Welcome to pymunge’s documentation!

API reference

Basic encoding and decoding

pymunge.encode(payload=None)

Create a MUNGE credential using the default context. Optionally, a payload (byte string) can be encapsulated as well.

If successful, returns the credential (a byte string), otherwise raises a MungeError.

pymunge.decode(cred)

Validate a MUNGE credential using the default context.

If successful, returns (payload, uid, gid, ctx), where payload is the payload encapsulated in the credential, uid, gid are the UID/GID of the process that created the credential, and ctx is a MungeContext set to the one used to create the credential.

If unsuccessful, a MungeError is raised. For certain errors (i.e. EMUNGE_CRED_EXPIRED, EMUNGE_CRED_REWOUND, EMUNGE_CRED_REPLAYED), the payload, uid and gid can still be obtained via the result property of the raised MungeError. Note that the context cannot be obtained from the MungeError; if you need it, manually create a MungeContext and use its decode() method.

MUNGE contexts

class pymunge.MungeContext(ctx=None)

A MUNGE context. Encapsulates a collection of options used when creating a credential, or obtained from decoding a credential.

MungeContext() creates a new context with default attributes. As contexts are mutable, the context’s attributes can subsequently be modified by assigning values to them.

If ctx != None, MungeContext(ctx) creates a copy of the context ctx. (For ctx == None, MungeContext(ctx) is equivalent to MungeContext().) Modifying attributes in the copy does not affect the attributes of the original context.

A MungeContext should be closed when it is no longer used. The easiest way to do this is to use the MungeContext as a context manager for a ‘with’ statement, which automatically closes the context when the ‘with’ scope ends, e.g.:

>>> with MungeContext() as ctx:
>>>     do stuff with ctx
>>> # ctx is now closed

Typical MungeContext usage patterns:

• For encoding:

>>> with MungeContext() as ctx:
>>>     (set attributes of ctx, if needed)
>>>     cred = ctx.encode(payload)

• For decoding:

>>> with MungeContext() as ctx:
>>>     payload, uid, gid = ctx.decode(cred)
>>>     (check attributes of ctx, if needed)

close()

Close this context, releasing any resources associated with it. Once a context is closed, it cannot be reopened. It also cannot be used to encode or decode credentials, nor can its attributes (other than closed) be read or set (in each case, a MungeError is raised). Calling close() on an already closed context has no effect.

decode(cred)

Validate a MUNGE credential. The attributes of this context will be set to those used to encode the credential.

If successful, returns (payload, uid, gid), where payload is the payload encapsulated in the credential, and uid, gid are the UID/GID of the process that created the credential. Otherwise a MungeError is raised. For certain errors (i.e. EMUNGE_CRED_EXPIRED, EMUNGE_CRED_REWOUND, EMUNGE_CRED_REPLAYED), the payload, uid and gid can still be obtained via the result property of the raised MungeError.

encode(payload=None)

Create a MUNGE credential using the options defined in this context. Optionally, a payload (byte string) can be encapsulated as well.

If successful, returns the credential (a byte string), otherwise raises a MungeError.

addr4

The IPv4 address of the host where the credential was encoded, in dotted-quad notation (e.g. ‘127.0.0.1’). This property cannot be explicitly set.

cipher_type

Symmetric cipher type (a CipherType).

closed

True if this context is closed, False otherwise. This property cannot be explicitly set, instead use the close() method to close the context.

decode_time

The time (in seconds since the epoch) at which the credential was decoded. This property cannot be explicitly set.

encode_time

The time (in seconds since the epoch) at which the credential was encoded. This property cannot be explicitly set.

gid_restriction

Numeric GID allowed to decode the credential. This value will be matched against the effective group ID of the process requesting the credential decode. Default is the special value GID_ANY, which means no GID restriction is set.

mac_type

Message authentication code type (a MACType).

realm

Security realm (a str). Not currently supported.

socket

Path of the local domain socket for connecting with munged, a str.

ttl

Time-to-live (in seconds). This value controls how long the credential is valid once it has been encoded.

When encoding a credential, two special values can be used:

• TTL_DEFAULT, which specifies the default according to the munged configuration. This is the default value of this property.
• TTL_MAXIMUM, which specifies the maximum allowed by the munged configuration.

uid_restriction

Numeric UID allowed to decode the credential. This value will be matched against the effective user ID of the process requesting the credential decode. Default is the special value UID_ANY, which means no UID restriction is set.

zip_type

Compression type (a ZipType).

Enumerations and constants

class pymunge.CipherType

Bases: enum.Enum

MUNGE symmetric cipher types

AES128 = 4

AES CBC with 128b-block/128b-key

AES256 = 5

AES CBC with 128b-block/256b-key

Blowfish = 2

Blowfish CBC with 64b-block/128b-key

CAST5 = 3

CAST5 CBC with 64b-block/128b-key

Default = 1

default cipher specified by daemon

Disabled = 0

encryption disabled

class pymunge.MACType

Bases: enum.Enum

MUNGE message authentication code types

Default = 1

default MAC specified by daemon

Disabled = 0

MAC disabled – invalid, btw

MD5 = 2

MD5 with 128b-digest

RIPEMD160 = 4

RIPEMD-160 with 160b-digest

SHA1 = 3

SHA-1 with 160b-digest

SHA256 = 5

SHA-256 with 256b-digest

SHA512 = 6

SHA-512 with 512b-digest

class pymunge.ZipType

Bases: enum.Enum

MUNGE compression types

Default = 1

default zip specified by daemon

Disabled = 0

compression disabled

bzlib = 2

bzip2 by Julian Seward

zlib = 3

zlib “deflate” by Gailly & Adler

pymunge.TTL_MAXIMUM

Use the maximum TTL allowed by the daemon.

pymunge.TTL_DEFAULT

Use the default TTL specified by the daemon.

pymunge.UID_ANY

Do not restrict decode to a specific UID.

pymunge.GID_ANY

Do not restrict decode to a specific GID.

Exceptions

class pymunge.MungeError(code, message, result=None)

Bases: Exception

Generic MUNGE exception. Generally raised when an underlying libmunge function returns an error code, or in a few cases when a pymunge wrapper detects an invalid argument.

MungeError instances have the following attributes:

• code: The error code (a MungeErrorCode, which is NOT an integer). To retrieve the raw error code as an integer, use code.value.
• message: The message string from libmunge. This is only the raw message without the exception type or the error code.
• result: Partial result, in most cases None. If a decode fails with one of certain errors (i.e. EMUNGE_CRED_EXPIRED, EMUNGE_CRED_REWOUND, EMUNGE_CRED_REPLAYED), result is a 3-tuple (payload, uid, gid) containing the results that would have been returned by the decode function or method.

class pymunge.MungeErrorCode

Bases: enum.Enum

MUNGE error codes.

EMUNGE_BAD_ARG = 2

Invalid argument

EMUNGE_BAD_CIPHER = 10

Bad credential cipher type

EMUNGE_BAD_CRED = 8

Bad credential format

EMUNGE_BAD_LENGTH = 3

Exceeded maximum message length

EMUNGE_BAD_MAC = 11

Bad credential message authentication code type

EMUNGE_BAD_REALM = 13

Bad credential security realm

EMUNGE_BAD_VERSION = 9

Bad credential version

EMUNGE_BAD_ZIP = 12

Bad credential compression type

EMUNGE_CRED_EXPIRED = 15

Credential expired

EMUNGE_CRED_INVALID = 14

Credential invalid

EMUNGE_CRED_REPLAYED = 17

Credential replayed

EMUNGE_CRED_REWOUND = 16

Credential created in the future

EMUNGE_CRED_UNAUTHORIZED = 18

Credential decode unauthorized

EMUNGE_NO_MEMORY = 5

Out of memory

EMUNGE_OVERFLOW = 4

Buffer overflow

EMUNGE_SNAFU = 1

Doh!

EMUNGE_SOCKET = 6

Munged communication error

EMUNGE_SUCCESS = 0

Whoohoo!

EMUNGE_TIMEOUT = 7

Munged timeout

Low-level API

pymunge.raw - low-level API

This module contains declarations of raw libmunge C functions and constants.

Importing this module causes the libmunge shared library to be loaded.

Note that most function prototypes differ slightly from their C counterparts, as follows:

• For all C functions that originally return an error code (munge_err_t), the corresponding Python wrapper instead checks the return value and raises a MungeError if the wrapped function returns anything other than EMUNGE_SUCCESS.
• Some functions originally return multiple values via pointer-based output arguments (e.g. uid and gid in munge_decode). The Python wrapper does not take these arguments and instead returns the multiple values as a tuple.

pymunge.raw.uid_t

The uid_t POSIX type. Specifies a numeric user ID.

alias of c_uint

pymunge.raw.gid_t

The gid_t POSIX type. Specifies a numeric group ID.

alias of c_uint

pymunge.raw.time_t

The time_t C type. Specifies a timestamp.

alias of c_long

pymunge.raw.munge_ctx_t

The munge_ctx_t C type, an opaque handle to a MUNGE context. The low-level version of MungeContext.

alias of c_void_p

pymunge.raw.munge_err_t

The munge_err_t C enumeration type. Specifies a MUNGE error code. The low-level version of MungeErrorCode.

alias of c_int

pymunge.raw.munge_opt_t

The munge_opt_t C enumeration type. Specifies a MUNGE context option.

alias of c_int

pymunge.raw.munge_enum_t

The munge_enum_t C enumeration type. Specifies a MUNGE enumeration.

alias of c_int

pymunge.raw.munge_encode(ctx, buf, len)

C prototype: munge_err_t munge_encode(char **cred, munge_ctx_t ctx, const void *buf, int len);

Note: when called from Python, returns cred instead of the munge_err_t.

Creates a credential contained in a base64 string. A payload specified by a buffer buf (a byte string) of length len can be encapsulated in as well. If the munge context ctx is None, the default context will be used. Returns the credential cred if the credential is successfully created; otherwise, raises a MungeError containing the error code and message. The error message may be more detailed if a ctx was specified.

pymunge.raw.munge_decode(cred, ctx)

C prototype: munge_err_t munge_decode(const char *cred, munge_ctx_t ctx, void **buf, int *len, uid_t *uid, gid_t *gid);

Note: when called from Python, returns (payload, uid, gid) instead of the munge_err_t, where payload is the contents of buf of length len. Example usage:

>>> payload, uid, gid = munge_decode(cred, ctx)

Validates the credential cred. If the munge context ctx is not None, it will be set to that used to encode the credential. If the credential is valid, returns the encapsulated payload byte string payload as well as the numeric UID uid and GID gid of the process that created the credential. If the credential is not valid, raises a MungeError containing the error code and message. The error message may be more detailed if a ctx was specified. For certain errors (ie, EMUNGE_CRED_EXPIRED, EMUNGE_CRED_REWOUND, EMUNGE_CRED_REPLAYED), the raised MungeError will contain the result (payload, uid, gid) which would have been returned if the credential were still valid.

pymunge.raw.munge_strerror(e)

C prototype: const char * munge_strerror(munge_err_t e);

Returns a descriptive string describing the munge errno e.

pymunge.raw.munge_ctx_create()

C prototype: munge_ctx_t munge_ctx_create(void);

Creates and returns a new munge context or None on error. Abandoning a context without calling munge_ctx_destroy() will result in a memory leak.

pymunge.raw.munge_ctx_copy(ctx)

C prototype: munge_ctx_t munge_ctx_copy(munge_ctx_t ctx);

Copies the context ctx, returning a new munge context or None on error. Abandoning a context without calling munge_ctx_destroy() will result in a memory leak.

pymunge.raw.munge_ctx_destroy(ctx)

C prototype: void munge_ctx_destroy(munge_ctx_t ctx);

Destroys the context ctx.

pymunge.raw.munge_ctx_strerror(ctx)

C prototype: const char * munge_ctx_strerror(munge_ctx_t ctx);

Returns a descriptive text string describing the munge error number according to the context ctx, or None if no error condition exists. This message may be more detailed than that returned by munge_strerror().

pymunge.raw.munge_ctx_get(ctx, opt, ptr)

C prototype: munge_err_t munge_ctx_get(munge_ctx_t ctx, munge_opt_t opt, ...);

Note: when called from Python, returns nothing.

Gets the value for the option opt associated with the munge context ctx, storing the result in the subsequent pointer argument. Refer to the munge_opt_t enum comments for argument types. If the result is a string, that string should not be freed or modified by the caller. Raises a MungeError upon failure.

pymunge.raw.munge_ctx_set(ctx, opt, val)

C prototype: munge_err_t munge_ctx_set(munge_ctx_t ctx, munge_opt_t opt, ...);

Note: when called from Python, returns nothing.

Sets the value for the option opt associated with the munge context ctx, using the value of the subsequent argument. Refer to the munge_opt_t enum comments for argument types. Raises a MungeError upon failure.

pymunge.raw.munge_enum_is_valid(type, val)

C prototype: int munge_enum_is_valid(munge_enum_t type, int val);

Note: when called from Python, the returned int is converted to a boolean.

Returns True if the given value val is a valid enumeration of the specified type type in the software configuration as currently compiled; otherwise returns False. Some enumerations correspond to options that can only be enabled at compile-time.

pymunge.raw.munge_enum_int_to_str(type, val)

C prototype: const char * munge_enum_int_to_str(munge_enum_t type, int val);

Converts the munge enumeration val of the specified type type into a text string. Returns the text string, or None on error.

pymunge.raw.munge_enum_str_to_int(type, str)

C prototype: int munge_enum_str_to_int(munge_enum_t type, const char *str);

Converts the case-insensitive byte string str into the corresponding munge enumeration of the specified type type. Returns a munge enumeration on success (>= 0), or -1 on error.

pymunge.raw.libmunge_filename = None

Name of the libmunge shared object.

pymunge.raw.libmunge = None

Handle to the loaded libmunge shared object (a ctypes.CDLL object).

pymunge.raw.MUNGE_OPT_CIPHER_TYPE = 0

symmetric cipher type (int)

pymunge.raw.MUNGE_OPT_MAC_TYPE = 1

message auth code type (int)

pymunge.raw.MUNGE_OPT_ZIP_TYPE = 2

compression type (int)

pymunge.raw.MUNGE_OPT_REALM = 3

security realm (str)

pymunge.raw.MUNGE_OPT_TTL = 4

time-to-live (int)

pymunge.raw.MUNGE_OPT_ADDR4 = 5

src IPv4 addr (struct in_addr)

pymunge.raw.MUNGE_OPT_ENCODE_TIME = 6

time when cred encoded (time_t)

pymunge.raw.MUNGE_OPT_DECODE_TIME = 7

time when cred decoded (time_t)

pymunge.raw.MUNGE_OPT_SOCKET = 8

socket for comm w/ daemon (str)

pymunge.raw.MUNGE_OPT_UID_RESTRICTION = 9

UID able to decode cred (uid_t)

pymunge.raw.MUNGE_OPT_GID_RESTRICTION = 10

GID able to decode cred (gid_t)

pymunge.raw.MUNGE_ENUM_CIPHER = 0

cipher enum type

pymunge.raw.MUNGE_ENUM_MAC = 1

mac enum type

pymunge.raw.MUNGE_ENUM_ZIP = 2

zip enum type

The pymunge.raw module provides access to the low-level C API of libmunge. See the module documentation.

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