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authorRichard Henderson <rth@twiddle.net>2010-07-27 10:25:34 -0700
committerEdgar E. Iglesias <edgar.iglesias@gmail.com>2010-07-29 08:32:28 +0200
commit9058abdd180843473d440958c79a1a781be723c1 (patch)
treeb96ffd72f01794a58d14e8b0dcccc32cbe6f4bac /linux-user/elfload.c
parent682674b84189d0cd1426eb9b9d4b6b0d4c24be52 (diff)
linux-user: Improve consistency checking in elf headers.
Validate more fields of the elf header. Extract those checks into two common functions to be used in both load_elf_interp and load_elf_binary. Signed-off-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Diffstat (limited to 'linux-user/elfload.c')
-rw-r--r--linux-user/elfload.c57
1 files changed, 33 insertions, 24 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 6b57a91a3e..86872b27df 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -919,6 +919,30 @@ static int elf_core_dump(int, const CPUState *);
#endif /* USE_ELF_CORE_DUMP */
static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias);
+/* Verify the portions of EHDR within E_IDENT for the target.
+ This can be performed before bswapping the entire header. */
+static bool elf_check_ident(struct elfhdr *ehdr)
+{
+ return (ehdr->e_ident[EI_MAG0] == ELFMAG0
+ && ehdr->e_ident[EI_MAG1] == ELFMAG1
+ && ehdr->e_ident[EI_MAG2] == ELFMAG2
+ && ehdr->e_ident[EI_MAG3] == ELFMAG3
+ && ehdr->e_ident[EI_CLASS] == ELF_CLASS
+ && ehdr->e_ident[EI_DATA] == ELF_DATA
+ && ehdr->e_ident[EI_VERSION] == EV_CURRENT);
+}
+
+/* Verify the portions of EHDR outside of E_IDENT for the target.
+ This has to wait until after bswapping the header. */
+static bool elf_check_ehdr(struct elfhdr *ehdr)
+{
+ return (elf_check_arch(ehdr->e_machine)
+ && ehdr->e_ehsize == sizeof(struct elfhdr)
+ && ehdr->e_phentsize == sizeof(struct elf_phdr)
+ && ehdr->e_shentsize == sizeof(struct elf_shdr)
+ && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN));
+}
+
/*
* 'copy_elf_strings()' copies argument/envelope strings from user
* memory to free pages in kernel mem. These are in a format ready
@@ -1150,33 +1174,16 @@ static abi_ulong load_elf_interp(struct elfhdr * interp_elf_ex,
int i;
bswap_ehdr(interp_elf_ex);
- /* First of all, some simple consistency checks */
- if ((interp_elf_ex->e_type != ET_EXEC &&
- interp_elf_ex->e_type != ET_DYN) ||
- !elf_check_arch(interp_elf_ex->e_machine)) {
+ if (!elf_check_ehdr(interp_elf_ex)) {
return ~((abi_ulong)0UL);
}
/* Now read in all of the header information */
-
- if (sizeof(struct elf_phdr) * interp_elf_ex->e_phnum > TARGET_PAGE_SIZE)
- return ~(abi_ulong)0UL;
-
elf_phdata = (struct elf_phdr *)
malloc(sizeof(struct elf_phdr) * interp_elf_ex->e_phnum);
-
if (!elf_phdata)
return ~((abi_ulong)0UL);
- /*
- * If the size of this structure has changed, then punt, since
- * we will be doing the wrong thing.
- */
- if (interp_elf_ex->e_phentsize != sizeof(struct elf_phdr)) {
- free(elf_phdata);
- return ~((abi_ulong)0UL);
- }
-
i = interp_elf_ex->e_phnum * sizeof(struct elf_phdr);
if (interp_elf_ex->e_phoff + i <= BPRM_BUF_SIZE) {
memcpy(elf_phdata, bprm_buf + interp_elf_ex->e_phoff, i);
@@ -1428,11 +1435,13 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
load_addr = 0;
load_bias = 0;
elf_ex = *((struct elfhdr *) bprm->buf); /* exec-header */
- bswap_ehdr(&elf_ex);
/* First of all, some simple consistency checks */
- if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
- (! elf_check_arch(elf_ex.e_machine))) {
+ if (!elf_check_ident(&elf_ex)) {
+ return -ENOEXEC;
+ }
+ bswap_ehdr(&elf_ex);
+ if (!elf_check_ehdr(&elf_ex)) {
return -ENOEXEC;
}
@@ -1444,7 +1453,8 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
}
/* Now read in all of the header information */
- elf_phdata = (struct elf_phdr *)malloc(elf_ex.e_phentsize*elf_ex.e_phnum);
+ elf_phdata = (struct elf_phdr *)
+ malloc(elf_ex.e_phnum * sizeof(struct elf_phdr));
if (elf_phdata == NULL) {
return -ENOMEM;
}
@@ -1549,8 +1559,7 @@ int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
interpreter_type = INTERPRETER_ELF;
}
- if (interp_elf_ex.e_ident[0] != 0x7f ||
- strncmp((char *)&interp_elf_ex.e_ident[1], "ELF",3) != 0) {
+ if (!elf_check_ident(&interp_elf_ex)) {
interpreter_type &= ~INTERPRETER_ELF;
}