summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorDave Martin <Dave.Martin@arm.com>2020-03-16 16:50:46 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2020-03-16 17:19:48 +0000
commitfe0f67660ee9c99408be5261ae045f8b41953b05 (patch)
tree77feaf03e85c305c35b45d870da4c473f1c0531e
parent8ef8f360cf30be12382f89ff48a57fbbd9b31c14 (diff)
elf: Allow arch to tweak initial mmap prot flags
An arch may want to tweak the mmap prot flags for an ELFexecutable's initial mappings. For example, arm64 is going to need to add PROT_BTI for executable pages in an ELF process whose executable is marked as using Branch Target Identification (an ARMv8.5-A control flow integrity feature). So that this can be done in a generic way, add a hook arch_elf_adjust_prot() to modify the prot flags as desired: arches can select CONFIG_HAVE_ELF_PROT and implement their own backend where necessary. By default, leave the prot flags unchanged. Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--fs/Kconfig.binfmt3
-rw-r--r--fs/binfmt_elf.c18
-rw-r--r--include/linux/elf.h12
3 files changed, 27 insertions, 6 deletions
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index d2cfe0729a73..2358368319b8 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -36,6 +36,9 @@ config COMPAT_BINFMT_ELF
config ARCH_BINFMT_ELF_STATE
bool
+config ARCH_HAVE_ELF_PROT
+ bool
+
config ARCH_USE_GNU_PROPERTY
bool
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 1fb67e506b68..cceb29d6ef1d 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -544,7 +544,8 @@ static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp,
#endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */
-static inline int make_prot(u32 p_flags)
+static inline int make_prot(u32 p_flags, struct arch_elf_state *arch_state,
+ bool has_interp, bool is_interp)
{
int prot = 0;
@@ -554,7 +555,8 @@ static inline int make_prot(u32 p_flags)
prot |= PROT_WRITE;
if (p_flags & PF_X)
prot |= PROT_EXEC;
- return prot;
+
+ return arch_elf_adjust_prot(prot, arch_state, has_interp, is_interp);
}
/* This is much more generalized than the library routine read function,
@@ -564,7 +566,8 @@ static inline int make_prot(u32 p_flags)
static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
struct file *interpreter,
- unsigned long no_base, struct elf_phdr *interp_elf_phdata)
+ unsigned long no_base, struct elf_phdr *interp_elf_phdata,
+ struct arch_elf_state *arch_state)
{
struct elf_phdr *eppnt;
unsigned long load_addr = 0;
@@ -596,7 +599,8 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) {
if (eppnt->p_type == PT_LOAD) {
int elf_type = MAP_PRIVATE | MAP_DENYWRITE;
- int elf_prot = make_prot(eppnt->p_flags);
+ int elf_prot = make_prot(eppnt->p_flags, arch_state,
+ true, true);
unsigned long vaddr = 0;
unsigned long k, map_addr;
@@ -1041,7 +1045,8 @@ out_free_interp:
}
}
- elf_prot = make_prot(elf_ppnt->p_flags);
+ elf_prot = make_prot(elf_ppnt->p_flags, &arch_state,
+ !!interpreter, false);
elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE;
@@ -1184,7 +1189,8 @@ out_free_interp:
if (interpreter) {
elf_entry = load_elf_interp(&loc->interp_elf_ex,
interpreter,
- load_bias, interp_elf_phdata);
+ load_bias, interp_elf_phdata,
+ &arch_state);
if (!IS_ERR((void *)elf_entry)) {
/*
* load_elf_interp() returns relocation
diff --git a/include/linux/elf.h b/include/linux/elf.h
index db5113479f5e..5d5b0321da0b 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -87,4 +87,16 @@ extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz,
bool compat, struct arch_elf_state *arch);
#endif
+#ifdef CONFIG_ARCH_HAVE_ELF_PROT
+int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state,
+ bool has_interp, bool is_interp);
+#else
+static inline int arch_elf_adjust_prot(int prot,
+ const struct arch_elf_state *state,
+ bool has_interp, bool is_interp)
+{
+ return prot;
+}
+#endif
+
#endif /* _LINUX_ELF_H */