[tip: perf/urgent] perf: Revert to requiring CAP_SYS_ADMIN for uprobes

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     ba677dbe77af5ffe6204e0f3f547f3ba059c6302
Gitweb:        https://git.kernel.org/tip/ba677dbe77af5ffe6204e0f3f547f3ba059c6302
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Wed, 02 Jul 2025 18:21:44 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 03 Jul 2025 10:33:55 +02:00

perf: Revert to requiring CAP_SYS_ADMIN for uprobes

Jann reports that uprobes can be used destructively when used in the
middle of an instruction. The kernel only verifies there is a valid
instruction at the requested offset, but due to variable instruction
length cannot determine if this is an instruction as seen by the
intended execution stream.

Additionally, Mark Rutland notes that on architectures that mix data
in the text segment (like arm64), a similar things can be done if the
data word is 'mistaken' for an instruction.

As such, require CAP_SYS_ADMIN for uprobes.

Fixes: c9e0924e5c2b ("perf/core: open access to probes for CAP_PERFMON privileged process")
Reported-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/CAG48ez1n4520sq0XrWYDHKiKxE_+WCfAK+qt9qkY4ZiBGmL-5g@xxxxxxxxxxxxxx
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index bf2118c..0db36b2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11116,7 +11116,7 @@ static int perf_uprobe_event_init(struct perf_event *event)
 	if (event->attr.type != perf_uprobe.type)
 		return -ENOENT;
 
-	if (!perfmon_capable())
+	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
 	/*