Improvements for the brand detection and prioritization.

MFC r315701 (by ed):
Set the interpreter path to /nonexistent.

MFC r315749:
Adjust r314851 to not require every brand to specify interpreter path.

MFC r315753:
Add a flag BI_BRAND_ONLY_STATIC to specify that the brand only
matches static binaries.

MFC r315754:
Update r315753 with the proper flag name.

MFC r316211:
A followup to r315749, two more places where brand->interp_path was
accessed unconditionally.

7 files changed, 26 insertions, 9 deletions

diff --git a/sys/amd64/cloudabi32/cloudabi32_sysvec.c b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
index fa2f9ae..abede1a 100644
--- a/sys/amd64/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
@@ -227,4 +227,5 @@ Elf32_Brandinfo cloudabi32_brand = {
 	.brand		= ELFOSABI_CLOUDABI,
 	.machine	= EM_386,
 	.sysvec		= &cloudabi32_elf_sysvec,
+	.flags		= BI_BRAND_ONLY_STATIC,
 };
diff --git a/sys/amd64/cloudabi64/cloudabi64_sysvec.c b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
index 3a21ff3..84f0cb3 100644
--- a/sys/amd64/cloudabi64/cloudabi64_sysvec.c
+++ b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
@@ -212,5 +212,5 @@ Elf64_Brandinfo cloudabi64_brand = {
 	.brand		= ELFOSABI_CLOUDABI,
 	.machine	= EM_X86_64,
 	.sysvec		= &cloudabi64_elf_sysvec,
-	.flags		= BI_CAN_EXEC_DYN,
+	.flags		= BI_CAN_EXEC_DYN | BI_BRAND_ONLY_STATIC,
 };
diff --git a/sys/arm/cloudabi32/cloudabi32_sysvec.c b/sys/arm/cloudabi32/cloudabi32_sysvec.c
index f4e231b..100fa47 100644
--- a/sys/arm/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/arm/cloudabi32/cloudabi32_sysvec.c
@@ -189,4 +189,5 @@ Elf32_Brandinfo cloudabi32_brand = {
 	.brand		= ELFOSABI_CLOUDABI,
 	.machine	= EM_ARM,
 	.sysvec		= &cloudabi32_elf_sysvec,
+	.flags		= BI_BRAND_ONLY_STATIC,
 };
diff --git a/sys/arm64/cloudabi64/cloudabi64_sysvec.c b/sys/arm64/cloudabi64/cloudabi64_sysvec.c
index fc786de..fbad0ba 100644
--- a/sys/arm64/cloudabi64/cloudabi64_sysvec.c
+++ b/sys/arm64/cloudabi64/cloudabi64_sysvec.c
@@ -181,5 +181,5 @@ Elf64_Brandinfo cloudabi64_brand = {
 	.brand		= ELFOSABI_CLOUDABI,
 	.machine	= EM_AARCH64,
 	.sysvec		= &cloudabi64_elf_sysvec,
-	.flags		= BI_CAN_EXEC_DYN,
+	.flags		= BI_CAN_EXEC_DYN | BI_BRAND_ONLY_STATIC,
 };
diff --git a/sys/i386/cloudabi32/cloudabi32_sysvec.c b/sys/i386/cloudabi32/cloudabi32_sysvec.c
index 45b9e5c..c2a21fa 100644
--- a/sys/i386/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/i386/cloudabi32/cloudabi32_sysvec.c
@@ -200,4 +200,5 @@ Elf32_Brandinfo cloudabi32_brand = {
 	.brand		= ELFOSABI_CLOUDABI,
 	.machine	= EM_386,
 	.sysvec		= &cloudabi32_elf_sysvec,
+	.flags		= BI_BRAND_ONLY_STATIC,
 };
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 33a31c0..491b9dd 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -273,6 +273,8 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 		bi = elf_brand_list[i];
 		if (bi == NULL)
 			continue;
+		if (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0)
+			continue;
 		if (hdr->e_machine == bi->machine && (bi->flags &
 		    (BI_BRAND_NOTE|BI_BRAND_NOTE_MANDATORY)) != 0) {
 			ret = __elfN(check_note)(imgp, bi->brand_note, osrel);
@@ -289,9 +291,11 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 			 * this, we return first brand which accepted
 			 * our note and, optionally, header.
 			 */
-			if (ret && bi_m == NULL && (strlen(bi->interp_path) +
-			    1 != interp_name_len || strncmp(interp,
-			    bi->interp_path, interp_name_len) != 0)) {
+			if (ret && bi_m == NULL && interp != NULL &&
+			    (bi->interp_path == NULL ||
+			    (strlen(bi->interp_path) + 1 != interp_name_len ||
+			    strncmp(interp, bi->interp_path, interp_name_len)
+			    != 0))) {
 				bi_m = bi;
 				ret = 0;
 			}
@@ -305,7 +309,8 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 	/* If the executable has a brand, search for it in the brand list. */
 	for (i = 0; i < MAX_BRANDS; i++) {
 		bi = elf_brand_list[i];
-		if (bi == NULL || bi->flags & BI_BRAND_NOTE_MANDATORY)
+		if (bi == NULL || (bi->flags & BI_BRAND_NOTE_MANDATORY) != 0 ||
+		    (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0))
 			continue;
 		if (hdr->e_machine == bi->machine &&
 		    (hdr->e_ident[EI_OSABI] == bi->brand ||
@@ -319,7 +324,11 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 				 * Again, prefer strictly matching
 				 * interpreter path.
 				 */
-				if (strlen(bi->interp_path) + 1 ==
+				if (interp_name_len == 0 &&
+				    bi->interp_path == NULL)
+					return (bi);
+				if (bi->interp_path != NULL &&
+				    strlen(bi->interp_path) + 1 ==
 				    interp_name_len && strncmp(interp,
 				    bi->interp_path, interp_name_len) == 0)
 					return (bi);
@@ -348,9 +357,12 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 	if (interp != NULL) {
 		for (i = 0; i < MAX_BRANDS; i++) {
 			bi = elf_brand_list[i];
-			if (bi == NULL || bi->flags & BI_BRAND_NOTE_MANDATORY)
+			if (bi == NULL || (bi->flags &
+			    (BI_BRAND_NOTE_MANDATORY | BI_BRAND_ONLY_STATIC))
+			    != 0)
 				continue;
 			if (hdr->e_machine == bi->machine &&
+			    bi->interp_path != NULL &&
 			    /* ELF image p_filesz includes terminating zero */
 			    strlen(bi->interp_path) + 1 == interp_name_len &&
 			    strncmp(interp, bi->interp_path, interp_name_len)
@@ -362,7 +374,8 @@ __elfN(get_brandinfo)(struct image_params *imgp, const char *interp,
 	/* Lacking a recognized interpreter, try the default brand */
 	for (i = 0; i < MAX_BRANDS; i++) {
 		bi = elf_brand_list[i];
-		if (bi == NULL || bi->flags & BI_BRAND_NOTE_MANDATORY)
+		if (bi == NULL || (bi->flags & BI_BRAND_NOTE_MANDATORY) != 0 ||
+		    (interp != NULL && (bi->flags & BI_BRAND_ONLY_STATIC) != 0))
 			continue;
 		if (hdr->e_machine == bi->machine &&
 		    __elfN(fallback_brand) == bi->brand)
diff --git a/sys/sys/imgact_elf.h b/sys/sys/imgact_elf.h
index 0ec04fc..40ad7c7 100644
--- a/sys/sys/imgact_elf.h
+++ b/sys/sys/imgact_elf.h
@@ -81,6 +81,7 @@ typedef struct {
 #define	BI_CAN_EXEC_DYN		0x0001
 #define	BI_BRAND_NOTE		0x0002	/* May have note.ABI-tag section. */
 #define	BI_BRAND_NOTE_MANDATORY	0x0004	/* Must have note.ABI-tag section. */
+#define	BI_BRAND_ONLY_STATIC	0x0008	/* Match only interp-less binaries. */
 } __ElfN(Brandinfo);
 
 __ElfType(Auxargs);