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Diffstat (limited to '')
| -rw-r--r-- | src/crypt.c | 605 |
1 files changed, 605 insertions, 0 deletions
diff --git a/src/crypt.c b/src/crypt.c new file mode 100644 index 0000000..47617e9 --- /dev/null +++ b/src/crypt.c @@ -0,0 +1,605 @@ +/* vi:set ts=8 sts=4 sw=4 noet: + * + * VIM - Vi IMproved by Bram Moolenaar + * + * Do ":help uganda" in Vim to read copying and usage conditions. + * Do ":help credits" in Vim to see a list of people who contributed. + * See README.txt for an overview of the Vim source code. + */ + +/* + * crypt.c: Generic encryption support. + */ +#include "vim.h" + +#if defined(FEAT_CRYPT) || defined(PROTO) +/* + * Optional encryption support. + * Mohsin Ahmed, mosh@sasi.com, 1998-09-24 + * Based on zip/crypt sources. + * Refactored by David Leadbeater, 2014. + * + * NOTE FOR USA: Since 2000 exporting this code from the USA is allowed to + * most countries. There are a few exceptions, but that still should not be a + * problem since this code was originally created in Europe and India. + * + * Blowfish addition originally made by Mohsin Ahmed, + * http://www.cs.albany.edu/~mosh 2010-03-14 + * Based on blowfish by Bruce Schneier (http://www.schneier.com/blowfish.html) + * and sha256 by Christophe Devine. + */ + +typedef struct { + char *name; /* encryption name as used in 'cryptmethod' */ + char *magic; /* magic bytes stored in file header */ + int salt_len; /* length of salt, or 0 when not using salt */ + int seed_len; /* length of seed, or 0 when not using salt */ +#ifdef CRYPT_NOT_INPLACE + int works_inplace; /* encryption/decryption can be done in-place */ +#endif + int whole_undofile; /* whole undo file is encrypted */ + + /* Optional function pointer for a self-test. */ + int (* self_test_fn)(); + + /* Function pointer for initializing encryption/decription. */ + void (* init_fn)(cryptstate_T *state, char_u *key, + char_u *salt, int salt_len, char_u *seed, int seed_len); + + /* Function pointers for encoding/decoding from one buffer into another. + * Optional, however, these or the _buffer ones should be configured. */ + void (*encode_fn)(cryptstate_T *state, char_u *from, size_t len, + char_u *to); + void (*decode_fn)(cryptstate_T *state, char_u *from, size_t len, + char_u *to); + + /* Function pointers for encoding and decoding, can buffer data if needed. + * Optional (however, these or the above should be configured). */ + long (*encode_buffer_fn)(cryptstate_T *state, char_u *from, size_t len, + char_u **newptr); + long (*decode_buffer_fn)(cryptstate_T *state, char_u *from, size_t len, + char_u **newptr); + + /* Function pointers for in-place encoding and decoding, used for + * crypt_*_inplace(). "from" and "to" arguments will be equal. + * These may be the same as decode_fn and encode_fn above, however an + * algorithm may implement them in a way that is not interchangeable with + * the crypt_(en|de)code() interface (for example because it wishes to add + * padding to files). + * This method is used for swap and undo files which have a rigid format. + */ + void (*encode_inplace_fn)(cryptstate_T *state, char_u *p1, size_t len, + char_u *p2); + void (*decode_inplace_fn)(cryptstate_T *state, char_u *p1, size_t len, + char_u *p2); +} cryptmethod_T; + +/* index is method_nr of cryptstate_T, CRYPT_M_* */ +static cryptmethod_T cryptmethods[CRYPT_M_COUNT] = { + /* PK_Zip; very weak */ + { + "zip", + "VimCrypt~01!", + 0, + 0, +#ifdef CRYPT_NOT_INPLACE + TRUE, +#endif + FALSE, + NULL, + crypt_zip_init, + crypt_zip_encode, crypt_zip_decode, + NULL, NULL, + crypt_zip_encode, crypt_zip_decode, + }, + + /* Blowfish/CFB + SHA-256 custom key derivation; implementation issues. */ + { + "blowfish", + "VimCrypt~02!", + 8, + 8, +#ifdef CRYPT_NOT_INPLACE + TRUE, +#endif + FALSE, + blowfish_self_test, + crypt_blowfish_init, + crypt_blowfish_encode, crypt_blowfish_decode, + NULL, NULL, + crypt_blowfish_encode, crypt_blowfish_decode, + }, + + /* Blowfish/CFB + SHA-256 custom key derivation; fixed. */ + { + "blowfish2", + "VimCrypt~03!", + 8, + 8, +#ifdef CRYPT_NOT_INPLACE + TRUE, +#endif + TRUE, + blowfish_self_test, + crypt_blowfish_init, + crypt_blowfish_encode, crypt_blowfish_decode, + NULL, NULL, + crypt_blowfish_encode, crypt_blowfish_decode, + }, + + /* NOTE: when adding a new method, use some random bytes for the magic key, + * to avoid that a text file is recognized as encrypted. */ +}; + +#define CRYPT_MAGIC_LEN 12 /* cannot change */ +static char crypt_magic_head[] = "VimCrypt~"; + +/* + * Return int value for crypt method name. + * 0 for "zip", the old method. Also for any non-valid value. + * 1 for "blowfish". + * 2 for "blowfish2". + */ + int +crypt_method_nr_from_name(char_u *name) +{ + int i; + + for (i = 0; i < CRYPT_M_COUNT; ++i) + if (STRCMP(name, cryptmethods[i].name) == 0) + return i; + return 0; +} + +/* + * Get the crypt method used for a file from "ptr[len]", the magic text at the + * start of the file. + * Returns -1 when no encryption used. + */ + int +crypt_method_nr_from_magic(char *ptr, int len) +{ + int i; + + if (len < CRYPT_MAGIC_LEN) + return -1; + + for (i = 0; i < CRYPT_M_COUNT; i++) + if (memcmp(ptr, cryptmethods[i].magic, CRYPT_MAGIC_LEN) == 0) + return i; + + i = (int)STRLEN(crypt_magic_head); + if (len >= i && memcmp(ptr, crypt_magic_head, i) == 0) + emsg(_("E821: File is encrypted with unknown method")); + + return -1; +} + +#ifdef CRYPT_NOT_INPLACE +/* + * Return TRUE if the crypt method for "method_nr" can be done in-place. + */ + int +crypt_works_inplace(cryptstate_T *state) +{ + return cryptmethods[state->method_nr].works_inplace; +} +#endif + +/* + * Get the crypt method for buffer "buf" as a number. + */ + int +crypt_get_method_nr(buf_T *buf) +{ + return crypt_method_nr_from_name(*buf->b_p_cm == NUL ? p_cm : buf->b_p_cm); +} + +/* + * Return TRUE when the buffer uses an encryption method that encrypts the + * whole undo file, not only the text. + */ + int +crypt_whole_undofile(int method_nr) +{ + return cryptmethods[method_nr].whole_undofile; +} + +/* + * Get crypt method specifc length of the file header in bytes. + */ + int +crypt_get_header_len(int method_nr) +{ + return CRYPT_MAGIC_LEN + + cryptmethods[method_nr].salt_len + + cryptmethods[method_nr].seed_len; +} + +/* + * Set the crypt method for buffer "buf" to "method_nr" using the int value as + * returned by crypt_method_nr_from_name(). + */ + void +crypt_set_cm_option(buf_T *buf, int method_nr) +{ + free_string_option(buf->b_p_cm); + buf->b_p_cm = vim_strsave((char_u *)cryptmethods[method_nr].name); +} + +/* + * If the crypt method for the current buffer has a self-test, run it and + * return OK/FAIL. + */ + int +crypt_self_test(void) +{ + int method_nr = crypt_get_method_nr(curbuf); + + if (cryptmethods[method_nr].self_test_fn == NULL) + return OK; + return cryptmethods[method_nr].self_test_fn(); +} + +/* + * Allocate a crypt state and initialize it. + */ + cryptstate_T * +crypt_create( + int method_nr, + char_u *key, + char_u *salt, + int salt_len, + char_u *seed, + int seed_len) +{ + cryptstate_T *state = (cryptstate_T *)alloc((int)sizeof(cryptstate_T)); + + state->method_nr = method_nr; + cryptmethods[method_nr].init_fn(state, key, salt, salt_len, seed, seed_len); + return state; +} + +/* + * Allocate a crypt state from a file header and initialize it. + * Assumes that header contains at least the number of bytes that + * crypt_get_header_len() returns for "method_nr". + */ + cryptstate_T * +crypt_create_from_header( + int method_nr, + char_u *key, + char_u *header) +{ + char_u *salt = NULL; + char_u *seed = NULL; + int salt_len = cryptmethods[method_nr].salt_len; + int seed_len = cryptmethods[method_nr].seed_len; + + if (salt_len > 0) + salt = header + CRYPT_MAGIC_LEN; + if (seed_len > 0) + seed = header + CRYPT_MAGIC_LEN + salt_len; + + return crypt_create(method_nr, key, salt, salt_len, seed, seed_len); +} + +/* + * Read the crypt method specific header data from "fp". + * Return an allocated cryptstate_T or NULL on error. + */ + cryptstate_T * +crypt_create_from_file(FILE *fp, char_u *key) +{ + int method_nr; + int header_len; + char magic_buffer[CRYPT_MAGIC_LEN]; + char_u *buffer; + cryptstate_T *state; + + if (fread(magic_buffer, CRYPT_MAGIC_LEN, 1, fp) != 1) + return NULL; + method_nr = crypt_method_nr_from_magic(magic_buffer, CRYPT_MAGIC_LEN); + if (method_nr < 0) + return NULL; + + header_len = crypt_get_header_len(method_nr); + if ((buffer = alloc(header_len)) == NULL) + return NULL; + mch_memmove(buffer, magic_buffer, CRYPT_MAGIC_LEN); + if (header_len > CRYPT_MAGIC_LEN + && fread(buffer + CRYPT_MAGIC_LEN, + header_len - CRYPT_MAGIC_LEN, 1, fp) != 1) + { + vim_free(buffer); + return NULL; + } + + state = crypt_create_from_header(method_nr, key, buffer); + vim_free(buffer); + return state; +} + +/* + * Allocate a cryptstate_T for writing and initialize it with "key". + * Allocates and fills in the header and stores it in "header", setting + * "header_len". The header may include salt and seed, depending on + * cryptmethod. Caller must free header. + * Returns the state or NULL on failure. + */ + cryptstate_T * +crypt_create_for_writing( + int method_nr, + char_u *key, + char_u **header, + int *header_len) +{ + int len = crypt_get_header_len(method_nr); + char_u *salt = NULL; + char_u *seed = NULL; + int salt_len = cryptmethods[method_nr].salt_len; + int seed_len = cryptmethods[method_nr].seed_len; + cryptstate_T *state; + + *header_len = len; + *header = alloc(len); + if (*header == NULL) + return NULL; + + mch_memmove(*header, cryptmethods[method_nr].magic, CRYPT_MAGIC_LEN); + if (salt_len > 0 || seed_len > 0) + { + if (salt_len > 0) + salt = *header + CRYPT_MAGIC_LEN; + if (seed_len > 0) + seed = *header + CRYPT_MAGIC_LEN + salt_len; + + /* TODO: Should this be crypt method specific? (Probably not worth + * it). sha2_seed is pretty bad for large amounts of entropy, so make + * that into something which is suitable for anything. */ + sha2_seed(salt, salt_len, seed, seed_len); + } + + state = crypt_create(method_nr, key, salt, salt_len, seed, seed_len); + if (state == NULL) + VIM_CLEAR(*header); + return state; +} + +/* + * Free the crypt state. + */ + void +crypt_free_state(cryptstate_T *state) +{ + vim_free(state->method_state); + vim_free(state); +} + +#ifdef CRYPT_NOT_INPLACE +/* + * Encode "from[len]" and store the result in a newly allocated buffer, which + * is stored in "newptr". + * Return number of bytes in "newptr", 0 for need more or -1 on error. + */ + long +crypt_encode_alloc( + cryptstate_T *state, + char_u *from, + size_t len, + char_u **newptr) +{ + cryptmethod_T *method = &cryptmethods[state->method_nr]; + + if (method->encode_buffer_fn != NULL) + /* Has buffer function, pass through. */ + return method->encode_buffer_fn(state, from, len, newptr); + if (len == 0) + /* Not buffering, just return EOF. */ + return (long)len; + + *newptr = alloc((long)len); + if (*newptr == NULL) + return -1; + method->encode_fn(state, from, len, *newptr); + return (long)len; +} + +/* + * Decrypt "ptr[len]" and store the result in a newly allocated buffer, which + * is stored in "newptr". + * Return number of bytes in "newptr", 0 for need more or -1 on error. + */ + long +crypt_decode_alloc( + cryptstate_T *state, + char_u *ptr, + long len, + char_u **newptr) +{ + cryptmethod_T *method = &cryptmethods[state->method_nr]; + + if (method->decode_buffer_fn != NULL) + /* Has buffer function, pass through. */ + return method->decode_buffer_fn(state, ptr, len, newptr); + + if (len == 0) + /* Not buffering, just return EOF. */ + return len; + + *newptr = alloc(len); + if (*newptr == NULL) + return -1; + method->decode_fn(state, ptr, len, *newptr); + return len; +} +#endif + +/* + * Encrypting "from[len]" into "to[len]". + */ + void +crypt_encode( + cryptstate_T *state, + char_u *from, + size_t len, + char_u *to) +{ + cryptmethods[state->method_nr].encode_fn(state, from, len, to); +} + +#if 0 // unused +/* + * decrypting "from[len]" into "to[len]". + */ + void +crypt_decode( + cryptstate_T *state, + char_u *from, + size_t len, + char_u *to) +{ + cryptmethods[state->method_nr].decode_fn(state, from, len, to); +} +#endif + +/* + * Simple inplace encryption, modifies "buf[len]" in place. + */ + void +crypt_encode_inplace( + cryptstate_T *state, + char_u *buf, + size_t len) +{ + cryptmethods[state->method_nr].encode_inplace_fn(state, buf, len, buf); +} + +/* + * Simple inplace decryption, modifies "buf[len]" in place. + */ + void +crypt_decode_inplace( + cryptstate_T *state, + char_u *buf, + size_t len) +{ + cryptmethods[state->method_nr].decode_inplace_fn(state, buf, len, buf); +} + +/* + * Free an allocated crypt key. Clear the text to make sure it doesn't stay + * in memory anywhere. + */ + void +crypt_free_key(char_u *key) +{ + char_u *p; + + if (key != NULL) + { + for (p = key; *p != NUL; ++p) + *p = 0; + vim_free(key); + } +} + +/* + * Check the crypt method and give a warning if it's outdated. + */ + void +crypt_check_method(int method) +{ + if (method < CRYPT_M_BF2) + { + msg_scroll = TRUE; + msg(_("Warning: Using a weak encryption method; see :help 'cm'")); + } +} + + void +crypt_check_current_method(void) +{ + crypt_check_method(crypt_get_method_nr(curbuf)); +} + +/* + * Ask the user for a crypt key. + * When "store" is TRUE, the new key is stored in the 'key' option, and the + * 'key' option value is returned: Don't free it. + * When "store" is FALSE, the typed key is returned in allocated memory. + * Returns NULL on failure. + */ + char_u * +crypt_get_key( + int store, + int twice) /* Ask for the key twice. */ +{ + char_u *p1, *p2 = NULL; + int round; + + for (round = 0; ; ++round) + { + cmdline_star = TRUE; + cmdline_row = msg_row; + p1 = getcmdline_prompt(NUL, round == 0 + ? (char_u *)_("Enter encryption key: ") + : (char_u *)_("Enter same key again: "), 0, EXPAND_NOTHING, + NULL); + cmdline_star = FALSE; + + if (p1 == NULL) + break; + + if (round == twice) + { + if (p2 != NULL && STRCMP(p1, p2) != 0) + { + msg(_("Keys don't match!")); + crypt_free_key(p1); + crypt_free_key(p2); + p2 = NULL; + round = -1; /* do it again */ + continue; + } + + if (store) + { + set_option_value((char_u *)"key", 0L, p1, OPT_LOCAL); + crypt_free_key(p1); + p1 = curbuf->b_p_key; + } + break; + } + p2 = p1; + } + + /* since the user typed this, no need to wait for return */ + if (msg_didout) + msg_putchar('\n'); + need_wait_return = FALSE; + msg_didout = FALSE; + + crypt_free_key(p2); + return p1; +} + + +/* + * Append a message to IObuff for the encryption/decryption method being used. + */ + void +crypt_append_msg( + buf_T *buf) +{ + if (crypt_get_method_nr(buf) == 0) + STRCAT(IObuff, _("[crypted]")); + else + { + STRCAT(IObuff, "["); + STRCAT(IObuff, *buf->b_p_cm == NUL ? p_cm : buf->b_p_cm); + STRCAT(IObuff, "]"); + } +} + +#endif /* FEAT_CRYPT */ |