kexec-tools: Add a new parameter to generic elf parsing functions

o Adding a new parameter to elf functions. This flag can be used to alter
  the function behaviour. Currently only one bit is being used for skipping
  the elf file len check while builing the elf info.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 15 insertions, 9 deletions

diff --git a/kexec/kexec-elf.c b/kexec/kexec-elf.c
index da2c788..929c79c 100644
--- a/kexec/kexec-elf.c
+++ b/kexec/kexec-elf.c
@@ -368,7 +368,8 @@ static int build_mem_elf64_phdr(const char *buf, off_t len,
 	return 0;
 }
 
-static int build_mem_phdrs(const char *buf, off_t len, struct mem_ehdr *ehdr)
+static int build_mem_phdrs(const char *buf, off_t len, struct mem_ehdr *ehdr,
+				uint32_t flags)
 {
 	size_t phdr_size, mem_phdr_size;
 	int i;
@@ -418,9 +419,11 @@ static int build_mem_phdrs(const char *buf, off_t len, struct mem_ehdr *ehdr)
 
 		/* Check the program headers to be certain
 		 * they are safe to use.
+		 * Skip the check if ELF_SKIP_FILESZ_CHECK is set.
 		 */
 		phdr = &ehdr->e_phdr[i];
-		if ((phdr->p_offset + phdr->p_filesz) > len) {
+		if (!(flags & ELF_SKIP_FILESZ_CHECK)
+			&& (phdr->p_offset + phdr->p_filesz) > len) {
 			/* The segment does not fit in the buffer */
 			if (probe_debug) {
 				fprintf(stderr, "ELF segment not in file\n");
@@ -580,7 +583,8 @@ static int build_mem_elf64_shdr(const char *buf, off_t len,
 	return 0;
 }
 
-static int build_mem_shdrs(const char *buf, off_t len, struct mem_ehdr *ehdr)
+static int build_mem_shdrs(const char *buf, off_t len, struct mem_ehdr *ehdr,
+				uint32_t flags)
 {
 	size_t shdr_size, mem_shdr_size;
 	int i;
@@ -628,11 +632,12 @@ static int build_mem_shdrs(const char *buf, off_t len, struct mem_ehdr *ehdr)
 		}
 		/* Check the section headers to be certain
 		 * they are safe to use.
+		 * Skip the check if ELF_SKIP_FILESZ_CHECK is set.
 		 */
 		shdr = &ehdr->e_shdr[i];
-		if ((shdr->sh_type != SHT_NOBITS) &&
-			((shdr->sh_offset + shdr->sh_size) > len))
-		{
+		if (!(flags & ELF_SKIP_FILESZ_CHECK)
+			&& (shdr->sh_type != SHT_NOBITS)
+			&& (shdr->sh_offset + shdr->sh_size) > len) {
 			/* The section does not fit in the buffer */
 			if (probe_debug) {
 				fprintf(stderr, "ELF section %d not in file\n",
@@ -729,7 +734,8 @@ void free_elf_info(struct mem_ehdr *ehdr)
 	memset(ehdr, 0, sizeof(*ehdr));
 }
 
-int build_elf_info(const char *buf, off_t len, struct mem_ehdr *ehdr)
+int build_elf_info(const char *buf, off_t len, struct mem_ehdr *ehdr,
+			uint32_t flags)
 {
 	int result;
 	result = build_mem_ehdr(buf, len, ehdr);
@@ -737,14 +743,14 @@ int build_elf_info(const char *buf, off_t len, struct mem_ehdr *ehdr)
 		return result;
 	}
 	if ((ehdr->e_phoff > 0) && (ehdr->e_phnum > 0)) {
-		result = build_mem_phdrs(buf, len, ehdr);
+		result = build_mem_phdrs(buf, len, ehdr, flags);
 		if (result < 0) {
 			free_elf_info(ehdr);
 			return result;
 		}
 	}
 	if ((ehdr->e_shoff > 0) && (ehdr->e_shnum > 0)) {
-		result = build_mem_shdrs(buf, len, ehdr);
+		result = build_mem_shdrs(buf, len, ehdr, flags);
 		if (result < 0) {
 			free_elf_info(ehdr);
 			return result;