xref: /openbmc/linux/fs/proc/kcore.c (revision a1e58bbd) 
1 /*
2  *	fs/proc/kcore.c kernel ELF core dumper
3  *
4  *	Modelled on fs/exec.c:aout_core_dump()
5  *	Jeremy Fitzhardinge <jeremy@sw.oz.au>
6  *	ELF version written by David Howells <David.Howells@nexor.co.uk>
7  *	Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
8  *	Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
9  *	Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
10  */
11 
12 #include <linux/mm.h>
13 #include <linux/proc_fs.h>
14 #include <linux/user.h>
15 #include <linux/capability.h>
16 #include <linux/elf.h>
17 #include <linux/elfcore.h>
18 #include <linux/vmalloc.h>
19 #include <linux/highmem.h>
20 #include <linux/init.h>
21 #include <asm/uaccess.h>
22 #include <asm/io.h>
23 
24 #define CORE_STR "CORE"
25 
26 static int open_kcore(struct inode * inode, struct file * filp)
27 {
28 	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
29 }
30 
31 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
32 
33 const struct file_operations proc_kcore_operations = {
34 	.read		= read_kcore,
35 	.open		= open_kcore,
36 };
37 
38 #ifndef kc_vaddr_to_offset
39 #define	kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
40 #endif
41 #ifndef	kc_offset_to_vaddr
42 #define	kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
43 #endif
44 
45 /* An ELF note in memory */
46 struct memelfnote
47 {
48 	const char *name;
49 	int type;
50 	unsigned int datasz;
51 	void *data;
52 };
53 
54 static struct kcore_list *kclist;
55 static DEFINE_RWLOCK(kclist_lock);
56 
57 void
58 kclist_add(struct kcore_list *new, void *addr, size_t size)
59 {
60 	new->addr = (unsigned long)addr;
61 	new->size = size;
62 
63 	write_lock(&kclist_lock);
64 	new->next = kclist;
65 	kclist = new;
66 	write_unlock(&kclist_lock);
67 }
68 
69 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
70 {
71 	size_t try, size;
72 	struct kcore_list *m;
73 
74 	*nphdr = 1; /* PT_NOTE */
75 	size = 0;
76 
77 	for (m=kclist; m; m=m->next) {
78 		try = kc_vaddr_to_offset((size_t)m->addr + m->size);
79 		if (try > size)
80 			size = try;
81 		*nphdr = *nphdr + 1;
82 	}
83 	*elf_buflen =	sizeof(struct elfhdr) +
84 			(*nphdr + 2)*sizeof(struct elf_phdr) +
85 			3 * ((sizeof(struct elf_note)) +
86 			     roundup(sizeof(CORE_STR), 4)) +
87 			roundup(sizeof(struct elf_prstatus), 4) +
88 			roundup(sizeof(struct elf_prpsinfo), 4) +
89 			roundup(sizeof(struct task_struct), 4);
90 	*elf_buflen = PAGE_ALIGN(*elf_buflen);
91 	return size + *elf_buflen;
92 }
93 
94 
95 /*****************************************************************************/
96 /*
97  * determine size of ELF note
98  */
99 static int notesize(struct memelfnote *en)
100 {
101 	int sz;
102 
103 	sz = sizeof(struct elf_note);
104 	sz += roundup((strlen(en->name) + 1), 4);
105 	sz += roundup(en->datasz, 4);
106 
107 	return sz;
108 } /* end notesize() */
109 
110 /*****************************************************************************/
111 /*
112  * store a note in the header buffer
113  */
114 static char *storenote(struct memelfnote *men, char *bufp)
115 {
116 	struct elf_note en;
117 
118 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
119 
120 	en.n_namesz = strlen(men->name) + 1;
121 	en.n_descsz = men->datasz;
122 	en.n_type = men->type;
123 
124 	DUMP_WRITE(&en, sizeof(en));
125 	DUMP_WRITE(men->name, en.n_namesz);
126 
127 	/* XXX - cast from long long to long to avoid need for libgcc.a */
128 	bufp = (char*) roundup((unsigned long)bufp,4);
129 	DUMP_WRITE(men->data, men->datasz);
130 	bufp = (char*) roundup((unsigned long)bufp,4);
131 
132 #undef DUMP_WRITE
133 
134 	return bufp;
135 } /* end storenote() */
136 
137 /*
138  * store an ELF coredump header in the supplied buffer
139  * nphdr is the number of elf_phdr to insert
140  */
141 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
142 {
143 	struct elf_prstatus prstatus;	/* NT_PRSTATUS */
144 	struct elf_prpsinfo prpsinfo;	/* NT_PRPSINFO */
145 	struct elf_phdr *nhdr, *phdr;
146 	struct elfhdr *elf;
147 	struct memelfnote notes[3];
148 	off_t offset = 0;
149 	struct kcore_list *m;
150 
151 	/* setup ELF header */
152 	elf = (struct elfhdr *) bufp;
153 	bufp += sizeof(struct elfhdr);
154 	offset += sizeof(struct elfhdr);
155 	memcpy(elf->e_ident, ELFMAG, SELFMAG);
156 	elf->e_ident[EI_CLASS]	= ELF_CLASS;
157 	elf->e_ident[EI_DATA]	= ELF_DATA;
158 	elf->e_ident[EI_VERSION]= EV_CURRENT;
159 	elf->e_ident[EI_OSABI] = ELF_OSABI;
160 	memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
161 	elf->e_type	= ET_CORE;
162 	elf->e_machine	= ELF_ARCH;
163 	elf->e_version	= EV_CURRENT;
164 	elf->e_entry	= 0;
165 	elf->e_phoff	= sizeof(struct elfhdr);
166 	elf->e_shoff	= 0;
167 #if defined(CONFIG_H8300)
168 	elf->e_flags	= ELF_FLAGS;
169 #else
170 	elf->e_flags	= 0;
171 #endif
172 	elf->e_ehsize	= sizeof(struct elfhdr);
173 	elf->e_phentsize= sizeof(struct elf_phdr);
174 	elf->e_phnum	= nphdr;
175 	elf->e_shentsize= 0;
176 	elf->e_shnum	= 0;
177 	elf->e_shstrndx	= 0;
178 
179 	/* setup ELF PT_NOTE program header */
180 	nhdr = (struct elf_phdr *) bufp;
181 	bufp += sizeof(struct elf_phdr);
182 	offset += sizeof(struct elf_phdr);
183 	nhdr->p_type	= PT_NOTE;
184 	nhdr->p_offset	= 0;
185 	nhdr->p_vaddr	= 0;
186 	nhdr->p_paddr	= 0;
187 	nhdr->p_filesz	= 0;
188 	nhdr->p_memsz	= 0;
189 	nhdr->p_flags	= 0;
190 	nhdr->p_align	= 0;
191 
192 	/* setup ELF PT_LOAD program header for every area */
193 	for (m=kclist; m; m=m->next) {
194 		phdr = (struct elf_phdr *) bufp;
195 		bufp += sizeof(struct elf_phdr);
196 		offset += sizeof(struct elf_phdr);
197 
198 		phdr->p_type	= PT_LOAD;
199 		phdr->p_flags	= PF_R|PF_W|PF_X;
200 		phdr->p_offset	= kc_vaddr_to_offset(m->addr) + dataoff;
201 		phdr->p_vaddr	= (size_t)m->addr;
202 		phdr->p_paddr	= 0;
203 		phdr->p_filesz	= phdr->p_memsz	= m->size;
204 		phdr->p_align	= PAGE_SIZE;
205 	}
206 
207 	/*
208 	 * Set up the notes in similar form to SVR4 core dumps made
209 	 * with info from their /proc.
210 	 */
211 	nhdr->p_offset	= offset;
212 
213 	/* set up the process status */
214 	notes[0].name = CORE_STR;
215 	notes[0].type = NT_PRSTATUS;
216 	notes[0].datasz = sizeof(struct elf_prstatus);
217 	notes[0].data = &prstatus;
218 
219 	memset(&prstatus, 0, sizeof(struct elf_prstatus));
220 
221 	nhdr->p_filesz	= notesize(&notes[0]);
222 	bufp = storenote(&notes[0], bufp);
223 
224 	/* set up the process info */
225 	notes[1].name	= CORE_STR;
226 	notes[1].type	= NT_PRPSINFO;
227 	notes[1].datasz	= sizeof(struct elf_prpsinfo);
228 	notes[1].data	= &prpsinfo;
229 
230 	memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
231 	prpsinfo.pr_state	= 0;
232 	prpsinfo.pr_sname	= 'R';
233 	prpsinfo.pr_zomb	= 0;
234 
235 	strcpy(prpsinfo.pr_fname, "vmlinux");
236 	strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
237 
238 	nhdr->p_filesz	+= notesize(&notes[1]);
239 	bufp = storenote(&notes[1], bufp);
240 
241 	/* set up the task structure */
242 	notes[2].name	= CORE_STR;
243 	notes[2].type	= NT_TASKSTRUCT;
244 	notes[2].datasz	= sizeof(struct task_struct);
245 	notes[2].data	= current;
246 
247 	nhdr->p_filesz	+= notesize(&notes[2]);
248 	bufp = storenote(&notes[2], bufp);
249 
250 } /* end elf_kcore_store_hdr() */
251 
252 /*****************************************************************************/
253 /*
254  * read from the ELF header and then kernel memory
255  */
256 static ssize_t
257 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
258 {
259 	ssize_t acc = 0;
260 	size_t size, tsz;
261 	size_t elf_buflen;
262 	int nphdr;
263 	unsigned long start;
264 
265 	read_lock(&kclist_lock);
266 	proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
267 	if (buflen == 0 || *fpos >= size) {
268 		read_unlock(&kclist_lock);
269 		return 0;
270 	}
271 
272 	/* trim buflen to not go beyond EOF */
273 	if (buflen > size - *fpos)
274 		buflen = size - *fpos;
275 
276 	/* construct an ELF core header if we'll need some of it */
277 	if (*fpos < elf_buflen) {
278 		char * elf_buf;
279 
280 		tsz = elf_buflen - *fpos;
281 		if (buflen < tsz)
282 			tsz = buflen;
283 		elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
284 		if (!elf_buf) {
285 			read_unlock(&kclist_lock);
286 			return -ENOMEM;
287 		}
288 		elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
289 		read_unlock(&kclist_lock);
290 		if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
291 			kfree(elf_buf);
292 			return -EFAULT;
293 		}
294 		kfree(elf_buf);
295 		buflen -= tsz;
296 		*fpos += tsz;
297 		buffer += tsz;
298 		acc += tsz;
299 
300 		/* leave now if filled buffer already */
301 		if (buflen == 0)
302 			return acc;
303 	} else
304 		read_unlock(&kclist_lock);
305 
306 	/*
307 	 * Check to see if our file offset matches with any of
308 	 * the addresses in the elf_phdr on our list.
309 	 */
310 	start = kc_offset_to_vaddr(*fpos - elf_buflen);
311 	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
312 		tsz = buflen;
313 
314 	while (buflen) {
315 		struct kcore_list *m;
316 
317 		read_lock(&kclist_lock);
318 		for (m=kclist; m; m=m->next) {
319 			if (start >= m->addr && start < (m->addr+m->size))
320 				break;
321 		}
322 		read_unlock(&kclist_lock);
323 
324 		if (m == NULL) {
325 			if (clear_user(buffer, tsz))
326 				return -EFAULT;
327 		} else if (is_vmalloc_addr((void *)start)) {
328 			char * elf_buf;
329 			struct vm_struct *m;
330 			unsigned long curstart = start;
331 			unsigned long cursize = tsz;
332 
333 			elf_buf = kzalloc(tsz, GFP_KERNEL);
334 			if (!elf_buf)
335 				return -ENOMEM;
336 
337 			read_lock(&vmlist_lock);
338 			for (m=vmlist; m && cursize; m=m->next) {
339 				unsigned long vmstart;
340 				unsigned long vmsize;
341 				unsigned long msize = m->size - PAGE_SIZE;
342 
343 				if (((unsigned long)m->addr + msize) <
344 								curstart)
345 					continue;
346 				if ((unsigned long)m->addr > (curstart +
347 								cursize))
348 					break;
349 				vmstart = (curstart < (unsigned long)m->addr ?
350 					(unsigned long)m->addr : curstart);
351 				if (((unsigned long)m->addr + msize) >
352 							(curstart + cursize))
353 					vmsize = curstart + cursize - vmstart;
354 				else
355 					vmsize = (unsigned long)m->addr +
356 							msize - vmstart;
357 				curstart = vmstart + vmsize;
358 				cursize -= vmsize;
359 				/* don't dump ioremap'd stuff! (TA) */
360 				if (m->flags & VM_IOREMAP)
361 					continue;
362 				memcpy(elf_buf + (vmstart - start),
363 					(char *)vmstart, vmsize);
364 			}
365 			read_unlock(&vmlist_lock);
366 			if (copy_to_user(buffer, elf_buf, tsz)) {
367 				kfree(elf_buf);
368 				return -EFAULT;
369 			}
370 			kfree(elf_buf);
371 		} else {
372 			if (kern_addr_valid(start)) {
373 				unsigned long n;
374 
375 				n = copy_to_user(buffer, (char *)start, tsz);
376 				/*
377 				 * We cannot distingush between fault on source
378 				 * and fault on destination. When this happens
379 				 * we clear too and hope it will trigger the
380 				 * EFAULT again.
381 				 */
382 				if (n) {
383 					if (clear_user(buffer + tsz - n,
384 								n))
385 						return -EFAULT;
386 				}
387 			} else {
388 				if (clear_user(buffer, tsz))
389 					return -EFAULT;
390 			}
391 		}
392 		buflen -= tsz;
393 		*fpos += tsz;
394 		buffer += tsz;
395 		acc += tsz;
396 		start += tsz;
397 		tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
398 	}
399 
400 	return acc;
401 }
402