revert_creds(inode->i_sb, old_cred); + revert_creds(old_cred); pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n", file, file, ovl_whatisit(inode, realinode), file->f_flags, @@ -209,7 +209,7 @@ static loff_t ovl_llseek(struct file *file, loff_t offset, int whence) old_cred = ovl_override_creds(inode->i_sb); ret = vfs_llseek(real.file, offset, whence); - ovl_revert_creds(inode->i_sb, old_cred); + revert_creds(old_cred); file->f_pos = real.file->f_pos; ovl_inode_unlock(inode); @@ -323,8 +323,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter) ovl_aio_cleanup_handler(aio_req); } out: - ovl_revert_creds(file_inode(file)->i_sb, old_cred); - + revert_creds(old_cred); ovl_file_accessed(file); fdput(real); @@ -389,7 +388,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) ovl_aio_cleanup_handler(aio_req); } out: - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); fdput(real); out_unlock: @@ -412,7 +411,7 @@ static ssize_t ovl_splice_read(struct file *in, loff_t *ppos, old_cred = ovl_override_creds(file_inode(in)->i_sb); ret = generic_file_splice_read(real.file, ppos, pipe, len, flags); - ovl_revert_creds(file_inode(in)->i_sb, old_cred); + revert_creds(old_cred); ovl_file_accessed(in); fdput(real); @@ -433,7 +432,7 @@ ovl_splice_write(struct pipe_inode_info *pipe, struct file *out, old_cred = ovl_override_creds(file_inode(out)->i_sb); ret = iter_file_splice_write(pipe, real.file, ppos, len, flags); - ovl_revert_creds(file_inode(out)->i_sb, old_cred); + revert_creds(old_cred); ovl_file_accessed(out); fdput(real); @@ -457,7 +456,7 @@ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync) if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) { old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fsync_range(real.file, start, end, datasync); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); } fdput(real); @@ -481,7 +480,7 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma) old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = call_mmap(vma->vm_file, vma); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); if (ret) { /* Drop reference count from new vm_file value */ @@ -509,7 +508,7 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fallocate(real.file, mode, offset, len); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); /* Update size */ ovl_copyattr(ovl_inode_real(inode), inode); @@ -531,7 +530,7 @@ static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice) old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fadvise(real.file, offset, len, advice); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); fdput(real); @@ -553,7 +552,7 @@ static long ovl_real_ioctl(struct file *file, unsigned int cmd, ret = security_file_ioctl(real.file, cmd, arg); if (!ret) ret = vfs_ioctl(real.file, cmd, arg); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); fdput(real); @@ -742,7 +741,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in, flags); break; } - ovl_revert_creds(file_inode(file_out)->i_sb, old_cred); + revert_creds(old_cred); /* Update size */ ovl_copyattr(ovl_inode_real(inode_out), inode_out); diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index fb0ec01774e6..2b14291beb86 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -80,7 +80,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) inode_lock(upperdentry->d_inode); old_cred = ovl_override_creds(dentry->d_sb); err = notify_change(upperdentry, attr, NULL); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); if (!err) ovl_copyattr(upperdentry->d_inode, dentry->d_inode); inode_unlock(upperdentry->d_inode); @@ -272,7 +272,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat, stat->nlink = dentry->d_inode->i_nlink; out: - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return err; } @@ -306,7 +306,7 @@ int ovl_permission(struct inode *inode, int mask) mask |= MAY_READ; } err = inode_permission(realinode, mask); - ovl_revert_creds(inode->i_sb, old_cred); + revert_creds(old_cred); return err; } @@ -323,7 +323,7 @@ static const char *ovl_get_link(struct dentry *dentry, old_cred = ovl_override_creds(dentry->d_sb); p = vfs_get_link(ovl_dentry_real(dentry), done); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return p; } @@ -366,7 +366,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, WARN_ON(flags != XATTR_REPLACE); err = vfs_removexattr(realdentry, name); } - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); /* copy c/mtime */ ovl_copyattr(d_inode(realdentry), inode); @@ -388,7 +388,7 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, old_cred = ovl_override_creds(dentry->d_sb); res = __vfs_getxattr(realdentry, d_inode(realdentry), name, value, size, flags); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return res; } @@ -416,7 +416,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) old_cred = ovl_override_creds(dentry->d_sb); res = vfs_listxattr(realdentry, list, size); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); if (res <= 0 || size == 0) return res; @@ -451,7 +451,7 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type) old_cred = ovl_override_creds(inode->i_sb); acl = get_acl(realinode, type); - ovl_revert_creds(inode->i_sb, old_cred); + revert_creds(old_cred); return acl; } @@ -485,7 +485,7 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, old_cred = ovl_override_creds(inode->i_sb); err = realinode->i_op->fiemap(realinode, fieinfo, start, len); - ovl_revert_creds(inode->i_sb, old_cred); + revert_creds(old_cred); return err; } diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 0bf283e55e2a..afb7b59eca98 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -1098,7 +1098,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, ovl_dentry_update_reval(dentry, upperdentry, DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); if (origin_path) { dput(origin_path->dentry); kfree(origin_path); @@ -1125,7 +1125,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, kfree(upperredirect); out: kfree(d.redirect); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return ERR_PTR(err); } @@ -1177,7 +1177,7 @@ bool ovl_lower_positive(struct dentry *dentry) dput(this); } } - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return positive; } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index da4a25ac9b01..06db4cf87f55 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -253,7 +253,6 @@ int ovl_want_write(struct dentry *dentry); void ovl_drop_write(struct dentry *dentry); struct dentry *ovl_workdir(struct dentry *dentry); const struct cred *ovl_override_creds(struct super_block *sb); -void ovl_revert_creds(struct super_block *sb, const struct cred *oldcred); int ovl_can_decode_fh(struct super_block *sb); struct dentry *ovl_indexdir(struct super_block *sb); bool ovl_index_all(struct super_block *sb); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 597f00982ade..1b5a2094df8e 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -18,7 +18,6 @@ struct ovl_config { int xino; bool metacopy; bool ovl_volatile; - bool override_creds; }; struct ovl_sb { diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 38d5b855c4a4..01620ebae1bd 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -286,7 +286,7 @@ static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd) } inode_unlock(dir->d_inode); } - ovl_revert_creds(rdd->dentry->d_sb, old_cred); + revert_creds(old_cred); return err; } @@ -796,7 +796,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) } err = 0; out: - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); return err; } @@ -848,7 +848,7 @@ static struct file *ovl_dir_open_realfile(const struct file *file, old_cred = ovl_override_creds(file_inode(file)->i_sb); res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE)); - ovl_revert_creds(file_inode(file)->i_sb, old_cred); + revert_creds(old_cred); return res; } @@ -986,7 +986,7 @@ int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) old_cred = ovl_override_creds(dentry->d_sb); err = ovl_dir_read_merged(dentry, list, &root); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); if (err) return err; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 28c5d291f836..d447958badc2 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -53,11 +53,6 @@ module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); MODULE_PARM_DESC(xino_auto, "Auto enable xino feature"); -static bool __read_mostly ovl_override_creds_def = true; -module_param_named(override_creds, ovl_override_creds_def, bool, 0644); -MODULE_PARM_DESC(ovl_override_creds_def, - "Use mounter's credentials for accesses"); - static void ovl_entry_stack_free(struct ovl_entry *oe) { unsigned int i; @@ -371,9 +366,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) ofs->config.metacopy ? "on" : "off"); if (ofs->config.ovl_volatile) seq_puts(m, ",volatile"); - if (ofs->config.override_creds != ovl_override_creds_def) - seq_show_option(m, "override_creds", - ofs->config.override_creds ? "on" : "off"); return 0; } @@ -426,8 +418,6 @@ enum { OPT_METACOPY_ON, OPT_METACOPY_OFF, OPT_VOLATILE, - OPT_OVERRIDE_CREDS_ON, - OPT_OVERRIDE_CREDS_OFF, OPT_ERR, }; @@ -447,8 +437,6 @@ static const match_table_t ovl_tokens = { {OPT_METACOPY_ON, "metacopy=on"}, {OPT_METACOPY_OFF, "metacopy=off"}, {OPT_VOLATILE, "volatile"}, - {OPT_OVERRIDE_CREDS_ON, "override_creds=on"}, - {OPT_OVERRIDE_CREDS_OFF, "override_creds=off"}, {OPT_ERR, NULL} }; @@ -508,7 +496,6 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); if (!config->redirect_mode) return -ENOMEM; - config->override_creds = ovl_override_creds_def; while ((p = ovl_next_opt(&opt)) != NULL) { int token; @@ -598,14 +585,6 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->ovl_volatile = true; break; - case OPT_OVERRIDE_CREDS_ON: - config->override_creds = true; - break; - - case OPT_OVERRIDE_CREDS_OFF: - config->override_creds = false; - break; - default: pr_err("unrecognized mount option \"%s\" or missing value\n", p); @@ -2028,6 +2007,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) kfree(splitlower); sb->s_root = root_dentry; + return 0; out_free_oe: diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index f87f228fd407..925af438c12e 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -37,17 +37,9 @@ const struct cred *ovl_override_creds(struct super_block *sb) { struct ovl_fs *ofs = sb->s_fs_info; - if (!ofs->config.override_creds) - return NULL; return override_creds(ofs->creator_cred); } -void ovl_revert_creds(struct super_block *sb, const struct cred *old_cred) -{ - if (old_cred) - revert_creds(old_cred); -} - /* * Check if underlying fs supports file handles and try to determine encoding * type, in order to deduce maximum inode number used by fs. @@ -831,7 +823,7 @@ int ovl_nlink_start(struct dentry *dentry) * value relative to the upper inode nlink in an upper inode xattr. */ err = ovl_set_nlink_upper(dentry); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); out: if (err) @@ -849,7 +841,7 @@ void ovl_nlink_end(struct dentry *dentry) old_cred = ovl_override_creds(dentry->d_sb); ovl_cleanup_index(dentry); - ovl_revert_creds(dentry->d_sb, old_cred); + revert_creds(old_cred); } ovl_inode_unlock(inode);