Add a link to the Elf_Brandinfo into the struc proc.

To allow the ABI to make a dicision based on the Brandinfo add a link
to the Elf_Brandinfo into the struct proc. Add a note that the high 8 bits
of Elf_Brandinfo flags is private to the ABI.

Note to MFC: it breaks KBI.

Reviewed by:		kib, markj
Differential Revision:	https://reviews.freebsd.org/D30918
MFC after:		2 weeks

5 files changed, 10 insertions, 2 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 8c56660b1fe4..98ce5460e360 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -1246,6 +1246,7 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 	map = &vmspace->vm_map;
 
 	imgp->proc->p_sysent = sv;
+	imgp->proc->p_elf_brandinfo = brand_info;
 
 	maxv = vm_map_max(map) - lim_max(td, RLIMIT_STACK);
 	if (et_dyn_addr == ET_DYN_ADDR_RAND) {
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
index b091d6061616..aff030cd432e 100644
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -397,6 +397,7 @@ do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
 #endif
 	int error, i, orig_osrel;
 	uint32_t orig_fctl0;
+	Elf_Brandinfo *orig_brandinfo;
 	static const char fexecv_proc_title[] = "(fexecv)";
 
 	imgp = &image_params;
@@ -427,6 +428,7 @@ do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
 	oldcred = p->p_ucred;
 	orig_osrel = p->p_osrel;
 	orig_fctl0 = p->p_fctl0;
+	orig_brandinfo = p->p_elf_brandinfo;
 
 #ifdef MAC
 	error = mac_execve_enter(imgp, mac_p);
@@ -499,6 +501,7 @@ interpret:
 
 	imgp->proc->p_osrel = 0;
 	imgp->proc->p_fctl0 = 0;
+	imgp->proc->p_elf_brandinfo = NULL;
 
 	/*
 	 * Implement image setuid/setgid.
@@ -894,6 +897,7 @@ exec_fail_dealloc:
 	if (error != 0) {
 		p->p_osrel = orig_osrel;
 		p->p_fctl0 = orig_fctl0;
+		p->p_elf_brandinfo = orig_brandinfo;
 	}
 
 	if (imgp->firstpage != NULL)
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index 949095a4d34e..3afcf2d3f0ef 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -100,7 +100,7 @@ _Static_assert(offsetof(struct proc, p_filemon) == 0x3b8,
     "struct proc KBI p_filemon");
 _Static_assert(offsetof(struct proc, p_comm) == 0x3d0,
     "struct proc KBI p_comm");
-_Static_assert(offsetof(struct proc, p_emuldata) == 0x4b0,
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x4b8,
     "struct proc KBI p_emuldata");
 #endif
 #ifdef __i386__
@@ -120,7 +120,7 @@ _Static_assert(offsetof(struct proc, p_filemon) == 0x268,
     "struct proc KBI p_filemon");
 _Static_assert(offsetof(struct proc, p_comm) == 0x27c,
     "struct proc KBI p_comm");
-_Static_assert(offsetof(struct proc, p_emuldata) == 0x308,
+_Static_assert(offsetof(struct proc, p_emuldata) == 0x30c,
     "struct proc KBI p_emuldata");
 #endif
 
diff --git a/sys/sys/imgact_elf.h b/sys/sys/imgact_elf.h
index 44a860359a75..97383c6eeeb8 100644
--- a/sys/sys/imgact_elf.h
+++ b/sys/sys/imgact_elf.h
@@ -91,6 +91,7 @@ typedef struct {
 	Elf_Brandnote *brand_note;
 	boolean_t	(*header_supported)(struct image_params *,
 	    int32_t *, uint32_t *);
+		/* High 8 bits of flags is private to the ABI */
 #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. */
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index ef27691ae4cd..36c07b3b5e78 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -702,6 +702,8 @@ struct proc {
 					       our subtree. */
 	uint16_t	p_elf_machine;	/* (x) ELF machine type */
 	uint64_t	p_elf_flags;	/* (x) ELF flags */
+	void		*p_elf_brandinfo; /* (x) Elf_Brandinfo, NULL for
+						 non ELF binaries. */
 /* End area that is copied on creation. */
 #define	p_endcopy	p_xexit