Secret Injection

The sesame CLI provides two commands for injecting vault secrets into running processes: sesame env for spawning a child process with secrets as environment variables, and sesame export for emitting secrets in shell, dotenv, or JSON format. Both commands enforce a runtime denylist that blocks security-sensitive environment variable names.

sesame env

sesame env spawns a child process with all secrets from the specified profile(s) injected as environment variables.

sesame env -p work -- my-application --flag

The command resolves profile specs from the -p flag or, if omitted, from the SESAME_PROFILES environment variable. If neither is set, the default profile name is used.

The child process also receives a SESAME_PROFILES environment variable containing a CSV of the resolved profile specs (e.g., work,braincraft:operations), allowing it to know its security context.

After the child process exits, all secret byte vectors are zeroized via zeroize::Zeroize before the parent process exits with the child’s exit code.

Multi-Profile Support

Multiple profiles can be specified as a comma-separated list:

sesame env -p "default,work" -- my-application

Secrets are fetched from each profile in order and merged with left-wins collision resolution: if the same secret key name exists in multiple profiles, the value from the first profile in the list is used. This is implemented in fetch_multi_profile_secrets() in open-sesame/src/ipc.rs, which uses a HashSet to track seen key names.

Prefix

The --prefix flag prepends a string to all generated environment variable names:

sesame env -p work --prefix MYAPP -- my-application
# Secret "api-key" becomes MYAPP_API_KEY

sesame export

sesame export emits secrets in one of three formats, suitable for shell evaluation or file generation.

Shell Format

sesame export -p work --format shell

Output:

export API_KEY="the-secret-value"
export DB_PASSWORD="another-value"

Dotenv Format

sesame export -p work --format dotenv

Output:

API_KEY="the-secret-value"
DB_PASSWORD="another-value"

JSON Format

sesame export -p work --format json

Output:

{"API_KEY":"the-secret-value","DB_PASSWORD":"another-value"}

After output, all intermediate string copies are zeroized via unsafe as_bytes_mut().zeroize().

Secret Name to Environment Variable Conversion

The secret_key_to_env_var() function in open-sesame/src/env.rs converts secret key names to environment variable names using the following rules:

The entire result is uppercased. If a prefix is provided, it is prepended with an underscore separator.

Examples (from tests in open-sesame/src/env.rs):

Environment Variable Denylist

The DENIED_ENV_VARS constant in open-sesame/src/env.rs defines environment variable names that must never be overwritten by secret injection. The is_denied_env_var() function checks against this list using case-insensitive comparison. The BASH_FUNC_ prefix is matched as a prefix (any variable starting with BASH_FUNC_ is denied).

If a secret’s converted name matches a denied variable, the secret is skipped with a warning printed to stderr. It is not injected into the child process or emitted in export output.

Full Denylist

Dynamic linker – arbitrary code execution:

• LD_PRELOAD
• LD_LIBRARY_PATH
• LD_AUDIT
• LD_DEBUG
• LD_DEBUG_OUTPUT
• LD_DYNAMIC_WEAK
• LD_PROFILE
• LD_SHOW_AUXV
• LD_BIND_NOW
• LD_BIND_NOT
• DYLD_INSERT_LIBRARIES
• DYLD_LIBRARY_PATH
• DYLD_FRAMEWORK_PATH

Core execution environment:

• PATH
• HOME
• USER
• SHELL
• LOGNAME
• LANG
• TERM
• DISPLAY
• WAYLAND_DISPLAY
• XDG_RUNTIME_DIR

Shell injection vectors:

• BASH_ENV
• ENV
• BASH_FUNC_ (prefix match)
• CDPATH
• GLOBIGNORE
• SHELLOPTS
• BASHOPTS
• PROMPT_COMMAND
• PS1, PS2, PS4
• MAIL, MAILPATH, MAILCHECK
• IFS

Language runtime code execution:

• PYTHONPATH, PYTHONSTARTUP, PYTHONHOME
• NODE_OPTIONS, NODE_PATH, NODE_EXTRA_CA_CERTS
• PERL5LIB, PERL5OPT
• RUBYLIB, RUBYOPT
• GOPATH, GOROOT, GOFLAGS
• JAVA_HOME, CLASSPATH, JAVA_TOOL_OPTIONS

Security and authentication:

• SSH_AUTH_SOCK
• GPG_AGENT_INFO
• KRB5_CONFIG, KRB5CCNAME
• SSL_CERT_FILE, SSL_CERT_DIR
• CURL_CA_BUNDLE, REQUESTS_CA_BUNDLE
• GIT_SSL_CAINFO
• NIX_SSL_CERT_FILE

Nix:

• NIX_PATH
• NIX_CONF_DIR

Sudo and privilege escalation:

• SUDO_ASKPASS
• SUDO_EDITOR
• VISUAL
• EDITOR

Systemd and D-Bus:

• SYSTEMD_UNIT_PATH
• DBUS_SESSION_BUS_ADDRESS

Open Sesame namespace:

• SESAME_PROFILE

Shell Escaping

The shell_escape() function in open-sesame/src/env.rs produces output safe for embedding in double-quoted export statements. The following transformations are applied:

JSON Escaping

The json_escape() function produces output safe for embedding in JSON string values: