/* $OpenBSD: sshbuf.c,v 1.19 2022/12/02 04:40:27 djm Exp $ */ /* * Copyright (c) 2011 Damien Miller * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "includes.h" __RCSID("$NetBSD: sshbuf.c,v 1.13.2.1 2023/08/11 15:36:40 martin Exp $"); #include #include #include #include #include #include "ssherr.h" #define SSHBUF_INTERNAL #include "sshbuf.h" #include "misc.h" #ifdef SSHBUF_DEBUG # define SSHBUF_TELL(what) do { \ printf("%s:%d %s: %s size %zu alloc %zu off %zu max %zu\n", \ __FILE__, __LINE__, __func__, what, \ buf->size, buf->alloc, buf->off, buf->max_size); \ fflush(stdout); \ } while (0) #else # define SSHBUF_TELL(what) #endif struct sshbuf { u_char *d; /* Data */ const u_char *cd; /* Const data */ size_t off; /* First available byte is buf->d + buf->off */ size_t size; /* Last byte is buf->d + buf->size - 1 */ size_t max_size; /* Maximum size of buffer */ size_t alloc; /* Total bytes allocated to buf->d */ int readonly; /* Refers to external, const data */ u_int refcount; /* Tracks self and number of child buffers */ struct sshbuf *parent; /* If child, pointer to parent */ }; static inline int sshbuf_check_sanity(const struct sshbuf *buf) { SSHBUF_TELL("sanity"); if (__predict_false(buf == NULL || (!buf->readonly && buf->d != buf->cd) || buf->refcount < 1 || buf->refcount > SSHBUF_REFS_MAX || buf->cd == NULL || buf->max_size > SSHBUF_SIZE_MAX || buf->alloc > buf->max_size || buf->size > buf->alloc || buf->off > buf->size)) { /* Do not try to recover from corrupted buffer internals */ SSHBUF_DBG(("SSH_ERR_INTERNAL_ERROR")); ssh_signal(SIGSEGV, SIG_DFL); raise(SIGSEGV); return SSH_ERR_INTERNAL_ERROR; } return 0; } static void sshbuf_maybe_pack(struct sshbuf *buf, int force) { SSHBUF_DBG(("force %d", force)); SSHBUF_TELL("pre-pack"); if (buf->off == 0 || buf->readonly || buf->refcount > 1) return; if (force || (buf->off >= SSHBUF_PACK_MIN && buf->off >= buf->size / 2)) { memmove(buf->d, buf->d + buf->off, buf->size - buf->off); buf->size -= buf->off; buf->off = 0; SSHBUF_TELL("packed"); } } struct sshbuf * sshbuf_new(void) { struct sshbuf *ret; if ((ret = calloc(sizeof(*ret), 1)) == NULL) return NULL; ret->alloc = SSHBUF_SIZE_INIT; ret->max_size = SSHBUF_SIZE_MAX; ret->readonly = 0; ret->refcount = 1; ret->parent = NULL; if ((ret->cd = ret->d = calloc(1, ret->alloc)) == NULL) { free(ret); return NULL; } return ret; } struct sshbuf * sshbuf_from(const void *blob, size_t len) { struct sshbuf *ret; if (blob == NULL || len > SSHBUF_SIZE_MAX || (ret = calloc(sizeof(*ret), 1)) == NULL) return NULL; ret->alloc = ret->size = ret->max_size = len; ret->readonly = 1; ret->refcount = 1; ret->parent = NULL; ret->cd = blob; ret->d = NULL; return ret; } int sshbuf_set_parent(struct sshbuf *child, struct sshbuf *parent) { int r; if ((r = sshbuf_check_sanity(child)) != 0 || (r = sshbuf_check_sanity(parent)) != 0) return r; if (child->parent != NULL && child->parent != parent) return SSH_ERR_INTERNAL_ERROR; child->parent = parent; child->parent->refcount++; return 0; } struct sshbuf * sshbuf_fromb(struct sshbuf *buf) { struct sshbuf *ret; if (sshbuf_check_sanity(buf) != 0) return NULL; if ((ret = sshbuf_from(sshbuf_ptr(buf), sshbuf_len(buf))) == NULL) return NULL; if (sshbuf_set_parent(ret, buf) != 0) { sshbuf_free(ret); return NULL; } return ret; } void sshbuf_free(struct sshbuf *buf) { if (buf == NULL) return; /* * The following will leak on insane buffers, but this is the safest * course of action - an invalid pointer or already-freed pointer may * have been passed to us and continuing to scribble over memory would * be bad. */ if (sshbuf_check_sanity(buf) != 0) return; /* * If we are a parent with still-extant children, then don't free just * yet. The last child's call to sshbuf_free should decrement our * refcount to 0 and trigger the actual free. */ buf->refcount--; if (buf->refcount > 0) return; /* * If we are a child, the free our parent to decrement its reference * count and possibly free it. */ sshbuf_free(buf->parent); buf->parent = NULL; if (!buf->readonly) { explicit_bzero(buf->d, buf->alloc); free(buf->d); } freezero(buf, sizeof(*buf)); } void sshbuf_reset(struct sshbuf *buf) { u_char *d; if (buf->readonly || buf->refcount > 1) { /* Nonsensical. Just make buffer appear empty */ buf->off = buf->size; return; } if (sshbuf_check_sanity(buf) != 0) return; buf->off = buf->size = 0; if (buf->alloc != SSHBUF_SIZE_INIT) { if ((d = recallocarray(buf->d, buf->alloc, SSHBUF_SIZE_INIT, 1)) != NULL) { buf->cd = buf->d = d; buf->alloc = SSHBUF_SIZE_INIT; } } explicit_bzero(buf->d, buf->alloc); } size_t sshbuf_max_size(const struct sshbuf *buf) { return buf->max_size; } size_t sshbuf_alloc(const struct sshbuf *buf) { return buf->alloc; } const struct sshbuf * sshbuf_parent(const struct sshbuf *buf) { return buf->parent; } u_int sshbuf_refcount(const struct sshbuf *buf) { return buf->refcount; } int sshbuf_set_max_size(struct sshbuf *buf, size_t max_size) { size_t rlen; u_char *dp; int r; SSHBUF_DBG(("set max buf = %p len = %zu", buf, max_size)); if ((r = sshbuf_check_sanity(buf)) != 0) return r; if (max_size == buf->max_size) return 0; if (buf->readonly || buf->refcount > 1) return SSH_ERR_BUFFER_READ_ONLY; if (max_size > SSHBUF_SIZE_MAX) return SSH_ERR_NO_BUFFER_SPACE; /* pack and realloc if necessary */ sshbuf_maybe_pack(buf, max_size < buf->size); if (max_size < buf->alloc && max_size > buf->size) { if (buf->size < SSHBUF_SIZE_INIT) rlen = SSHBUF_SIZE_INIT; else rlen = ROUNDUP(buf->size, SSHBUF_SIZE_INC); if (rlen > max_size) rlen = max_size; SSHBUF_DBG(("new alloc = %zu", rlen)); if ((dp = recallocarray(buf->d, buf->alloc, rlen, 1)) == NULL) return SSH_ERR_ALLOC_FAIL; buf->cd = buf->d = dp; buf->alloc = rlen; } SSHBUF_TELL("new-max"); if (max_size < buf->alloc) return SSH_ERR_NO_BUFFER_SPACE; buf->max_size = max_size; return 0; } size_t sshbuf_len(const struct sshbuf *buf) { if (sshbuf_check_sanity(buf) != 0) return 0; return buf->size - buf->off; } size_t sshbuf_avail(const struct sshbuf *buf) { if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1) return 0; return buf->max_size - (buf->size - buf->off); } const u_char * sshbuf_ptr(const struct sshbuf *buf) { if (sshbuf_check_sanity(buf) != 0) return NULL; return buf->cd + buf->off; } u_char * sshbuf_mutable_ptr(const struct sshbuf *buf) { if (sshbuf_check_sanity(buf) != 0 || buf->readonly || buf->refcount > 1) return NULL; return buf->d + buf->off; } int sshbuf_check_reserve(const struct sshbuf *buf, size_t len) { int r; if ((r = sshbuf_check_sanity(buf)) != 0) return r; if (buf->readonly || buf->refcount > 1) return SSH_ERR_BUFFER_READ_ONLY; SSHBUF_TELL("check"); /* Check that len is reasonable and that max_size + available < len */ if (len > buf->max_size || buf->max_size - len < buf->size - buf->off) return SSH_ERR_NO_BUFFER_SPACE; return 0; } int sshbuf_allocate(struct sshbuf *buf, size_t len) { size_t rlen, need; u_char *dp; int r; SSHBUF_DBG(("allocate buf = %p len = %zu", buf, len)); if ((r = sshbuf_check_reserve(buf, len)) != 0) return r; /* * If the requested allocation appended would push us past max_size * then pack the buffer, zeroing buf->off. */ sshbuf_maybe_pack(buf, buf->size + len > buf->max_size); SSHBUF_TELL("allocate"); if (len + buf->size <= buf->alloc) return 0; /* already have it. */ /* * Prefer to alloc in SSHBUF_SIZE_INC units, but * allocate less if doing so would overflow max_size. */ need = len + buf->size - buf->alloc; rlen = ROUNDUP(buf->alloc + need, SSHBUF_SIZE_INC); SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen)); if (rlen > buf->max_size) rlen = buf->alloc + need; SSHBUF_DBG(("adjusted rlen %zu", rlen)); if ((dp = recallocarray(buf->d, buf->alloc, rlen, 1)) == NULL) { SSHBUF_DBG(("realloc fail")); return SSH_ERR_ALLOC_FAIL; } buf->alloc = rlen; buf->cd = buf->d = dp; if ((r = sshbuf_check_reserve(buf, len)) < 0) { /* shouldn't fail */ return r; } SSHBUF_TELL("done"); return 0; } int sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp) { u_char *dp; int r; if (dpp != NULL) *dpp = NULL; SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len)); if ((r = sshbuf_allocate(buf, len)) != 0) return r; dp = buf->d + buf->size; buf->size += len; if (dpp != NULL) *dpp = dp; return 0; } int sshbuf_consume(struct sshbuf *buf, size_t len) { int r; SSHBUF_DBG(("len = %zu", len)); if ((r = sshbuf_check_sanity(buf)) != 0) return r; if (len == 0) return 0; if (len > sshbuf_len(buf)) return SSH_ERR_MESSAGE_INCOMPLETE; buf->off += len; /* deal with empty buffer */ if (buf->off == buf->size) buf->off = buf->size = 0; SSHBUF_TELL("done"); return 0; } int sshbuf_consume_end(struct sshbuf *buf, size_t len) { int r; SSHBUF_DBG(("len = %zu", len)); if ((r = sshbuf_check_sanity(buf)) != 0) return r; if (len == 0) return 0; if (len > sshbuf_len(buf)) return SSH_ERR_MESSAGE_INCOMPLETE; buf->size -= len; SSHBUF_TELL("done"); return 0; }