From 948d0e24f33c3b411b5ec1e320acec889e6781b8 Mon Sep 17 00:00:00 2001

From: Vincent Mihalkovic <vmihalko@redhat.com>

Date: Mon, 6 Feb 2023 15:04:33 +0100

Subject: [PATCH] Improve detection of static-pie binaries, and don't call them

 "dynamically linked", but call them "static-pie" linked.

363d7fcf703ad3ebf37b45693b2c9e43eb8b4176

---

 src/readelf.c | 35 +++++++++++++++++++++++++----------

 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/src/readelf.c b/src/readelf.c

index 9c75c0a..0011659 100644

--- a/src/readelf.c

+++ b/src/readelf.c

@@ -1040,7 +1040,7 @@ do_auxv_note(struct magic_set *ms, unsigned char *nbuf, uint32_t type,

 private size_t

 dodynamic(struct magic_set *ms, void *vbuf, size_t offset, size_t size,

-    int clazz, int swap)

+    int clazz, int swap, int *pie, size_t *need)

 {

 	Elf32_Dyn dh32;

 	Elf64_Dyn dh64;

@@ -1058,11 +1058,15 @@ dodynamic(struct magic_set *ms, void *vbuf, size_t offset, size_t size,

 	switch (xdh_tag) {

 	case DT_FLAGS_1:

+                *pie = 1;

 		if (xdh_val & DF_1_PIE)

 			ms->mode |= 0111;

 		else

 			ms->mode &= ~0111;

 		break;

+        case DT_NEEDED:

+                (*need)++;

+                break;

 	default:

 		break;

 	}

@@ -1529,9 +1533,10 @@ doshn(struct magic_set *ms, int clazz, int swap, int fd, off_t off, int num,

 }

 /*

- * Look through the program headers of an executable image, searching

- * for a PT_INTERP section; if one is found, it's dynamically linked,

- * otherwise it's statically linked.

+ * Look through the program headers of an executable image, to determine

+ * if it is statically or dynamically linked. If it has a dynamic section,

+ * it is pie, and does not have an interpreter or needed libraries, we

+ * call it static pie.

  */

 private int

 dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

@@ -1540,12 +1545,13 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 {

 	Elf32_Phdr ph32;

 	Elf64_Phdr ph64;

-	const char *linking_style = "statically";

+	const char *linking_style;

 	unsigned char nbuf[BUFSIZ];

 	char ibuf[BUFSIZ];

 	char interp[BUFSIZ];

 	ssize_t bufsize;

-	size_t offset, align, len;

+	size_t offset, align, len, need = 0;

+        int pie = 0, dynamic = 0;

 	if (size != xph_sizeof) {

 		if (file_printf(ms, ", corrupted program header size") == -1)

@@ -1569,7 +1575,6 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 		/* Things we can determine before we seek */

 		switch (xph_type) {

 		case PT_DYNAMIC:

-			linking_style = "dynamically";

 			doread = 1;

 			break;

 		case PT_NOTE:

@@ -1610,6 +1615,7 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 		/* Things we can determine when we seek */

 		switch (xph_type) {

 		case PT_DYNAMIC:

+			dynamic = 1;

 			offset = 0;

                         // Let DF_1 determine if we are PIE or not.

                         ms->mode &= ~0111;

@@ -1617,7 +1623,8 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 				if (offset >= (size_t)bufsize)

 					break;

 				offset = dodynamic(ms, nbuf, offset,

-				    CAST(size_t, bufsize), clazz, swap);

+				    CAST(size_t, bufsize), clazz, swap,

+				    &pie, &need);

 				if (offset == 0)

 					break;

 			}

@@ -1626,6 +1633,7 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 			break;

 		case PT_INTERP:

+                        need++;

                         if (ms->flags & MAGIC_MIME)

                                 continue;

 			if (bufsize && nbuf[0]) {

@@ -1660,8 +1668,15 @@ dophn_exec(struct magic_set *ms, int clazz, int swap, int fd, off_t off,

 	}

 	if (ms->flags & MAGIC_MIME)

 		return 0;

-	if (file_printf(ms, ", %s linked", linking_style)

-	    == -1)

+	if (dynamic) {

+		if (pie && need == 0)

+			linking_style = "static-pie";

+		else

+			linking_style = "dynamically";

+	} else {

+		linking_style = "statically";

+	}

+	if (file_printf(ms, ", %s linked", linking_style) == -1)

 		return -1;

 	if (interp[0])

 		if (file_printf(ms, ", interpreter %s",

-- 

2.39.1