Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
module: Factor out elf_validity_ehdr
Factor out verification of the ELF header and document what is checked.
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
authored by
Matthew Maurer
and committed by
Luis Chamberlain
90f8f312
f4392216
+47
-23
+47
-23
kernel/module/main.c
+47
-23
kernel/module/main.c
···
1664
1664
return 0;
1665
1665
}
1666
1666
1667
+
/**
1668
+
* elf_validity_ehdr() - Checks an ELF header for module validity
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+
* @info: Load info containing the ELF header to check
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+
*
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* Checks whether an ELF header could belong to a valid module. Checks:
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*
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* * ELF header is within the data the user provided
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* * ELF magic is present
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* * It is relocatable (not final linked, not core file, etc.)
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* * The header's machine type matches what the architecture expects.
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* * Optional arch-specific hook for other properties
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* - module_elf_check_arch() is currently only used by PPC to check
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* ELF ABI version, but may be used by others in the future.
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*
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* Return: %0 if valid, %-ENOEXEC on failure.
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+
*/
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static int elf_validity_ehdr(const struct load_info *info)
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+
{
1685
+
if (info->len < sizeof(*(info->hdr))) {
1686
+
pr_err("Invalid ELF header len %lu\n", info->len);
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+
return -ENOEXEC;
1688
+
}
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+
if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) {
1690
+
pr_err("Invalid ELF header magic: != %s\n", ELFMAG);
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+
return -ENOEXEC;
1692
+
}
1693
+
if (info->hdr->e_type != ET_REL) {
1694
+
pr_err("Invalid ELF header type: %u != %u\n",
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+
info->hdr->e_type, ET_REL);
1696
+
return -ENOEXEC;
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+
}
1698
+
if (!elf_check_arch(info->hdr)) {
1699
+
pr_err("Invalid architecture in ELF header: %u\n",
1700
+
info->hdr->e_machine);
1701
+
return -ENOEXEC;
1702
+
}
1703
+
if (!module_elf_check_arch(info->hdr)) {
1704
+
pr_err("Invalid module architecture in ELF header: %u\n",
1705
+
info->hdr->e_machine);
1706
+
return -ENOEXEC;
1707
+
}
1708
+
return 0;
1709
+
}
1710
+
1667
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/*
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* Check userspace passed ELF module against our expectations, and cache
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* useful variables for further processing as we go.
···
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unsigned int num_info_secs = 0, info_idx;
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unsigned int num_sym_secs = 0, sym_idx;
1739
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1740
-
if (info->len < sizeof(*(info->hdr))) {
1741
-
pr_err("Invalid ELF header len %lu\n", info->len);
1742
-
goto no_exec;
1743
-
}
1696
+
err = elf_validity_ehdr(info);
1697
+
if (err < 0)
1698
+
return err;
1744
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1745
-
if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) {
1746
-
pr_err("Invalid ELF header magic: != %s\n", ELFMAG);
1747
-
goto no_exec;
1748
-
}
1749
-
if (info->hdr->e_type != ET_REL) {
1750
-
pr_err("Invalid ELF header type: %u != %u\n",
1751
-
info->hdr->e_type, ET_REL);
1752
-
goto no_exec;
1753
-
}
1754
-
if (!elf_check_arch(info->hdr)) {
1755
-
pr_err("Invalid architecture in ELF header: %u\n",
1756
-
info->hdr->e_machine);
1757
-
goto no_exec;
1758
-
}
1759
-
if (!module_elf_check_arch(info->hdr)) {
1760
-
pr_err("Invalid module architecture in ELF header: %u\n",
1761
-
info->hdr->e_machine);
1762
-
goto no_exec;
1763
-
}
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if (info->hdr->e_shentsize != sizeof(Elf_Shdr)) {
1765
1701
pr_err("Invalid ELF section header size\n");
1766
1702
goto no_exec;