Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
modules: Support extended MODVERSIONS info
Adds a new format for MODVERSIONS which stores each field in a separate
ELF section. This initially adds support for variable length names, but
could later be used to add additional fields to MODVERSIONS in a
backwards compatible way if needed. Any new fields will be ignored by
old user tooling, unlike the current format where user tooling cannot
tolerate adjustments to the format (for example making the name field
longer).
Since PPC munges its version records to strip leading dots, we reproduce
the munging for the new format. Other architectures do not appear to
have architecture-specific usage of this information.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
authored by
Matthew Maurer
and committed by
Masahiro Yamada
54ac1ac8
8c6d7b41
+162
-10
+22
-2
arch/powerpc/kernel/module_64.c
+22
-2
arch/powerpc/kernel/module_64.c
···
369
369
}
370
370
}
371
371
372
+
/* Same as normal versions, remove a leading dot if present. */
373
+
static void dedotify_ext_version_names(char *str_seq, unsigned long size)
374
+
{
375
+
unsigned long out = 0;
376
+
unsigned long in;
377
+
char last = '\0';
378
+
379
+
for (in = 0; in < size; in++) {
380
+
/* Skip one leading dot */
381
+
if (last == '\0' && str_seq[in] == '.')
382
+
in++;
383
+
last = str_seq[in];
384
+
str_seq[out++] = last;
385
+
}
386
+
/* Zero the trailing portion of the names table for robustness */
387
+
memset(&str_seq[out], 0, size - out);
388
+
}
389
+
372
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/*
373
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* Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
374
392
* seem to be defined (value set later).
···
456
438
me->arch.toc_section = i;
457
439
if (sechdrs[i].sh_addralign < 8)
458
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sechdrs[i].sh_addralign = 8;
459
-
}
460
-
else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
441
+
} else if (strcmp(secstrings + sechdrs[i].sh_name, "__versions") == 0)
461
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dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
462
443
sechdrs[i].sh_size);
444
+
else if (strcmp(secstrings + sechdrs[i].sh_name, "__version_ext_names") == 0)
445
+
dedotify_ext_version_names((void *)hdr + sechdrs[i].sh_offset,
446
+
sechdrs[i].sh_size);
463
447
464
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if (sechdrs[i].sh_type == SHT_SYMTAB)
465
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dedotify((void *)hdr + sechdrs[i].sh_offset,
+11
kernel/module/internal.h
+11
kernel/module/internal.h
···
86
86
unsigned int vers;
87
87
unsigned int info;
88
88
unsigned int pcpu;
89
+
unsigned int vers_ext_crc;
90
+
unsigned int vers_ext_name;
89
91
} index;
90
92
};
91
93
···
391
389
struct kernel_symbol *ks, struct tracepoint * const *tp);
392
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int check_modstruct_version(const struct load_info *info, struct module *mod);
393
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int same_magic(const char *amagic, const char *bmagic, bool has_crcs);
392
+
struct modversion_info_ext {
393
+
size_t remaining;
394
+
const u32 *crc;
395
+
const char *name;
396
+
};
397
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void modversion_ext_start(const struct load_info *info, struct modversion_info_ext *ver);
398
+
void modversion_ext_advance(struct modversion_info_ext *ver);
399
+
#define for_each_modversion_info_ext(ver, info) \
400
+
for (modversion_ext_start(info, &ver); ver.remaining > 0; modversion_ext_advance(&ver))
394
401
#else /* !CONFIG_MODVERSIONS */
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402
static inline int check_version(const struct load_info *info,
396
403
const char *symname,
+84
-8
kernel/module/main.c
+84
-8
kernel/module/main.c
···
2074
2074
}
2075
2075
2076
2076
/**
2077
+
* elf_validity_cache_index_versions() - Validate and cache version indices
2078
+
* @info: Load info to cache version indices in.
2079
+
* Must have &load_info->sechdrs and &load_info->secstrings populated.
2080
+
* @flags: Load flags, relevant to suppress version loading, see
2081
+
* uapi/linux/module.h
2082
+
*
2083
+
* If we're ignoring modversions based on @flags, zero all version indices
2084
+
* and return validity. Othewrise check:
2085
+
*
2086
+
* * If "__version_ext_crcs" is present, "__version_ext_names" is present
2087
+
* * There is a name present for every crc
2088
+
*
2089
+
* Then populate:
2090
+
*
2091
+
* * &load_info->index.vers
2092
+
* * &load_info->index.vers_ext_crc
2093
+
* * &load_info->index.vers_ext_names
2094
+
*
2095
+
* if present.
2096
+
*
2097
+
* Return: %0 if valid, %-ENOEXEC on failure.
2098
+
*/
2099
+
static int elf_validity_cache_index_versions(struct load_info *info, int flags)
2100
+
{
2101
+
unsigned int vers_ext_crc;
2102
+
unsigned int vers_ext_name;
2103
+
size_t crc_count;
2104
+
size_t remaining_len;
2105
+
size_t name_size;
2106
+
char *name;
2107
+
2108
+
/* If modversions were suppressed, pretend we didn't find any */
2109
+
if (flags & MODULE_INIT_IGNORE_MODVERSIONS) {
2110
+
info->index.vers = 0;
2111
+
info->index.vers_ext_crc = 0;
2112
+
info->index.vers_ext_name = 0;
2113
+
return 0;
2114
+
}
2115
+
2116
+
vers_ext_crc = find_sec(info, "__version_ext_crcs");
2117
+
vers_ext_name = find_sec(info, "__version_ext_names");
2118
+
2119
+
/* If we have one field, we must have the other */
2120
+
if (!!vers_ext_crc != !!vers_ext_name) {
2121
+
pr_err("extended version crc+name presence does not match");
2122
+
return -ENOEXEC;
2123
+
}
2124
+
2125
+
/*
2126
+
* If we have extended version information, we should have the same
2127
+
* number of entries in every section.
2128
+
*/
2129
+
if (vers_ext_crc) {
2130
+
crc_count = info->sechdrs[vers_ext_crc].sh_size / sizeof(u32);
2131
+
name = (void *)info->hdr +
2132
+
info->sechdrs[vers_ext_name].sh_offset;
2133
+
remaining_len = info->sechdrs[vers_ext_name].sh_size;
2134
+
2135
+
while (crc_count--) {
2136
+
name_size = strnlen(name, remaining_len) + 1;
2137
+
if (name_size > remaining_len) {
2138
+
pr_err("more extended version crcs than names");
2139
+
return -ENOEXEC;
2140
+
}
2141
+
remaining_len -= name_size;
2142
+
name += name_size;
2143
+
}
2144
+
}
2145
+
2146
+
info->index.vers = find_sec(info, "__versions");
2147
+
info->index.vers_ext_crc = vers_ext_crc;
2148
+
info->index.vers_ext_name = vers_ext_name;
2149
+
return 0;
2150
+
}
2151
+
2152
+
/**
2077
2153
* elf_validity_cache_index() - Resolve, validate, cache section indices
2078
2154
* @info: Load info to read from and update.
2079
2155
* &load_info->sechdrs and &load_info->secstrings must be populated.
···
2163
2087
* * elf_validity_cache_index_mod()
2164
2088
* * elf_validity_cache_index_sym()
2165
2089
* * elf_validity_cache_index_str()
2166
-
*
2167
-
* If versioning is not suppressed via flags, load the version index from
2168
-
* a section called "__versions" with no validation.
2090
+
* * elf_validity_cache_index_versions()
2169
2091
*
2170
2092
* If CONFIG_SMP is enabled, load the percpu section by name with no
2171
2093
* validation.
···
2186
2112
err = elf_validity_cache_index_str(info);
2187
2113
if (err < 0)
2188
2114
return err;
2189
-
2190
-
if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
2191
-
info->index.vers = 0; /* Pretend no __versions section! */
2192
-
else
2193
-
info->index.vers = find_sec(info, "__versions");
2115
+
err = elf_validity_cache_index_versions(info, flags);
2116
+
if (err < 0)
2117
+
return err;
2194
2118
2195
2119
info->index.pcpu = find_pcpusec(info);
2196
2120
···
2399
2327
2400
2328
/* Track but don't keep modinfo and version sections. */
2401
2329
info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
2330
+
info->sechdrs[info->index.vers_ext_crc].sh_flags &=
2331
+
~(unsigned long)SHF_ALLOC;
2332
+
info->sechdrs[info->index.vers_ext_name].sh_flags &=
2333
+
~(unsigned long)SHF_ALLOC;
2402
2334
info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
2403
2335
2404
2336
return 0;
+45
kernel/module/version.c
+45
kernel/module/version.c
···
19
19
unsigned int versindex = info->index.vers;
20
20
unsigned int i, num_versions;
21
21
struct modversion_info *versions;
22
+
struct modversion_info_ext version_ext;
22
23
23
24
/* Exporting module didn't supply crcs? OK, we're already tainted. */
24
25
if (!crc)
25
26
return 1;
27
+
28
+
/* If we have extended version info, rely on it */
29
+
if (info->index.vers_ext_crc) {
30
+
for_each_modversion_info_ext(version_ext, info) {
31
+
if (strcmp(version_ext.name, symname) != 0)
32
+
continue;
33
+
if (*version_ext.crc == *crc)
34
+
return 1;
35
+
pr_debug("Found checksum %X vs module %X\n",
36
+
*crc, *version_ext.crc);
37
+
goto bad_version;
38
+
}
39
+
pr_warn_once("%s: no extended symbol version for %s\n",
40
+
info->name, symname);
41
+
return 1;
42
+
}
26
43
27
44
/* No versions at all? modprobe --force does this. */
28
45
if (versindex == 0)
···
102
85
bmagic += strcspn(bmagic, " ");
103
86
}
104
87
return strcmp(amagic, bmagic) == 0;
88
+
}
89
+
90
+
void modversion_ext_start(const struct load_info *info,
91
+
struct modversion_info_ext *start)
92
+
{
93
+
unsigned int crc_idx = info->index.vers_ext_crc;
94
+
unsigned int name_idx = info->index.vers_ext_name;
95
+
Elf_Shdr *sechdrs = info->sechdrs;
96
+
97
+
/*
98
+
* Both of these fields are needed for this to be useful
99
+
* Any future fields should be initialized to NULL if absent.
100
+
*/
101
+
if (crc_idx == 0 || name_idx == 0) {
102
+
start->remaining = 0;
103
+
return;
104
+
}
105
+
106
+
start->crc = (const u32 *)sechdrs[crc_idx].sh_addr;
107
+
start->name = (const char *)sechdrs[name_idx].sh_addr;
108
+
start->remaining = sechdrs[crc_idx].sh_size / sizeof(*start->crc);
109
+
}
110
+
111
+
void modversion_ext_advance(struct modversion_info_ext *vers)
112
+
{
113
+
vers->remaining--;
114
+
vers->crc++;
115
+
vers->name += strlen(vers->name) + 1;
105
116
}
106
117
107
118
/*