Hi,
This patch series addresses the VM_READ_CAPS/VM_WRITE_CAPS flags issue:
https://git.morello-project.org/morello/kernel/linux/-/issues/36
io_uring system uses buffers shared with userspace to read the io events
and report their results. The structs that populate the submission and
completion queues can contain capabilities. Shared mappings don't have
the Load/Store capabilities permission to avoid leaking capabilities
outside their original address space, so add two new VM flags that would
allow the kernel to set up such mappings.
While at it, also fix pte_modify to allow setting PTE_*_CAPS flags, add
new the new rc/wc smaps flags, and remove the automatic addition of
PTE_*_CAPS to user mappings.
To note: this wouldn't allow userspace to make arbitrary shared mappings
with tag access, the new VM flags would be for internal use only for the
time being.
v2:
- Removed Patch 1 from the series as it wasn't essential
- Added docs to Documentation/filesystems/proc.rst
- Removed VM_RW_CAPS
- Moved definition of VM_*_CAPS just after the definition of VM_MTE
- Added details for a TODO related to file-backed mappings
- Introduced Patch 3 that removes an assumption about shared mappings
Review branch:
https://git.morello-project.org/tudcre01/linux/-/commits/vm_rw_caps_v2/
Thanks,
Tudor
Tudor Cretu (3):
arm64: morello: Add VM_READ_CAPS and VM_WRITE_CAPS flags
arm64: morello: Explicitly add VM_*_CAPS to private user mappings
arm64: morello: Check against VM_WRITE_CAPS in access_remote_cap
Documentation/filesystems/proc.rst | 2 ++
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/mman.h | 26 ++++++++++++++++++++++++--
arch/arm64/include/asm/page.h | 3 ++-
arch/arm64/include/asm/pgtable-prot.h | 12 +++++-------
arch/arm64/kernel/morello.c | 7 +++----
fs/proc/task_mmu.c | 4 ++++
include/linux/mm.h | 8 ++++++++
8 files changed, 49 insertions(+), 14 deletions(-)
--
2.25.1
Introduce new printk's pointer format extension to support capabilities,
with one being denoted by specifying the 'l' length modifier alongside
the 'p' type character => "%lp". In addition to the raw capability
format, adding '#' flag will generate the simplified one, being slightly
more verbose. In both cases, the actual result is subject to
pointer hashing (address only) unless either 'x' qualifier or
no_hash_pointers command line parameter is being provided.
For more details see the docs, updated here as well.
While at it, add some testcases to validate new format alongside
checkpatchpl new warning, to raise the awareness of potential misuse.
Signed-off-by: Beata Michalska <beata.michalska(a)arm.com>
---
v4:
- Docs: removing spurious new lines and adding missing 'dot'.
- test: add incrementing total_tests and drop breaking on failure for hashed
formats, plus fixing accounting for actual tests skipped
- lib/vsprintf.c:
- Drop the comment about potentially breaking capability into separate
values corresponding to tag, metadata and value
- moved length var declaration into if block as this is the right scope
for it
v3:
- Docs: style/spelling changes
- test: improved code layout (as per review comments), dropped stale SEAL
permission, fixed accounting for skipped tests
- lib/vsprintf.c:
- switched from __cheri_fromcap to cheri_address_get
- fixed indentations
- vbin_printf: adjusted comment for storing caps in bin buffer
- bstr_printf: added missing check for buffer end
v2:
- Rephrase/rearrange docs + adding link to the CHERI guidelines on printf
formats (also dropping 'hybrid-mode' mentions)
- Code readability/formatting improvements (as per review comments)
- Adding '0x' prefix for relevant simplified format components
- Removing missing permissions from the final output in simplified format
- Use pointer_string directly when no hashing is expected
- Added support for vbin_printf/bstr_printf (trace_printk is now able to print
capabilities)
Review branch available at:
https://git.morello-project.org/Bea/linux/-/tree/morello/cap_printk_v4
---
Documentation/core-api/printk-formats.rst | 60 ++++++
lib/test_printf.c | 158 +++++++++++++++
lib/vsprintf.c | 231 +++++++++++++++++++++-
scripts/checkpatch.pl | 13 +-
4 files changed, 458 insertions(+), 4 deletions(-)
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 5e89497ba314..a4840ac9c001 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -202,6 +202,66 @@ Example::
printk("test: difference between pointers: %td\n", ptr2 - ptr1);
+Capabilities
+------------
+
+::
+
+ %lp[x] 1:ffffc00000010005:0123456789abcdef
+ %#lp[x] 0x0123456789abcdef [rwxRWE,0x0000000000000000-0xffffffffffffffff]
+
+For printing CHERI architectural capabilities (when supported, otherwise
+the result of using it is undefined). Formatting based on:
+https://github.com/CTSRD-CHERI/cheri-c-programming/wiki/Displaying-Capabilities
+with a small detour of dropping support for basic format in favour of the raw
+one, with the assumption that the actual address can be printed with existing
+printk formats (subject to appropriate casting when dealing with capabilities
+and non-capability formats, which otherwise renders undefined behaviour).
+
+The ``l`` modifier distinguishes capability pointers from standard (integer)
+pointers, giving the following capability format being printed::
+
+ Capability tag:High bits:Low bits
+ ------------------------------------
+ <tag>:<127:64>:<63:0>
+
+
+Specifying ``#`` modifier results in printing capabilities in a simplified format::
+
+ <address> [<permissions>,<base>-<top>] (<attr>)
+
+where::
+
+ - permissions - none or any combination of:
+ - 'r' : CHERI_PERM_LOAD
+ - 'w' : CHERI_PERM_STORE
+ - 'x' : CHERI_PERM_EXECUTE
+ - 'R' : CHERI_PERM_LOAD_CAP
+ - 'W' : CHERI_PERM_STORE_CAP
+ - 'E' : ARM_CAP_PERMISSION_EXECUTIVE
+ - base - lower bound
+ - top - upper bound
+ - attr - none or any combination of:
+ - 'invalid' : capability's tag is clear
+ - 'sentry' : capability is a sealed entry
+ - 'sealed' : capability is sealed with a type other than the
+ sealed entry object type
+
+The above applies to formats with either ``no_hash_pointers`` parameter being
+enabled or ``x`` modifier being provided - otherwise subject to hashing
+(address only, with remaining bits being disregarded).
+
+Refer to `Unmodified Addresses`_ for potential security implications.
+
+Currently only Morello architecture is being supported.
+
+Note:
+An attempt to use this format with a non-capability type is undefined behaviour.
+There are no safety nets, so extra caution is advised! Handle with care.
+Same applies when capabilities are not supported, as the use of either the ``#``
+flag or the ``l`` length modifier is undefined behaviour when combined with
+%p.
+
Struct Resources
----------------
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 07309c45f327..1b877b68a30d 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -24,6 +24,10 @@
#include <linux/property.h>
+#ifdef __CHERI__
+#include <cheriintrin.h>
+#endif
+
#include "../tools/testing/selftests/kselftest_module.h"
#define BUF_SIZE 256
@@ -755,6 +759,159 @@ errptr(void)
#endif
}
+static void __init
+capability_pointer(void)
+{
+#ifdef __CHERI__
+ enum action {
+ /* No action - use as is */
+ CAP_AXN_NONE,
+ /* Clear capability tag */
+ CAP_TAG_CLEAR,
+ /* Derive null-capability */
+ CAP_NULL_DERIVE
+ };
+
+ struct {
+ const char *plain_fmt;
+ const char *fmt;
+ const char *expected;
+ int action;
+ } const setup[] = {
+ {
+ .plain_fmt = "%lp",
+ .fmt = "%lpx",
+ .expected = "1:d800400059ab89ab:"PTR_STR,
+ .action = CAP_AXN_NONE,
+ },
+ {
+ .plain_fmt = "%#lp",
+ .fmt = "%#lpx",
+ .expected = "0x"PTR_STR" [rwRW,0xffff0123456789ab-0xffff0123456799ab]",
+ .action = CAP_AXN_NONE,
+ },
+ {
+ .plain_fmt = "%lp",
+ .fmt = "%lpx",
+ .expected = "0:d800400059ab89ab:"PTR_STR,
+ .action = CAP_TAG_CLEAR,
+ },
+ {
+ .plain_fmt = "%#lp",
+ .fmt = "%#lpx",
+ .expected = "0x"PTR_STR" [rwRW,0xffff0123456789ab-0xffff0123456799ab] (invalid)",
+ .action = CAP_TAG_CLEAR,
+ },
+ {
+ .plain_fmt = "%lp",
+ .fmt = "%lpx",
+ .expected = PTR_STR,
+ .action = CAP_NULL_DERIVE,
+ },
+ {
+ .plain_fmt = "%#lp",
+ .fmt = "%#lpx",
+ .expected = PTR_STR,
+ .action = CAP_NULL_DERIVE,
+ }
+ };
+
+ char buf[PLAIN_BUF_SIZE];
+ const char * const cap_fmt_non_hashed[] = {"%lp", "%#lp"};
+ int nchars;
+
+ void * __capability cap = cheri_ddc_get();
+
+ /* Expecting basic permissions to be set */
+ size_t perms = CHERI_PERM_GLOBAL | CHERI_PERM_LOAD | CHERI_PERM_LOAD_CAP |
+ CHERI_PERM_STORE | CHERI_PERM_STORE_CAP;
+
+ size_t bounds = 4096;
+
+ cap = cheri_address_set(cap, (ptraddr_t)PTR);
+ cap = cheri_perms_and(cap, perms);
+ /*
+ * Basic checks so that the actual output can be safely compared
+ * to the expected one
+ */
+ if (!cheri_tag_get(cap) || cheri_perms_get(cap) != perms
+ || cheri_is_sealed(cap)) {
+ pr_warn("Failed to create capability for testing - skipping");
+ skipped_tests += no_hash_pointers ?
+ ARRAY_SIZE(cap_fmt_non_hashed) + ARRAY_SIZE(setup) * 2 :
+ ARRAY_SIZE(cap_fmt_non_hashed) + ARRAY_SIZE(setup);
+ return;
+ }
+
+ cap = cheri_bounds_set_exact(cap, bounds);
+
+ /* Verify hashing */
+ if (no_hash_pointers) {
+ pr_warn("Skipping capability hashing tests\n");
+ skipped_tests += ARRAY_SIZE(cap_fmt_non_hashed);
+ goto non_hashed;
+ }
+
+ for (int i = 0; i < ARRAY_SIZE(cap_fmt_non_hashed); ++i) {
+ nchars = snprintf(buf, PLAIN_BUF_SIZE, cap_fmt_non_hashed[i],
+ cap);
+
+ total_tests++;
+ /*
+ * Should be ADDR_WIDTH in this case , but hey, let's not be picky
+ * about it, at least not here ... not yet ...
+ */
+ if (nchars != PTR_WIDTH) {
+ /*
+ * This also covers the case when the value has not been
+ * actually hashed, as nchars would then be greater than
+ * PTR_WIDTH
+ */
+ pr_warn("Something went wrong with hashing capability value\n");
+ failed_tests++;
+ continue;
+ }
+
+ if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
+ pr_warn("crng possibly not yet initialized - capability value buffer contains \"%s\"",
+ PTR_VAL_NO_CRNG);
+ } else if (strncmp(buf, ZEROS, strlen(ZEROS)) != 0) {
+ pr_warn("Unexpected format for supposedly hashed capability value\n");
+ failed_tests++;
+ continue;
+ }
+ }
+
+non_hashed:
+ for (int i = 0; i < ARRAY_SIZE(setup); ++i) {
+ void * __capability current_cap;
+
+ switch (setup[i].action) {
+ case CAP_TAG_CLEAR:
+ current_cap = cheri_tag_clear(cap);
+ break;
+ case CAP_NULL_DERIVE:
+ /* Null-derived capability */
+ current_cap = cheri_address_set(0, cheri_address_get(cap));
+ break;
+ default:
+ current_cap = cap;
+ break;
+ }
+
+ if (no_hash_pointers)
+ test(setup[i].expected, setup[i].plain_fmt, current_cap);
+ else
+ ++skipped_tests;
+
+ test(setup[i].expected, setup[i].fmt, current_cap);
+ }
+
+ return;
+
+#endif /* CONFIG_ARM64_MORELLO */
+}
+
static void __init
test_pointer(void)
{
@@ -781,6 +938,7 @@ test_pointer(void)
errptr();
fwnode_pointer();
fourcc_pointer();
+ capability_pointer();
}
static void __init selftest(void)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 40d26a07a133..0ffd72546b85 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -51,6 +51,10 @@
#include <asm/byteorder.h> /* cpu_to_le16 */
#include <asm/unaligned.h>
+#ifdef __CHERI__
+#include <cheriintrin.h>
+#endif
+
#include <linux/string_helpers.h>
#include "kstrtox.h"
@@ -435,7 +439,10 @@ enum format_type {
FORMAT_TYPE_UINT,
FORMAT_TYPE_INT,
FORMAT_TYPE_SIZE_T,
- FORMAT_TYPE_PTRDIFF
+ FORMAT_TYPE_PTRDIFF,
+#ifdef __CHERI__
+ FORMAT_TYPE_CAPABILITY,
+#endif
};
struct printf_spec {
@@ -2488,6 +2495,181 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
}
+#ifdef __CHERI__
+/*
+ * Support for printing capabilities with %[#]lp[x] format.
+ * It stands slightly in contradiction to kernel extensions
+ * for pointer printk formats as it is using the 'l' length
+ * modifier instead of relying on extended format specifiers.
+ * Currently supported formats:
+ *
+ * lp[x] - Hex value of full capability bits preceded with capability tag:
+ * <tag>:<127:64>:<63:0>
+ * (* outcome subject to kernel pointer hashing )
+ * #lp[x] - Simplified format as:
+ * <address> [permissions=[rwxRWE],<base>-<top>] (attr=[invalid,sentry,sealed])
+ * (* outcome subject to kernel pointer hashing )
+ *
+ * Details at:
+ * Documentation/core-api/printk-formats.rst
+ * (keep both updated when making any changes)
+ *
+ * * - only the address undergoes hashing, remaining bits are being disregarded
+ *
+ */
+static noinline_for_stack
+char *capability(const char *fmt, char *buf, char *end, void * __capability cap,
+ struct printf_spec spec)
+{
+/*
+ * Write to the buffer only when there is a space for it, otherwise
+ * just advance the buffer marker to account for the space needed to
+ * store full value here
+ */
+#define update_buf_single(buf, end, c) \
+ do { if (buf < end) *buf++ = c; else ++buf; } while (0)
+
+ /*
+ * For null-derived capabilities switch to basic format
+ * (address only).
+ * Same applies when hashing is active.
+ */
+ if ((!cheri_tag_get(cap) && !__builtin_cheri_copy_from_high(cap)) ||
+ (likely(!no_hash_pointers) && *fmt != 'x')) {
+
+ /* Avoid adding prefix */
+ spec.flags &= ~SPECIAL;
+ return pointer(fmt, buf, end, (void *)cheri_address_get(cap),
+ spec);
+ }
+
+ if (spec.flags & SPECIAL) { /* Simplified format for capabilities */
+ int orig_field_width = spec.field_width;
+ cheri_perms_t perms = cheri_perms_get(cap);
+ ptraddr_t base, top;
+ const char *start = buf;
+ char *attr_start;
+ unsigned int i;
+ int attrib = 0;
+ int orig_flags;
+
+ /* Note: order matters to match the format expected */
+ struct {
+ cheri_perms_t cperm; char id;
+ } static const __perms[] = {
+ { CHERI_PERM_LOAD, 'r' },
+ { CHERI_PERM_STORE, 'w' },
+ { CHERI_PERM_EXECUTE, 'x' },
+ { CHERI_PERM_LOAD_CAP, 'R' },
+ { CHERI_PERM_STORE_CAP, 'W' },
+#ifdef CONFIG_ARM64_MORELLO
+ { ARM_CAP_PERMISSION_EXECUTIVE, 'E' }
+#endif
+ };
+
+ /*
+ * Things get slightly confusing here when it comes to
+ * precision. The standard format specification claims that
+ * precision might cause truncation of the actual output,
+ * contrary to width.
+ * CHERI on the other hand suggests, that precision used
+ * with the 'p' specifier should determine the width of
+ * addresses though following current formatting for pointer types,
+ * unless explicitly stated, the width will be enforced, leaving
+ * precision being ineffective. Furthermore, according to the guide,
+ * in theory precision should not affect the way the Raw and Simplified
+ * formats are being handled (the non-address related parts).
+ * Stick with that one.
+ * Note: Using precision with pointers/capabilities with
+ * active hashing might lead to slightly unexpected output.
+ * That's the result of applying the precision while
+ * respecting the field width.
+ *
+ * Width in this case refers to the width of final string generated for
+ * the simplified format
+ */
+ spec.field_width = -1;
+ orig_flags = spec.flags;
+ spec.flags &= ~(ZEROPAD | LEFT);
+
+ buf = pointer_string(buf, end, (void *)cheri_address_get(cap),
+ spec);
+
+ update_buf_single(buf, end, ' ');
+ update_buf_single(buf, end, '[');
+ for (i = 0; i < ARRAY_SIZE(__perms); ++i) {
+ if (perms & __perms[i].cperm)
+ update_buf_single(buf, end, __perms[i].id);
+ }
+ update_buf_single(buf, end, ',');
+
+ base = cheri_base_get(cap);
+ buf = pointer_string(buf, end, (void *)base, spec);
+ update_buf_single(buf, end, '-');
+
+ top = base + cheri_length_get(cap);
+ buf = pointer_string(buf, end, (void *)top, spec);
+ update_buf_single(buf, end, ']');
+
+ /* Attributes */
+ /* Reset precision to output full attribute identifiers here */
+ spec.precision = -1;
+
+ /*
+ * Keep track of the attribute start section to format
+ * it properly in case there are attributes to be reported.
+ * Otherwise simply rolling on a buffer might lead to overflowing
+ * past the terminating character if the buffer is big enough.
+ */
+ attr_start = buf;
+ buf += 2;
+
+ if (!cheri_tag_get(cap)) {
+ buf = string_nocheck(buf, end, "invalid", spec);
+ ++attrib;
+ }
+ if (cheri_is_sentry(cap)) {
+ if (attrib++)
+ update_buf_single(buf, end, ',');
+ buf = string_nocheck(buf, end, "sentry", spec);
+
+ }
+ if (cheri_is_sealed(cap)) {
+ if (attrib++)
+ update_buf_single(buf, end, ',');
+ buf = string_nocheck(buf, end, "sealed", spec);
+ }
+
+ if (attrib) {
+ update_buf_single(attr_start, end, ' ');
+ update_buf_single(attr_start, end, '(');
+ update_buf_single(buf, end, ')');
+ } else {
+ buf = attr_start; /* Rollback on space and opening bracket */
+ }
+
+ /* Restore the originally requested width */
+ spec.field_width = orig_field_width;
+ spec.flags |= orig_flags;
+
+ return widen_string(buf, buf - start, end, spec);
+ }
+
+ /*
+ * Raw format: hex dump of full capability
+ */
+ update_buf_single(buf, end, cheri_tag_get(cap) ? '1' : '0');
+ update_buf_single(buf, end, ':');
+ buf = pointer_string(buf, end,
+ (void *) __builtin_cheri_copy_from_high(cap),
+ spec);
+ update_buf_single(buf, end, ':');
+ return pointer_string(buf, end, (void *)cheri_address_get(cap), spec);
+
+#undef update_buf_single
+}
+#endif /* __CHERI__ */
+
/*
* Helper function to decode printf style format.
* Each call decode a token from the format and return the
@@ -2624,6 +2806,10 @@ int format_decode(const char *fmt, struct printf_spec *spec)
case 'p':
spec->type = FORMAT_TYPE_PTR;
+#ifdef __CHERI__
+ if (qualifier == 'l')
+ spec->type = FORMAT_TYPE_CAPABILITY;
+#endif
return ++fmt - start;
case '%':
@@ -2717,6 +2903,7 @@ set_precision(struct printf_spec *spec, int prec)
*
* - ``%n`` is unsupported
* - ``%p*`` is handled by pointer()
+ * - ``%lp[x]`` and ``%#lp[x]`` is handled by capability()
*
* See pointer() or Documentation/core-api/printk-formats.rst for more
* extensive description.
@@ -2818,7 +3005,15 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
*str = '%';
++str;
break;
-
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY:
+ str = capability(fmt, str, end,
+ va_arg(args, void * __capability),
+ spec);
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+#endif
case FORMAT_TYPE_INVALID:
/*
* Presumably the arguments passed gcc's type
@@ -3138,7 +3333,25 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
while (isalnum(*fmt))
fmt++;
break;
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY:
+ /*
+ * Capabilities shall be handled now: subject to
+ * required alignment, plus exercising extra caution
+ * when storing the capability in the buffer directly.
+ */
+ str = capability(fmt, str, end,
+ va_arg(args, void * __capability),
+ spec);
+ if (str + 1 < end)
+ *str++ = '\0';
+ else
+ end[-1] = '\0'; /* Must be null terminated */
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+#endif
default:
switch (spec.type) {
@@ -3319,7 +3532,21 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
fmt++;
break;
}
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY:
+ if (str < end) {
+ long length = strlen(args);
+
+ memcpy(str, args, min(length, (end - str)));
+
+ str += length;
+ args += length + 1;
+ }
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+#endif
case FORMAT_TYPE_PERCENT_CHAR:
if (str < end)
*str = '%';
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 577e02998701..867e0a01ae9f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6760,7 +6760,7 @@ sub process {
my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
$fmt =~ s/%%//g;
- while ($fmt =~ /(\%[\*\d\.]*p(\w)(\w*))/g) {
+ while ($fmt =~ /(\%[\*\d\.#l]*p(\w)(\w*))/g) {
$specifier = $1;
$extension = $2;
$qualifier = $3;
@@ -6768,7 +6768,8 @@ sub process {
($extension eq "f" &&
defined $qualifier && $qualifier !~ /^w/) ||
($extension eq "4" &&
- defined $qualifier && $qualifier !~ /^cc/)) {
+ defined $qualifier && $qualifier !~ /^cc/) ||
+ ($specifier =~ /lp/ && $extension ne "x")) {
$bad_specifier = $specifier;
last;
}
@@ -6780,6 +6781,14 @@ sub process {
"Using vsprintf specifier '\%px' potentially exposes the kernel memory layout, if you don't really need the address please consider using '\%p'.\n" . "$here\n$stat_real\n");
}
}
+
+ if ($fmt =~ /\%[\*\d\.#]*lp/) {
+ my $stat_real = get_stat_real($linenr, $lc);
+
+ WARN("VSPRINTF_POINTER_EXTENSION",
+ "Using vsprintf specifier '\%[#]lp[x]' is undefined behaviour when used with non-capability types. Make sure you got it right.\n" . "$here\n$stat_real\n");
+ }
+
if ($bad_specifier ne "") {
my $stat_real = get_stat_real($linenr, $lc);
my $ext_type = "Invalid";
--
2.25.1
The PTRACE_POKEDATA request writes a word of data to the tracee's
memory. In PCuABI the size of the write remains 8 bytes. Currently the
kernel erroneously writes 16 bytes, thereby overwriting 8 bytes of
unrelated memory. Fix this by restoring the type of the data argument of
generic_ptrace_pokedata() to unsigned long.
Fixes: ("kernel/ptrace: Modify ptrace syscall to accept capability arguments")
Signed-off-by: Kristina Martsenko <kristina.martsenko(a)arm.com>
---
include/linux/ptrace.h | 2 +-
kernel/ptrace.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index a4c84dbbe084..cfdd378636c7 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -108,7 +108,7 @@ static inline void ptrace_unlink(struct task_struct *child)
int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
user_uintptr_t data);
int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
- user_uintptr_t data);
+ unsigned long data);
/**
* ptrace_parent - return the task that is tracing the given task
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index c278ae0058a6..e5343257131f 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -1350,7 +1350,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
}
int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
- user_uintptr_t data)
+ unsigned long data)
{
int copied;
--
2.30.2
Hi,
This patch series addresses the VM_READ_CAPS/VM_WRITE_CAPS flags issue:
https://git.morello-project.org/morello/kernel/linux/-/issues/36
io_uring system uses buffers shared with userspace to read the io events
and report their results. The structs that populate the submission and
completion queues can contain capabilities. Shared mappings don't have
the Load/Store capabilities permission to avoid leaking capabilities
outside their original address space, so add two new VM flags that would
allow the kernel to set up such mappings.
While at it, also fix pte_modify to allow setting PTE_*_CAPS flags, add
new the new rc/wc smaps flags, and remove the automatic addition of
PTE_*_CAPS to user mappings.
To note: this wouldn't allow userspace to make arbitrary shared mappings
with tag access, the new VM flags would be for internal use only for the
time being.
Review branch:
https://git.morello-project.org/tudcre01/linux/-/commits/vm_rw_caps_v1/
Thanks,
Tudor
---
Tudor Cretu (3):
arm64: pgtable: Allow PTE_*_CAPS in the pte_modify mask
arm64: mm: Add VM_READ_CAPS and VM_WRITE_CAPS flags
arm64: mm: Use VM_*_CAPS instead of enabling PTE_*_CAPS to default
user mappings
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/mman.h | 19 +++++++++++++++++--
arch/arm64/include/asm/page.h | 2 +-
arch/arm64/include/asm/pgtable-prot.h | 12 +++++-------
arch/arm64/include/asm/pgtable.h | 2 +-
fs/proc/task_mmu.c | 4 ++++
include/linux/mm.h | 9 +++++++++
7 files changed, 38 insertions(+), 11 deletions(-)
--
2.25.1
typeof is (still) a GNU extension, which means that it cannot be
used when building ISO C (e.g. -std=c99). It should therefore be
avoided in uapi headers in favour of the ISO-friendly __typeof__.
Reported-by: Ruben Ayrapetyan <ruben.ayrapetyan(a)arm.com>
Signed-off-by: Kevin Brodsky <kevin.brodsky(a)arm.com>
---
This is really an upstream issue that has gone unnoticed so far,
probably because __ALIGN_KERNEL is not widely used. Our recent commit
a5cf170fd954 ("uapi: siginfo.h: Modify struct sigevent for PCuABI")
revealed it, as it uses __ALIGN_KERNEL in siginfo.h in such a way that
the macro is always expanded, so any userspace ISO C/C++ code including
siginfo.h gets a build failure.
Thinking about posting this on LKML, any opinion for/against or
suggestion?
Thanks,
Kevin
include/uapi/linux/const.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/uapi/linux/const.h b/include/uapi/linux/const.h
index af2a44c08683..a429381e7ca5 100644
--- a/include/uapi/linux/const.h
+++ b/include/uapi/linux/const.h
@@ -28,7 +28,7 @@
#define _BITUL(x) (_UL(1) << (x))
#define _BITULL(x) (_ULL(1) << (x))
-#define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
+#define __ALIGN_KERNEL(x, a) __ALIGN_KERNEL_MASK(x, (__typeof__(x))(a) - 1)
#define __ALIGN_KERNEL_MASK(x, mask) (((x) + (mask)) & ~(mask))
#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
--
2.34.1
__kernel_uintcap_t is an arm64-specific uapi type, so it does not
make sense to use it to define uintcap_t. Besides, uintcap_t is only
defined if CHERI is available, so defining it as __uintcap_t
directly is perfectly fine.
Fixes: ("linux/types.h: Introduce uintcap_t")
Signed-off-by: Kevin Brodsky <kevin.brodsky(a)arm.com>
---
include/linux/types.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/types.h b/include/linux/types.h
index e50e886a544f..e5175b9e8831 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -63,7 +63,7 @@ typedef unsigned long ptraddr_t;
#endif
#ifdef __CHERI__
-typedef __kernel_uintcap_t uintcap_t;
+typedef __uintcap_t uintcap_t;
#endif
#ifdef CONFIG_HAVE_UID16
--
2.34.1
On 15/11/2022 10:43, Teo Couprie Diaz wrote:
> On 11/11/2022 17:49, Kristina Martsenko wrote:
>
>> The PTRACE_POKEDATA request writes a word of data to the tracee's
>> memory. In PCuABI the size of the write remains 8 bytes. Currently the
>> kernel erroneously writes 16 bytes, thereby overwriting 8 bytes of
>> unrelated memory. Fix this by restoring the type of the data argument of
>> generic_ptrace_pokedata() to unsigned long.
>
> The fix makes sense by itself, maybe it's my lack of experience with kernel dev but do we always expect it to be 8 bytes of data to trace ?
The ptrace man page states that it's a machine "word", so 8 on 64-bit systems
and 4 on 32-bit systems. (It remains 8 on Morello according to the PCuABI spec,
there is a new request type PTRACE_POKECAP for writing 16-byte capabilities.)
> If so, isn't there some type that could be more specific (and ideally fixed in size) that could be used here as to prevent further confusion later and be sure that the right amount of bytes will always be written ?
Yeah, that would make sense. But the C language doesn't have a type for the
machine word size, and I think the kernel just uses "unsigned long" for that.
Also note that in this particular case I'm just reverting part of the change
made in commit 343ca6c6706e ("kernel/ptrace: Modify ptrace syscall to accept
capability arguments"), not introducing a new change.
>
> I'm also a bit confused when looking a the function where it gets called from :
>
> int ptrace_request(struct task_struct *child, long request,
> user_uintptr_t addr, user_uintptr_t data)
>
> Here `addr` is an `user_uinptr_t`, which gets passed to `generic_ptrace_pokedata()` which will use it to poke said data. But there the type of `addr` is `unsigned long`, shouldn't it be `user_uintptr_t` as well ?
>
The type in ptrace_request() needs to be user_uintptr_t because ptrace is a
multiplexed syscall that can take both pointers and integers in the 'addr' and
'data' arguments. Based on the request type (the big switch statement in
ptrace_request()), the argument gets interpreted as either a pointer or integer.
In the case of PTRACE_POKEDATA, the PCuABI spec [1] states that 'addr' is
interpreted as a 64-bit value, because it holds an address in the tracee's
address space (for which the tracer doesn't have a capability). So the call to
generic_ptrace_pokedata() implicitly converts it to unsigned long.
> It also means that `data` is going through the same kind of type change, but it's probably less of an issue because it's just data to be copied around.
'data' also needs to be interpreted as a 64-bit value for the PTRACE_POKEDATA
request type because it needs to be the size of a 'word', as described above.
>
>
> I'm not sure what I am saying is really relevant, if not please ignore ! :)
Thanks for having a look!
Kristina
[1] https://git.morello-project.org/morello/kernel/linux/-/wikis/Morello-pure-c…
> Regards,
> Téo
>
>> Fixes: ("kernel/ptrace: Modify ptrace syscall to accept capability arguments")
>> Signed-off-by: Kristina Martsenko <kristina.martsenko(a)arm.com>
>> ---
>> include/linux/ptrace.h | 2 +-
>> kernel/ptrace.c | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
>> index a4c84dbbe084..cfdd378636c7 100644
>> --- a/include/linux/ptrace.h
>> +++ b/include/linux/ptrace.h
>> @@ -108,7 +108,7 @@ static inline void ptrace_unlink(struct task_struct *child)
>> int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
>> user_uintptr_t data);
>> int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
>> - user_uintptr_t data);
>> + unsigned long data);
>> /**
>> * ptrace_parent - return the task that is tracing the given task
>> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
>> index c278ae0058a6..e5343257131f 100644
>> --- a/kernel/ptrace.c
>> +++ b/kernel/ptrace.c
>> @@ -1350,7 +1350,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
>> }
>> int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
>> - user_uintptr_t data)
>> + unsigned long data)
>> {
>> int copied;
>>
Introduce new printk's pointer format extension to support capabilities,
with one being denoted by specifying the 'l' length modifier alongside
the 'p' type character => "%lp". In addition to the raw capability
format, adding '#' flag will generate the simplified one, being slightly
more verbose. In both cases, the actual result is subject to
pointer hashing (address only) unless either 'x' qualifier or
no_hash_pointers command line parameter is being provided.
For more details see the docs, updated here as well.
While at it, add some testcases to validate new format alongside
checkpatchpl new warning, to raise the awareness of potential misuse.
Signed-off-by: Beata Michalska <beata.michalska(a)arm.com>
---
v2:
- Rephrase/rearrange docs + adding link to the CHERI guidelines on printf
formats (also dropping 'hybrid-mode' mentions)
- Code readability/formatting improvements (as per review comments)
- Adding '0x' prefix for relevant simplified format components
- Removing missing permissions from the final output in simplified format
- Use pointer_string directly when no hashing is expected
- Added support for vbin_printf/bstr_printf (trace_printk is now able to print
capabilities)
Review branch available at:
https://git.morello-project.org/Bea/linux/-/tree/morello/cap_printk
---
Documentation/core-api/printk-formats.rst | 68 +++++++
lib/test_printf.c | 133 ++++++++++++
lib/vsprintf.c | 233 +++++++++++++++++++++-
scripts/checkpatch.pl | 13 +-
4 files changed, 443 insertions(+), 4 deletions(-)
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 5e89497ba314..bd97a9750e54 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -202,6 +202,74 @@ Example::
printk("test: difference between pointers: %td\n", ptr2 - ptr1);
+Capabilities
+------------
+
+::
+
+ %lp[x] 1:ffffc00000010005:0123456789abcdef
+ %#lp[x] 0x0123456789abcdef [rwxRWE,0x0000000000000000-0xffffffffffffffff]
+
+
+For printing CHERI architectural capabilities (when supported, otherwise
+the result of using it is undefined). Formatting based on:
+https://github.com/CTSRD-CHERI/cheri-c-programming/wiki/Displaying-Capabilities
+with a small detour of dropping support for basic format in favour of the raw
+one, with the assumption that the actual address can be printed with existing
+printk formats (subject to appropriate casting when dealing with capabilities
+and non-capability formats, which otherwise renders undefined behavior).
+
+The ``l`` modifier distinguishes capability pointers from standard (integer)
+pointers, giving the following capability format being printed:
+
+::
+
+ Capability tag:High bits:Low bits
+ ------------------------------------
+ <tag>:<127:64>:<63:0>
+
+
+Specifying ``#`` modifier results in printing capabilities in a simplified format:
+
+::
+
+ <address> [<permissions>,<base>-<top>] (<attr>)
+
+where:
+
+::
+
+ - permissions - none or any combination of:
+ - 'r' : CHERI_PERM_LOAD
+ - 'w' : CHERI_PERM_STORE
+ - 'x' : CHERI_PERM_EXECUTE
+ - 'R' : CHERI_PERM_LOAD_CAP
+ - 'W' : CHERI_PERM_STORE_CAP
+ - 'E' : ARM_CAP_PERMISSION_EXECUTIVE
+ - base - lower bound
+ - top - upper bound
+ - attr - none or any combination of:
+ - 'invalid' : capability's tag is clear
+ - 'sentry' : capability is a sealed entry
+ - 'sealed' : capability is sealed with a type other than the
+ sealed entry object type
+
+
+The above applies to formats with either `'no_hash_pointers'` parameter being
+enabled or ``x`` modifier being provided - otherwise subject to hashing
+(address only, with remaining bits being disregarded)
+
+Refer to ``'Unmodified Addresses'`` for potential security implications.
+
+Currently only Morello architecture is being supported.
+
+Note:
+An attempt to use this format with a non-capability type is undefined behaviour.
+There are no safety nests, so extra consciousness is advised! Handle with care.
+Same applies when capabilities are not supported, as the use of either the ``#``
+flag or the ``l`` length modifier is undefined behaviour when combined with
+%p.
+
Struct Resources
----------------
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 07309c45f327..71d5b8d1c9b5 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -24,6 +24,10 @@
#include <linux/property.h>
+#ifdef __CHERI__
+#include <cheriintrin.h>
+#endif
+
#include "../tools/testing/selftests/kselftest_module.h"
#define BUF_SIZE 256
@@ -755,6 +759,134 @@ errptr(void)
#endif
}
+static void __init
+capability_pointer(void)
+{
+#ifdef __CHERI__
+
+ enum action {
+ /* No action - use as is */
+ CAP_AXN_NONE,
+ /* Clear capability tag */
+ CAP_TAG_CLEAR,
+ /* Derive null-capability */
+ CAP_NULL_DERIVE
+ };
+
+ struct __setup {
+ char *plain_fmt;
+ char *fmt;
+ char *expected;
+ int action;
+ } const setup[] = {
+ { "%lp", "%lpx", "1:da00400059ab89ab:"PTR_STR, CAP_AXN_NONE },
+ { "%#lp", "%#lpx",
+ "0x"PTR_STR" [rwRW,0xffff0123456789ab-0xffff0123456799ab]",
+ CAP_AXN_NONE
+ },
+ { "%lp", "%lpx", "0:da00400059ab89ab:"PTR_STR, CAP_TAG_CLEAR },
+ { "%#lp", "%#lpx",
+ "0x"PTR_STR" [rwRW,0xffff0123456789ab-0xffff0123456799ab] (invalid)",
+ CAP_TAG_CLEAR
+ },
+ { "%lp", "%lpx", PTR_STR, CAP_NULL_DERIVE },
+ { "%#lp", "%#lpx", PTR_STR, CAP_NULL_DERIVE }
+ };
+
+ char buf[PLAIN_BUF_SIZE];
+ const char * const cap_fmt[] = {"%lp", "%#lp"};
+ int nchars;
+
+ void * __capability cap = cheri_ddc_get();
+
+ /* Expecting basic permissions to be set */
+ size_t perms = CHERI_PERM_GLOBAL | CHERI_PERM_LOAD | CHERI_PERM_LOAD_CAP |
+ CHERI_PERM_STORE | CHERI_PERM_STORE_CAP | CHERI_PERM_SEAL;
+
+ size_t bounds = 4096;
+
+ cap = cheri_address_set(cap, (ptraddr_t)PTR);
+ cap = cheri_perms_and(cap, perms);
+ /*
+ * Basic checks so that the actual output can be safely compared
+ * to the expected one
+ */
+ if (!cheri_tag_get(cap) || cheri_perms_get(cap) != perms
+ || cheri_is_sealed(cap)) {
+ pr_warn("Failed to create capability for testing - skipping");
+ skipped_tests += no_hash_pointers ? 4 + ARRAY_SIZE(setup) :
+ 4 + ARRAY_SIZE(setup)/2;
+ return;
+ }
+
+ cap = cheri_bounds_set_exact(cap, bounds);
+
+ /* Verify hashing */
+ if (no_hash_pointers) {
+ pr_warn("Skipping capability hashing tests\n");
+ skipped_tests += 4;
+ goto non_hashed;
+ }
+
+ for (int i = 0; i < ARRAY_SIZE(cap_fmt); ++i) {
+
+ nchars = snprintf(buf, PLAIN_BUF_SIZE, cap_fmt[i], cap);
+
+ /*
+ * Should be ADDR_WIDTH in this case , but hey, let's not be picky
+ * about it, at least not here ... not yet ...
+ */
+ if (nchars != PTR_WIDTH) {
+ /*
+ * This also covers the case when the value has not been
+ * actually hashed as otherwise nchars would be greater than
+ * PTR_WIDTH
+ */
+ pr_warn("Something went wrong with hashing capability value\n");
+ goto failed;
+ }
+
+ if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
+ pr_warn("crng possibly not yet initialized - capability value buffer contains \"%s\"",
+ PTR_VAL_NO_CRNG);
+ } else if (strncmp(buf, ZEROS, strlen(ZEROS)) != 0) {
+ pr_warn("Unexpected format for supposedly hashed capability value\n");
+ goto failed;
+ }
+ }
+
+non_hashed:
+ for (int i = 0; i < ARRAY_SIZE(setup); ++i) {
+ void * __capability current_cap = cap;
+
+ switch (setup[i].action) {
+ case CAP_TAG_CLEAR:
+ current_cap = cheri_tag_clear(current_cap);
+ break;
+ case CAP_NULL_DERIVE:
+ /* Null-derived capability */
+ current_cap = (void *__capability)
+ (__cheri_addr uintcap_t)((void *)cheri_base_get(current_cap));
+ break;
+ default:
+ break;
+ }
+
+ if (no_hash_pointers)
+ test(setup[i].expected, setup[i].plain_fmt, current_cap);
+ else
+ ++skipped_tests;
+
+ test(setup[i].expected, setup[i].fmt, current_cap);
+ }
+
+ return;
+
+failed:
+ failed_tests++;
+#endif /* CONFIG_ARM64_MORELLO */
+}
+
static void __init
test_pointer(void)
{
@@ -781,6 +913,7 @@ test_pointer(void)
errptr();
fwnode_pointer();
fourcc_pointer();
+ capability_pointer();
}
static void __init selftest(void)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 40d26a07a133..af08619ebd42 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -51,6 +51,10 @@
#include <asm/byteorder.h> /* cpu_to_le16 */
#include <asm/unaligned.h>
+#ifdef __CHERI__
+#include <cheriintrin.h>
+#endif
+
#include <linux/string_helpers.h>
#include "kstrtox.h"
@@ -435,7 +439,10 @@ enum format_type {
FORMAT_TYPE_UINT,
FORMAT_TYPE_INT,
FORMAT_TYPE_SIZE_T,
- FORMAT_TYPE_PTRDIFF
+ FORMAT_TYPE_PTRDIFF,
+#ifdef __CHERI__
+ FORMAT_TYPE_CAPABILITY,
+#endif
};
struct printf_spec {
@@ -2488,6 +2495,181 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
}
+#ifdef __CHERI__
+/*
+ * Support for printing capabilities with %[#]lp[x] format.
+ * It stands slightly in contradiction to kernel extensions
+ * for pointer printk formats as it is using the 'l' length
+ * modifier instead of relying on extended format specifiers.
+ * Currently supported formats:
+ *
+ * lp[x] - Hex value of full capability bits preceded with capability tag:
+ * <tag>:<127:64>:<63:0>
+ * (* outcome subject to kernel pointer hashing )
+ * #lp[x] - Simplified format as:
+ * <address> [permissions=[rwxRWE],<base>-<top>] (attr=[invalid,sentry,sealed])
+ * (* outcome subject to kernel pointer hashing )
+ *
+ * Details at:
+ * Documentation/core-api/printk-formats.rst
+ * (keep both updated case making any changes)
+ *
+ * * - only the address undergoes hashing, remaining bits are being disregarded
+ *
+ */
+static noinline_for_stack
+char *capability(const char *fmt, char *buf, char *end, void * __capability cap,
+ struct printf_spec spec)
+{
+/*
+ * Write to the buffer only when there is a space for it, otherwise
+ * just advance the buffer marker to account for the space needed to
+ * store full value here
+ */
+#define update_buf_single(buf, end, c) \
+ do { if (buf < end) *buf++ = c; else ++buf; } while (0)
+
+ /*
+ * For null-derived capabilities switch to basic format
+ * (address only).
+ * Same applies when hashing is active.
+ */
+ if ((!cheri_tag_get(cap) &&
+ !__builtin_cheri_copy_from_high(cap))
+ || (likely(!no_hash_pointers) && *fmt != 'x')) {
+
+ /* Avoid adding prefix */
+ spec.flags &= ~SPECIAL;
+ return pointer(fmt, buf, end, (__cheri_fromcap void *)(cap), spec);
+ }
+
+ if (spec.flags & SPECIAL) { /* Simplified format for capabilities */
+ int orig_field_width = spec.field_width;
+ cheri_perms_t perms = cheri_perms_get(cap);
+ ptraddr_t base, top;
+ const char *start = buf;
+ char *attr_start;
+ unsigned int i;
+ int attrib = 0;
+ int orig_flags;
+
+ /* Note: order matters to match the format expected */
+ struct {
+ cheri_perms_t cperm; char id;
+ } static const __perms[] = {
+ { CHERI_PERM_LOAD, 'r' },
+ { CHERI_PERM_STORE, 'w' },
+ { CHERI_PERM_EXECUTE, 'x' },
+ { CHERI_PERM_LOAD_CAP, 'R' },
+ { CHERI_PERM_STORE_CAP, 'W' },
+#ifdef CONFIG_ARM64_MORELLO
+ { ARM_CAP_PERMISSION_EXECUTIVE, 'E' }
+#endif
+ };
+
+ /*
+ * Things get slightly confusing here when it comes to
+ * precision. The standard format specification claims that
+ * precision might cause truncation of the actual output,
+ * contrary to width.
+ * CHERI on the other hand suggests, that precision used
+ * with the 'p' specifier should determine the width of
+ * addresses though following current formatting for pointer types,
+ * unless explicitly stated, the width will be enforced, leaving
+ * precision being ineffective. Furthermore, according to the guide,
+ * in theory precision should not affect the way the Raw and Simplified
+ * formats are being handled (the non-address related parts).
+ * Stick with that one.
+ * Note: Using precision with pointers/capabilities with
+ * active hashing might lead to slightly unexpected output.
+ * That's the result of applying the precision while
+ * respecting the field width.
+ *
+ * Width in this case refers to the width of final string generated for
+ * the simplified format
+ */
+ spec.field_width = -1;
+ orig_flags = spec.flags;
+ spec.flags &= ~(ZEROPAD | LEFT);
+
+ buf = pointer_string(buf, end, (__cheri_fromcap void *)cap, spec);
+
+ update_buf_single(buf, end, ' ');
+ update_buf_single(buf, end, '[');
+ for (i = 0; i < ARRAY_SIZE(__perms); ++i) {
+ if (perms & __perms[i].cperm)
+ update_buf_single(buf, end, __perms[i].id);
+ }
+ update_buf_single(buf, end, ',');
+
+ base = cheri_base_get(cap);
+ buf = pointer_string(buf, end, (void *)base, spec);
+ update_buf_single(buf, end, '-');
+
+ top = base + cheri_length_get(cap);
+ buf = pointer_string(buf, end, (void *)top, spec);
+ update_buf_single(buf, end, ']');
+
+ /* Attributes */
+ /* Reset precision to output full attribute identifiers here */
+ spec.precision = -1;
+
+ /*
+ * Keep track of the attribute start section to format
+ * it properly in case there are attributes to be reported.
+ * Otherwise simply rolling on a buffer might lead to overflowing
+ * past the terminating character if the buffer is big enough.
+ */
+ attr_start = buf;
+ buf += 2;
+
+ if (!cheri_tag_get(cap)) {
+ buf = string_nocheck(buf, end, "invalid", spec);
+ ++attrib;
+ }
+ if (cheri_is_sentry(cap)) {
+ if (attrib++)
+ update_buf_single(buf, end, ',');
+ buf = string_nocheck(buf, end, "sentry", spec);
+
+ }
+ if (cheri_is_sealed(cap)) {
+ if (attrib++)
+ update_buf_single(buf, end, ',');
+ buf = string_nocheck(buf, end, "sealed", spec);
+ }
+
+ if (attrib) {
+ update_buf_single(attr_start, end, ' ');
+ update_buf_single(attr_start, end, '(');
+ update_buf_single(buf, end, ')');
+ } else {
+ buf = attr_start; /* Rollback on space and opening bracket */
+ }
+
+ /* Restore the originally requested width */
+ spec.field_width = orig_field_width;
+ spec.flags |= orig_flags;
+
+ return widen_string(buf, buf - start, end, spec);
+ }
+
+ /*
+ * Raw format: hex dump of full capability
+ */
+ update_buf_single(buf, end, cheri_tag_get(cap) ? '1' : '0');
+ update_buf_single(buf, end, ':');
+ buf = pointer_string(buf, end,
+ (void *) __builtin_cheri_copy_from_high(cap),
+ spec);
+ update_buf_single(buf, end, ':');
+ return pointer_string(buf, end, (__cheri_fromcap void *)(cap),
+ spec);
+
+#undef update_buf_single
+}
+#endif /* __CHERI__ */
+
/*
* Helper function to decode printf style format.
* Each call decode a token from the format and return the
@@ -2624,6 +2806,10 @@ int format_decode(const char *fmt, struct printf_spec *spec)
case 'p':
spec->type = FORMAT_TYPE_PTR;
+#ifdef __CHERI__
+ if (qualifier == 'l')
+ spec->type = FORMAT_TYPE_CAPABILITY;
+#endif
return ++fmt - start;
case '%':
@@ -2717,6 +2903,7 @@ set_precision(struct printf_spec *spec, int prec)
*
* - ``%n`` is unsupported
* - ``%p*`` is handled by pointer()
+ * - ``%lp[x]`` and ``%#lp[x]`` is handled by capability()
*
* See pointer() or Documentation/core-api/printk-formats.rst for more
* extensive description.
@@ -2818,7 +3005,15 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
*str = '%';
++str;
break;
-
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY:
+ str = capability(fmt, str, end,
+ va_arg(args, void * __capability),
+ spec);
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+#endif
case FORMAT_TYPE_INVALID:
/*
* Presumably the arguments passed gcc's type
@@ -3138,7 +3333,28 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
while (isalnum(*fmt))
fmt++;
break;
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY:
+ /*
+ * Capabilities need to be handled now: subject to
+ * LoadCap/StoreCap permission which would make this
+ * unsafe if storing the capability in the buffer
+ * directly. Otherwise breaking down the capability
+ * to extract the information requested (format)
+ * would be rather counter-productive
+ */
+ str = capability(fmt, str, end,
+ va_arg(args, void * __capability),
+ spec);
+ if (str + 1 < end)
+ *str++ = '\0';
+ else
+ end[-1] = '\0'; /* Must be null terminated */
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+#endif
default:
switch (spec.type) {
@@ -3319,7 +3535,20 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
fmt++;
break;
}
+#ifdef __CHERI__
+ case FORMAT_TYPE_CAPABILITY: {
+ long length = strlen(args);
+
+ memcpy(str, args, min(length, (end - str)));
+ str += length;
+ args += length + 1;
+
+ while (isalnum(*fmt))
+ fmt++;
+ break;
+ }
+#endif
case FORMAT_TYPE_PERCENT_CHAR:
if (str < end)
*str = '%';
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 577e02998701..867e0a01ae9f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6760,7 +6760,7 @@ sub process {
my $fmt = get_quoted_string($lines[$count - 1], raw_line($count, 0));
$fmt =~ s/%%//g;
- while ($fmt =~ /(\%[\*\d\.]*p(\w)(\w*))/g) {
+ while ($fmt =~ /(\%[\*\d\.#l]*p(\w)(\w*))/g) {
$specifier = $1;
$extension = $2;
$qualifier = $3;
@@ -6768,7 +6768,8 @@ sub process {
($extension eq "f" &&
defined $qualifier && $qualifier !~ /^w/) ||
($extension eq "4" &&
- defined $qualifier && $qualifier !~ /^cc/)) {
+ defined $qualifier && $qualifier !~ /^cc/) ||
+ ($specifier =~ /lp/ && $extension ne "x")) {
$bad_specifier = $specifier;
last;
}
@@ -6780,6 +6781,14 @@ sub process {
"Using vsprintf specifier '\%px' potentially exposes the kernel memory layout, if you don't really need the address please consider using '\%p'.\n" . "$here\n$stat_real\n");
}
}
+
+ if ($fmt =~ /\%[\*\d\.#]*lp/) {
+ my $stat_real = get_stat_real($linenr, $lc);
+
+ WARN("VSPRINTF_POINTER_EXTENSION",
+ "Using vsprintf specifier '\%[#]lp[x]' is undefined behaviour when used with non-capability types. Make sure you got it right.\n" . "$here\n$stat_real\n");
+ }
+
if ($bad_specifier ne "") {
my $stat_real = get_stat_real($linenr, $lc);
my $ext_type = "Invalid";
--
2.25.1
This series makes it possible for purecap apps to use the io_uring system.
With these patches, all io_uring LTP tests pass in both Purecap and compat
modes. Note that the LTP tests only address the basic functionality of the
io_uring system and a significant portion of the multiplexed functionality
is untested.
Review branch:
https://git.morello-project.org/tudcre01/linux/-/commits/io_uring_v1
Tudor Cretu (4):
compiler_types: Add (u)intcap_t to native_words
arm64: mm: Add VM_READ_CAPS and VM_WRITE_CAPS flags
io_uring: Implement compat versions of uAPI structs and handle them
io_uring: Use user pointer type in the uAPI structs
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/mman.h | 6 +
fs/io_uring.c | 734 ++++++++++++++++++++++++++-------
fs/proc/task_mmu.c | 4 +
include/linux/compiler_types.h | 7 +
include/linux/mm.h | 10 +
include/uapi/linux/io_uring.h | 32 +-
7 files changed, 623 insertions(+), 171 deletions(-)
--
2.25.1
