xref: /freebsd/sys/kern/kern_ctf.c (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
1 /*-
2  * Copyright (c) 2008 John Birrell <jb@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 
29 /*
30  * Note this file is included by both link_elf.c and link_elf_obj.c.
31  *
32  * The CTF header structure definition can't be used here because it's
33  * (annoyingly) covered by the CDDL. We will just use a few bytes from
34  * it as an integer array where we 'know' what they mean.
35  */
36 #define CTF_HDR_SIZE		36
37 #define CTF_HDR_STRTAB_U32	7
38 #define CTF_HDR_STRLEN_U32	8
39 
40 #ifdef DDB_CTF
41 static void *
42 z_alloc(void *nil, u_int items, u_int size)
43 {
44 	void *ptr;
45 
46 	ptr = malloc(items * size, M_TEMP, M_NOWAIT);
47 	return ptr;
48 }
49 
50 static void
51 z_free(void *nil, void *ptr)
52 {
53 	free(ptr, M_TEMP);
54 }
55 
56 #endif
57 
58 static int
59 link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
60 {
61 #ifdef DDB_CTF
62 	Elf_Ehdr *hdr = NULL;
63 	Elf_Shdr *shdr = NULL;
64 	caddr_t ctftab = NULL;
65 	caddr_t raw = NULL;
66 	caddr_t shstrtab = NULL;
67 	elf_file_t ef = (elf_file_t) lf;
68 	int flags;
69 	int i;
70 	int nbytes;
71 	int resid;
72 	int vfslocked;
73 	size_t sz;
74 	struct nameidata nd;
75 	struct thread *td = curthread;
76 	uint8_t ctf_hdr[CTF_HDR_SIZE];
77 #endif
78 	int error = 0;
79 
80 	if (lf == NULL || lc == NULL)
81 		return (EINVAL);
82 
83 	/* Set the defaults for no CTF present. That's not a crime! */
84 	bzero(lc, sizeof(*lc));
85 
86 #ifdef DDB_CTF
87 	/*
88 	 * First check if we've tried to load CTF data previously and the
89 	 * CTF ELF section wasn't found. We flag that condition by setting
90 	 * ctfcnt to -1. See below.
91 	 */
92 	if (ef->ctfcnt < 0)
93 		return (0);
94 
95 	/* Now check if we've already loaded the CTF data.. */
96 	if (ef->ctfcnt > 0) {
97 		/* We only need to load once. */
98 		lc->ctftab = ef->ctftab;
99 		lc->ctfcnt = ef->ctfcnt;
100 		lc->symtab = ef->ddbsymtab;
101 		lc->strtab = ef->ddbstrtab;
102 		lc->strcnt = ef->ddbstrcnt;
103 		lc->nsym   = ef->ddbsymcnt;
104 		lc->ctfoffp = (uint32_t **) &ef->ctfoff;
105 		lc->typoffp = (uint32_t **) &ef->typoff;
106 		lc->typlenp = &ef->typlen;
107 		return (0);
108 	}
109 
110 	/*
111 	 * We need to try reading the CTF data. Flag no CTF data present
112 	 * by default and if we actually succeed in reading it, we'll
113 	 * update ctfcnt to the number of bytes read.
114 	 */
115 	ef->ctfcnt = -1;
116 
117 	NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, lf->pathname, td);
118 	flags = FREAD;
119 	error = vn_open(&nd, &flags, 0, NULL);
120 	if (error)
121 		return (error);
122 	vfslocked = NDHASGIANT(&nd);
123 	NDFREE(&nd, NDF_ONLY_PNBUF);
124 
125 	/* Allocate memory for the FLF header. */
126 	if ((hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK)) == NULL) {
127 		error = ENOMEM;
128 		goto out;
129 	}
130 
131 	/* Read the ELF header. */
132 	if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
133 	    0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
134 	    td)) != 0)
135 		goto out;
136 
137 	/* Sanity check. */
138 	if (!IS_ELF(*hdr)) {
139 		error = ENOEXEC;
140 		goto out;
141 	}
142 
143 	nbytes = hdr->e_shnum * hdr->e_shentsize;
144 	if (nbytes == 0 || hdr->e_shoff == 0 ||
145 	    hdr->e_shentsize != sizeof(Elf_Shdr)) {
146 		error = ENOEXEC;
147 		goto out;
148 	}
149 
150 	/* Allocate memory for all the section headers */
151 	if ((shdr = malloc(nbytes, M_LINKER, M_WAITOK)) == NULL) {
152 		error = ENOMEM;
153 		goto out;
154 	}
155 
156 	/* Read all the section headers */
157 	if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
158 	    hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
159 	    &resid, td)) != 0)
160 		goto out;
161 
162 	/*
163 	 * We need to search for the CTF section by name, so if the
164 	 * section names aren't present, then we can't locate the
165 	 * .SUNW_ctf section containing the CTF data.
166 	 */
167 	if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB)
168 		goto out;
169 
170 	/* Allocate memory to buffer the section header strings. */
171 	if ((shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER,
172 	    M_WAITOK)) == NULL) {
173 		error = ENOMEM;
174 		goto out;
175 	}
176 
177 	/* Read the section header strings. */
178 	if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
179 	    shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
180 	    UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, &resid,
181 	    td)) != 0)
182 		goto out;
183 
184 	/* Search for the section containing the CTF data. */
185 	for (i = 0; i < hdr->e_shnum; i++)
186 		if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
187 			break;
188 
189 	/* Check if the CTF section wasn't found. */
190 	if (i >= hdr->e_shnum)
191 		goto out;
192 
193 	/* Read the CTF header. */
194 	if ((error = vn_rdwr(UIO_READ, nd.ni_vp, ctf_hdr, sizeof(ctf_hdr),
195 	    shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
196 	    NOCRED, &resid, td)) != 0)
197 		goto out;
198 
199 	/* Check the CTF magic number. (XXX check for big endian!) */
200 	if (ctf_hdr[0] != 0xf1 || ctf_hdr[1] != 0xcf)
201 		goto out;
202 
203 	/* Check if version 2. */
204 	if (ctf_hdr[2] != 2)
205 		goto out;
206 
207 	/* Check if the data is compressed. */
208 	if ((ctf_hdr[3] & 0x1) != 0) {
209 		uint32_t *u32 = (uint32_t *) ctf_hdr;
210 
211 		/*
212 		 * The last two fields in the CTF header are the offset
213 		 * from the end of the header to the start of the string
214 		 * data and the length of that string data. se this
215 		 * information to determine the decompressed CTF data
216 		 * buffer required.
217 		 */
218 		sz = u32[CTF_HDR_STRTAB_U32] + u32[CTF_HDR_STRLEN_U32] +
219 		    sizeof(ctf_hdr);
220 
221 		/*
222 		 * Allocate memory for the compressed CTF data, including
223 		 * the header (which isn't compressed).
224 		 */
225 		if ((raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK)) == NULL) {
226 			error = ENOMEM;
227 			goto out;
228 		}
229 	} else {
230 		/*
231 		 * The CTF data is not compressed, so the ELF section
232 		 * size is the same as the buffer size required.
233 		 */
234 		sz = shdr[i].sh_size;
235 	}
236 
237 	/*
238 	 * Allocate memory to buffer the CTF data in it's decompressed
239 	 * form.
240 	 */
241 	if ((ctftab = malloc(sz, M_LINKER, M_WAITOK)) == NULL) {
242 		error = ENOMEM;
243 		goto out;
244 	}
245 
246 	/*
247 	 * Read the CTF data into the raw buffer if compressed, or
248 	 * directly into the CTF buffer otherwise.
249 	 */
250 	if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
251 	    shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
252 	    td->td_ucred, NOCRED, &resid, td)) != 0)
253 		goto out;
254 
255 	/* Check if decompression is required. */
256 	if (raw != NULL) {
257 		z_stream zs;
258 		int ret;
259 
260 		/*
261 		 * The header isn't compressed, so copy that into the
262 		 * CTF buffer first.
263 		 */
264 		bcopy(ctf_hdr, ctftab, sizeof(ctf_hdr));
265 
266 		/* Initialise the zlib structure. */
267 		bzero(&zs, sizeof(zs));
268 		zs.zalloc = z_alloc;
269 		zs.zfree = z_free;
270 
271 		if (inflateInit(&zs) != Z_OK) {
272 			error = EIO;
273 			goto out;
274 		}
275 
276 		zs.avail_in = shdr[i].sh_size - sizeof(ctf_hdr);
277 		zs.next_in = ((uint8_t *) raw) + sizeof(ctf_hdr);
278 		zs.avail_out = sz - sizeof(ctf_hdr);
279 		zs.next_out = ((uint8_t *) ctftab) + sizeof(ctf_hdr);
280 		if ((ret = inflate(&zs, Z_FINISH)) != Z_STREAM_END) {
281 			printf("%s(%d): zlib inflate returned %d\n", __func__, __LINE__, ret);
282 			error = EIO;
283 			goto out;
284 		}
285 	}
286 
287 	/* Got the CTF data! */
288 	ef->ctftab = ctftab;
289 	ef->ctfcnt = shdr[i].sh_size;
290 
291 	/* We'll retain the memory allocated for the CTF data. */
292 	ctftab = NULL;
293 
294 	/* Let the caller use the CTF data read. */
295 	lc->ctftab = ef->ctftab;
296 	lc->ctfcnt = ef->ctfcnt;
297 	lc->symtab = ef->ddbsymtab;
298 	lc->strtab = ef->ddbstrtab;
299 	lc->strcnt = ef->ddbstrcnt;
300 	lc->nsym   = ef->ddbsymcnt;
301 	lc->ctfoffp = (uint32_t **) &ef->ctfoff;
302 	lc->typoffp = (uint32_t **) &ef->typoff;
303 	lc->typlenp = &ef->typlen;
304 
305 out:
306 	VOP_UNLOCK(nd.ni_vp, 0);
307 	vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
308 	VFS_UNLOCK_GIANT(vfslocked);
309 
310 	if (hdr != NULL)
311 		free(hdr, M_LINKER);
312 	if (shdr != NULL)
313 		free(shdr, M_LINKER);
314 	if (shstrtab != NULL)
315 		free(shstrtab, M_LINKER);
316 	if (ctftab != NULL)
317 		free(ctftab, M_LINKER);
318 	if (raw != NULL)
319 		free(raw, M_LINKER);
320 #else
321 	error = EOPNOTSUPP;
322 #endif
323 
324 	return (error);
325 }
326